Superior Semicircular Canal Dehiscence and Bone Conduction in Chinchilla

Songer, Jocelyn E.; Brinsko, Kelly M.; Rosowski, John J.

doi:10.1142/9789812703019_0035

Cited by 10 publications

(18 citation statements)

References 3 publications

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“…We found that a correlation exists, with larger dehiscences requiring lower stimulator frequencies to invoke nystagmic responses. These findings agree with animal model studies (11,12) in which the size of the dehiscence influenced the magnitude of the recorded cochlear potential. We are currently examining whether this relationship can be explained by laws of fluid dynamics; such a model may provide further insight into pathophysiologic mechanisms of SSCD.…”

Section: Discussionsupporting

confidence: 89%

The Effects of Superior Semicircular Canal Dehiscence on the Labyrinth

Rajan

Leaper

Goggin

et al. 2008

Otology &Amp; Neurotology

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Section: Discussionsupporting

confidence: 89%

The Effects of Superior Semicircular Canal Dehiscence on the Labyrinth

Rajan

Leaper

Goggin

et al. 2008

Otology &Amp; Neurotology

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“…At 500 Hz, the present study showed an 8.7 dB decrease in the chinchillas response to AC stimuli. Combining the above with the SCD induced increase of 8.1 dB in the sensitivity to BC sound Songer et al, 2004) leads to an SCD induced air-bone gap of 16.8 dB at 500 Hz in chinchilla.…”

Section: Comparison To Clinical Studiesmentioning

confidence: 89%

The effect of superior canal dehiscence on cochlear potential in response to air-conducted stimuli in chinchilla

Songer

Rosowski

2005

Hearing Research

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A superior semicircular canal dehiscence (SCD) is a break or hole in the bony wall of the superior semicircular canal. Patients with SCD syndrome present with a variety of symptoms: some with vestibular symptoms, others with auditory symptoms (including low-frequency conductive hearing loss) and yet others with both. We are interested in whether or not mechanically altering the superior canal by introducing a dehiscence is sufficient to cause the low-frequency conductive hearing loss associated with SCD syndrome. We evaluated the effect of a surgically introduced dehiscence on auditory responses to air-conducted (AC) stimuli in 11 chinchilla ears. Cochlear potential (CP) was recorded at the round-window before and after a dehiscence was introduced. In each ear, a decrease in CP in response to low frequency (<2 kHz) sound stimuli was observed after the introduction of the dehiscence. The dehiscence was then patched with cyanoacrylate glue leading to a reversal of the dehiscence-induced changes in CP. The reversible decrease in auditory sensitivity observed in chinchilla is consistent with the elevated AC thresholds observed in patients with SCD. According to the 'third-window' hypothesis the SCD shunts sound-induced stapes velocity away from the cochlea, resulting in decreased auditory sensitivity to AC sounds. The data collected in this study are consistent with predictions of this hypothesis.

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“…Such a new window placed on the vestibular side of the inner ear diverts airconducted sound energy that enters the inner ear away from the cochlea (Rosowski, et al, 2004b;Songer & Rosowski, 2005, 2006a, where the diversion of sound energy through an open dehiscence has been directly observed in animal and temporal-bone models of SCD (Chien, Ravicz, Rosowski, & Merchant, 2007;Rosowski, et al, 2004b, Songer, 2006. Animal and computer models have also demonstrated that SCD can also induce a hypersensitivity to low-frequency bone-conducted sound (Rosowski, et al, 2004b;Songer, 2006;Songer, Brinsko, & Rosowski, 2004). The effects of a third window in the vestibular side of the inner ear are not restricted to the superior canal.…”

Section: Ldv Measurements In Ears With Superior Semicircular Canal Dementioning

confidence: 99%

Clinical Utility of Laser-Doppler Vibrometer Measurements in Live Normal and Pathologic Human Ears

2008

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The laser-Doppler vibrometer (LDV) is a research tool that can be used to quickly measure the soundinduced velocity of the tympanic membrane near the umbo (the inferior tip of the malleus) in live human subjects and patients. In this manuscript we demonstrate the LDV to be a sensitive and selective tool for the diagnosis and differentiation of various ossicular disorders in patients with intact tympanic membranes and aerated middle ears. Patients with partial or total ossicular interruption or malleus fixation are readily separated from normal-hearing subjects with the LDV. The combination of LDV measurements and air-bone gap can distinguish patients with fixed stapes from those with normal ears. LDV measurements can also help differentiate air-bone gaps produced by ossicular pathologies from those associated with pathologies of inner-ear sound conduction such as a superior semicircular canal dehiscence.The key audiological tool for defining conductive hearing loss is the air-bone gap, which is the difference between air-conducted and bone-conducted hearing levels. The pathology associated with such gaps may, in certain cases, be readily observable during otoscopic examination, for example, cerumen impaction, perforations of the tympanic membrane (TM), acute otitis media, chronic otitis media, etc. However, the diagnosis of the precise pathology causing a conductive hearing loss in patients with an intact TM is difficult, and conclusive diagnosis is often only made at the time of exploratory middle ear surgery.Although there are tools available for presurgical diagnosis of such disorders, they have imperfect selectivity and sensitivity. Tympanometry and acoustic-reflex testing, in conjunction with audiometry, are sensitive to different ossicular disorders (Jerger, 1975;Margolis & Shanks, 1985), for example (1) a normal tympanogram coupled with a lack of ipsilateral acoustic reflex and a significant air-bone gap that is either flat or upward sloping with increasing frequency is usually associated with stapes fixation. (2) A hypomobile tympanogram with a loss of reflex thresholds and a mild to moderate conductive loss is often associated with malleus fixation. (3) A hyper-mobile tympanogram with a loss of ipsilateral reflex and either a 50-dB flat or downward sloping conductive loss is usually associated with either a total or partial ossicular disarticulation.A major problem with the above scheme is that standard single-frequency (226 Hz) tympanometry is relatively insensitive to ossicular disorders and many ears with fixed or Address for correspondence: John Rosowski, Eaton-Peabody Lab, Massachusetts Eye & Ear Infirmary, 243 Charles Street, Boston, MA 02114. E-mail: John_Rosowski@meei.harvard.edu. NIH Public Access NIH-PA Author ManuscriptNIH-PA Author Manuscript NIH-PA Author Manuscript interrupted ossicular chains are not reliably differentiated by this technique. The selectivity and sensitivity of tympanometry to ossicular disorders can be improved by measurements at multiple frequencies (Lily, 1984;...

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Superior Semicircular Canal Dehiscence and Bone Conduction in Chinchilla

Cited by 10 publications

References 3 publications

The Effects of Superior Semicircular Canal Dehiscence on the Labyrinth

The Effects of Superior Semicircular Canal Dehiscence on the Labyrinth

The effect of superior canal dehiscence on cochlear potential in response to air-conducted stimuli in chinchilla

Clinical Utility of Laser-Doppler Vibrometer Measurements in Live Normal and Pathologic Human Ears

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