Toshiaki Yagi

Clinical Evaluation of the Auditory Evoked Brain Stem Response

A clinical evaluation of the auditory evoked brain stem response (BSR) has been performed in eleven artificial, and twelve pathological cases of conductive hearing loss, and also in seven patients with deafness from Menieres disease. The latency of wave V of the BSR was plotted as a function of auditory stimulus intensity (of clicks from 10 dB to 85 dBHL) to produce latency-intensity (L-I) curves for subjects with hearing losses, and compared to those from a normal population. L-I curves from conductive hearing losses of both artificial, and pathological cases showed characteristic horizontal shifts to the right (in dBHL); thresholds determined by BSR audiometry were within 15 dB of the thresholds obtained by standard audiometry (4 kHz) in 83 f of these cases. L-I curves from Menieres patients were within the normal range at high stimulus intensities but showed a marked deviation from normal at low intensities; thresholds estimated by BSR audiometry in Menieres disease were usually lower than those determined by standard audiometry (4 kHz). The results indicate that BSR audiometry can be useful in the evaluation, differentiation, and threshold determination of peripheral auditory pathologies.

Lidocaine Hydrochloride Depression of Cochlear Microphonics and Action Potentials in the Cat

The depressive effects of lidocaine hydrochloride on cochlear function were observed in 18 cats. Round window cochlear microphonics and action potentials were recorded before and after lidocaine application onto the round window membrane. Lidocaine hydrochloride depressed both CM and AP and these effects were always reversible with a maximum recovery time of six hours. The times of maximum depression and recovery of cochlear function were directly related to lidocaine concentration. It seems possible that fairly reproducible, reversible cochlear lesions can be made by expanding on this study.

Suspected Sacculogenic Dizziness; Surgical Treatment By Partial Ablation — A Case Report

This report concerns the findings and subsequent surgical procedures in a case of a 36-year-old male who complained of a four year history of frequent attacks of dizziness and tinnitus in the right ear. The dizzy attacks were vibratory in nature, or short duration and of short intervals, and always simultaneously accompanied by tinnitus. Hearing acuity in the right ear was slightly impaired but within normal limits. The history, clinical examination and pertympanal inner ear anesthesia supported the diagnosis of a lesion in the labyrinth, possibly in the otolithic organs as opposed to the ampullae. Surgical extirpation of the utricle and the lateral and anterior ampullae was initially attempted. The operation temporarily abolished the dizzy attacks and hearing was preserved. However, the patient suffered a recurrence of his symptoms two months after the surgery. Subsequent to this recurrence, a surgical modification of the saccule was then attempted which successfully abolished his dizziness but unfortunately destroyed the hearing in this ear. The essential objectives outlined in this report are twofold. Primarily, the authors have attempted a description of the clinical manifestations of an inner ear lesion localized in a specific part of the labyrinth. Secondly, a description was presented of the partial success of selective surgical ablation of damaged inner ear structures with an attempt to preserve the unaffected individual endorgans.

Auditory-Evoked Brain Stem Responses in the Human: Response Differences Between Monaural and Binaural Stimulation

The effects of the monaural and binaural stimulation to the auditory-evoked brain stem response (BSR) were studied in 16 normal hearing adults. The BSRs were recorded from the scalp using computer averaging technique. A click was used for a stimulating sound. The latencies of waves I through VII, the overall BSR amplitude and probability of detection of the various waves were compared as a function of monaural stimulation (with ipsilateral and contralateral recording) and binaural stimulation (with unilateral recording). Overall amplitude of the BSR waveform following binaural stimulation was larger than the amplitude following monaural stimulation. Also, the waveform and the amplitude of the BSR following binaural stimulation were quite similar to the simple summation of the monaural ipsilateral and contralateral recordings. This finding may be comparable to psychoacoustic data wherein simultaneous binaural auditory stimulation results in a threshold which is about 3dB lower than monaural stimulation.