Toru Ohashi

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).

Age-Related Changes in the Vestibular-Evoked Myogenic Potentials

OBJECTIVE We sought to investigate the effects of gender and age on the vestibular-evoked myogenic potential (VEMP). STUDY DESIGN AND SETTINGS Sixty healthy adult volunteers (28 male and 32 female) were investigated in this study. The subject age was distributed between 20 and 77 years old. RESULTS No gender-related differences were detected in the VEMP. There was a significant correlation between age and both the evoking threshold and the pInII amplitude of the VEMP, whereas no significant correlation was observed between age and left-right differences of the VEMP. CONCLUSIONS The correlation between age and the parameters of the VEMP is presumably secondary to age-related functional changes in the sensory and neural elements of the VEMP. It is safe to evaluate the VEMP using the value of the non-affected side when assessing unilateral lesions. However, it may be necessary to take age into account in evaluating the VEMP when bilateral lesions are suspected.

Vestibular-evoked myogenic potential in patients with unilateral vestibular neuritis: abnormal VEMP and its recovery.

The incidence of inferior vestibular nerve disorders in patients suffering from unilateral vestibular neuritis and the recovery of these disorders were evaluated by monitoring the vestibular-evoked myogenic potential (VEMP). Eight patients ranged from 21 to 73 years that suffered from unilateral vestibular neuritis underwent VEMP and caloric testing. Abnormal VEMP was observed in two of the eight patients with unilateral vestibular neuritis. Two patients were diagnosed as having an inferior vestibular nerve disorder. One of these patients showed recovery of the inferior vestibular nerve function as assessed by the VEMP. Disorders of the inferior vestibular nerve function and their recovery was confirmed by our current results. The time course of recoveries of the superior and inferior vestibular nerve systems were similar in the two patients.

Acoustic tensor tympani response and vestibular-evoked myogenic potential.

Objective To investigate the acoustic response properties and the vestibular‐evoked myogenic potential (VEMP) in various lesions.

Hearing Impairment and Tinnitus Pitch in Patients With Unilateral Tinnitus: Comparison of Sudden Hearing Loss and Chronic Tinnitus

Objectives The objectives were to analyze the results of pitch‐matching and loudness‐balance testing in patients with unilateral tinnitus and to evaluate the relationship between audiological findings based on the tinnitus‐affected and tinnitus‐unaffected threshold differences and tinnitus pitch by using linear interpolation methods. In addition, the effects of the duration of the tinnitus on this relationship were investigated. Sudden sensorineural hearing loss with tinnitus was selected for the “acute tinnitus” group, and unilateral tinnitus with unknown disease and a duration of more than 3 months was selected for the “chronic tinnitus” group.

Tonsillectomy Using an Ultrasonically Activated Scalpel

INTRODUCTION Tonsillectomy is one of the most popular surgeries in otorhinolaryngology. Although the progress of antibiotics enhances improvement of treatment for tonsillitis, there are still many indications for tonsillectomy. It is performed in adults and children and sometimes brings about lethal complications. Bleeding is an important, dangerous complication that limits operative indications. The establishment of a safe, bloodless operative procedure will increase the number of cases with operative indication. In 1992 an ultrasonically activated scalpel that achieves effective coagulation and safe cutting of tissue was introduced. 1 The ultrasonic activated scalpel is an instrument that potentially causes minimal tissue injury and provides good hemostasis. Ultrasonically activated vibrations (55,500 cycles per second) can cut the tissue. The ultrasonically activated scalpel is composed of a generator, handpiece, and blade (Fig. 1). The handpiece houses the acoustic system, which is composed of the transducer and the mount. There is no vibration in the handpiece when the system is activated. The three components of the acoustic system vibrate harmonically at 55,500 cycles per second. 2 In this report we introduce a method of tonsillectomy with the aid of an ultrasonically activated scalpel, especially stressing the effectiveness of this device.

Recovery of human compound action potential using a paired-click stimulation paradigm

The recovery process from adaptation of the compound action potential (CAP) was studied using an equilevel paired click stimulation paradigm in humans with normal hearing. The CAP amplitude to the second click of paired clicks was normalized to the amplitude to the first click. The second-click CAP amplitude recovered as a function of interclick interval (ICI) between the first and the second click of a pair. A regression line fitted to the recovered amplitude data demonstrated the logarithmic function of the ICI. Full recovery times changed from 118 to 278 ms with increasing click intensity. The regression lines for higher click intensities exhibited two different slopes in two ICI ranges: from 3 to 100 and 120 to 300 ms. We suppose that the CAP recovery for ICI <100 ms is attributable to both the relative refractoriness of auditory nerve and the short-term adaptation mechanisms, while, for ICI >100 ms chiefly to the short-term adaptation mechanisms. The recovery process of the second-click CAP slowed with increasing intensity, which is a similar result to that obtained in the animal experiments by Parham et al. The input-output (I-O) curve of the second-click CAP amplitudes exhibited a different slopes above and below 60 dB normal hearing level (nHL). We assume that the mechanisms underlying this characteristic curve pattern differ from those for the I-O curve of the CAP in response to single-click stimuli. We expect that investigating the CAP recovery in pathological ears will provide clinically useful information on cochlear synaptic function.

Zinc deficiency and tinnitus

OBJECTIVE To determine if there is a correlation between serum zinc levels and audiometric performance in tinnitus patients. METHODS Seventy-three patients participated in this study. Patients age was restricted to 20-59 years. All patients were examined at the otolaryngology outpatient clinic of the St. Marianna University Toyoko Hospital. The control group consisted of 38 age- and sex-matched healthy volunteers. A blood sample was taken to measure serum zinc levels. Hypozincemia was set at a level of the mean minus one S.D. in the control group. An average hearing sensitivity was calculated as the mean value of hearing thresholds at five frequencies: 250, 500, 1000, 2000, and 4000 Hz. Normal hearing was indicated when the hearing threshold at each of these frequencies was within 20 dB of normal thresholds. RESULTS There was no significant difference in serum zinc levels between patients with tinnitus and controls. However, patients with tinnitus who had normal hearing had significantly lower serum zinc levels compared to controls. In contrast, no significant difference in serum zinc levels was found between patients with tinnitus who had hearing loss, and controls. A significant correlation between average hearing sensitivity and serum zinc level was observed. CONCLUSIONS These findings suggest that zinc is involved in the generation of tinnitus, especially in patients whose hearing is relatively normal.

Sound-Evoked Myogenic Potentials and Responses With 3-ms Latency in Auditory Brainstem Response

Objectives The vestibular‐evoked myogenic potential (VEMP) has shed new light on vestibular testing. A large negative deflection with a 3‐ms latency within the auditory brainstem response (ABR) has been reported in some patients with deafness. This negative deflection has been termed the N3 potential and it is assumed to be a vestibular‐evoked potential. This study investigated the relationship between the VEMP and the N3 potential.

Postoperative pain in tonsillectomy: comparison of ultrasonic tonsillectomy versus blunt dissection tonsillectomy.

Intraoperative blood loss, postoperative pain, and postoperative appetite were compared between 15 adult patients who underwent tonsillectomy using an ultrasonically activated scalpel (UT) and 15 adult patients who underwent blunt dissection tonsillectomy with cold steel instruments (BT). The average intraoperative blood loss of the UT group was 4.6 ± 1.9 ml (mean ± standard deviation), while that of BT group was 41.9 ± 12.9 ml. This difference was highly statistically significant (p < 0.0001). In contrast, there were no significant differences in the VAS pain and appetite scores between patients who underwent UT and those who underwent BT on any day in the 6-day postoperative period. Our current results show that UT is a safe technique, and we believe that it should be considered a useful alternative for tonsil surgery.