ABSTRACT
Cases are presented which show the clinical utility of recording an electrocochleographic response to bone-conducted stimuli. The procedure is fraught with problems of acoustic control and artifact generation, but has distinct although limited values in clarifying masking dilemmas in patients with bilateral hearing loss.
Subject(s)
Bone Conduction , Cochlea/physiology , Adolescent , Aged , Electrophysiology , Female , Hearing Disorders/diagnosis , Humans , Male , Middle AgedABSTRACT
A follow-up study of 35 children subjected to electrocochleography (Ecog) was conducted to determine (1) agreement of Ecog results with other audiometric measures obtained subsequently, and (2) accuracy of recommendations for patient management made on the basis of Ecog results. The latter was determined by parental experience, educational placement and achievement, and information from medical and paramedical personnel currently managing the children. These data indicate that Ecog test results are valuable in helping select between possible management alternatives in children who are not testable by behavioral means. However, discussion of two "problem" cases points to possible errors of management that could be made if Ecog results were the only available diagnostic information.
Subject(s)
Acoustic Stimulation , Audiometry/methods , Cochlear Nerve , Hearing Disorders/diagnosis , Action Potentials , Child , Child, Preschool , Humans , Infant , Retrospective StudiesABSTRACT
Using tone burst stimuli with fixed parameters of rise time and duration, a functional relationship has been demonstrated between frequency and intensity of the stimulus and peak latency of electrocochleographic recordings. The feasibility of a "map" of the human cochlear partition has been shown for frequencies above 2 kHz.
Subject(s)
Action Potentials , Cochlea/physiology , Vestibulocochlear Nerve/physiology , Basilar Membrane/physiology , Electrophysiology/instrumentation , Humans , Reaction TimeABSTRACT
Nicotine administered in high doses intravenously (1 mg/kg) and intracochlearly (10 mM) exhibited very little effect on guinea pig cochlear potentials. When administered chronically (1-20 mg/kg, i.p. for 20 days), nicotine demonstrated no effect on cochlear potentials or the number of observed hair cell scars monitored 21 days after the treatment was terminated. Neither chronic nicotine treatment (1-20 mg/kg, i.p. for 20 days) nor acute reserpine pretreatment (5 mg/kg, i.p. 24 hours before) altered the hair cell damaging effects of an intense pure tone (4 kHz, 126 dB SPL, 30 min). No nicotine ototoxicity was detected by the methods used in this study.
Subject(s)
Cochlea/drug effects , Nicotine/pharmacology , Noise/adverse effects , Reserpine/pharmacology , Animals , Blood Pressure/drug effects , Cochlea/innervation , Cochlea/pathology , Dose-Response Relationship, Drug , Female , Guinea Pigs , Male , Organ of Corti/drug effects , Organ of Corti/pathologyABSTRACT
Summary--Aminooxyacetic acid (AOAA; 1 MM) when perfused through the scala tympani of guinea pigs produced a biphasic reduction in the endocochlear potential, together with a shift in the input-output functions of the cochlear microphonics and the compound action potential of the cochlear nerve. Since the ionic (Na+, K+) content of the scala media was not alerted, it appears that such changes did not underlie the reduction recorded in the endocochlear potential. The negative direct current potential recorded in the organ of Corti did not appear to be affected by the drug. Attempts to antagonize the effects of AOAA with pyridoxine failed.
