Alternobaric effects on the endolymph.

Hearing loss and vertigo experienced as a result of environmental pressure change has been the subject of many superficial inquiries. The mechanism of these conditions remains obscure. In human volunteers and a rhesus monkey, the effects of intratympanic as well as ear canal pressure changes on the endolymphatic system were measured using electronystagmography (ENG). For the monkey histological evaluation of the pressure effects on auditory structures was performed. We were unable to cause any ENG effects on the monkey neither did we produce intracochlear pathology. The data obtained in humans using a similar approach are presented and explanations for the mechanism related to hearing loss and vertigo in barotrauma are discussed.