Hearing Decrease After Loss of Cerebrospinal Fluid: a New Hydrops Model

Abstract

Walsted A. Salomon G. Thomsen J. Tos M. Hearing decrease after loss of cerebrospinal fluid. a new hydrops model? Acta Otolaryngol (Stockh) 1991: 111: 468-476.

In a prospective study of 12 patients undergoing operation for acoustic neuromas the hearing on the contralateral ear was tested before and systematically day by day after operation. in 11 cases a perceptive loss of at least 20 dB was found at one or more frequencies during the first 2 postoperative weeks. a maximal average threshold decrease of 16.5 dB was found in the trebble (2.4. 8 kHz average), while a tendency of a more pronounced decrease of 19.6 dB was seen in the low frequencies (125. 250. 500 Hz average). After 3 months the hearing had normalized in all cases. the explanation for the transitional loss supports the present theory: the loss of cerebrospinal fluid during operation diminishes the CSF pressure. This decrease is transmitted to the perilymph via the cochlear aqueduct producing a transitory perilymphatic hypotonia, which in turn hydromechanically results in a relative endolymphatic hypertension mimicking an endolymphatic hydrops thus representing a human hydrops model.

Key Words:

• endolymphatic hydrops model in humans
• cerebrospinal fluid pressure and hearing
• hearing decrease after loss of CSF. perilymphatic hypotonia