Postural hypotension--cochleo-vestibular hypoxia--deafness.

The postural hypotension syndrome i.e. a sudden fall in blood pressure as a result of sudden rising, leading to severe vertigo and fainting has been known for a very long time, but the diagnostic criteria for hypotension has changed recently. Medical textbooks claim that unless systolic B.P. falls more than 20 mm upon rising it is not hypotension. A recent British investigation employing radio-active isotope tomography has shown that an orthostatic fall in B.P. of 10 mm in elderly persons may cause a 60% decrease in cerebral blood-flow lasting several minutes (2). It has been estimated that at least 30% of the patients in nursing-homes suffer from vertigo. Last year 6000 elderly persons in Denmark were treated for fracture of the femoral neck. This study points out that concurrent with vertigo and fainting the cochlea does suffer from decreased blood supply, and hearing subsequently deteriorates. The reason why this has not been recognized until now is that while vertigo comes and disappears within minutes and is distinctly felt by the patient, the hearing loss develops nearly as slowly as does hearing loss caused by moderate noise exposure over many years. Axelsson et al. in a recent study point out that at least TTS is influenced by cochlear blood flow (4).