Shoulder‐Touch test to reveal incongruencies in persons with functional motor disorders

BACKGROUND AND PURPOSE: Clinical experience suggests that many patients with functional motor disorders (FMD), despite reporting severe balance problems, typically do not fall frequently. This discrepancy may hint towards a functional component. Here, we explored the role of the Shoulder‐Touch test, which features a light touch on the patient's shoulders, to reveal a possible functional etiology of postural instability. METHODS: We enrolled consecutive outpatients with a definite diagnosis of FMD. Patients with Parkinson's disease (PD) or progressive supranuclear palsy (PSP) with postural instability served as controls. Each patient underwent a clinical evaluation including testing for postural instability using the retropulsion test. Patients with an abnormal retropulsion test (score ≥ 1) also received a light touch on their shoulders to explore the presence (S‐Touch+) or absence (S‐Touch−) of an incongruent, exaggerated postural response, defined as taking three or more steps to recover or a fall if not caught by the examiner. RESULTS: From a total sample of 52 FMD patients, 48 patients were recruited. Twenty‐five patients (52%) had an abnormal retropulsion test. Twelve of these 25 patients (48%) had an S‐Touch+, either because of need to take two or more steps (n = 4) or a fall if not caught by the examiner (n = 8). None of the 23 PD/PSP patients manifested S‐Touch+. The sensitivity of the S‐Touch test was 48%, whereas its specificity was 100%. CONCLUSION: The S‐Touch test has a high specificity, albeit with a modest sensitivity, to reveal a functional etiology of postural instability in persons with FMD.