Sympathetic skin response in patients with reflex sympathetic dystrophy.

The sympathetic skin response (SSR) was recorded in four patients diagnosed with reflex sympathetic dystrophy (RSD) in one upper limb using Kozin's clinical criteria in conjunction with a three-phase bone scan. All patients had sustained cerebral vascular accidents and were classified as Stage I RSD. The SSR was recorded in both hands after each of ten contralateral median nerve surface stimulations and in both feet after each of ten contralateral peroneal nerve surface stimulations. Amplitude, onset latency, and number of phases were recorded for all responses in each limb. Mean amplitude, onset latency, and the number of phases of the five largest potentials were then determined. In all patients, there was a statistically significant difference in the amplitude and latency of the SSR in the involved limb compared with the uninvolved limb; mean amplitude of the involved limb was greater than the mean amplitude of the uninvolved limb (P < 0.001), and latency to onset of the SSR in the involved limb was shorter than that of the uninvolved limb (P < 0.001). There was no statistically significant difference in mean amplitude and latency between the involved side and uninvolved side responses as measured at the feet.