Mayumi Okada

Evoked Otoacoustic Emissions and Electrocochleography in a Patient with Multiple Sclerosis

A 24-year-old woman with multiple sclerosis had right-sided hearing impairment with tinnitus. She underwent electrocochleography (ECochG) and examination of evoked otoacoustic emissions (EOAEs) to assess cochlear function. An acoustic probe to measure EOAEs was inserted into the external ear canal. The ECochG action potential and cochlear microphonics were recorded by a transtympanic needle electrode technique. Both fast and slow components of EOAEs appeared in either the period of deteriorated hearing acuity or when it was improved. They showed normal detection thresholds and input-output curves during both periods. Cochlear microphonics with almost normal detection thresholds and input-output functions were obtained during the period of deteriorated hearing acuity. Action potential (N1) input-output curves during relapse with hearing loss were notably lower in amplitude and longer in latency than those obtained at the time hearing impairment showed improvement. The EOAE and ECochG findings suggested that this patient had almost normal cochlear function, and we assumed from the magnetic resonance imaging and auditory brain stem response findings as well as the ECochG that the hearing impairment was caused by dysfunction of auditory pathways in the brain stem, including structures that contribute to generation of the N1 potential of the ECochG.

A Case of Objective Tinnitus with Palatal Myoclonus

An 8-year-old girl complained of rhythmical high pitched tone tinnitus in both ears. The tinnitus became audible to the examiner by inserting an otoscope and was synchronized palatal myoclonus. There were no obvious abnormalities on pure tone audiometry, X-ray, MRI, EEG or other neurological examinations. The contraction of the Eustachean tube due to palatal myoclonus was observed through a nasopharyngeal fiberscope. Tinnitus was attributed to the constraction of the tube because the sounds occurred when the tube opened. Sound analysis of the tinnitus showed that the tinnitus had a duration of 10-20 ms, frequency of about 2 kHz and irregular rythme of 100-150 times per minute. The literature on the origin and mechanism of objective tinnitus is reviewed. We consider the origin of tinnitus in this case was Eustachean tube contraction due to essential palatal myoclonus.

Statistical Analysis of Patients with Vertigo and Dizziness

A statistical analysis of 2305 patients complaining of vertigo and dizziness who visited our clinic between 1985 and 1991 was performed. Forty-three point seven percent of patients had not been referred by other hospitals or clinics. Moreover, this percentage has resecently been increasing. The ages of the patients were usually between 30-69 years and peaked between 50-59 years. The percentages of males and females were 46.9% and 53.1% respectively. Central disorder included 19% of the patients, peripheral vestibular disorders included 57%, unknown origin was 20% and other was 4%. There were more patients with Menieres disease, sudden deafness, benign paroxysmal positional vertigo than with other peripheral vestibular disorders. Cerebrovascular insufficiency accounted for about 55% of central disorders and the prevalence increased among patients over 40 years old. Hypertention, hyperlipidemia, diabetes mellitus comprised about 55.8% of all complications.