1/3. Variance of vestibular-evoked myogenic potentials.OBJECTIVES/HYPOTHESIS: Vestibular-evoked myogenic potential (VEMP) has been thought to originate from sacculus. The variance of this potential and the effectiveness of the adjustments of pInII amplitudes using average muscle tonus of ipsilateral sternocleidomastoid muscle were evaluated. In addition, clinical application of VEMP was examined in patients with acoustic tumors (ATs) and vestibular neurolabyrinthitis (VNL). STUDY DESIGN: Prospective evaluation of the VEMP in 18 normal volunteers and 6 patients. methods: Variance and left-right difference of each parameter, including pI latency, nII latency, pInII amplitude, and threshold, was analyzed. Input-output function of pInII amplitude was evaluated. Average muscle tonus was calculated in 20 ears and applied for adjustment of pInII amplitude. Sensitivity of each parameter of VEMP was examined in 3 patients with ATs and 3 patients with VNL. RESULTS: VEMP was present in all 36 ears of 18 control subjects. Thresholds of VEMP for normal subjects were 80 to 95 dB normal hearing level (nHL). The muscle tonus affected pInII amplitude significantly; however, no statistically significant improvement was observed in test-retest investigation after adjustment using muscle tonus. The threshold of the affected side was elevated compared with the non-affected side in all patients with ATs, whereas 2 of 3 patients showed normal pInII-ratio. One patient with VNL presented normal VEMP, whereas 2 patients presented no VEMP to the highest stimulus intensity. CONCLUSIONS: Interaural difference of thresholds might be the most useful parameters. Adjustment using average muscle tonus is not necessary when the subject is able to get sufficient muscle tonus.- - - - - - - - - - ranking = 1keywords = hearing (Clic here for more details about this article) |
2/3. Isolated vestibular areflexia after blunt head trauma.The sudden unilateral loss of vestibular function is a frequent cause of vertigo. This condition is called vestibular neuronitis or vestibular neuritis. Its cause remains unknown, but many authors consider it to be a sequel of vestibular viral infection. We report the history and clinical findings of 5 patients in whom a unilateral vestibular loss occurred after head trauma. None of these patients complained of hearing loss. In all cases, the vertigo gradually subsided over days or weeks. The follow-up showed the partial recovery of vestibular function in 2 cases, while vestibular areflexia persisted in 3. The clinical course and findings were similar in every respect to those in patients with classic idiopathic vestibular neuronitis.- - - - - - - - - - ranking = 2.8373348989787keywords = hearing loss, hearing (Clic here for more details about this article) |
3/3. Acute vestibular neuritis visualized by 3-T magnetic resonance imaging with high-dose gadolinium.Sudden idiopathic unilateral loss of vestibular function without other signs or symptoms is called acute vestibular neuritis. It has been suggested that reactivation of human herpes simplex virus 1 could cause vestibular neuritis, bell palsy, and sudden unilateral hearing loss. Enhancement of the facial nerve on gadolinium-enhanced magnetic resonance imaging (MRI) is a common finding in bell palsy, but enhancement of the vestibular nerve has never been reported in acute vestibular neuritis. We present 2 consecutive cases of acute vestibular neuritis where high-field-strength MRI (3.0 T) with high-dose (0.3 mmol/kg of body weight) gadolinium-pentetic acid showed isolated enhancement of the vestibular nerve on the affected side only. These findings support the hypothesis of a viral and inflammatory cause of acute vestibular neuritis and might have implications for its treatment.- - - - - - - - - - ranking = 2.8373348989787keywords = hearing loss, hearing (Clic here for more details about this article) |