Basal sympatho-adrenal function in quadriplegic man

Plasma catecholamines (CA) were measured at 15 min intervals over a 4 h time period in 5 supine, chronic, quadriplegic male human subjects. CA levels fluctuated over time through a wide range, often exhibiting brief bursts of very high CA levels which differed from the slower duration fluctuations seen in normal subjects. Spikes of increased plasma CA often, but not always, correlated with muscle spasms, urination or pain and were often accompanied by appropriate changes in blood pressure and heart rate. When examined over a 4 h period, the subjects' median plasma norepinephrine (NE) levels (305.5±26.8pg/ml) were within the normal, age-corrected range while plasma epinephrine (E) levels (210.4±48.9pg/ml) were higher than those seen in normal control subjects (89.0±6.9pg/ml) tested under similar conditions. Also, plasma NE and E levels in the quadriplegics correlated positively in 3 out of 5 subjects which was similar to the balance in normal subjects. Therefore, resting sympatho-adrenal tone, as indicated by plasma catecholamine levels, in quadriplegics is not decreased, but is either normal or increased. Activation of these systems is probably under the control of local spinal reflexes which appear to be capable of maintaining many of the resting autonomic functions of the individual.