The Sympathetic Skin Response in Quadriplegia

Abstract

Cervical spinal cord injury is known to produce severe autonomic dysfunction presum ably due to disrupted communication between the intermediolateral column of thoracic cord and supraspinal influences. To assess one objective measure of sympathetic outflow in this population, sympathetic skin responses (SSR) in sixteen complete and incom plete quadriplegics (mean age 43, range 17-70) were compared to sixteen healthy con trols (mean age 39, range 21-70). Palmar SSRs were elicited by electrical stimulation of 20.0mA for 0.2ms applied in random sequence to cervical and thoracic dermatomes, cor responding to regions above and below the levels of injury. Unexpectedly, responses were obtained from both stimulation sites in fifteen of sixteen quadriplegics, and stimulation site did not significantly affect SSR amplitude. Following cervical stimulation, mean patient amplitudes were 77% less than controls (599 vs. 2549 μV, p = 0.0002) and laten cies 62% greater (2.33 vs. 1.44 sec, p = 0.04). Thoracic stimulation elicited patient ampli tudes 65% less than controls (565 vs. 1627μV, p = 0.0004), and latencies 60% greater (2.50 vs. 1.56 sec, p = 0.03). An inverse relationship between severity of injury and ampli tude was observed. Habituation occurred at both stimulation sites in normals, but only after cervical stimulation in quadriplegics. Amplitude and latency did not correlate with time elapsed from injury. We conclude that the SSR can be measured in most patients with quadriplegia; amplitudes are low and latencies high compared to normal controls. © 1995, Sage Publications. All rights reserved.