Catecholamine-induced hypertension in lumbosacral paraplegia: five case reports

Hypertension in the patient with SCI is relatively rare and generally restricted to patients with high-level injuries where autonomic dysreflexia can occur. Resting blood pressure in individuals with SCI has been described as lower than that in the normal population. This report describes five previously normotensive teenagers with subsequent paraplegia as a result of gunshot wounds who presented with hypertension secondary to idiopathic elevation of plasma or urinary catecholamine levels. A clonidine suppression test was used as a neuroprobe to inhibit centrally mediated sympathetic outflow, excluding the probability of an extra-axial autonomous catecholamine-secreting tumor as the possible source of hypertension. Positive suppression was achieved in four patients (41%, 37.2%, 4.8%, and 37.2% decreases). One patient had values corresponding to orthostatic changes (an increase of 63%) because of poor compliance with the test. This patient was lost to follow-up; in the remaining four, hypertension resolved at 12, 8, 9, and 6 weeks postinjury. The increased circulating catecholamine level appears to be promoted by a centrally mediated response to the SCI. Elevated blood pressure probably results from an upgraded receptor regulation or an increased receptor sensitivity on the affected cells in the absence of restraining spinal reflexes. The pathophysiology of such hypertension seems to be secondary to autonomic dysfunction and, although it may be transient, it should be treated promptly and reevaluated periodically until stabilization is achieved.