HYPOTENSIVE AND BRADYCARDIAC RESPONSES TO THYROTROPIN-RELEASING-HORMONE IN A COMATOSE PATIENT

A 46-year-old female motorcyclist, who suffered injuries to the brain stem in a traffic accident, showed hypotensive and bradycardiac responses to thyrotropin-releasing hormone (TRH) given to counter consciousness disturbance. The cardiodepressive responses to TRH were reduced with i.v. pretreatment with atropine sulfate, suggesting an involvement of the vagal nervous system in the development of the responses. Furthermore, this patient had complicated impairments in the sympathetic nervous system, which were revealed by the results of testing baroreceptor reflex sensitivity to pharmacological alterations in blood pressure. We thus speculate that the hypotensive and bradycardiac effects of TRH observed in this patient may result from derangements of the sympathetic nervous system caused by the injuries. This case report is believed to be a novel description of the cardiodepressive effects of TRH.