Hideji Okuno

Vestibular schwannoma showing a dural tail on contrastenhanced magnetic resonance images

The dural tail on contrast-enhanced magnetic resonance (MR) images, frequently observed in meningiomas, has been used to distinguish between cerebellopontine angle meningiomas and vestibular schwannomas. We report on a 66-year-old female with vestibular schwannoma showing the dural tail on contrast-enhanced MR images. Histological examination revealed that the dural tail corresponded to the thickened dura mater comprising of collagen fibres and scattered hyalinization with no tumoral invasion.

Electrically Evoked Auditory Brainstem Response by Direct Electrical Stimulation to the Cochlear Nerve in Acoustic Neuroma Patients

The electrically evoked auditory brainstem response (EABR) was recorded by direct electrical stimulation of the cochlear nerve in 8 acoustic neuroma patients. The EABR by electrical stimulation of the cochlear nerve at the fundus of the internal auditory canal was almost similar to those previously reported from cochlear implant patients in waveform morphology and wave latencies. However, the wave corresponding to wave II in human auditory ABR was not recorded in the EABRs by stimulation of the distal part of the intracranial cochlear nerve. These results suggest that the cochlear nucleus does not contribute to the generation of wave II in ABR.

Ethyl Loflazepate in the Treatment of Tinnitus

Ethyl loflazepate (Meilax®) was administered orally to 91 patients suffering from tinnitus, 58 with tinnitus and sensorineural hearing loss, 27 with tinnitus without hearing loss, and 6 with tinnitus accompanied by sudden deafness. The clinical severity of tinnitus was evaluated every two weeks in terms of loudness, continuity and annoyance. Medication was rate of as effective in 27.5%, moderately effevtive in 33%, slightly effective in 17.6% and not effective in 21.8% at the end of treatment. Effectiveness depend on the duration of treatment. Patients treated for a relatively long period showed greater clinical improvement. Two patients complained of sleepiness as a side effect. It was concluded that ethyl loflazepate is effective in reducing severity of tinnitus.

Hearing Assessment of Non-noise Exposed Population Survey on Company Employees in Metropolitan Tokyo

平成2年度に実施された一企業 (第3次産業) の東京地域の従業員での成人健診における選別聴力検査とその有所見者の再受診の結果につき, 検査システムの有効性や信頼性, また, 集団 (企業) の聴力の問題の把握や, 各個人の耳疾患や加齢による聴力低下の早期発見という目的をどの様に果たしたかを検討事項として, 調査を行った。その結果, 検査システムの有効性・信頼性を向上させるためのいくつかの改善すべき点を認めた。 特に再受診率を高めることが今後の課題であると思われた。 しかし, 検査システムとしては問題があったが, 伝音難聴をはじめとして各種難聴疾患を発見・指摘しこの点での目的は果たせていた。 加齢による聴力低下や集団としての聴力の問題の検討は健診の充実とともに, 今後の調査の継続が必要と思われた。

Aeration of the tympanomastoid cavity and eustachian tube function.

The degree of opening and closing of the eustachian tube varied with changes in body position. However, neither the duration of auditory tube opening and closing nor the opening pressure varied.The physiological reason for such findings appears to involve the anatomic course of the pharyngeal orifice of the auditory tube and of the auditory tube itself, protecting the middle ear cavity from invasion by secretions and from infections. When a patient with mild dysfunction of the auditory tube lies on his side, the middle ear cavity pressure becomes markedly positive. Involvement of congestion in the venous plexus of the middle ear cavity and of gas emission is suggested in this shifting of tympanic compliance to the positive pressure side with change in head position or when lying on the side. These findings, show that the ventilation of the middle ear cavity under environmental pressure, keeping the internal pressure of the middle ear cavity equal or slightly higher than atmospheric pressure at all times, serves to maintain the conductive efficiency of the middle ear cavity through adjusting of the internal pressure of the middle ear cavity to atmospheric pressure by the opening and closing of the auditory tube.

Implications of the Results of Stepping Test in Patients with Unilateral Vestibular Dysfunction

The stepping test is a dynamic test for the evaluation of equilibratory function, whose accuracy is so high that it enables us to detect even a slightly compensatory stage labyrinthine disturbance undetectable with static equilibratory function tests. Because it is a equilibrium movement test, it requires a more precise adjustment of the pyramidal and extrapyramidal systems. A stepping test with eyes closed allows us to record and observe even a slightest disturbance of the pyramidal and extrapyramidal tract that cannot be demonstrated with static equilibratory function tests. In patients with unilateral labyrinthine disturbance, a deviation occurs during the stepping test. No publication is available, however, that deals with the time course change in the stepping record.We recorded the center of gravity in the stepping test by KINETOGRAVICORDER and studied time-course change in the recording. Our findings were as follows:Nine patients with unilateral Menieres disease (in normal phase), selected as subjects, were instructed to face front in the dark. In that position, they performed steppings in an exact rhythm (1.2Hz) with eyes closed, while recordings were taken to examine the onset of deviation. Deviation started with the 8th to 17th step (average 12.4th step), or 6.4sec to 13.6sec (average 9.95sec) after the initiation of steppings.The above results suggest that: (1) A voluntary movement due to central programming is eliminated by approximately about 12 steppings to be replaced by an extrapyramidal reflex. The period during which the said 12 steppings or thereabouts are performed (about 10sec) is the latent time for deviation, (2) a regular rhythm accelerates the manifestation of laterality in the motor reflex, (3) the imposition of regular rhythm has an element of the Jendrassik maneuver, so that it encourages the manifestation of deviation in steppings. We concluded therefore that the stepping test would yield sufficiently meaningful data even if the number of steps to be taken was reduced from that in the past test.