Tremor in multiple system atrophy: a systematic literature review

Area of Science:

• Neurology
• Movement Disorders
• Clinical Neurophysiology

Background:

• Tremor affects up to 80% of patients with multiple system atrophy (MSA), but its characteristics are poorly understood.
• Differentiating MSA tremor from other disorders like Parkinson's disease (PD) is crucial for accurate diagnosis.
• Phenotypic variability of tremor in MSA necessitates detailed characterization.

Purpose of the Study:

• To determine the prevalence and characteristics of tremor in MSA.
• To analyze tremor distribution across MSA phenotypes (MSA-P and MSA-C) and body regions.
• To assess the responsiveness of MSA tremor to various treatments.

Main Methods:

• Systematic literature search of PubMed for studies reporting tremor in MSA, adhering to PRISMA guidelines.
• Screening of eligible studies, data extraction, and risk of bias assessment using JBI critical appraisal tools.
• Review of data from 25 studies including 963 patients with MSA.

Main Results:

• Tremor prevalence and type differ significantly between MSA-P and MSA-C.
• MSA-C predominantly exhibits a ~3-Hz pseudo-orthostatic tremor, while MSA-P shows 7-8 Hz postural and 5-6 Hz rest tremor.
• Levodopa provided tremor improvement in 11.8-92% of cases, with greater efficacy in MSA-P and action tremor.

Conclusions:

• Tremor is a frequent and phenotypically diverse manifestation in multiple system atrophy.
• A 3-Hz pseudo-orthostatic tremor is a key feature distinguishing MSA-C.
• Treatment response to levodopa is variable, suggesting tailored therapeutic approaches are needed.