Ototoxicity of topical gentamicin preparations.
OBJECTIVE
To document that commercially available topical gentamicin-containing eardrops carry a risk of ototoxicity if they reach the middle ear through a tympanic membrane defect.


METHODS
Clinical study, retrospective case-note review.


METHODS
Department of Otolaryngology, The Toronto Hospital, University of Toronto.


METHODS
Sixteen patients were identified with well-documented histories, physical findings and laboratory investigations consistent with topical gentamicin-induced ototoxicity. One patient with incapacitating unilateral Meniere's disease underwent successful intentional vestibular ablation using topical gentamicin/steroid drops.


RESULTS
In all cases of inadvertent ototoxicity, patients had used the drops for longer than 7 days (average 20.7 d) prior to symptoms developing. All patients developed vestibulotoxicity that was confirmed on ENG testing. Only 1 patient had a noticeable worsening of cochlear reserve. Deliberate and successful therapeutic ablation of vestibular function in a patient with unilateral Meniere's disease confirms the vestibulotoxic nature of commercially available topical gentamicin preparations.


CONCLUSIONS
Physicians should consider the potential for ototoxicity if gentamicin-containing eardrops (and by extrapolation all topical aminoglycoside drops) are used for longer than 7 days in patients with a tympanic membrane defect. These preparations should not be used in the presence of healthy middle ear mucosa and should be discontinued shortly after the discharge has stopped. It is important to recognize that toxicity is primarily vestibular rather than cochlear.
Department of Otolaryngology, The Toronto Hospital, University of Toronto, Ontario, Canada.
A P
AP
Bath
R M
RM
Walsh
M L
ML
Bance
J A
JA
Rutka
D000287:Administration, Topical; D000328:Adult; D000368:Aged; D007758:Ear, Inner / Q000187:drug effects*; D005260:Female; D005839:Gentamicins / Q000008:administration & dosage / Q000009:adverse effects*; D006311:Hearing Disorders / Q000139:chemically induced; D006801:Humans; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D014717:Vertigo / Q000139:chemically induced; D015837:Vestibular Diseases / Q000139:chemically induced
D005839:Gentamicins