Chronic labyrinthine ischemia. 
The purpose of the present study was to describe the audiological and vestibular deficit in patients presumed to suffer from chronic impairment of the blood supply to the labyrinth.  Thirty-nine subjects affected by various pathologies often impairing systemic blood circulation, which also presented labyrinthine damage of unclear origin, were evaluated for a possible relationship between these two conditions.  At the time of this study 80 per cent of the subjects showed also a certain degree of increased blood viscosity.  The most common finding in the group was slow and progressive bilateral sensorineural loss of hearing.  In most of the subjects the labyrinthine damage began with high-tone loss which, in time, became a flat curve.  Less common, but still found in many patients, was a fluctuation in threshold.  Short periods of spontaneous subjective improvement in hearing were accompanied by a better result in the Pure Tone Audiogram and Speech Reception Threshold.  The discrimination scores remained generally lower than expected.  Vestibular examination revealed pathological results for all the subjects in at least some of the tests.  The mild subjective complaints concerning equilibrium could be explained by a central nervous system compensation.