Clinical features of sudden sensorineural hearing loss in diabetic patients

Clinical studies of sudden sensorineural hearing loss (SSNHL) rarely focus on diabetic patients. We attempted to elucidate the clinical features of SSNHL in diabetic patients and to evaluate the factors influencing hearing deficits.

Retrospective.

A retrospective review of diabetic patients with SSNHL was conducted at National Taiwan University Hospital from 1984 to 2003. The demographic and clinical characteristics, audiometries, and course of hearing recovery were reviewed.

Sixty-seven patients (38 men and 29 women) with a mean age of 60.1 +/-11.9 years were recruited. The mean duration of diabetes was 7. 5 +/- 7.7 years. The mean fasting plasma glucose (FPG), postprandial plasma glucose (PPG), and glycosylated hemoglobin (HbA1C) at admission were 12.4 +/- 5.3 mmol/L, 14.5 +/- 5.4 mmol/L, and 9.9 +/- 2.9 mmol/L, respectively. Profound hearing loss was very common in this series (44.8%). Hearing impairment was also noted in the opposite ear, especially in the high frequencies. Presenting symptoms, the duration of diabetes, the FPG, and the HbA1C had no significant correlations with the severity of hearing loss. After adjusting for sex and age, a high PPG level was significantly associated with opposite-ear hearing deficits in the middle frequencies. In follow-up, the low and middle tone hearing thresholds in the lesion ears improved more than that at high frequencies, but they still did not return to baseline. Hearing consistently improved within 2 months after disease onset, but improvements were rare thereafter. With suitable treatment, optimal glycemic control could be achieved even under high-dose steroid regimens.

In diabetic patients with SSNHL, hearing loss in the contralateral ear and the profound type hearing loss in the lesion ear were commonly noted. The age and PPG level had significant correlations to contra-ear hearing loss. The poor prognosis of sudden deafness in diabetes patients may be caused by preexisting microvascular lesions in the inner ear, and the PPG level could be a risk factor indicator for cochlear dysfunction in diabetic patients. High-dose glucocorticoid should not be contraindicant in diabetic patients with SSNHL. Whether a longer duration of treatment will result in more hearing improvement is worthy of further study.