Achieving Mild Therapeutic Hypothermia in the Human Cochlea.

Objective: To determine temperature and duration of cooling necessary for achieving cochlear mild therapeutic hypothermia (MTH) via ear canal cooling using cool water and earmold attached to a Peltier device.

Study Design And Setting: Human temporal bone lab study performed at the University of Mississippi Medical Center.

Interventions: Cochlear cooling via the ear canal using water irrigation and an earmold attached to a Peltier device. Temperature analysis through implanted thermal probes within the cochlea.

Main Outcome Measures: Temperature changes in the cochlea.

Results: Irrigation of the ear canal with water resulted in achieving MTH in approximately 4 minutes using cool water (30°C) and in approximately 2 minutes using ice-chilled water. After 20 minutes, irrigation of the ear canal using cool water plateaued at a ∆2°C while cooling with ice-chilled water results in an average ∆4.5°C. We observed MTH using a medium-length earmold attached to a Peltier device after approximately 22 minutes of cooling and achieved a maximal average ∆ of 2.3°C after 60 minutes of cooling. Finally, we observed that a longer earmold (C2L) with greater proximity to the eardrum resulted in more efficient intracochlear temperature change, achieving MTH in approximately 16 minutes.

Conclusions: MTH of the cochlea can be achieved with water-based ear canal irrigation and via a Peltier device connected to an aluminum earmold.