Development and content validation of a questionnaire for functional movement disorders

From shell shock tremors to TikTok tics, functional movement disorders have long been assumed to be motor expressions of emotional turmoil. However, psychodynamic explanations are increasingly complemented by neurophysiological findings, meaning that specialized physiotherapy is gaining in importance alongside psychotherapy. Still, there is no disease-specific outcome measure that adequately assesses patient-relevant aspects of this heterogeneous condition. Such a questionnaire was developed and its content was validated in a multistage development process. The relevance and comprehensibility of the items were first evaluated by a panel of experts and then by affected patients, and questions and possible response categories were adjusted accordingly. The resultant revised questionnaire yields good content-related validity and thus allows, for the first time, a quantification of the subjective complaints and implications associated with functional movement disorders. The next step will be a multicenter study to analyze the psychometric properties and factorial structure of this new instrument.