Suggestibility as a valuable criterion for laboratory-supported definite functional movement disorders

OBJECTIVE: To evaluate the application of suggestibility in electrophysiologic studies as a tool to increase the diagnostic certainty of “laboratory-supported definite” FMD. METHODS: We retrospectively reviewed the electrophysiologic studies performed in our center on patients with FMD. Recordings where suggestibility was included in the test battery were then selected. RESULTS: We present three cases with equivocal clinical features, but with findings on electrophysiologic studies that were consistent with “laboratory-supported definite” FMD. CONCLUSION: When combined with other tests, demonstration of suggestibility in electrophysiologic studies may increase the accuracy in differentiating functional from organic movement disorders. SIGNIFICANCE: This case series is an essential first step in evaluating the applicability of suggestibility as an electrophysiologic criterion to aid in the diagnosis of FMD. Application in a larger cohort, incorporation in a test battery, and validation studies, including quantitative evaluation of suggestibility, are required to assess the reliability and the added value of this test.