Kiyomi Yoshino

Indications and Results of Gentamycin Injection into the Middle Ear of Patients with Meniere's Disease

Forty-six cases in whom endolymphatic drainage surgery was performed between 1986 and 1992 were followed up for more than 2 years. The results of numerical values (1985 AAOHNS) revealed complete control of definite spells in 26 cases; substantial control of definite spells in 18 cases; limited control of definite spells in 1 case; and insignificant control of definite spells in 1 case. Hence, endolymphatic drainage surgery for Meniéres disease was effective. There are, however, cases who cannot be operated on because of old age or underlying diseases. In these, we injected gentamycin sulfates mixed with prednisolone through a ventilated tube into the middle ear. The results for gentamycin injection based on numerical values showed complete control of definite spells in 12 cases; and substantial control of definite spells in 7 cases. Our treatment of choice for Meniéres disease is endolymphatic drainage surgery which resulted in 96% control of vertigo. In patients for whom operation has failed, in old patients and in those with hearing impairment more than 50 dB, gentamycin injection into the middle ear has proved to be an effective procedure to control vertigo attacks.

Postoperative Changes of Electrocochleography in an Acoustic Tumor Case.

The Electrocochleography (ECoG) findings obtained from 43-year-old woman with an acoustic tumor were studied pre-, per- and post-operatively. Although Compound Action Potential (CAP) presented a normal wavef orm in response to click during the whole process of surgical manipulation, it was transformed in shape into an abnormally broadened negative waveform with mild hearing exacerbation, and it remains unchanged to date.This broad response was considered to be a receptor potential, because it showed no adaptational amplitude reduction. Additionally, postoperative ECoG to tone burst stimuli demonstrated an increase in DC potential following stimulus envelope. Consequently, a broad negative response to click was considered to be mainly composed of an enlarged negative SP.The generation mechanism underlying the phenomenon of an abnormally increased negative SP following excision of an acoustic neuroma was discussed along with several references.CAP as an indicator for intraoperative monitoring may scarecely predict the postoperative auditory function. The establishment of a more reliable monitoring method is required for surgery on cerebellopontine angle tumors.