Frequency characteristics of summating potential in Menière's disease.

SP iso-response functions in 9 patients with Menière's disease were examined for differences in the properties between +SP and -SP. The iso-response functions of +SP and -SP exhibited a large difference. The iso-response function for +SP was centered at high frequencies (around 9 kHz in most cases) with fairly steep slopes on both sides towards both higher and lower frequencies, whereas -SP showed a low-pass function. The tendency was found for patients with normal hearing at high frequencies to have a larger Q10dB than patients with a hearing loss. The difference in properties between +SP and -SP suggests the possibility that +SP may provide different information on the pathophysiology of Ménière's disease from that obtained from -SP.