Autonomic neuroscience : basic & clinical
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Spinal cord injury (SCI) causes serious disturbances in autonomic innervation and malfunction of the sympathetic nervous system that controls the pelvic organs, blood pressure, skin temperature and sweating. We studied sympathetic sudomotor pathways in 6 healthy subjects and 14 patients with sensory and motor complete SCI on cervical, thoracic and lumbar level. Sympathetic skin responses (SSRs) were provoked by auditory bursts and electrical stimulation of median, pudendal and tibial nerve and recorded from the palmar and plantar skin. ⋯ SSRs following pudendal nerve stimulation in complete SCI above the level L1 are mediated by sacral somatic afferents and a sympathetic pathway originating at the upper lumbar level. The underlying sacro-lumbar reflex circuit is organized on spinal level and requires intact lumbar segments. Tibial nerve stimulation was not found to elicit SSRs below a SCI lesion and we suppose that this type of electrical stimulation cannot activate the spinal sudomotor reflex circuit.