[Multimodal evoked potentials for evaluation of diabetic encephalopathy]

The consequences of chronic diabetes mellitus in the brain are less known than peripheral nerves lesion. Despite of the progress in research the connections between these consequences and metabolic or vascular disorders which accompany diabetes are not univocally determined. The aim of the study is assessment of conduction in central afferent tracts and the velocity of blood flow in pre- and intracerebral arteries in patients chronically treated because of diabetes mellitus. We examined 63 diabetic patients at the age 48.9 +/- 12.9, treated with hypoglycaemic drugs for 13.5 +/- 8.2 years. The symptoms of cranial diabetic neuropathy (CDN) mainly in the form of eyeball motor disturbances were observed in 26 patients. The others had neither signs of central nervous system lesions nor other chronic disease. We estimated patient clinical condition of visual evoked potentials [VEP(s)], brainstem auditory evoked potentials [BAEP(s)] latency, somatosensory evoked potentials [SSEP(s)] and evaluated ultrasonically the mean blood flow velocity in pre- and intracerebral arteries. It was ascertained that the patients with CDN were older and their treatment duration was shorter. Moreover diabetes mellitus type 2 (76.9% p < 0.001) and insufficient metabolic control of the disease (80.8% p < 0.001) were significantly more frequently found in this group. The latencies of assessed multimodal evoked potentials [MEP(s)] in all patients were significantly longer than in the control group. In patients with CDN the lengthening of SSEP(s) latency occurred significantly more frequently than in the other patients. Diabetic retinopathy, arterial hypertension and the changes in blood flow velocity in pre- and intracerebral arteries were more frequently noted in the subgroup of patients with CDN. The difference in flow velocity in pre- and intracerebral arteries between both examined groups was significant.

1. High frequency of lengthened MEP(s) latency in patients suffering from diabetes indicates the presence of subclinical diabetic encephalopathy. 2. Cranial diabetic neuropathy not necessarily influence on central conduction time assessed by the EP method. 3. Diabetic encephalopathy seems to be dependent both on metabolic disorders and vascular changes.