Benign Paroxysmal Positional Vertigo after Dental Procedures: A Population-Based Case-Control Study

by Tzu-Pu Chang, Yueh-Wen Lin, Pi-Yu Sung, Hsun-Yang Chuang, Hsien-Yang Chung, Wen-Ling Liao

Background

Benign paroxysmal positional vertigo (BPPV), the most common type of vertigo in the general population, is thought to be caused by dislodgement of otoliths from otolithic organs into the semicircular canals. In most cases, however, the cause behind the otolith dislodgement is unknown. Dental procedures, one of the most common medical treatments, are considered to be a possible cause of BPPV, although this has yet to be proven. This study is the first nationwide population-based case-control study conducted to investigate the correlation between BPPV and dental manipulation.

Methods

Patients diagnosed with BPPV between January 1, 2007 and December 31, 2012 were recruited from the National Health Insurance Research Database in Taiwan. We further identified those who had undergone dental procedures within 1 month and within 3 months before the first diagnosis date of BPPV. We also identified the comorbidities of the patients with BPPV, including head trauma, osteoporosis, migraine, hypertension, diabetes, hyperlipidemia and stroke. These variables were then compared to those in age- and gender-matched controls.

Results

In total, 768 patients with BPPV and 1536 age- and gender-matched controls were recruited. In the BPPV group, 9.2% of the patients had undergone dental procedures within 1 month before the diagnosis of BPPV. In contrast, only 5.5% of the controls had undergone dental treatment within 1 month before the date at which they were identified (P = 0.001). After adjustments for demographic factors and comorbidities, recent exposure to dental procedures was positively associated with BPPV (adjusted odds ratio 1.77; 95% confidence interval 1.27–2.47). This association was still significant if we expanded the time period from 1 month to 3 months (adjusted odds ratio 1.77; 95% confidence interval 1.39–2.26).

Conclusions

Our results demonstrated a correlation between dental procedures and BPPV. The specialists who treat patients with BPPV should consider dental procedures to be a risk factor, and dentists should recognize BPPV as a possible complication of dental treatment.

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Long-range propagation of nonlinear infrasound waves through an absorbing atmosphere

The Navier–Stokes equations are solved using a finite-difference, time-domain (FDTD) approach for axi-symmetric environmental models, allowing three-dimensional acoustic propagation to be simulated using a two-dimensional Cylindrical coordinate system. A method to stabilize the FDTD algorithm in a viscous medium at atmospheric densities characteristic of the lower thermosphere is described. The stabilization scheme slightly alters the governing equations but results in quantifiable dispersion characteristics. It is shown that this method leaves sound speeds and attenuation unchanged at frequencies that are well resolved by the temporal sampling rate but strongly attenuates higher frequencies. Numerical experiments are performed to assess the effect of source strength on the amplitudes and spectral content of signals recorded at ground level at a range of distances from the source. It is shown that the source amplitudes have a stronger effect on a signal's dominant frequency than on its amplitude. Applying the stabilized code to infrasound propagation through realistic atmospheric profiles shows that nonlinear propagation alters the spectral content of low amplitude thermospheric signals, demonstrating that nonlineareffects are significant for all detectable thermospheric returns.

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Using two-dimensional impedance maps to study weak scattering in sparse random media

Impedance maps (ZMs) have been proposed as a tool for modeling acoustic properties of tissuemicrostructure. Three-dimensional (3D) ZMs are constructed from a series of adjacent histological tissue slides that have been stained to emphasize acoustic impedance structures. The power spectrum of a 3DZM can be related to the ultrasoundbackscatter coefficient, which can be further reduced to a form factor. The goal of this study is to demonstrate the ability to estimate form factors using two-dimensional (2D) ZMs instead of 3DZMs, which have reduced computational and financial cost. The proposed method exploits the properties of isotropic media to estimate the correlation coefficient from slices before estimating the 3D volume power spectrum. Simulated sparse collections of objects were used to study the method by comparing the results obtained using 2DZMs to those predicted by theory. 2DZM analysis was conducted on normal rabbit liver histology and compared to 3DZM analysis of the same histology. The mean percent error between effective scatterer diameter estimates from 2DZMs and 3DZMs of rabbit liver histology was form factors for sparse collections of objects.

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Concert hall acoustics: Recent findingsa)

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Seasonal and diel variability of the underwater noise in the Baltic Sea

The results of ambient seanoise measurements performed in strongly stratified shallow basins in the southern Baltic Sea are presented. The experiments were conducted with an autonomous hydroacoustic buoy that was equipped with two omnidirectional hydrophones located inside and outside the seasonal waveguide. Data were collected in two areas with contrastingly diverse sound propagation conditions—at the Bornholm Deep in winter and at the Gdansk Deep in summer. The noise spectrum levels indicate a strong dependence on the sound propagation conditions (season, location) and show significant differences with the observation depth. At frequencies f noise at the same wind speeds is approximately 10–15 dB higher in winter than in summer. The wind-driven component of the noise frequently does not match the patterns of the Knudsen curves. Furthermore, the noise demonstrates the diel variability. The relative differences of the noise spectrum levels inside and outside of the subsurface winter waveguide reveal regular changes by as much as 15 dB, and are the most visible in the frequency range of 1–2 kHz after sunset. The changes are synchronized with the vertical migration of marine organisms and correspond to the resonant frequencies of the fishes' swim bladders.

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Using Language Sample Analysis to Assess Spoken Language Production in Adolescents

Purpose

This tutorial discusses the importance of language sample analysis and how Systematic Analysis of Language Transcripts (SALT) software can be used to simplify the process and effectively assess the spoken language production of adolescents.

Method

Over the past 30 years, thousands of language samples have been collected from typical speakers, aged 3–18 years, in conversational and narrative contexts. These samples have been formatted as reference databases included with SALT. Using the SALT software, individual samples are compared with age- and grade-matched samples selected from these databases.

Results

Two case studies illustrate that comparison with database samples of typical adolescents, matched by grade and elicitation context, highlights language measures that are higher or lower than the database mean values. Differences in values are measured in standard deviations.

Conclusion

Language sample analysis remains a powerful method of documenting language use in everyday speaking situations. A sample of talking reveals an individual's ability to meet specific speaking demands. These demands vary across contexts, and speakers can have difficulty in any one or all of these communication tasks. Language use for spoken communication is a foundation for literacy attainment and contributes to success in navigating relationships for school, work, and community participation.

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Using Language Sample Analysis to Assess Spoken Language Production in Adolescents

Purpose

This tutorial discusses the importance of language sample analysis and how Systematic Analysis of Language Transcripts (SALT) software can be used to simplify the process and effectively assess the spoken language production of adolescents.

Method

Over the past 30 years, thousands of language samples have been collected from typical speakers, aged 3–18 years, in conversational and narrative contexts. These samples have been formatted as reference databases included with SALT. Using the SALT software, individual samples are compared with age- and grade-matched samples selected from these databases.

Results

Two case studies illustrate that comparison with database samples of typical adolescents, matched by grade and elicitation context, highlights language measures that are higher or lower than the database mean values. Differences in values are measured in standard deviations.

Conclusion

Language sample analysis remains a powerful method of documenting language use in everyday speaking situations. A sample of talking reveals an individual's ability to meet specific speaking demands. These demands vary across contexts, and speakers can have difficulty in any one or all of these communication tasks. Language use for spoken communication is a foundation for literacy attainment and contributes to success in navigating relationships for school, work, and community participation.

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Using Language Sample Analysis to Assess Spoken Language Production in Adolescents

Purpose

This tutorial discusses the importance of language sample analysis and how Systematic Analysis of Language Transcripts (SALT) software can be used to simplify the process and effectively assess the spoken language production of adolescents.

Method

Over the past 30 years, thousands of language samples have been collected from typical speakers, aged 3–18 years, in conversational and narrative contexts. These samples have been formatted as reference databases included with SALT. Using the SALT software, individual samples are compared with age- and grade-matched samples selected from these databases.

Results

Two case studies illustrate that comparison with database samples of typical adolescents, matched by grade and elicitation context, highlights language measures that are higher or lower than the database mean values. Differences in values are measured in standard deviations.

Conclusion

Language sample analysis remains a powerful method of documenting language use in everyday speaking situations. A sample of talking reveals an individual's ability to meet specific speaking demands. These demands vary across contexts, and speakers can have difficulty in any one or all of these communication tasks. Language use for spoken communication is a foundation for literacy attainment and contributes to success in navigating relationships for school, work, and community participation.

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