By performing electrochleography (AP, SP and CM) on 34 patients with sudden deafness, it was thought that the pathophysiology of this disease could be deduced. The various waveform patterns of AP and SP responses obtained in cases of sudden deafness were classified into the following types: 1) AP high response; 2) decreased AP high response; 3) AP low response; 4) dominant -SP; 5) -SP or +SP; and 6) AP, SP no response. The cases showing the type of dominant -SP and AP high response had satisfactory prognoses. In these cases the sensory epithelium and the cochlear nerve seemed to indicate a reversible condition being affected by the temporary functional block. Furthermore, it seemed to indicate that the neural regions related to the source of AP(N1) response were impaired in cases in which CM were recorded at normal response threshold in spite of the absence of AP(N1) response. In the unsatisfactory prognosis cases with decreased AP high response, AP low response and AP, SP no response in which only the extremely low or depressed CM responses could be recorded, it seemed that the sensory epithelium and the cochlear nerve were affected permanently, although the degree of impairment varied.

Acoustic Stimulation↗

PubMedDate not supplied

Interferon-induced sudden hearing loss.

With the increasing long-term use of interferon (IFN), several new adverse effects have been recognized. Very little attention, however, has been paid to auditory acuity. We encountered 3 cases of sudden hearing loss associated with IFN. We then conducted a prospective study to assess the auditory function of 73 patients receiving IFN. Auditory disability (tinnitus and/or hearing loss) occurred in 32 patients (43.8%) during IFN therapy, among which audiometry documented sensorineural hearing loss in 27 cases (36.9%); 17 (48.6%) of the 35 patients receiving IFN-beta had auditory disability, including hearing loss in 13 cases (37.1%), and 15 (39.5%) of 38 patients receiving IFN-alpha suffered from auditory disability. There was not much difference between the influences of IFN-alpha and -beta. Auditory disability frequently developed in the later stages of treatment, and most patients recovered 7-14 days after the discontinuation of IFN. The results demonstrate that sudden hearing loss can occur as a side effect of treatment with IFN. This may reveal the association between autoimmunity and sudden hearing loss.

Adult↗