Hereditary Transthyretin Amyloidosis in Eight Chinese Families.

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Hereditary Transthyretin Amyloidosis in Eight Chinese Families.

Chin Med J (Engl). 2015 Nov;128(21):2902-5

Authors: Meng LC, Lyu H, Zhang W, Liu J, Wang ZX, Yuan Y

Abstract
BACKGROUND: Mutations of transthyretin (TTR) cause the most common type of autosomal-dominant hereditary systemic amyloidosis, which occurs worldwide. To date, more and more mutations in the TTR gene have been reported. Some variations in the clinical presentation are often observed in patients with the same mutation or the patients in the same family. The purpose of this study was to find out the clinicopathologic and genetic features of Chinese patients with hereditary TTR amyloidosis.
METHODS: Clinical and necessary examination materials were collected from nine patients of eight families with hereditary TTR amyloidosis at Peking University First Hospital from January 2007 to November 2014. Sural nerve biopsies were taken for eight patients and skin biopsies were taken in the calf/upper arm for two patients, for light and electron microscopy examination. The TTR genes from the nine patients were analyzed.
RESULTS: The onset age varied from 23 to 68 years. The main manifestations were paresthesia, proximal and/or distal weakness, autonomic dysfunction, cardiomyopathy, vitreous opacity, hearing loss, and glossohypertrophia. Nerve biopsy demonstrated severe loss of myelinated fibers in seven cases and amyloid deposits in three. One patient had skin amyloid deposits which were revealed from electron microscopic examination. Genetic analysis showed six kinds of mutations of TTR gene, including Val30Met, Phe33Leu, Ala36Pro, Val30Ala, Phe33Val, and Glu42Gly in exon 2.
CONCLUSIONS: Since the pathological examinations of sural nerve were negative for amyloid deposition in most patients, the screening for TTR mutations should be performed in all the adult patients, who are clinically suspected with hereditary TTR amyloidosis.

PMID: 26521788 [PubMed - in process]

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GeneReviews(®)

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GeneReviews(®)

Book. 1993

Authors: Pagon RA, Adam MP, Ardinger HH, Wallace SE, Amemiya A, Bean LJH, Bird TD, Fong CT, Mefford HC, Smith RJH, Stephens K

Abstract
CLINICAL CHARACTERISTICS: CLCN2-related leukoencephalopathy (CC2L) is characterized by nonspecific neurologic findings, mild visual impairment from chorioretinopathy or optic atrophy, male infertility, and characteristic findings on brain MRI. Neurologic findings include mild ataxia (action tremor and gait instability following initially normal motor development; occasionally mild spasticity), learning disabilities in some (ranging from mild to severe cognitive impairment), and headaches in some (usually intermittent, severe, and diffuse). Affected individuals remain ambulatory and do not require support for walking, and none has become blind. To date CC2L has been reported or identified in 16 individuals from 15 families. It is not yet known if the findings occurring in single individuals (i.e., vertigo, tinnitus, and progressive hearing loss; psychiatric symptoms; and paroxysmal kinesigenic dyskinesia) are part of the phenotypic spectrum or unrelated findings.
DIAGNOSIS/TESTING: The diagnosis of CC2L is established in a proband by identification of biallelic pathogenic variants in CLCN2 on molecular genetic testing.
MANAGEMENT: Treatment of manifestations: Supportive care including physical therapy and rehabilitation to improve motor function, special education as needed, treatment of headache, guidance for visual impairment. Surveillance: Annual: neurologic examination, ophthalmologic examination, and audiologic assessment Evaluation of relatives at risk: Presymptomatic diagnosis and treatment is warranted in older and younger sibs of a proband to identify those who would benefit from early diagnosis and routine surveillance for motor, cognitive, vision, and hearing impairment.
GENETIC COUNSELING: CC2L is inherited in an autosomal recessive manner. At conception, each sib of an affected individual has a 25% chance of being affected, a 50% chance of being an asymptomatic carrier, and a 25% chance of being unaffected and not a carrier. Carrier testing for at-risk family members and prenatal testing for pregnancies at increased risk are possible when the CLCN2 pathogenic variants in the family are known.

PMID: 26539602

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Tinnitus Pro

Auditory therapy is one of the more increasingly popular forms of treatment for tinnitus. Tinnitus, which is more commonly termed as ringing of the ears, may also be indicated by a patient hearing other sounds that are not generated in the external environment. If you have tinnitus, you may hear chirping, buzzing, swishing, static or other sounds, and these sounds may come and go or be constant. If you have been diagnosed with tinnitus, you may take a closer look at some of the different auditory therapy solutions on the market that are designed to reduce the severity and frequency of your symptoms.

A Popular Option for Treating Tinnitus
Tinnitus Pro is a popular type of auditory therapy that is designed to be easy to use and to produce effective results. You simply download the app from the Apple iTunes store. The app will search which octaves you have trouble hearing, and it will incorporate tonal therapy into your favorite types of music. Then, you simply listen to your favorite songs through the app on a regular basis, and you will receive auditory therapy while doing so.

A Better Alternative
While Tinnitus Pro is one option available, it may not be the best option. AudioNotch, for example, is designed to work on multiple platforms, so it is suitable for more people to use as an effective treatment for tinnitus. It can be used on a PC, an iPhone and android phones. In addition, it has Notched Natural Sounds for you to choose from, and this is not an option with Tinnitus Pro. This gives you a better overall experience because it enhances the variety of sounds you can listen to. After all, you may not always want to listen to the same type of music every day, or you may enjoy the zen-like experience of nature sounds earlier in the morning or later in the day.

Tinnitus can take a major toll on your life, impacting your ability to work, sleep and have personal relationships with friends and family members. Some people find that their lives are so altered by it that they develop depression or other conditions. If you are suffering from tinnitus, consider trying AudioNotch as a form of auditory therapy. You may be pleasantly surprised to discover that this is a convenient and effective way to improve your symptoms and to take control of your condition.

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Effects of Intralabyrinthine Hemorrhage on the Cochlear Elements: A Human Temporal Bone Study.

Hypothesis: To compare histopathologic findings in the cochlea of human temporal bones with versus without intralabyrinthine hemorrhage. Background: Hemorrhagic labyrinthitis can cause sensorineural damage, sudden hearing loss, and vertigo. Yet, to our knowledge, no studies have quantitatively described histopathologic effects of intralabyrinthine hemorrhage on the elements of the cochlea. Methods: We analyzed 46 human temporal bone samples from 23 patients with unilateral intralabyrinthine hemorrhage (23 samples from ears with intralabyrinthine hemorrhage and 23 samples from contralateral ears without). We noted the location of hemorrhage in the inner ear, the degree of endolymphatic hydrops, the number of spiral ganglion cells and hair cells, mean loss of fibrocytes in spiral ligament, and areas of the stria vascularis and spiral ligament. Results: Intralabyrinthine hemorrhage caused significant loss of outer hair cells in the lower basal (p = 0.001), upper basal (p = 0.005), and lower middle (p = 0.012) cochlear turns. The degree of endolymphatic hydrops was significantly different between the hemorrhagic and contralateral sides (p = 0.011). But we found no significant difference between the 2 sides in the number of inner hair cells, spiral ganglion cells, and fibrocytes, or in the areas of the stria vascularis and spiral ligament between the two groups (p > 0.05). Conclusion: These findings suggest that such patients could be good candidates for hearing aid or cochlear implant if they have profound sensorineural hearing loss. Copyright (C) 2015 by Otology & Neurotology, Inc. Image copyright (C) 2010 Wolters Kluwer Health/Anatomical Chart Company

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Transcanal Micro-Osteotome Only Technique for Excision of Exostoses.

Objectives: To evaluate the outcomes and complications of transcanal excision of exostoses using micro-osteotomes, without a postauricular incision or the use of the drill. Study Design: A retrospective chart review of patients undergoing exostoses excision. Setting: Tertiary Care Medical Center. Subjects and Methods: All of the patients underwent surgical removal of the exostoses using only a 1 or 2 mm micro-osteotomes. Patients were followed postoperatively and associated complications were evaluated. Results: One-hundred thirty-eight ears in 106 patients were treated for obstructive exostosis. The average age of patients was 43 +/- 16 years. Of these, 99 were man (93%) and 7 were woman (7%). A majority of the patients (84%, n = 89) had 90 to 100% obstruction of the ear canal. Complete ear canal healing was observed in 80% of patients by 3 weeks. All but one patient had healed by 6 weeks postoperatively. There were 9 (6.5%) slit tympanic membrane perforations that healed with intraoperative gelfoam or fascia myringoplasty. One patient had an anterior canal mobilization which required Xeroform packing for 3 weeks for stabilization. There were no postoperative vertigo, facial paresis, conductive/sensorineural hearing loss, soft tissue stenoses, and no skin grafting required. Conclusions: This is the first study to report a series of patients performing solely a transcanal approach using micro-osteotomes for removing exostoses. Results indicate that it is a safe procedure with low complication rate and expeditious healing. Patients with 100% obstruction can have this procedure performed with no significant increase in morbidity. Copyright (C) 2015 by Otology & Neurotology, Inc. Image copyright (C) 2010 Wolters Kluwer Health/Anatomical Chart Company

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Deeper Cochlear Implant Electrode Insertion Angle Improves Detection of Musical Sound Quality Deterioration Related to Bass Frequency Removal.

Background: Cochlear implant (CI) electrode arrays typically do not reach the most apical regions of the cochlea that intrinsically encode low frequencies. This may contribute to diminished implant-mediated musical sound quality perception. The objective of this study was to assess the effect of varying degrees of apical cochlear stimulation (measured by angular insertion depth) on musical sound quality discrimination. Hypothesis: Increased apical cochlear stimulation will improve low-frequency perception and musical sound quality discrimination. Methods: Standard (31.5 mm, n = 17) and medium (24 mm, n = 8) array Med-EL CI users, and normal hearing (NH) listeners (n = 16) participated. Imaging confirmed angular insertion depth. Participants completed a musical discrimination task in which they listened to a real-world musical stimulus (labeled reference) and provided sound quality ratings to versions of the reference, which included a hidden reference and test stimuli with increasing amounts of low-frequency removal. Scores for each CI users were calculated on the basis of how much their ratings differed from NH listeners for each stimulus version. Results: Medium array and standard users had significantly different insertion depths (389.4+/-64.5 and 583.9 +/- 78.5 degrees, respectively; p

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Angioleiomyoma of the External Auditory Canal.

No abstract available

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Auditory event-related potentials to words: Implications for audiologists.

Auditory event-related potentials to words: Implications for audiologists.

Int J Audiol. 2015 Sep;54(9):642-643

Authors: Golob EJ

PMID: 26653105 [PubMed - as supplied by publisher]

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Auditory event-related potentials to words: Implications for audiologists.

Auditory event-related potentials to words: Implications for audiologists.

Int J Audiol. 2015 Sep;54(9):642-643

Authors: Golob EJ

PMID: 26653105 [PubMed - as supplied by publisher]

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Geriatric Audiology, second edition.

Geriatric Audiology, second edition.

Int J Audiol. 2015 Jun;54(6):433

Authors: Dawes P

PMID: 26652927 [PubMed - as supplied by publisher]

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Geriatric Audiology, second edition.

Geriatric Audiology, second edition.

Int J Audiol. 2015 Jun;54(6):433

Authors: Dawes P

PMID: 26652927 [PubMed - as supplied by publisher]

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Hearing: Anatomy, Physiology, and Disorders of the Auditory System (3rd ed.).

Hearing: Anatomy, Physiology, and Disorders of the Auditory System (3rd ed.).

Int J Audiol. 2015 Mar;54(3):210

Authors: Atcherson SR

PMID: 26652760 [PubMed - as supplied by publisher]

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Hearing: Anatomy, Physiology, and Disorders of the Auditory System (3rd ed.).

Hearing: Anatomy, Physiology, and Disorders of the Auditory System (3rd ed.).

Int J Audiol. 2015 Mar;54(3):210

Authors: Atcherson SR

PMID: 26652760 [PubMed - as supplied by publisher]

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Noise exposure and oxidative balance in auditory and extra-auditory structures in adult and developing animals. Pharmacological approaches aimed to minimize its effects.

Noise exposure and oxidative balance in auditory and extra-auditory structures in adult and developing animals. Pharmacological approaches aimed to minimize its effects.

Pharmacol Res. 2015 Dec 3;

Authors: Molina SJ, Miceli M, Guelman LR

Abstract
Noise coming from urban traffic, household appliances or discotheques might be as hazardous to the health of exposed people as occupational noise, because may likewise cause hearing loss, changes in hormonal, cardiovascular and immune systems and behavioral alterations. Besides, noise can affect sleep, work performance and productivity as well as communication skills. Moreover, exposure to noise can trigger an oxidative imbalance between reactive oxygen species (ROS) and the activity of antioxidant enzymes in different structures, which can contribute to tissue damage. In this review we systematized the information from reports concerning noise effects on cell oxidative balance in different tissues, focusing on auditory and non-auditory structures. We paid specific attention to in vivo studies, including results obtained in adult and developing subjects. Finally, we discussed the pharmacological strategies tested by different authors aimed to minimize the damaging effects of noise on living beings.

PMID: 26657417 [PubMed - as supplied by publisher]

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Electrogenic transport and K(+) ion channel expression by the human endolymphatic sac epithelium.

Electrogenic transport and K(+) ion channel expression by the human endolymphatic sac epithelium.

Sci Rep. 2015;5:18110

Authors: Kim SH, Kim BG, Kim JY, Roh KJ, Suh MJ, Jung J, Moon IS, Moon SK, Choi JY

Abstract
The endolymphatic sac (ES) is a cystic organ that is a part of the inner ear and is connected to the cochlea and vestibule. The ES is thought to be involved in inner ear ion homeostasis and fluid volume regulation for the maintenance of hearing and balance function. Many ion channels, transporters, and exchangers have been identified in the ES luminal epithelium, mainly in animal studies, but there has been no functional study investigating ion transport using human ES tissue. We designed the first functional experiments on electrogenic transport in human ES and investigated the contribution of K(+) channels in the electrogenic transport, which has been rarely identified, even in animal studies, using electrophysiological/pharmacological and molecular biological methods. As a result, we identified functional and molecular evidence for the essential participation of K(+) channels in the electrogenic transport of human ES epithelium. The identified K(+) channels involved in the electrogenic transport were KCNN2, KCNJ14, KCNK2, and KCNK6, and the K(+) transports via those channels are thought to play an important role in the maintenance of the unique ionic milieu of the inner ear fluid.

PMID: 26655723 [PubMed - as supplied by publisher]

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Hearing Loss After Vestibular Implantation in Sand Rats With Normal Hearing.

Related Articles

Hearing Loss After Vestibular Implantation in Sand Rats With Normal Hearing.

JAMA Otolaryngol Head Neck Surg. 2015 Sep;141(9):840-4

Authors: Mizrachi A, Hilly O, Raveh E, Attias J, Nageris BI

Abstract
IMPORTANCE: Bilateral vestibular failure is a debilitating condition that may lead to oscillopia and adversely affect quality of life. Researchers have suggested that vestibular function might be restored with implantation of an external mechanical stimulation device. However, it is essential that such a device must not interfere with normal hearing.
OBJECTIVE: To evaluate the effect of vestibular implant insertion on hearing in a sand rat model with normal hearing.
DESIGN, SETTING, AND SUBJECTS: The study was conducted in a tertiary medical center in accord with the guidelines of the Rabin Medical Center Animal Care and Use Committee. The experiment was performed in 6 adult, 6-month-old, fat sand rats (Psammomys obesus), which have a unique aural anatomy that permits access to the inner ear. The study dates were March 2013 to March 2014.
INTERVENTIONS: The sand rats were anesthetized and electrodes were implanted unilaterally (in 6 sand rats) or bilaterally (in 2 sand rats) in all 3 semicircular canals (lateral, then posterior, and then superior) by fenestration of the respective ampullas. To measure air and bone conduction thresholds, auditory nerve brainstem evoked responses to alternating polarity clicks and 1-kHz tone bursts were tested before surgery, at each operative stage, and after surgery.
MAIN OUTCOMES AND MEASURES: Air or bone conduction threshold shifts after implantation of a vestibular implant electrode array in each semicircular canal.
RESULTS: After unilateral implantation of the vestibular implant, sand rats showed a sideways head tilt, whereas after bilateral implantation, sand rats ran around in circles and were unable to stand still or walk on a treadmill. On statistical analysis, statistically significant differences from preoperative values were obtained across all stages of surgery for air conduction thresholds. The largest and statistically significant air conduction shift for 1-kHz stimuli (mean [SD, 13.7 [2.8] dB; P < .004) as well as for clicks (12.5 [2.1] dB; P < .002) was found for the superior canal electrode insertion. For the posterior canal, the air conduction thresholds to 1-kHz stimuli and to clicks shifted significantly after electrode insertion (mean [SD], 7.5 [2.3] dB; P < .01 and 7.5 [0.9] dB; P < .001). For the lateral canal, only the threshold to clicks changed significantly (mean [SD], 5.5 [1.7] dB; P < .02). Bone conduction thresholds did not change significantly after vestibular electrode insertion.
CONCLUSIONS AND RELEVANCE: Implantation of a vestibular device is associated with mild to moderate conductive hearing loss in fat sand rats with normal hearing, especially when the device is placed in the posterior and superior semicircular canals. Bilateral implantation is associated with major vestibular pathologic results. Further studies are needed in animals with cochlear or vestibular disorders before it can be definitively concluded that vestibular implantation carries only a minor risk to hearing.

PMID: 26225636 [PubMed - indexed for MEDLINE]

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Aural localization of silent objects by active human biosonar: neural representations of virtual echo-acoustic space.

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Aural localization of silent objects by active human biosonar: neural representations of virtual echo-acoustic space.

Eur J Neurosci. 2015 Mar;41(5):533-45

Authors: Wallmeier L, Kish D, Wiegrebe L, Flanagin VL

Abstract
Some blind humans have developed the remarkable ability to detect and localize objects through the auditory analysis of self-generated tongue clicks. These echolocation experts show a corresponding increase in 'visual' cortex activity when listening to echo-acoustic sounds. Echolocation in real-life settings involves multiple reflections as well as active sound production, neither of which has been systematically addressed. We developed a virtualization technique that allows participants to actively perform such biosonar tasks in virtual echo-acoustic space during magnetic resonance imaging (MRI). Tongue clicks, emitted in the MRI scanner, are picked up by a microphone, convolved in real time with the binaural impulse responses of a virtual space, and presented via headphones as virtual echoes. In this manner, we investigated the brain activity during active echo-acoustic localization tasks. Our data show that, in blind echolocation experts, activations in the calcarine cortex are dramatically enhanced when a single reflector is introduced into otherwise anechoic virtual space. A pattern-classification analysis revealed that, in the blind, calcarine cortex activation patterns could discriminate left-side from right-side reflectors. This was found in both blind experts, but the effect was significant for only one of them. In sighted controls, 'visual' cortex activations were insignificant, but activation patterns in the planum temporale were sufficient to discriminate left-side from right-side reflectors. Our data suggest that blind and echolocation-trained, sighted subjects may recruit different neural substrates for the same active-echolocation task.

PMID: 25728174 [PubMed - indexed for MEDLINE]

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Endolymphatic sac tumors.

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Endolymphatic sac tumors.

Otolaryngol Clin North Am. 2015 Apr;48(2):317-30

Authors: Wick CC, Manzoor NF, Semaan MT, Megerian CA

Abstract
Endolymphatic sac tumors (ELST) are slow-growing, locally aggressive, low-grade malignancies that originate from the epithelium of the endolymphatic duct and sac. ELST often present with sensorineural hearing loss, tinnitus, and vertigo, which may mimic Meniere disease. Large tumors may present with additional cranial neuropathies. Management is primarily via microsurgical excision. Radiation therapy has a limited role for residual or unresectable disease. Early detection may enable hearing preservation techniques. ELST have an association with von Hippel-Lindau disease.

PMID: 25650230 [PubMed - indexed for MEDLINE]

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Neuroprotective effects of cutamesine, a ligand of the sigma-1 receptor chaperone, against noise-induced hearing loss.

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Neuroprotective effects of cutamesine, a ligand of the sigma-1 receptor chaperone, against noise-induced hearing loss.

J Neurosci Res. 2015 May;93(5):788-95

Authors: Yamashita D, Sun GW, Cui Y, Mita S, Otsuki N, Kanzaki S, Nibu K, Ogawa K, Matsunaga T

Abstract
The sigma-1 receptor, which is expressed throughout the brain, provides physiological benefits that include higher brain function. The sigma-1 receptor functions as a chaperone in the endoplasmic reticulum and may control cell death and regeneration within the central nervous system. Cutamesine (1-(3,4-dimethoxyphenethyl)-4-(3-phenylpropyl) piperazine dihydrochloride) is a ligand selective for this receptor and may mediate neuroprotective effects in the context of neurodegenerative disease. We therefore assessed whether cutamesine protects the inner ear from noise-induced or aging-associated hearing loss. Immunohistochemistry and Western blotting revealed that the sigma-1 receptor is present in adult cochlea. We treated mice with 0, 3, or 30 mg/kg cutamesine from 10 days before noise exposure until the end of the study. All subjects were exposed to a 120-dB, 4-kHz octave-band noise for 2 hr. We assessed auditory thresholds by measuring the auditory-evoked brainstem responses at 4, 8, and 16 kHz, prior to and 1 week, 1 month, or 3 months following noise exposure. For the aging study, measurements were made before treatment was initiated and after 3 or 9 months of cutamesine treatment. Damage to fibrocytes within the cochlear spiral limbus was assessed by quantitative histology. Cutamesine significantly reduced threshold shifts and cell death within the spiral limbus in response to intense noise. These effects were not dose or time dependent. Conversely, cutamesine did not prevent aging-associated hearing loss. These results suggest that cutamesine reduces noise-induced hearing loss and cochlear damage during the acute phase that follows exposure to an intense noise.

PMID: 25612541 [PubMed - indexed for MEDLINE]

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Three week loading for the Baha BI-300® implant system.

Related Articles

Three week loading for the Baha BI-300® implant system.

Am J Otolaryngol. 2015 Mar-Apr;36(2):195-9

Authors: Wazen JJ, Daugherty J, Darley S, Wycherly B

Abstract
PURPOSE: The timing of loading of titanium craniofacial implants is dependent upon implant characteristics, host factors, and the bonding of titanium oxide and bone referred to as osseointegration. The purpose of this feasibility study seeks to determine the safety of early loading of the Baha BI-300 implant system (Cochlear Limited, Englewood, CO), which has been modified with novel surface texture and geometric design.
SUBJECTS AND METHODS: This prospective study measures implant stability as determined by clinical evaluation and resonance frequency analysis at implantation and at 1, 3, 6, 12, 24 and 52weeks post-op in 20 patients who underwent single-stage implantation and exteriorization of the BI-300. The processor was loaded at 3weeks post-operatively. A modified Holger's classification system was used to evaluate skin reactions.
RESULTS: There was a positive linear trend in mean implant stability scores from implantation to 52weeks. Only one subject (5%) had a mild local soft tissue Holger's grade 1 score at 24weeks. No implant loss or postoperative complications were encountered as a result of the 3-week loading.
CONCLUSION: Three-week loading of the BI-300 implant did not result in any implant loss or failure of osseointegration. Earlier activation of the external processor with earlier hearing rehabilitation resulted in improved patient satisfaction. Further studies are needed to confirm these results for more universal adoption of early loading in adults.

PMID: 25465654 [PubMed - indexed for MEDLINE]

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Expression of metalloproteinases 2 and 9 and tissue inhibitors 1 and 2 as predictors of lymph node metastases in oropharyngeal squamous cell carcinoma.

Related Articles

Expression of metalloproteinases 2 and 9 and tissue inhibitors 1 and 2 as predictors of lymph node metastases in oropharyngeal squamous cell carcinoma.

Head Neck. 2015 Mar;37(3):418-22

Authors: Burduk PK, Bodnar M, Sawicki P, Szylberg Ł, Wiśniewska E, Kaźmierczak W, Martyńska M, Marszałek A

Abstract
BACKGROUND: The matrix metalloproteinases (MMPs) and their tissue inhibitor of metalloproteinases (TIMPs) can decompose extracellular matrix (ECM) components and brake down basement membranes and, thus, promote tumor local invasion and metastasis.
METHODS: We studied 41 patients with squamous cell carcinoma (SCC) of the oropharynx who underwent surgical treatment. Material was diagnosed by routine procedure and examined by immunohistochemical analysis and dot blot technique. We searched for correlations between expressions of MMPs, such as MMP-2 and MMP-9 and their tissue inhibitors TIMP-1 and TIMP-2 and treatment outcome.
RESULTS: We found cytoplasmic expression of analyzed proteins, both in cancer cells and tumor stroma. The expression of analyzed antigens was higher in patients with lymph node metastases comparing patients without lymph node involvement.
CONCLUSION: Our data suggest that microenvironment changes are one of key factors in tumor progression. Divergent expression of MMPs and their inhibitors might be used as prognostic factor of oropharyngeal carcinoma progression.

PMID: 24436008 [PubMed - indexed for MEDLINE]

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Noise exposure and oxidative balance in auditory and extra-auditory structures in adult and developing animals. Pharmacological approaches aimed to minimize its effects.

Noise exposure and oxidative balance in auditory and extra-auditory structures in adult and developing animals. Pharmacological approaches aimed to minimize its effects.

Pharmacol Res. 2015 Dec 3;

Authors: Molina SJ, Miceli M, Guelman LR

Abstract
Noise coming from urban traffic, household appliances or discotheques might be as hazardous to the health of exposed people as occupational noise, because may likewise cause hearing loss, changes in hormonal, cardiovascular and immune systems and behavioral alterations. Besides, noise can affect sleep, work performance and productivity as well as communication skills. Moreover, exposure to noise can trigger an oxidative imbalance between reactive oxygen species (ROS) and the activity of antioxidant enzymes in different structures, which can contribute to tissue damage. In this review we systematized the information from reports concerning noise effects on cell oxidative balance in different tissues, focusing on auditory and non-auditory structures. We paid specific attention to in vivo studies, including results obtained in adult and developing subjects. Finally, we discussed the pharmacological strategies tested by different authors aimed to minimize the damaging effects of noise on living beings.

PMID: 26657417 [PubMed - as supplied by publisher]

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Electrogenic transport and K(+) ion channel expression by the human endolymphatic sac epithelium.

Electrogenic transport and K(+) ion channel expression by the human endolymphatic sac epithelium.

Sci Rep. 2015;5:18110

Authors: Kim SH, Kim BG, Kim JY, Roh KJ, Suh MJ, Jung J, Moon IS, Moon SK, Choi JY

Abstract
The endolymphatic sac (ES) is a cystic organ that is a part of the inner ear and is connected to the cochlea and vestibule. The ES is thought to be involved in inner ear ion homeostasis and fluid volume regulation for the maintenance of hearing and balance function. Many ion channels, transporters, and exchangers have been identified in the ES luminal epithelium, mainly in animal studies, but there has been no functional study investigating ion transport using human ES tissue. We designed the first functional experiments on electrogenic transport in human ES and investigated the contribution of K(+) channels in the electrogenic transport, which has been rarely identified, even in animal studies, using electrophysiological/pharmacological and molecular biological methods. As a result, we identified functional and molecular evidence for the essential participation of K(+) channels in the electrogenic transport of human ES epithelium. The identified K(+) channels involved in the electrogenic transport were KCNN2, KCNJ14, KCNK2, and KCNK6, and the K(+) transports via those channels are thought to play an important role in the maintenance of the unique ionic milieu of the inner ear fluid.

PMID: 26655723 [PubMed - as supplied by publisher]

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Hearing Loss After Vestibular Implantation in Sand Rats With Normal Hearing.

Related Articles

Hearing Loss After Vestibular Implantation in Sand Rats With Normal Hearing.

JAMA Otolaryngol Head Neck Surg. 2015 Sep;141(9):840-4

Authors: Mizrachi A, Hilly O, Raveh E, Attias J, Nageris BI

Abstract
IMPORTANCE: Bilateral vestibular failure is a debilitating condition that may lead to oscillopia and adversely affect quality of life. Researchers have suggested that vestibular function might be restored with implantation of an external mechanical stimulation device. However, it is essential that such a device must not interfere with normal hearing.
OBJECTIVE: To evaluate the effect of vestibular implant insertion on hearing in a sand rat model with normal hearing.
DESIGN, SETTING, AND SUBJECTS: The study was conducted in a tertiary medical center in accord with the guidelines of the Rabin Medical Center Animal Care and Use Committee. The experiment was performed in 6 adult, 6-month-old, fat sand rats (Psammomys obesus), which have a unique aural anatomy that permits access to the inner ear. The study dates were March 2013 to March 2014.
INTERVENTIONS: The sand rats were anesthetized and electrodes were implanted unilaterally (in 6 sand rats) or bilaterally (in 2 sand rats) in all 3 semicircular canals (lateral, then posterior, and then superior) by fenestration of the respective ampullas. To measure air and bone conduction thresholds, auditory nerve brainstem evoked responses to alternating polarity clicks and 1-kHz tone bursts were tested before surgery, at each operative stage, and after surgery.
MAIN OUTCOMES AND MEASURES: Air or bone conduction threshold shifts after implantation of a vestibular implant electrode array in each semicircular canal.
RESULTS: After unilateral implantation of the vestibular implant, sand rats showed a sideways head tilt, whereas after bilateral implantation, sand rats ran around in circles and were unable to stand still or walk on a treadmill. On statistical analysis, statistically significant differences from preoperative values were obtained across all stages of surgery for air conduction thresholds. The largest and statistically significant air conduction shift for 1-kHz stimuli (mean [SD, 13.7 [2.8] dB; P < .004) as well as for clicks (12.5 [2.1] dB; P < .002) was found for the superior canal electrode insertion. For the posterior canal, the air conduction thresholds to 1-kHz stimuli and to clicks shifted significantly after electrode insertion (mean [SD], 7.5 [2.3] dB; P < .01 and 7.5 [0.9] dB; P < .001). For the lateral canal, only the threshold to clicks changed significantly (mean [SD], 5.5 [1.7] dB; P < .02). Bone conduction thresholds did not change significantly after vestibular electrode insertion.
CONCLUSIONS AND RELEVANCE: Implantation of a vestibular device is associated with mild to moderate conductive hearing loss in fat sand rats with normal hearing, especially when the device is placed in the posterior and superior semicircular canals. Bilateral implantation is associated with major vestibular pathologic results. Further studies are needed in animals with cochlear or vestibular disorders before it can be definitively concluded that vestibular implantation carries only a minor risk to hearing.

PMID: 26225636 [PubMed - indexed for MEDLINE]

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Aural localization of silent objects by active human biosonar: neural representations of virtual echo-acoustic space.

Related Articles

Aural localization of silent objects by active human biosonar: neural representations of virtual echo-acoustic space.

Eur J Neurosci. 2015 Mar;41(5):533-45

Authors: Wallmeier L, Kish D, Wiegrebe L, Flanagin VL

Abstract
Some blind humans have developed the remarkable ability to detect and localize objects through the auditory analysis of self-generated tongue clicks. These echolocation experts show a corresponding increase in 'visual' cortex activity when listening to echo-acoustic sounds. Echolocation in real-life settings involves multiple reflections as well as active sound production, neither of which has been systematically addressed. We developed a virtualization technique that allows participants to actively perform such biosonar tasks in virtual echo-acoustic space during magnetic resonance imaging (MRI). Tongue clicks, emitted in the MRI scanner, are picked up by a microphone, convolved in real time with the binaural impulse responses of a virtual space, and presented via headphones as virtual echoes. In this manner, we investigated the brain activity during active echo-acoustic localization tasks. Our data show that, in blind echolocation experts, activations in the calcarine cortex are dramatically enhanced when a single reflector is introduced into otherwise anechoic virtual space. A pattern-classification analysis revealed that, in the blind, calcarine cortex activation patterns could discriminate left-side from right-side reflectors. This was found in both blind experts, but the effect was significant for only one of them. In sighted controls, 'visual' cortex activations were insignificant, but activation patterns in the planum temporale were sufficient to discriminate left-side from right-side reflectors. Our data suggest that blind and echolocation-trained, sighted subjects may recruit different neural substrates for the same active-echolocation task.

PMID: 25728174 [PubMed - indexed for MEDLINE]

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Endolymphatic sac tumors.

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Endolymphatic sac tumors.

Otolaryngol Clin North Am. 2015 Apr;48(2):317-30

Authors: Wick CC, Manzoor NF, Semaan MT, Megerian CA

Abstract
Endolymphatic sac tumors (ELST) are slow-growing, locally aggressive, low-grade malignancies that originate from the epithelium of the endolymphatic duct and sac. ELST often present with sensorineural hearing loss, tinnitus, and vertigo, which may mimic Meniere disease. Large tumors may present with additional cranial neuropathies. Management is primarily via microsurgical excision. Radiation therapy has a limited role for residual or unresectable disease. Early detection may enable hearing preservation techniques. ELST have an association with von Hippel-Lindau disease.

PMID: 25650230 [PubMed - indexed for MEDLINE]

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Neuroprotective effects of cutamesine, a ligand of the sigma-1 receptor chaperone, against noise-induced hearing loss.

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Neuroprotective effects of cutamesine, a ligand of the sigma-1 receptor chaperone, against noise-induced hearing loss.

J Neurosci Res. 2015 May;93(5):788-95

Authors: Yamashita D, Sun GW, Cui Y, Mita S, Otsuki N, Kanzaki S, Nibu K, Ogawa K, Matsunaga T

Abstract
The sigma-1 receptor, which is expressed throughout the brain, provides physiological benefits that include higher brain function. The sigma-1 receptor functions as a chaperone in the endoplasmic reticulum and may control cell death and regeneration within the central nervous system. Cutamesine (1-(3,4-dimethoxyphenethyl)-4-(3-phenylpropyl) piperazine dihydrochloride) is a ligand selective for this receptor and may mediate neuroprotective effects in the context of neurodegenerative disease. We therefore assessed whether cutamesine protects the inner ear from noise-induced or aging-associated hearing loss. Immunohistochemistry and Western blotting revealed that the sigma-1 receptor is present in adult cochlea. We treated mice with 0, 3, or 30 mg/kg cutamesine from 10 days before noise exposure until the end of the study. All subjects were exposed to a 120-dB, 4-kHz octave-band noise for 2 hr. We assessed auditory thresholds by measuring the auditory-evoked brainstem responses at 4, 8, and 16 kHz, prior to and 1 week, 1 month, or 3 months following noise exposure. For the aging study, measurements were made before treatment was initiated and after 3 or 9 months of cutamesine treatment. Damage to fibrocytes within the cochlear spiral limbus was assessed by quantitative histology. Cutamesine significantly reduced threshold shifts and cell death within the spiral limbus in response to intense noise. These effects were not dose or time dependent. Conversely, cutamesine did not prevent aging-associated hearing loss. These results suggest that cutamesine reduces noise-induced hearing loss and cochlear damage during the acute phase that follows exposure to an intense noise.

PMID: 25612541 [PubMed - indexed for MEDLINE]

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Three week loading for the Baha BI-300® implant system.

Related Articles

Three week loading for the Baha BI-300® implant system.

Am J Otolaryngol. 2015 Mar-Apr;36(2):195-9

Authors: Wazen JJ, Daugherty J, Darley S, Wycherly B

Abstract
PURPOSE: The timing of loading of titanium craniofacial implants is dependent upon implant characteristics, host factors, and the bonding of titanium oxide and bone referred to as osseointegration. The purpose of this feasibility study seeks to determine the safety of early loading of the Baha BI-300 implant system (Cochlear Limited, Englewood, CO), which has been modified with novel surface texture and geometric design.
SUBJECTS AND METHODS: This prospective study measures implant stability as determined by clinical evaluation and resonance frequency analysis at implantation and at 1, 3, 6, 12, 24 and 52weeks post-op in 20 patients who underwent single-stage implantation and exteriorization of the BI-300. The processor was loaded at 3weeks post-operatively. A modified Holger's classification system was used to evaluate skin reactions.
RESULTS: There was a positive linear trend in mean implant stability scores from implantation to 52weeks. Only one subject (5%) had a mild local soft tissue Holger's grade 1 score at 24weeks. No implant loss or postoperative complications were encountered as a result of the 3-week loading.
CONCLUSION: Three-week loading of the BI-300 implant did not result in any implant loss or failure of osseointegration. Earlier activation of the external processor with earlier hearing rehabilitation resulted in improved patient satisfaction. Further studies are needed to confirm these results for more universal adoption of early loading in adults.

PMID: 25465654 [PubMed - indexed for MEDLINE]

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Expression of metalloproteinases 2 and 9 and tissue inhibitors 1 and 2 as predictors of lymph node metastases in oropharyngeal squamous cell carcinoma.

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Expression of metalloproteinases 2 and 9 and tissue inhibitors 1 and 2 as predictors of lymph node metastases in oropharyngeal squamous cell carcinoma.

Head Neck. 2015 Mar;37(3):418-22

Authors: Burduk PK, Bodnar M, Sawicki P, Szylberg Ł, Wiśniewska E, Kaźmierczak W, Martyńska M, Marszałek A

Abstract
BACKGROUND: The matrix metalloproteinases (MMPs) and their tissue inhibitor of metalloproteinases (TIMPs) can decompose extracellular matrix (ECM) components and brake down basement membranes and, thus, promote tumor local invasion and metastasis.
METHODS: We studied 41 patients with squamous cell carcinoma (SCC) of the oropharynx who underwent surgical treatment. Material was diagnosed by routine procedure and examined by immunohistochemical analysis and dot blot technique. We searched for correlations between expressions of MMPs, such as MMP-2 and MMP-9 and their tissue inhibitors TIMP-1 and TIMP-2 and treatment outcome.
RESULTS: We found cytoplasmic expression of analyzed proteins, both in cancer cells and tumor stroma. The expression of analyzed antigens was higher in patients with lymph node metastases comparing patients without lymph node involvement.
CONCLUSION: Our data suggest that microenvironment changes are one of key factors in tumor progression. Divergent expression of MMPs and their inhibitors might be used as prognostic factor of oropharyngeal carcinoma progression.

PMID: 24436008 [PubMed - indexed for MEDLINE]

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Determination of the mastoid surface area and volume based on micro-CT scanning of human temporal bones. Geometrical parameters depend on scanning resolutions

Publication date: Available online 15 December 2015
Source:Hearing Research
Author(s): Olivier Cros, Hans Knutsson, Mats Andersson, Elin Pawels, Magnus Borga, Michael Gaihede
The mastoid air cell system (MACS) with its large complex of interconnected air cells reflects an enhanced surface area (SA) relative to its volume (V), which may indicate that the MACS is adapted to gas exchange and has a potential role in middle ear pressure regulation. These geometric parameters of the MACS have been studied by high resolution clinical CT scanning. However, the resolution of these scans is limited to a voxel size of around 0.6 mm in all dimensions, and so, the geometrical parameters are also limited. Small air cells may appear below the resolution and cannot be detected. Such air cells may contribute to a much higher SA, and thus, also the SA/V ratio. More accurate parameters are important for analysis of the function of the MACS including physiological modeling.Our aim was to determine the SA, V, and SA/V ratio in the MACS in human temporal bones at highest resolution by using micro-CT-scanning. Further, the influence of the resolution on these parameters was investigated by downsampling the data. Eight normally aerated temporal bones were scanned at the highest possible resolution (30-60 μm). The SA was determined using a triangular mesh fitted onto the segmented MACS. The V was determined by summing all the voxels containing air. Downsampling of the original data was applied four times by a factor of 2.The mean SA was 194 cm², the mean V was 9 cm³, and the mean SA/V amounted to 22 cm^-1 (22 cm²/cm³). Decreasing the resolution resulted in a non-linear decrement of SA and SA/V, whereas V was mainly independent of the resolution.The current study found significantly higher SA and SA/V compared with previous studies using clinical CT scanning at lower resolutions. These findings indicate a role of the MACS different from that of the tympanum, though they are limited to only a smaller sample of temporal bones without knowledge about the disease history of the subjects. The current data on mastoid geometry seems important for a more accurate modeling of the middle ear physiology and future studies may include morphological investigations of the air cells with possible implications for their postnatal development.



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On the connection between the tympanic membrane and the malleus

Publication date: Available online 15 December 2015
Source:Hearing Research
Author(s): Daniel De Greef, Jana Goyens, Isabel Pintelon, John-Paul Bogers, Vincent Van Rompaey, Evert Hamans, Paul Van de Heyning, Joris J.J. Dirckx
BackgroundThe tympano-mallear connection (TMC) is the soft-tissue connection between the tympanic membrane (TM) and the manubrium of the malleus. Some studies suggest that its mechanical properties may have a substantial influence on the mechanics and transfer function of the middle ear. However, relatively little is known about the dimensions of the TMC and its variability among individuals.MethodThirteen samples were collected from human temporal bones, consisting of only the malleus and the TM. They were imaged using μCT without contrast enhancing agent. From the μCT images, the TMC dimensions were measured in both anterior-posterior direction (TMC width) and medial-lateral direction (TMC thickness). Three selected samples were examined using histological microscopy.ResultsBoth TMC width and thickness featured a large variability among individuals. The minimal TMC width along the manubrium for different individuals covered a range between 83 and 840 μm. The minimal thickness ranged from 48 to 249 μm and the maximal thickness from 236 to 691 μm. Histological sections showed that the TMC consists of a narrow core of dense regular connective tissue, surrounded by loose connective tissue. In some samples, either of these two components was absent in the TMC at some manubrium locations. The configuration of these components varied among the samples as well.ConclusionOur data confirm that a large inter-individual variability exists in the properties of the TM-malleus connection in humans in terms of its dimensions, tissue composition and configuration. Average data and their variability margins will be useful input for testing the importance of the TMC in finite element models.



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Pressure buffering by the tympanic membrane. In vivo measurements of middle ear pressure fluctuations during elevator motion

Publication date: Available online 15 December 2015
Source:Hearing Research
Author(s): Simona Padurariu, Daniël de Greef, Henrik Jacobsen, Ernest Nlandu Kamavuako, Joris J. Dirckx, Michael Gaihede
ObjectivesThe tympanic membrane (TM) represents a pressure buffer, which contributes to the overall pressure regulation of the middle ear (ME). This buffer capacity is based on its viscoelastic properties combined with those of the attached ossicular chain, muscles and ligaments. The current work presents a set of in vivo recordings of the ME pressure variations normally occurring in common life: elevator motion. This is defined as a situation of smooth ambient pressure increase or decrease on a limited range and at a low rate of pressure change. Based on these recordings, the purpose was a quantitative analysis of the TM buffer capacity including the TM compliance.MethodsThe pressure changes in seven normal adult MEs with intact TM’s were continuously recorded directly inside the ME cavity during four different elevator trips using a high precision instrument. The TM buffer capacity was determined by the ratio between the changes in ME and the ambient pressure. Further, the ME volumes were calculated by Boyle’s Law from pressure recordings during inflation-deflation tests; subsequently the TM compliance could be also calculated. Finally, the correlation between the ME volume and buffer function was determined.ResultsTwenty-one elevator trips could be used for the analysis. The overall mean TM pressure buffering capacity was 23.3 % (SEM = 3.4), whereas the mean overall compliance was 28.9 × 10^-3 μL/Pa (SEM = 4.8). A strong negative linear correlation was found between the TM buffer capacity and the ME volumes (R² = 0.92).ConclusionsThese results were in fair agreement with the literature obtained in clinical as well as temporal bone experiments, and they provide an in vivo reference for the normal ME function as well as for ME modeling. The TM buffer capacity was found more efficient in smaller mastoids. Possible clinical implications are discussed.



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Determination of the mastoid surface area and volume based on micro-CT scanning of human temporal bones. Geometrical parameters depend on scanning resolutions

Publication date: Available online 15 December 2015
Source:Hearing Research
Author(s): Olivier Cros, Hans Knutsson, Mats Andersson, Elin Pawels, Magnus Borga, Michael Gaihede
The mastoid air cell system (MACS) with its large complex of interconnected air cells reflects an enhanced surface area (SA) relative to its volume (V), which may indicate that the MACS is adapted to gas exchange and has a potential role in middle ear pressure regulation. These geometric parameters of the MACS have been studied by high resolution clinical CT scanning. However, the resolution of these scans is limited to a voxel size of around 0.6 mm in all dimensions, and so, the geometrical parameters are also limited. Small air cells may appear below the resolution and cannot be detected. Such air cells may contribute to a much higher SA, and thus, also the SA/V ratio. More accurate parameters are important for analysis of the function of the MACS including physiological modeling.Our aim was to determine the SA, V, and SA/V ratio in the MACS in human temporal bones at highest resolution by using micro-CT-scanning. Further, the influence of the resolution on these parameters was investigated by downsampling the data. Eight normally aerated temporal bones were scanned at the highest possible resolution (30-60 μm). The SA was determined using a triangular mesh fitted onto the segmented MACS. The V was determined by summing all the voxels containing air. Downsampling of the original data was applied four times by a factor of 2.The mean SA was 194 cm², the mean V was 9 cm³, and the mean SA/V amounted to 22 cm^-1 (22 cm²/cm³). Decreasing the resolution resulted in a non-linear decrement of SA and SA/V, whereas V was mainly independent of the resolution.The current study found significantly higher SA and SA/V compared with previous studies using clinical CT scanning at lower resolutions. These findings indicate a role of the MACS different from that of the tympanum, though they are limited to only a smaller sample of temporal bones without knowledge about the disease history of the subjects. The current data on mastoid geometry seems important for a more accurate modeling of the middle ear physiology and future studies may include morphological investigations of the air cells with possible implications for their postnatal development.



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On the connection between the tympanic membrane and the malleus

Publication date: Available online 15 December 2015
Source:Hearing Research
Author(s): Daniel De Greef, Jana Goyens, Isabel Pintelon, John-Paul Bogers, Vincent Van Rompaey, Evert Hamans, Paul Van de Heyning, Joris J.J. Dirckx
BackgroundThe tympano-mallear connection (TMC) is the soft-tissue connection between the tympanic membrane (TM) and the manubrium of the malleus. Some studies suggest that its mechanical properties may have a substantial influence on the mechanics and transfer function of the middle ear. However, relatively little is known about the dimensions of the TMC and its variability among individuals.MethodThirteen samples were collected from human temporal bones, consisting of only the malleus and the TM. They were imaged using μCT without contrast enhancing agent. From the μCT images, the TMC dimensions were measured in both anterior-posterior direction (TMC width) and medial-lateral direction (TMC thickness). Three selected samples were examined using histological microscopy.ResultsBoth TMC width and thickness featured a large variability among individuals. The minimal TMC width along the manubrium for different individuals covered a range between 83 and 840 μm. The minimal thickness ranged from 48 to 249 μm and the maximal thickness from 236 to 691 μm. Histological sections showed that the TMC consists of a narrow core of dense regular connective tissue, surrounded by loose connective tissue. In some samples, either of these two components was absent in the TMC at some manubrium locations. The configuration of these components varied among the samples as well.ConclusionOur data confirm that a large inter-individual variability exists in the properties of the TM-malleus connection in humans in terms of its dimensions, tissue composition and configuration. Average data and their variability margins will be useful input for testing the importance of the TMC in finite element models.



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Pressure buffering by the tympanic membrane. In vivo measurements of middle ear pressure fluctuations during elevator motion

Publication date: Available online 15 December 2015
Source:Hearing Research
Author(s): Simona Padurariu, Daniël de Greef, Henrik Jacobsen, Ernest Nlandu Kamavuako, Joris J. Dirckx, Michael Gaihede
ObjectivesThe tympanic membrane (TM) represents a pressure buffer, which contributes to the overall pressure regulation of the middle ear (ME). This buffer capacity is based on its viscoelastic properties combined with those of the attached ossicular chain, muscles and ligaments. The current work presents a set of in vivo recordings of the ME pressure variations normally occurring in common life: elevator motion. This is defined as a situation of smooth ambient pressure increase or decrease on a limited range and at a low rate of pressure change. Based on these recordings, the purpose was a quantitative analysis of the TM buffer capacity including the TM compliance.MethodsThe pressure changes in seven normal adult MEs with intact TM’s were continuously recorded directly inside the ME cavity during four different elevator trips using a high precision instrument. The TM buffer capacity was determined by the ratio between the changes in ME and the ambient pressure. Further, the ME volumes were calculated by Boyle’s Law from pressure recordings during inflation-deflation tests; subsequently the TM compliance could be also calculated. Finally, the correlation between the ME volume and buffer function was determined.ResultsTwenty-one elevator trips could be used for the analysis. The overall mean TM pressure buffering capacity was 23.3 % (SEM = 3.4), whereas the mean overall compliance was 28.9 × 10^-3 μL/Pa (SEM = 4.8). A strong negative linear correlation was found between the TM buffer capacity and the ME volumes (R² = 0.92).ConclusionsThese results were in fair agreement with the literature obtained in clinical as well as temporal bone experiments, and they provide an in vivo reference for the normal ME function as well as for ME modeling. The TM buffer capacity was found more efficient in smaller mastoids. Possible clinical implications are discussed.



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Determination of the mastoid surface area and volume based on micro-CT scanning of human temporal bones. Geometrical parameters depend on scanning resolutions

Publication date: Available online 15 December 2015
Source:Hearing Research
Author(s): Olivier Cros, Hans Knutsson, Mats Andersson, Elin Pawels, Magnus Borga, Michael Gaihede
The mastoid air cell system (MACS) with its large complex of interconnected air cells reflects an enhanced surface area (SA) relative to its volume (V), which may indicate that the MACS is adapted to gas exchange and has a potential role in middle ear pressure regulation. These geometric parameters of the MACS have been studied by high resolution clinical CT scanning. However, the resolution of these scans is limited to a voxel size of around 0.6 mm in all dimensions, and so, the geometrical parameters are also limited. Small air cells may appear below the resolution and cannot be detected. Such air cells may contribute to a much higher SA, and thus, also the SA/V ratio. More accurate parameters are important for analysis of the function of the MACS including physiological modeling.Our aim was to determine the SA, V, and SA/V ratio in the MACS in human temporal bones at highest resolution by using micro-CT-scanning. Further, the influence of the resolution on these parameters was investigated by downsampling the data. Eight normally aerated temporal bones were scanned at the highest possible resolution (30-60 μm). The SA was determined using a triangular mesh fitted onto the segmented MACS. The V was determined by summing all the voxels containing air. Downsampling of the original data was applied four times by a factor of 2.The mean SA was 194 cm², the mean V was 9 cm³, and the mean SA/V amounted to 22 cm^-1 (22 cm²/cm³). Decreasing the resolution resulted in a non-linear decrement of SA and SA/V, whereas V was mainly independent of the resolution.The current study found significantly higher SA and SA/V compared with previous studies using clinical CT scanning at lower resolutions. These findings indicate a role of the MACS different from that of the tympanum, though they are limited to only a smaller sample of temporal bones without knowledge about the disease history of the subjects. The current data on mastoid geometry seems important for a more accurate modeling of the middle ear physiology and future studies may include morphological investigations of the air cells with possible implications for their postnatal development.



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On the connection between the tympanic membrane and the malleus

Publication date: Available online 15 December 2015
Source:Hearing Research
Author(s): Daniel De Greef, Jana Goyens, Isabel Pintelon, John-Paul Bogers, Vincent Van Rompaey, Evert Hamans, Paul Van de Heyning, Joris J.J. Dirckx
BackgroundThe tympano-mallear connection (TMC) is the soft-tissue connection between the tympanic membrane (TM) and the manubrium of the malleus. Some studies suggest that its mechanical properties may have a substantial influence on the mechanics and transfer function of the middle ear. However, relatively little is known about the dimensions of the TMC and its variability among individuals.MethodThirteen samples were collected from human temporal bones, consisting of only the malleus and the TM. They were imaged using μCT without contrast enhancing agent. From the μCT images, the TMC dimensions were measured in both anterior-posterior direction (TMC width) and medial-lateral direction (TMC thickness). Three selected samples were examined using histological microscopy.ResultsBoth TMC width and thickness featured a large variability among individuals. The minimal TMC width along the manubrium for different individuals covered a range between 83 and 840 μm. The minimal thickness ranged from 48 to 249 μm and the maximal thickness from 236 to 691 μm. Histological sections showed that the TMC consists of a narrow core of dense regular connective tissue, surrounded by loose connective tissue. In some samples, either of these two components was absent in the TMC at some manubrium locations. The configuration of these components varied among the samples as well.ConclusionOur data confirm that a large inter-individual variability exists in the properties of the TM-malleus connection in humans in terms of its dimensions, tissue composition and configuration. Average data and their variability margins will be useful input for testing the importance of the TMC in finite element models.



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Pressure buffering by the tympanic membrane. In vivo measurements of middle ear pressure fluctuations during elevator motion

Publication date: Available online 15 December 2015
Source:Hearing Research
Author(s): Simona Padurariu, Daniël de Greef, Henrik Jacobsen, Ernest Nlandu Kamavuako, Joris J. Dirckx, Michael Gaihede
ObjectivesThe tympanic membrane (TM) represents a pressure buffer, which contributes to the overall pressure regulation of the middle ear (ME). This buffer capacity is based on its viscoelastic properties combined with those of the attached ossicular chain, muscles and ligaments. The current work presents a set of in vivo recordings of the ME pressure variations normally occurring in common life: elevator motion. This is defined as a situation of smooth ambient pressure increase or decrease on a limited range and at a low rate of pressure change. Based on these recordings, the purpose was a quantitative analysis of the TM buffer capacity including the TM compliance.MethodsThe pressure changes in seven normal adult MEs with intact TM’s were continuously recorded directly inside the ME cavity during four different elevator trips using a high precision instrument. The TM buffer capacity was determined by the ratio between the changes in ME and the ambient pressure. Further, the ME volumes were calculated by Boyle’s Law from pressure recordings during inflation-deflation tests; subsequently the TM compliance could be also calculated. Finally, the correlation between the ME volume and buffer function was determined.ResultsTwenty-one elevator trips could be used for the analysis. The overall mean TM pressure buffering capacity was 23.3 % (SEM = 3.4), whereas the mean overall compliance was 28.9 × 10^-3 μL/Pa (SEM = 4.8). A strong negative linear correlation was found between the TM buffer capacity and the ME volumes (R² = 0.92).ConclusionsThese results were in fair agreement with the literature obtained in clinical as well as temporal bone experiments, and they provide an in vivo reference for the normal ME function as well as for ME modeling. The TM buffer capacity was found more efficient in smaller mastoids. Possible clinical implications are discussed.



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Auditory event-related potentials to words: Implications for audiologists.

Auditory event-related potentials to words: Implications for audiologists.

Int J Audiol. 2015 Sep;54(9):642-643

Authors: Golob EJ

PMID: 26653105 [PubMed - as supplied by publisher]

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Geriatric Audiology, second edition.

Geriatric Audiology, second edition.

Int J Audiol. 2015 Jun;54(6):433

Authors: Dawes P

PMID: 26652927 [PubMed - as supplied by publisher]

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Hearing: Anatomy, Physiology, and Disorders of the Auditory System (3rd ed.).

Hearing: Anatomy, Physiology, and Disorders of the Auditory System (3rd ed.).

Int J Audiol. 2015 Mar;54(3):210

Authors: Atcherson SR

PMID: 26652760 [PubMed - as supplied by publisher]

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Auditory event-related potentials to words: Implications for audiologists.

Auditory event-related potentials to words: Implications for audiologists.

Int J Audiol. 2015 Sep;54(9):642-643

Authors: Golob EJ

PMID: 26653105 [PubMed - as supplied by publisher]

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Geriatric Audiology, second edition.

Geriatric Audiology, second edition.

Int J Audiol. 2015 Jun;54(6):433

Authors: Dawes P

PMID: 26652927 [PubMed - as supplied by publisher]

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Hearing: Anatomy, Physiology, and Disorders of the Auditory System (3rd ed.).

Hearing: Anatomy, Physiology, and Disorders of the Auditory System (3rd ed.).

Int J Audiol. 2015 Mar;54(3):210

Authors: Atcherson SR

PMID: 26652760 [PubMed - as supplied by publisher]

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Determination of the mastoid surface area and volume based on micro-CT scanning of human temporal bones. Geometrical parameters depend on scanning resolutions

Publication date: Available online 15 December 2015
Source:Hearing Research
Author(s): Olivier Cros, Hans Knutsson, Mats Andersson, Elin Pawels, Magnus Borga, Michael Gaihede
The mastoid air cell system (MACS) with its large complex of interconnected air cells reflects an enhanced surface area (SA) relative to its volume (V), which may indicate that the MACS is adapted to gas exchange and has a potential role in middle ear pressure regulation. These geometric parameters of the MACS have been studied by high resolution clinical CT scanning. However, the resolution of these scans is limited to a voxel size of around 0.6 mm in all dimensions, and so, the geometrical parameters are also limited. Small air cells may appear below the resolution and cannot be detected. Such air cells may contribute to a much higher SA, and thus, also the SA/V ratio. More accurate parameters are important for analysis of the function of the MACS including physiological modeling.Our aim was to determine the SA, V, and SA/V ratio in the MACS in human temporal bones at highest resolution by using micro-CT-scanning. Further, the influence of the resolution on these parameters was investigated by downsampling the data. Eight normally aerated temporal bones were scanned at the highest possible resolution (30-60 μm). The SA was determined using a triangular mesh fitted onto the segmented MACS. The V was determined by summing all the voxels containing air. Downsampling of the original data was applied four times by a factor of 2.The mean SA was 194 cm², the mean V was 9 cm³, and the mean SA/V amounted to 22 cm^-1 (22 cm²/cm³). Decreasing the resolution resulted in a non-linear decrement of SA and SA/V, whereas V was mainly independent of the resolution.The current study found significantly higher SA and SA/V compared with previous studies using clinical CT scanning at lower resolutions. These findings indicate a role of the MACS different from that of the tympanum, though they are limited to only a smaller sample of temporal bones without knowledge about the disease history of the subjects. The current data on mastoid geometry seems important for a more accurate modeling of the middle ear physiology and future studies may include morphological investigations of the air cells with possible implications for their postnatal development.



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On the connection between the tympanic membrane and the malleus

Publication date: Available online 15 December 2015
Source:Hearing Research
Author(s): Daniel De Greef, Jana Goyens, Isabel Pintelon, John-Paul Bogers, Vincent Van Rompaey, Evert Hamans, Paul Van de Heyning, Joris J.J. Dirckx
BackgroundThe tympano-mallear connection (TMC) is the soft-tissue connection between the tympanic membrane (TM) and the manubrium of the malleus. Some studies suggest that its mechanical properties may have a substantial influence on the mechanics and transfer function of the middle ear. However, relatively little is known about the dimensions of the TMC and its variability among individuals.MethodThirteen samples were collected from human temporal bones, consisting of only the malleus and the TM. They were imaged using μCT without contrast enhancing agent. From the μCT images, the TMC dimensions were measured in both anterior-posterior direction (TMC width) and medial-lateral direction (TMC thickness). Three selected samples were examined using histological microscopy.ResultsBoth TMC width and thickness featured a large variability among individuals. The minimal TMC width along the manubrium for different individuals covered a range between 83 and 840 μm. The minimal thickness ranged from 48 to 249 μm and the maximal thickness from 236 to 691 μm. Histological sections showed that the TMC consists of a narrow core of dense regular connective tissue, surrounded by loose connective tissue. In some samples, either of these two components was absent in the TMC at some manubrium locations. The configuration of these components varied among the samples as well.ConclusionOur data confirm that a large inter-individual variability exists in the properties of the TM-malleus connection in humans in terms of its dimensions, tissue composition and configuration. Average data and their variability margins will be useful input for testing the importance of the TMC in finite element models.



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Pressure buffering by the tympanic membrane. In vivo measurements of middle ear pressure fluctuations during elevator motion

Publication date: Available online 15 December 2015
Source:Hearing Research
Author(s): Simona Padurariu, Daniël de Greef, Henrik Jacobsen, Ernest Nlandu Kamavuako, Joris J. Dirckx, Michael Gaihede
ObjectivesThe tympanic membrane (TM) represents a pressure buffer, which contributes to the overall pressure regulation of the middle ear (ME). This buffer capacity is based on its viscoelastic properties combined with those of the attached ossicular chain, muscles and ligaments. The current work presents a set of in vivo recordings of the ME pressure variations normally occurring in common life: elevator motion. This is defined as a situation of smooth ambient pressure increase or decrease on a limited range and at a low rate of pressure change. Based on these recordings, the purpose was a quantitative analysis of the TM buffer capacity including the TM compliance.MethodsThe pressure changes in seven normal adult MEs with intact TM’s were continuously recorded directly inside the ME cavity during four different elevator trips using a high precision instrument. The TM buffer capacity was determined by the ratio between the changes in ME and the ambient pressure. Further, the ME volumes were calculated by Boyle’s Law from pressure recordings during inflation-deflation tests; subsequently the TM compliance could be also calculated. Finally, the correlation between the ME volume and buffer function was determined.ResultsTwenty-one elevator trips could be used for the analysis. The overall mean TM pressure buffering capacity was 23.3 % (SEM = 3.4), whereas the mean overall compliance was 28.9 × 10^-3 μL/Pa (SEM = 4.8). A strong negative linear correlation was found between the TM buffer capacity and the ME volumes (R² = 0.92).ConclusionsThese results were in fair agreement with the literature obtained in clinical as well as temporal bone experiments, and they provide an in vivo reference for the normal ME function as well as for ME modeling. The TM buffer capacity was found more efficient in smaller mastoids. Possible clinical implications are discussed.



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Determination of the mastoid surface area and volume based on micro-CT scanning of human temporal bones. Geometrical parameters depend on scanning resolutions

Publication date: Available online 15 December 2015
Source:Hearing Research
Author(s): Olivier Cros, Hans Knutsson, Mats Andersson, Elin Pawels, Magnus Borga, Michael Gaihede
The mastoid air cell system (MACS) with its large complex of interconnected air cells reflects an enhanced surface area (SA) relative to its volume (V), which may indicate that the MACS is adapted to gas exchange and has a potential role in middle ear pressure regulation. These geometric parameters of the MACS have been studied by high resolution clinical CT scanning. However, the resolution of these scans is limited to a voxel size of around 0.6 mm in all dimensions, and so, the geometrical parameters are also limited. Small air cells may appear below the resolution and cannot be detected. Such air cells may contribute to a much higher SA, and thus, also the SA/V ratio. More accurate parameters are important for analysis of the function of the MACS including physiological modeling.Our aim was to determine the SA, V, and SA/V ratio in the MACS in human temporal bones at highest resolution by using micro-CT-scanning. Further, the influence of the resolution on these parameters was investigated by downsampling the data. Eight normally aerated temporal bones were scanned at the highest possible resolution (30-60 μm). The SA was determined using a triangular mesh fitted onto the segmented MACS. The V was determined by summing all the voxels containing air. Downsampling of the original data was applied four times by a factor of 2.The mean SA was 194 cm², the mean V was 9 cm³, and the mean SA/V amounted to 22 cm^-1 (22 cm²/cm³). Decreasing the resolution resulted in a non-linear decrement of SA and SA/V, whereas V was mainly independent of the resolution.The current study found significantly higher SA and SA/V compared with previous studies using clinical CT scanning at lower resolutions. These findings indicate a role of the MACS different from that of the tympanum, though they are limited to only a smaller sample of temporal bones without knowledge about the disease history of the subjects. The current data on mastoid geometry seems important for a more accurate modeling of the middle ear physiology and future studies may include morphological investigations of the air cells with possible implications for their postnatal development.



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On the connection between the tympanic membrane and the malleus

Publication date: Available online 15 December 2015
Source:Hearing Research
Author(s): Daniel De Greef, Jana Goyens, Isabel Pintelon, John-Paul Bogers, Vincent Van Rompaey, Evert Hamans, Paul Van de Heyning, Joris J.J. Dirckx
BackgroundThe tympano-mallear connection (TMC) is the soft-tissue connection between the tympanic membrane (TM) and the manubrium of the malleus. Some studies suggest that its mechanical properties may have a substantial influence on the mechanics and transfer function of the middle ear. However, relatively little is known about the dimensions of the TMC and its variability among individuals.MethodThirteen samples were collected from human temporal bones, consisting of only the malleus and the TM. They were imaged using μCT without contrast enhancing agent. From the μCT images, the TMC dimensions were measured in both anterior-posterior direction (TMC width) and medial-lateral direction (TMC thickness). Three selected samples were examined using histological microscopy.ResultsBoth TMC width and thickness featured a large variability among individuals. The minimal TMC width along the manubrium for different individuals covered a range between 83 and 840 μm. The minimal thickness ranged from 48 to 249 μm and the maximal thickness from 236 to 691 μm. Histological sections showed that the TMC consists of a narrow core of dense regular connective tissue, surrounded by loose connective tissue. In some samples, either of these two components was absent in the TMC at some manubrium locations. The configuration of these components varied among the samples as well.ConclusionOur data confirm that a large inter-individual variability exists in the properties of the TM-malleus connection in humans in terms of its dimensions, tissue composition and configuration. Average data and their variability margins will be useful input for testing the importance of the TMC in finite element models.



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Pressure buffering by the tympanic membrane. In vivo measurements of middle ear pressure fluctuations during elevator motion

Publication date: Available online 15 December 2015
Source:Hearing Research
Author(s): Simona Padurariu, Daniël de Greef, Henrik Jacobsen, Ernest Nlandu Kamavuako, Joris J. Dirckx, Michael Gaihede
ObjectivesThe tympanic membrane (TM) represents a pressure buffer, which contributes to the overall pressure regulation of the middle ear (ME). This buffer capacity is based on its viscoelastic properties combined with those of the attached ossicular chain, muscles and ligaments. The current work presents a set of in vivo recordings of the ME pressure variations normally occurring in common life: elevator motion. This is defined as a situation of smooth ambient pressure increase or decrease on a limited range and at a low rate of pressure change. Based on these recordings, the purpose was a quantitative analysis of the TM buffer capacity including the TM compliance.MethodsThe pressure changes in seven normal adult MEs with intact TM’s were continuously recorded directly inside the ME cavity during four different elevator trips using a high precision instrument. The TM buffer capacity was determined by the ratio between the changes in ME and the ambient pressure. Further, the ME volumes were calculated by Boyle’s Law from pressure recordings during inflation-deflation tests; subsequently the TM compliance could be also calculated. Finally, the correlation between the ME volume and buffer function was determined.ResultsTwenty-one elevator trips could be used for the analysis. The overall mean TM pressure buffering capacity was 23.3 % (SEM = 3.4), whereas the mean overall compliance was 28.9 × 10^-3 μL/Pa (SEM = 4.8). A strong negative linear correlation was found between the TM buffer capacity and the ME volumes (R² = 0.92).ConclusionsThese results were in fair agreement with the literature obtained in clinical as well as temporal bone experiments, and they provide an in vivo reference for the normal ME function as well as for ME modeling. The TM buffer capacity was found more efficient in smaller mastoids. Possible clinical implications are discussed.



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