Paroxysmal neurogenic hypertension and its prevention in patients with cervical spinal cord lesions.

Ten patients with clinically complete cervical spinal cord transection of traumatic origin were studied. These subjects do not have supraspinal control of their sympathetic outflow and are prone to marked elevations of blood pressure during visceral and somatic stimulation. This is a result of reflex sympathetic activity via the isolated spinal cord. The arterial blood pressures and heart rates of these patients were recorded on separate occasions during elevation of the urinary bladder pressure and before and after treatment with propranolol, labetalol, phenoxybenzamine and guanethidine. Guanethidine seems to afford the best protection against the marked hypertension occurring during autonomic hyperreflexia. In contrast to the ganglionic blocking agents, it has no anticholinergic or CNS side-effects, and reflex sweating, a valuable indicator of an impending abdominal catastrophe, still occurs. The findings that negative inotropic drugs, i.e. propranolol, guanethidine and labetalol, reduce the marked elevations in pulse pressure which occur during acute bladder distension in quadriplegic patients, suggest that inotropic cardiac responses are mediated by cardiac sympathetic nerves which leave the spinal cord above the T5 level.