Amplitude loss of electrically and magnetically evoked sympathetic skin responses in early stages of type 1 (insulin-dependent) diabetes mellitus without signs of dysautonomia.

The sympathetic skin responses following both electrical nerve (eSSRs) and magnetic (mSSRs) brain stimulations have been investigated in 19 insulin-dependent diabetic patients with no evidence of a peripheral neuropathy or dysautonomia and compared to those obtained in 10 age-matched healthy subjects. SSR was recorded from the right hand and foot, controlateral to the stimulated side. The main findings were amplitude loss and disappearance of the eSSR in 12/19 (63.2%) and 11/19 (57.9%) patients, occurring more frequently than the mSSR; 7/19 (36.8%) and 5/19 (26.3%) were recorded from the hand and foot, respectively. The SSR to electrical stimulation was significantly reduced in the upper and lower extremities (p < 0.0001) compared to control results, whereas latencies were normal to both stimulation modalities. Only in two cases the responses were absent from the foot, one following electrical stimulation and the other after magnetic stimulation. No correlation was found between the SSR and metabolic indexes of diabetes mellitus or conduction velocity studies. On the basis of these data an early impairment of afferent pathways may be postulated.