Cochlear temperature correlates with both temporalis muscle and rectal temperatures. Application for testing the otoprotective effect of hypothermia

Conclusions. During systemic hypothermia, the internal temperature of the rat cochlea correlates best with the temporalis muscle and rectal temperatures. These positive correlations will be used in future studies to assess the efficacy of mild and moderate hypothermia to protect hearing against the progressive loss caused by electrode insertion in a clinically relevant model of cochlear implantation trauma. Objective. To monitor the internal temperature of the cochlea during induced systemic hypothermia using a reference tissue instead of an internal cochlear temperature probe. Material and methods. The temperatures of the cochlea, brain, temporalis muscle and rectum were determined during periods of normothermia ( 37 degrees C), mild ( 33 degrees C) and moderate ( 30 degrees C) hypothermia and slow rewarming in anesthetized adult Fisher rats. These values were compared using statistical analysis to establish the best correlations between the temperature of the cochlea and the temperature at the three other temperature measurement sites. Results. The strongest correlations with the internal temperature of the cochlea during the induction of mild- to- moderate hypothermia were obtained for the temperatures of the ipsilateral temporalis muscle and rectum.