Combined cardiovascular and sweating autonomic testing to differentiate multiple system atrophy from Parkinson's disease

Abstract

It can be difficult to differentiate multiple system atrophy (MSA) with predominant parkinsonism (MSA-P), a very disabling but rare disease, from Parkinson's disease (PD). Autonomic dysfunction, particularly cardiovascular autonomic neuropathy (CAN), is classically more pronounced in MSA. We investigated whether testing for CAN combined with sweat function assessment was helpful to differentiate patients with MSA from those with PD. In this retrospective study, 62 patients with MSA-P and 96 with PD, comparable in age, BMI and sex ratio with disease duration of 4.3±2.5 years for MSA vs. 11.5±6 years for PD (P<0.0001) were tested for CAN using heart rate changes with deep breathing (HR-DB), stand test (HR-ST) and Valsalva maneuver (HR-VM) and blood pressure changes during stand test (BPs-ST and BPd-ST), Valsalva maneuver (BPs-VM-II and IV), hand grip (BPd-HG) and the total "Ewing" score tests (EwS), and for sweating function using electrochemical skin conductance for hands and feet (HESC and FESC). In MSA-P abnormal EwS, HR-DB, BP-ST and ESC were more frequent compared to PD, despite longer disease duration for PD. Using a model adjusted for sex, BMI, age, disease duration and treatment, the Odds Ratio for having MSA-P vs. PD based on EwS was 2.71, on HR-DB 2.36, on BP-ST 2.87 and on ESC 4.94 while it was 11.68 (2.17-62.79) for the combination of the three last tests. Assessment of HR-DB, BP-ST and ESC, that is, rapid and non-invasive could be helpful in combination as a first simple screening to differentiate MSA-P from PD.