Tympanostomy tubes and otic drops

Abstract

Otic drops have been proposed as a form of prophylaxis against the otitis media which follows middle ear contamination by water in patients with tympanostomy tubes. The potential adverse effects of this form of therapy were studied in chinchillas with tympanostomy tubes; 31 chinchillas underwent bilateral tympanostomy tube insertion. Seven animals had a mixture of green dye and Cortisporin otic suspension placed in both external auditory canals 24 hours following the placement of tympanostomy tubes and were sacrificed 30 minutes later for gross examination; 3 of these animals had previous eustachian tube obstruction with Silastic sponge. Twenty-one animals had Cortisporin otic suspension placed in the right external auditory canal on postoperative days 3, 4, 5, 6 and 7. No otic drops were placed in the left ear. Ten of these 20 animals had VIIIth nerve action potentials measured on postoperative day 17 and the other 11 animals had VIIIth nerve action potentials measured on postoperative day 42 followed by immediate sacrifice for histological examination and scanning electronmicroscopy. The remaining 3 animals had VIIIth nerve action potentials measured 21 days following tympanostomy tube insertion and served as electrophysiological controls. The 8 ears receiving Cortisporin otic drops mixed with green dye from animals with normal eustachian tubes showed staining of the round window membrane at sacrifice, while the 6 ears receiving Cortisporin otic suspension and green dye from animals with eustachian tube obstruction demonstrated no dye in the middle ear. All animals receiving Cortisporin otic drops in the right ear showed an intra-aural difference in action potentials with the right ear being attenuated by an average of 10.3 dB at 2,000 Hz, 12 dB at 4,000 Hz, 21 dB and 8,000 Hz, and 26 dB at 12,000 Hz. Morphological study revealed hair cell loss in the hook portion of the cochlea in those animals receiving Cortisporin otic drops. It was concluded from this study that, in patients with patent tympanostomy tubes in place, potentially ototoxic topical agents should be used with caution.

Acute cochleovestibular toxicity due to topical application of potassium iodide

“…Whereas previous studies have demonstrated that the pressure in the external ear canal must exceed 10 cmH 2 O to make fluid pass through a tympanostomy tube [5], the potassium solution apparently entered the middle ear cavity through a tympanostomy tube in the present case.…”

Investigation of Topical Ciprofloxacin Ototoxicity in Guinea Pigs

“…These topical preparations mostly contain an aminoglycoside antibiotic and various solvents. Ototoxic side effects of aminoglycosides are known with their systemic applications; topical ototoxicity has also been demonstrated both in animal experiments and as case reports in their clinical use (3)(4)(5). Thus, an alternative antibiotic with a lower risk of ototoxicity than aminoglycosides could find safer application.…”

The Ototoxicity of Ceftazidime in the Chinchilla Middle Ear

“…Ceftazidime (Tazicef, Smith Kline & French Labo¬ ratories, Philadelphia, Pa) is a thirdgeneration cephalosporin antibiotic with a broad antibacterial spectrum. It is effective against many gram-posiAccepted for publication February 1,1989 tive and gram-negative organisms in¬ cluding Staphylococcus aureus, Haemophilus influenzae, Pseudomonas aeruginosa, and many other enteric organisms.6'8 As such, ceftazidime is an appropriate antimicrobial agent to in¬ vestigate as a potential ototopical an¬ tibiotic. To our knowledge, ototoxic side effects resulting from middle ear administration of ceftazidime have not been previously studied.…”