Cardiovascular reflexes in syringomyelia.

Cardiovascular reflexes were assessed by simple noninvasive tests in 18 patients with syringomyelia restricted to the spinal cord (syringomyelia) and 22 patients with syringomyelia and brainstem signs (syringobulbia), and the results compared with a control group. Postural hypotension occurred more frequently in patients with bilateral brainstem signs, palatal weakness or vocal cord palsy. Vagal cardiovascular reflexes were disturbed in patients with clinical evidence of involvement of the Xth cranial nerve, and also in those with other brainstem signs. The integrity of the efferent limb of the reflex arc was demonstrated in three patients by testing the heart rate response to intravenous atropine. It was observed that cardiovascular reflexes may be impaired in patients free of symptoms of autonomic dysfunction. These findings may be relevant to the occurrence of sudden death in such patients and to the possible anatomical localization of the defect.