PERIPHERAL AUTONOMIC INVOLVEMENT IN THE CARPAL-TUNNEL SYNDROME

The sympathetic skin response (SSR), evoked from the middle finger of both hands by electrical stimuli to the median nerve (MN) at the wrist , was studied in 21 patients with bilateral carpal tunnel syndrome (CT S) and in 16 patients with monolateral CTS (14 at the right and 2 at t he left side) without clinical signs of autonomic involvement. In mono lateral and bilateral CTS there was a decrease in the SSR areas of bot h sides. In monolateral CTS the decrease was greater contralaterally t o the lesion. A decrease in the SSR in CTS generally indicates a local blockade of sympathetic nerve excitability due to MN entrapment. Cont ralateral reduction of the sympathetic response suggests an involvemen t of the efferent pathway of the autonomic reflex far from the lesion at the wrist. However, dispersion of the excitement over a long distan ce and throughout numerous synaptic connections may affect contralater al more than homolateral SSR excitability. Finally, sympathetic damage in CTS is in accord with the anatomofunctional correlation (in the pe ripheral nerve and ganglia) between somatic sensory, which were most m arkedly involved in our patients, and sympathetic afferent nerve fiber s.