Biomarkers in functional movement disorders: a systematic review. Issue 12 (21st October 2020)

• Record Type: Journal Article
• Authors: Thomsen, Birgitte Liang Chen; Teodoro, Tiago; Edwards, Mark J
• Is Part Of: Journal of neurology, neurosurgery and psychiatry. Volume 91:Issue 12(2020)
• Page Start: 1261
• Page End: 1269
• Publication Date: 2020-10-21
• Subjects: functional neurological disorder -- movement disorders -- functional imaging -- EEG -- EMG; Neurology -- Periodicals; Nervous system -- Surgery -- Periodicals; Psychiatry -- Periodicals; 616.8
• DOI: 10.1136/jnnp-2020-323141
• Languages: English
• ISSNs: 0022-3050

Abstract

Abstract : Functional movement disorders (FMD) are proposed to reflect a specific problem with voluntary control of movement, despite normal intent to move and an intact neural capacity for movement. In many cases, a positive diagnosis of FMD can be established on clinical grounds. However, the diagnosis remains challenging in certain scenarios, and there is a need for predictors of treatment response and long-term prognosis. In this context, we performed a systematic review of biomarkers in FMD. Eighty-six studies met our predefined criteria and were included. We found fairly reliable electroencephalography and electromyography-based diagnostic biomarkers for functional myoclonus and tremor. Promising biomarkers have also been described for functional paresis, gait and balance disorders. In contrast, there is still a lack of diagnostic biomarkers of functional dystonia and tics, where clinical diagnosis is often also more challenging. Importantly, many promising findings focus on pathophysiology and reflect group-level comparisons, but cannot differentiate on an individual basis. Some biomarkers also require access to time-consuming and resource-consuming techniques such as functional MRI. In conclusion, there are important gaps in diagnostic biomarkers in FMD in the areas of most clinical uncertainty. There is also is a lack of treatment response and prognostic biomarkers to aid in the selection of patients who would benefit from rehabilitation and other forms of treatment.