The eye of the beholder: Inter-rater agreement among experts on psychogenic jerky movement disorders

Objective: The current criteria for conversion disorder in the Diagnostic and Statistical Manual of Mental Disorders rely on the assumption that neurological disorders can be distinguished from conversion disorders through clinical assessment. This study aims to assess inter-rater agreement among clinicians with experience in the diagnosis of various hyperkinetic jerky movements, including psychogenic jerks. Methods: 60 patients with psychogenic jerks, myoclonus or tics were rated by international experts using a standardised survey resembling daily clinical practice. The survey included the following diagnostic steps: a short video offering a visual impression of the patients and their jerky movements, medical history, neurological examination (on video), additional investigations and the findings of a standardised psychiatric interview. The diagnosis and diagnostic certainty were scored after each step. Results: After all clinical information was given, moderate inter-rater agreement was reached (κ=0.56 ±0.1) with absolute agreement (100%) of experts on the diagnosis in 12 (20%) patients and reasonable agreement (>75%) in 43 (72%) patients. Psychiatric evaluation did not contribute to inter-rater agreement or diagnostic certainty. Conclusions: Our findings illustrate the fact that experienced movement disorder specialists moderately agree on the clinical diagnosis of jerky movements. Clinical assessment, especially by a team of clinicians in challenging individual cases, might improve diagnostic agreement.