Cardiac sympathetic denervation in Parkinson disease

Background: In Parkinson disease, orthostatic hypotension can result from L -dopa treatment or from sympathetic neurocirculatory failure. The latter is detected by abnormal blood pressure responses to the Valsalva maneuver and can be associated with loss of functional cardiac sympathetic nerve termin als. Objective: To determine the frequency of cardiac sympathetic denervation in Parkinson disease, with or without sympathetic neurocirculatory failure, a nd its association with disease duration, severity, and L-dopa treatment. Design: Intergroup comparisons in resting patients. Setting: National Institutes of Health Clinical Center, Bethesda, Maryland. Patients: 29 patients with Parkinson disease (9 with sympathetic neurocircu latory failure, 10 who had stopped receiving or had never been treated with L-dopa), 24 patients with multiple-system atrophy (17 with sympathetic neu rocirculatory failure, 8 receiving L-dopa), 7 patients with pure autonomic failure, 33 controls with episodic or persistent orthostatic intolerance wi thout sympathetic neurocirculatory failure, and 19 normal volunteers. Measurements: Beat-to-beat blood pressure responses to the Valsalva maneuve r, Interventricular septal 6-[F-18]fluorodopamine-derived radioactivity, ca rdiac extraction fraction of [H-3]norepinephrine, appearance rate of norepi nephrine in coronary sinus plasma (cardiac norepinephrine spillover) and ve nous-arterial differences in levels of dihydroxyphenylglycol (DHPG) and end ogenous L-dopa. Results: Of the 29 patients with Parkinson disease, 9 with sympathetic neur ocirculatory failure and 11 without had low septal 6-[F-18]fluorodopamine-d erived radioactivity (2861 +/- 453 Bq/mL per MBq/kg and 5217 +/- 525 Bq/mL per MBq/kg, respectively). All 6 patients with Parkinson disease and decrea sed 6-[F-18]fluorodopamine-derived radioactivity who underwent right-heart catheterization had a decreased cardiac extraction fraction of [H-3]norepin ephrine and virtually no cardiac norepinephrine spillover or venous-arteria l increments in plasma levels of DHPG and L-dopa. Sympathetic neurocirculat ory failure and decreased 6-[F-18]fluorodopamine-derived radioactivity were unrelated to disease duration, disease severity, or L-dopa treatment. Conclusions: Many patients with Parkinson disease-including all those with sympathetic neurocirculatory failure-have evidence of cardiac sympathetic d enervation. This suggests that loss of catecholamine innervation in Parkins on disease occurs in the nigrostriatal system in the brain and in the sympa thetic nervous system in the heart.