Loss of Autonomic Nervous System Control of Blood Pressure in Patients with Parkinson’s Disease

Parkinson’s disease (PD) manifests with motor symptoms of tremor, bradykinesia, muscle rigidity and postural instability. However, various nonmotor symptoms (NMS) have recently been recognized, among which autonomic dysfunction is observed long before the advent of motor symptoms and is aggravated through the course of the disease. Blood pressure (BP) abnormalities also result from autonomic dysfunction which induces orthostatic hypotension (OH), postprandial hypotension (PPH), nocturnal hypertension (NH) and, in particular, great fluctuation of BP over the range of 100 mmHg in a day that is often monitored by 24-hour ambulatory blood pressure monitoring (ABPM). A number of investigations on autonomic dysfunction in PD using 123I-meta-iodobenzylguanidine (MIBG) myocardial scintigraphy, neuropathology and immunohistochemistry indicate the centripetal degeneration of the cardiac sympathetic nerves and other autonomic pathology in other organs. Since PD patients have lost neural control of BP, their BP should depend on humoral factors that cannot respond to changes in and out of the body as promptly as autonomic nerves. This may be one of the reasons for irregularly fluctuating and unpredictable BP. Hypertensive fluctuation is much riskier than OH and PPH for vascular events of cerebrovascular disease, cardiovascular disease and other organopathies. Non-medical and medical treatments such as calcium channel blocking may be effective to stabilize BP in patients.