Tympanic membrane displacement analysis after glycerol intake: effects on intracranial and intracochlear fluid pressure.

BACKGROUND

Intracranial pressure is transmitted to the perilymph of the cochlea via the cochlear aqueduct and to the endolymph via Reissner's membrane. The tympanic membrane displacement analyzer (TDA) is a new system that may provide a useful, noninvasive, indirect method to identify intracranial and intracochlear pressure changes.

METHODS

We performed measurements in 20 persons with normal hearing and in 29 patients with various unilateral diseases of the inner ear such as sudden hearing loss or Meniere's disease. Another series of measurements were done in 15 normal-hearing persons and in 15 patients with Meniere's disease before and after oral ingestion of glycerol.

RESULTS

In the first series of measurements, no significant differences in the tympanic membrane displacement were found between normal-hearing individuals and patients with unilateral diseases of the inner ear. In the second series, in all individuals a temporary, relative decrease in intracochlear pressure was found after oral ingestion of glycerol but without any significant difference between the two groups.

CONCLUSIONS

These results revealed that the TDA is apparently not useful in the evaluation of patients having Meniere's disease.