Summating potential/action potential ratio in perilymph fistula.
A prospective study of electrocochleography in patients with clinically suspected perilymph fistula was undertaken to determine its predictive value in that disorder. One hundred forty-four patients suspected of having perilymph fistula had electrocochleography performed--34 of these (39 ears) had exploratory tympanotomy. Of the 19 ears with normal preoperative summating potential/action potential (SP/AP) ratio, ten had perilymph fistula identified at the time of surgery. Of the 20 ears with abnormal SP/AP ratio, 16 had perilymph fistula confirmed at exploration, 18 had resolution of symptoms after oval window and round membrane grafting, and only one ear had postoperative persistence of the abnormal SP/AP ratio. This study suggests that an abnormal SP/AP ratio is not only predictive of endolymphatic hydrops, but also of perilymph fistula (both problems of inner ear fluid imbalance). This study also suggests that, while abnormal SP/AP ratio is fairly specific for inner ear fluid imbalance, it is not sensitive.
Meyerhoff
W L
WL
Department of Otorhinolaryngology, University of Texas Southwestern Medical Center, Dallas 75235-9035.
Yellin
M W
MW
D000293:Adolescent; D000328:Adult; D000368:Aged; D001300:Audiometry, Evoked Response; D002648:Child; D002675:Child, Preschool; D003055:Cochlear Microphonic Potentials / Q000502:physiology*; D004427:Ear Diseases / Q000503:physiopathology*; D007758:Ear, Inner; D004432:Ear, Middle; D005072:Evoked Potentials, Auditory / Q000502:physiology*; D005260:Female; D005402:Fistula / Q000503:physiopathology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D010498:Perilymph; D011446:Prospective Studies