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Abstract
Objectives The prevalence of restless legs syndrome (RLS) in functional movement disorders (FMD) is not known. Patients with FMD often present with multiple motor and sensory symptoms. Some of these symptoms might be due to comorbid RLS. Therefore, our objective was to evaluate possible association between FMD and RLS.
Design Case–control study.
Setting Movement Disorders Center, 1st Faculty of Medicine and General University Hospital in Prague, Czech Republic.
Participants 96 consecutive patients with clinically established FMD (80 females, mean age (SD) 45.0 (13) years), and 76 matched controls.
Primary and secondary outcome measures The primary outcome measure was prevalence of RLS based on updated International RLS Study Group criteria. Secondary outcome measures included prevalence of periodic limb movements (PLM) using actigraphy; pain, motor and sensory symptoms in lower limbs; organic comorbidities and medication affecting RLS.
Results RLS criteria were fulfilled in 43.8% of patients (95% CI 34 to 54) and in 7.9% of controls (95% CI 3 to 17, p<0.00001). Both RLS and PLM indices (PLMi) ≥22.5/hour were found in 21.2% of patients with FMD and 2.6% of controls. Patients with FMD with RLS had a higher mean PLMi (p<0.001) and a higher proportion of PLMi ≥22.5/hour (p<0.01) than RLS-negative patients. Patients with RLS had higher prevalence of pain and sensory symptoms in lower limbs, no difference was found in medication and prevalence of organic comorbidities in patients with FMD with and without RLS.
Conclusions We found an increased prevalence of RLS in patients with FMD. Clinical diagnosis of RLS was supported by actigraphic measurement of clinically relevant PLM in a significant proportion of patients with FMD. Although functional motor and sensory symptoms may mimic RLS, RLS may be unrecognised in patients with FMD. This finding may have clinical implications in management of FMD, and it raises the possibility of common pathophysiological mechanisms of FMD and RLS/PLM.
- restless legs syndrome
- functional movement disorders
- periodic limb movements
- actigraphy
- psychogenic movement disorders
- sensory symptoms
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Footnotes
Patient consent for publication Not required.
TS and MS contributed equally.
Contributors All authors meet the ICMJE criteria for authorship. TS was responsible for the concept and design of the study, clinical data acquisition, data analysis and interpretation, and drafting of the original report which was reviewed and revised by all co-authors. MS was responsible for actigraphic data collection, all actigraphic analysis, data interpretation and drafting of the original report. DK was responsible for study design, clinical data acquisition, data analysis including statistics and interpretation and drafting of the original report. KŠ was responsible for clinical data acquisition, data analysis and interpretation. MH was responsible for data analysis and interpretation. ER was responsible for data analysis and interpretation. Funding was obtained by TS and ER.
Funding This study was supported by Ministry of Health of the Czech Republic, grant AZV ČR 16-29651. MH is supported by the NINDS Intramural Program.
Competing interests None declared.
Ethics approval Ethics Committee of the General University Hospital in Prague (approval number 26/15 Grant).
Provenance and peer review Not commissioned; externally peer reviewed.
Data sharing statement There are no additional unpublished data from the study.