Validation of "laboratory‐supported" criteria for functional (psychogenic) tremor. Issue 4 (16th February 2016)

• Record Type: Journal Article
• Authors: Schwingenschuh, Petra; Saifee, Tabish A.; Katschnig‐Winter, Petra; Macerollo, Antonella; Koegl‐Wallner, Mariella; Culea, Valeriu; Ghadery, Christine; Hofer, Edith; Pendl, Tamara; Seiler, Stephan; Werner, Ulrike; Franthal, Sebastian; Maurits, Natasha M.; Tijssen, Marina A.; Schmidt, Reinhold; Rothwell, John C.; Bhatia, Kailash P.; Edwards, Mark J.
• Is Part Of: Movement disorders. Volume 31:Issue 4(2016)
• Page Start: 555
• Page End: 562
• Publication Date: 2016-02-16
• Subjects: Psychogenic -- functional -- diagnostic criteria -- electrophysiological criteria; Movement disorders -- Periodicals; 610
• DOI: 10.1002/mds.26525
• Languages: English
• ISSNs: 0885-3185

Abstract

ABSTRACT: Background: In a small group of patients, we have previously shown that a combination of electrophysiological tests was able to distinguish functional (psychogenic) tremor and organic tremor with excellent sensitivity and specificity. Objectives: This study aims to validate an electrophysiological test battery as a tool to diagnose patients with functional tremor with a "laboratory‐supported" level of certainty. Methods: For this prospective data collection study, we recruited 38 new patients with functional tremor (mean age 37.9 ± 24.5 years; mean disease duration 5.9 ± 9.0 years) and 73 new patients with organic tremor (mean age 55.4 ± 25.4 years; mean disease duration 15.8 ± 17.7 years). Tremor was recorded at rest, posture (with and without loading), action, while performing tapping tasks (1, 3, and 5 Hz), and while performing ballistic movements with the less‐affected hand. Electrophysiological tests were performed by raters blinded to the clinical diagnosis. We calculated a sum score for all performed tests (maximum of 10 points) and used a previously suggested cut‐off score of 3 points for a diagnosis of laboratory‐supported functional tremor. Results: We demonstrated good interrater reliability and test‐retest reliability. Patients with functional tremor had a higher average score on the test battery when compared with patients with organic tremor (3.6 ± 1.4 points vs 1.0 ± 0.8 points; P < .001), and the predefined cut‐off score for laboratory‐supported functional tremor yielded a test sensitivity of 89.5% and a specificity of 95.9%. Conclusion: We now propose this test battery as the basis of laboratory‐supported criteria for the diagnosis of functional tremor, and we encourage its use in clinical and research practice. © 2016 International Parkinson and Movement Disorder Society