Ten patients with Multiple Sclerosis (MS) and ten with Myotonic Dystrophy (MD) underwent an evaluation of cardiovascular reflexes by classic tests, tilt table test and mental stressors. Sympathetic and parasympathetic changes were detected by classical tests in MS patients. Mental stressors appeared able to reveal blood pressure control impairment in MD patients. Lower differential blood pressure was observed during mental stressors administration in MS with brainstem lesions at MRI.