Auditory brainstem evoked responses in the clinical evaluation and follow-up of insulin-dependent diabetic subjects

In the last few years the use of ABR in the dysmetabolic encephalopathies has aroused considerable interest. Even though brainstem involvement in these syndromes is not yet entirely understood, ABR techniques have provided new and important insights. We studied 60 insulin-dependent diabetic subjects, 29 females and 31 males aged to 17 to 55 yrs, and observed ABR abnormalities in 28.2% of the cases. This impairment affects the I-V interval or central transmission time (CTT), which is considered the most reliable index of brainstem function. The ABR pattern was considered pathologic when the CTT was due 2DS as compared with a sex- and age-matched control. Follow-up studies performed on 20 of these subjects revealed no significant variation in the ABR tracing. This fact, together with the absence or correlation between ABR involvement and metabolic control and glycemia level during the test, could be attributed to a 'structural' damage of the brainstem tissue. In diabetics, we observed a significant correlation (p less than 0.05) between I-V interval shift and an EMG-proved reduction in motor conduction velocity (MCV) of the peroneal nerve. We also found a high incidence of ABR impairment (53%) in diabetics with cardiovascular autonomic failure.