Parkinsonian and Cerebellar Phenotypes of Probable MSA: An Insight in to Prognostic Factors Based on Autonomic Functions

BACKGROUND: Multiple system atrophy is an adult-onset, sporadic, neurodegenerative disorder with parkinsonian (MSA-P) and cerebellar (MSA-C) subtypes. OBJECTIVE: We aimed to elucidate differences in prognostic factors between MSA subtypes. METHODS: The study population comprised 45 probable MSA patients (MSA-P = 22; MSA-C = 23) and 45 healthy controls. Clinical parameters, heart rate variability (HRV), and conventional cardiac autonomic function testing (AFT) were the study tools. RESULTS: Mean age of onset of MSA was 54.7 ± 9 years for MSA-P and 51.9 ± 7 years for MSA-C subgroups. Median disease duration was 2 years in both subgroups. A greater percentage of MSA-P patients (45.5%) had beneficial response to levodopa (P < 0.01). Patients in both subgroups reported significant autonomic disturbances, such as postural symptoms, bladder disturbances, and erectile dysfunction. MSA-P patients had a trend for a greater number of falls and bladder disturbances than MSA-C patients (P = 0.05). Cardiac AFT showed that in MSA-P, 22.2% had definitive and 77.7% had severe autonomic dysfunction, whereas in MSA-C, 9.5% had early, 28.5% had definitive, and 57.1% had severe autonomic dysfunction. HRV analysis showed significant reduction in overall HRV, sympathetic activity, and parasympathetic activity in MSA patients as compared with controls (P < 0.0001). The sympathetic limb was more severely affected in MSA-P patients as compared with MSA-C patients (P < 0.05). CONCLUSION: Autonomic dysfunction and postural instability, negative prognostic markers, were relatively more common in the MSA-P than in the MSA-C patients. This implies that MSA-P patients have poorer prognosis as compared with MSA-C. Dopaminergic medications can be beneficial in MSA-P patients.