Hearing problems and hormonal disturbances in the elderly

The most frequent hormonal diseases attracting audiological interest are hypothyroidism (myxodema) and diabetes mellitus. For many years these diseases have been considered to cause hearing disorders with the lesion located predominantly in the inner ear and central auditory pathways, resulting in sensorineural hearing loss. However, the causal relationship between hearing loss and hypothyroidism has been questioned, and thus a study was undertaken to elucidate this problem. A sample of hypothyroid patients (n = 15) with a median age of 76 years (range 61-92) underwent audiological examination before and after treatment with L-thyroxine (average 5 months; range 2-12), and re-examination (n = 13) after an observation period of average 40 months (range 32-46). No significant improvement in their hearing thresholds, speech reception thresholds or discrimination scores could be demonstrated, and the hearing ability in the hypothyroid patients did not differ significantly from that found in an age- and sex-matched population. In addition, histological investigation of the temporal bones from an 83-year-old woman with myxoedema showed no morphological changes or deposition of glycosaminoglycans. Audiological examinations in patients with insulin-dependent diabetes mellitus also show contradictory results. Therefore, the cochlear and retrocochlear hearing functions were evaluated in 20 patients with diabetic microangiopathy with a median age of 41 years (range 25-66), and in 19 patients without microangiopathy with a median age of 27 years (range 17-42). No significant differences in hearing thresholds or discrimination scores were present between the two diabetic groups, nor was any difference found between the diabetic patients and an age- and sex-matched population. In the patients with long-term insulin-dependent diabetes mellitus, brainstem audiometry revealed abnormal responses in 40%, indicating the presence of diabetic encephalopathy.