Autonomic dysfunction in diphtheritic neuropathy.

Sympathetic and parasympathetic function and somatic nerve conduction were assessed in ten patients with diphtheritic neuropathy and 28 controls. None of the patients had postural hypotension. The Valsalva ratio was abnormal in two patients who also had myocarditis, but it was normal in five cases. Cardiac vagal dysfunction was found in five patients. One case showed cardiac parasympathetic denervation despite normal conduction velocity in the limbs.