Clinical features of malignant syndrome in Parkinson's disease and related neurological disorders.

Introduction: We elucidated the cause and clinical characteristics of malignant syndrome (MS) in patients with Parkinson's disease (PD), early-onset parkinsonism (EOP), and other neurological disorders.

Materials And Methods: Subjects were 260 patients with PD or EOP, and three patients with other neurological disorders associated with MS. We studied clinical symptoms before and after the onset of MS, and evaluated autonomic function particularly before the onset of MS.

Results: The overall incidence of MS accompanying PD and EOP in our department was eight of 260 patients (3.1%). The incidence of MS in EOP was significantly higher than that in PD. All patients with MS showed comparatively longer duration of illness and advanced stage of PD and EOP. Factors triggering MS included reduced dosage or discontinuation of anti-parkinsonian drugs, reduction of oral intake, dehydration, infectious disease, postoperative state, and treatment with major tranquilizers. Although patients demonstrated marked autonomic symptoms at the onset of MS, in many cases autonomic dysfunction developed before the onset of MS. Even EOP patients, who usually demonstrated milder autonomic dysfunction, showed abnormalities in the correlation between circadian rhythm of blood pressure and pulse rate, and/or abnormal gastric emptying test, suggesting that autonomic dysfunction plays an important role in the cause of MS. Cooling the body, fluid replacement, resumption or increasing the dosage of anti-parkinsonian drugs and administration of dantrolene sodium overcame MS in all cases.

Conclusion: Autonomic dysfunction is related to the cause and clinical features of MS in PD, EOP and some other neurological disorders.