The influence of raised body temperature on auditory evoked brainstem responses.

The influence of raised body temperature on the auditory evoked brainstem responses (BSER) has been investigated in 9 healthy volunteers. Ipsi- and contralateral BSER recordings were obtained before and after raising body temperature by at least 1 degree C by means of a specially constructed heat cradle. In two of the subjects further BSER recordings were obtained after their body temperature had been allowed to fall again to its preheated level. The results for wave V have been analysed in detail: the latency in the 5 men shortened from a mean of 5.84 ms (s.d. 0.193) to a mean of 5.62 ms (s.d. 0.185). For the 4 women the figures were 5.87 ms (s.d. 0.105) and 5.68 ms (s.d. 0.105). Using paired t-tests this change is highly significant (P less than 0.001). Similar changes were observed in the other waves although they were less consistent. In the 2 subjects who were allowed to cool again after heating, the BSER wave latencies returned to their preheated values. It is concluded that nerve conduction rates in the auditory pathway are influenced by body temperature and that this may have to be taken into account when interpreting BSER recordings.