Technical improvement of chronic infusion of drugs into the guinea pig cochlea by an osmotic pump

Objective: To introduce an improved technique of chronic infusion of drugs into the guinea pig cochlea using an osmotic pump. Methods: A stainless steel tube was surgically implanted into the basal turn of the guinea pig cochlea and connected to the pump. Artificial perilymphatic fluid was infused into the cochlea. Auditory brainstem responses （ABRs） and hair cell morphology were examined. Results: In eight artificial perilymphatic fluid infused cochleas, the thresholds of ABRs were kept in the normal level and no hair cell loss was found 14 days after the beginning of infusion. Conclusion: This result indicates that the improved technique perfects the method of osmotic pump implant for chronic infusion of drugs into the inner ear.