Biomarkers in functional movement disorders: a systematic review

Area of Science:

• Neurology
• Neuroscience
• Biomarker Research

Background:

• Functional movement disorders (FMD) involve impaired voluntary movement control despite intact neural capacity.
• Clinical diagnosis is often sufficient, but challenges exist, necessitating better diagnostic and prognostic tools.
• There is a need for reliable biomarkers to guide treatment and predict outcomes in FMD.

Purpose of the Study:

• To systematically review existing biomarkers for functional movement disorders.
• To identify reliable diagnostic biomarkers and predictors of treatment response and prognosis.
• To highlight gaps in current biomarker research for FMD.

Main Methods:

• Systematic review of 86 studies meeting predefined criteria.
• Analysis of electroencephalography (EEG), electromyography (EMG), and functional MRI (fMRI) findings.
• Evaluation of biomarkers for diagnostic accuracy, treatment response, and prognosis.

Main Results:

• Reliable EEG and EMG biomarkers exist for functional myoclonus and tremor.
• Promising biomarkers are emerging for functional paresis, gait, and balance disorders.
• Diagnostic biomarkers are lacking for functional dystonia and tics; many current biomarkers are group-level and not individually predictive.

Conclusions:

• Significant gaps exist in diagnostic biomarkers for FMD, particularly for conditions with diagnostic uncertainty.
• There is a critical lack of biomarkers predicting treatment response and long-term prognosis in FMD.
• Further research is needed to develop individually predictive and clinically applicable biomarkers for FMD.