Sudden sensorineural hearing loss (SSNHL) is defined as the sudden onset of unilateral sensorineural hearing loss of ≥30 dB over at least three contiguous audiometric frequencies (1). Diabetes is a risk factor of SSNHL, possibly due to microangiopathy (2). Currently, the clinical studies of SSNHL rarely focus on diabetic patients. The correlations between biochemical data and hearing outcomes in SSNHL are seldom analyzed. We analyzed the characteristics of SSNHL in diabetic patients and tried to elucidate the possible prognostic factors.
Medical charts of diabetic patients admitted for SSNHL from 1984 to 2003 were retrospectively reviewed. A total of 67 patients (38 men and 29 women) with a mean age of 60.1 ± 11.9 years were included. Their mean duration of diabetes was 7.5 ± 7.7 years and mean HbA1c 9.9 ± 2.9%. Measuring by initial and follow-up pure-tone audiometries, improvement in hearing was divided into favorable outcome (FO) (hearing returned to at least the same level as the opposite ear or with improvement ≥30 dB) or poor outcome (PO) (hearing improvement <30 dB) groups.
All of the patients denied previous episodes of SSNHL. After treatment, 23 patients (34.3%) had a favorable hearing outcome, while 44 patients (65.7%) had a poor hearing outcome. The age and sex distributions were not statistically different in the FO and PO groups. Duration of diabetes, medication type, and control levels of diabetes, hypertension, or hyperlipidemia were also not correlated with hearing outcome. Factors such as the type of initial audiogram, the period of SSNHL onset to therapy, and the presenting symptoms (vertigo, tinnitus, aural fullness, etc.) had no significant impact on the hearing prognosis.
SSNHL occurring in the summer had better a hearing outcome than that occurring in the nonsummer seasons (adjustedfor sex and age, odds ratio [OR] for the PO group 0.093 [95% CI 0.02–0.428], P = 0.002). The glucocorticoid regimen had a dose-dependent effect on the outcome (χ2 for trend test 5.4159, P = 0.020). Using no steroid treatment as a reference group, the adjusted OR for the PO group was 0.762 (0.231–2.516, P = 0.656) and 0.355 (0.157–0.802, P = 0.013) for the low- and high-steroid groups (prednisolone 1 mg · kg−1 · day−1 for at least 7 days), respectively. When we compared the hearing outcomes using binary covariates, such as using or not using steroids, the difference was not significant. Vitamin B treatment had a significantly adverse effect for hearing recovery (adjusted OR for the PO group was 3.676 [1.081–12.5], P = 0.037). The adjusted OR for the PO group for every gram per liter increment of serum albumin was 0.659 (0.471–0.922, P = 0.015). The increment in serum lactate dehydrogenase was borderline significantly correlated with poor hearing outcome (P = 0.050), but the effect was not significant after adjustment for sex and age. In multivariate logistic regression, only the increment in albumin remained independently associated with the hearing outcome.
In conclusion, our data reveal that onset in summer and higher serum albumin concentrations are favorable prognostic factors of SSNHL in diabetic patients. A vitamin B regimen may lead to a poor hearing outcome. We suggest a high-dose glucocorticoid treatment for SSNHL in diabetic patients. Further prospective studies are needed to confirm the true effects of these prognostic factors.