Electrocochleography and gentamicin therapy for Ménière's disease: a preliminary report.
OBJECTIVE
It is widely held that an enlarged summating potential (SP) relative to the eighth nerve action potential (AP) is a reflection of endolymphatic hydrops. Aminoglycosides are an accepted treatment for incapacitating Ménière's disease and are known to affect both sensory and secretory cells of the inner ear. The intent of this study was to determine whether this effect on secretory cells could be objectively confirmed by virtue of changes in the electrocochleogram (ECoG) of patients receiving gentamicin therapy for Ménière's disease.


METHODS
This was a prospective longitudinal study of repeated ECoG measures in three groups of subjects. Ménière's patients undergoing gentamicin treatment were compared with two control groups: individuals with stable Ménière's disease and normal-hearing control subjects.


METHODS
The study was conducted at a tertiary referral center.


METHODS
The sample included 21 normal-hearing subjects, 15 patients with stable unilateral Ménière's disease, and 12 with disabling unilateral Ménière's disease.


METHODS
For patients with disabling Ménière's disease, gentamicin was administered transtympanically. Audiograms, impedance tests, and ECoG were performed twice for all subjects.


METHODS
The SP and AP amplitudes, AP latency, and SP/AP ratio of the EcoG were measured.


RESULTS
A statistically significant reduction in the SP/AP ratio was observed after gentamicin administration (analysis of variance interaction effect: F2 = 5.64; p = 0.0065).


CONCLUSIONS
The significant reduction in the SP/AP ratio in the gentamicin-treated Ménière's group supports the hypothesis that gentamicin improves the electrophysiologic function of the cochlea, possibly by reducing the severity of the associated endolymphatic hydrops.
Adamonis
J
J
Audiology Services, Sunnybrook and Women's College Health Sciences Centre, University of Toronto, Ontario, Canada.
Stanton
S G
SG
Cashman
M Z
MZ
Mattan
K
K
Nedzelski
J M
JM
Chen
J M
JM
D000158:Acoustic Impedance Tests; D000704:Analysis of Variance; D000900:Anti-Bacterial Agents / Q000627:therapeutic use*; D001299:Audiometry; D001300:Audiometry, Evoked Response / Q000379:methods*; D016022:Case-Control Studies; D003055:Cochlear Microphonic Potentials; D016903:Drug Monitoring / Q000379:methods*; D005839:Gentamicins / Q000627:therapeutic use*; D006801:Humans; D008575:Meniere Disease / Q000145:classification / Q000175:diagnosis* / Q000188:drug therapy*; D011446:Prospective Studies; D011930:Reaction Time; D012720:Severity of Illness Index
D000900:Anti-Bacterial Agents; D005839:Gentamicins