Sympathetic dysfunction of central origin in patients with ALS

Amyotrophic lateral sclerosis (ALS) is a severe, progressive disease affecting both the central and peripheral parts of the motor nervous system. Some studies have shown unequivocal indications of a more disseminated disease also affecting the autonomic nervous system. We therefore evaluated the centrally and peripherally mediated autonomic vascular reflexes by (i) the local 133-Xenon washout technique, and (ii) the head-up tilt table test. The results correlated to clinical scores. We examined nine ALS patients and 15 age-matched controls. The 133-Xenon washout test showed a significant reduction in the centrally mediated sympathetic vasoconstrictor response, but a preserved locally mediated response in the patients. In the head-up tilt table test, the patients had a significantly higher mean arterial blood pressure (MAP) compared with controls, probably due to a general increase in vascular resistance. There were no correlations between the ALS Severity Scores and blood flow changes, diastolic blood pressure or MAP. Our study supports previous results, but indicates abnormalities consistent with a solely centrally located sympathetic dysfunction in ALS, independent of the stage of the disease.