Yoshie Inoue

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.

Implantation of Solvent Dehydrated Dura for Preventing Frey's Syndrome.

We attempted to prevent Freys syndrome by using solvent dehydrated human dura mater in the closing procedure after parotidectomy. The area was covered by the dura and sutured. The presence or absence of symptome was noted subjectively and by Minors method. One out of 17 patients reported a positive symptom during the observation period of 6 to 35 months.Neither foreign body reaction, infection nor other adverse reaction occured after the dura implantation. This method is useful in prevention of Freys syndrome.