Audiological and vestibular evaluation of new coagulation factor C homology mutation carriers in a Chinese family / 中华耳鼻咽喉头颈外科杂志

<p><b>OBJECTIVE</b>To analyze the clinical features of audiological and vestibular function in a Chinese family with late onset autosomal dominant nonsyndromic sensorineural hearing loss.</p><p><b>METHODS</b>Comprehensive audiological and vestibular evaluation including pure tone audiometry, auditory brainstem response (ABR), electrocochleogram (EcochG), oculomotor testing, caloric tests, rotational testing, computerized dynamic posturography and vestibular evoked myogenic potentials (VEMP) were conducted to identify the hearing and vestibular impairment.</p><p><b>RESULTS</b>All affected family members shared sensorineural hearing loss with full penetrance starting between the second and fifth decade of life as a high frequency loss which progresses to a severe to profound loss at the sixth to seventh decade. The extensive vestibular evaluation indicated that all affected members performed normally in computerized dynamic posturography and caloric testing. Impairment of the saccular otolith in all of six affected members was suggested by results of the VEMP test. The velocity step test generated abnormal time constants and sinusoidal oscillation test generated abnormal gains and phase in affected members indicated that horizontal canal vestibular hyporeflexia in history. All affected subjects examined in this family showed completely normal ocular motor responses in oculomotor testing, including smooth pursuit, optokinetic nystagmus, gaze and saccade.</p><p><b>CONCLUSIONS</b>The predominant feature of the Chinese DFNA9 family was that all the affected subjects harboring COCH mutation in the vWFA2 domain didn't suffer the vestibular symptoms during their life time and comprehensive vestibular assessment revealed only subtle vestibular hypofunction in affected members of this family. There is a genotype-phenotype correlation in DFNA9.</p>

Characteristics of vestibular-ocular reflex in guinea pigs during eccentric sinusoidal rotation / 中国应用生理学杂志

<p><b>AIM</b>To observe the characteristics of vestibular-ocular reflex (VOR) of guinea pigs during eccentric sinusoidal rotation in different frequencies and radius, and compare them with that during axis rotation, obtain the parameters which reflect otolith functions, and provide experimental evidence for the establishment of otolith function test.</p><p><b>METHODS</b>Guinea pigs were placed in axis of rotation and in an heading out eccentric position apart from rotation axis of 330 mm, 660 mm and 990 mm respectively, their VOR were recorded and compared under stimulus of sinusoidal rotations in the frequencies of 0.1, 0.2, 0.3, 0.4, 0.5 and 0.6 Hz with the peak velocity of 60 degrees/s in each position.</p><p><b>RESULTS</b>Both frequency and eccentric radius had significant effects on the VOR gain, it increased with the increase of frequencies and radius. The largest increase of the gain occurred at the frequencies of 0.3 and 0.4Hz, and no significant changes were observed above these frequencies.</p><p><b>CONCLUSION</b>Enhancement ratio (ER) of VOR gain can reflect the extent of its increase with radius, and can be used as an index of otolith function, the stimulus profile of eccentric rotation at frequency of 0.4Hz and radius of 990mm is recommended as the stimulus profile for the otolith function test.</p>

Clinical significance of vibration-induced nystagmus in patients with unilateral peripheral vestibular disorders / 中华耳鼻咽喉头颈外科杂志

<p><b>OBJECTIVE</b>To clarify the clinical significance of vibration-induced nystagmus (VIN) and to calculate the sensitivity and the specificity of the vibration test.</p><p><b>METHODS</b>One hundred and twelve patients with unilateral peripheral vestibular disorders and 30 normal subjects were enrolled into this study. However, patients with spontaneous nystagmus were excluded. Vibratory stimuli (approximately 92Hz) were presented to the mastoids and the forehead. Patients and normal subjects also underwent head shaking testing and caloric testing.</p><p><b>RESULTS</b>Of the 112 patients, 91 (81%) showed VIN which were mainly horizontal. VIN was more frequently evoked on the mastoids than on the forehead. In the majority of patients (76 cases), the direction of VIN was toward the healthy side, whereas patients with Meniere's disease (15 cases), showed nystagmus toward the affected side. None of 30 normal subjects showed VIN. Whereas, HSN was found in 70 (63%) patients and 9 (30%) in normal subjects. Of 112 patients, 10 showed a canal paresis (CP) value of caloric test less than 25% ,while 32 with a CP value between 25% and 40%, 48 with a CP value between 40% and 70%, and 22 with a CP value more than 70%. It is notable that with increasing canal paresis value on caloric testing, VIN was more likely to be evoked.</p><p><b>CONCLUSIONS</b>VIN testing is a simple, non-invasive and well-tolerated clinical test that indicates unilateral peripheral vestibular dysfunction. VIN testing had greater sensitivity and the specificity than HSN testing in the diagnosis of unilateral peripheral vestibular disorders.</p>