Autonomic nervous disorder in motor neuron disease: a study of advanced stage patients

Autonomic functions were studied in 10 respiratory-support patients with motor neuron disease (MND) at its most advanced stage by means of hemodynamic function tests. The mean duration of disease was 83.4 months (SD 28.0, range 50-140 months). All the patients in this study had lost their ability to breathe spontaneously and were ventilated by respirator. Hemodynamic function tests were performed in 8 out of 10 patients. These patients showed exaggerated sympathetic vasomotor reflexes, increased reflex hypertension and tachycardia in response to the cold pressor test and increased response to administration of adrenaline. However, the responses to both the Aschner eyeball pressure test and injection of atropine were normal, indicating normal parasympathetic nervous system function. Plasma and urine levels of norepinephrine, epinephrine and their metabolites were almost normal in all 10 patients, as were serum dopamine-beta-hydroxylase levels. In patients with the most advanced stage of MND, hyperfunction of the adrenergic sympathetic nervous system was observed, and this was considered to be a symptom characteristic of MND.