Diagnostic performance of the “Huffing and Puffing” sign in psychogenic (functional) movement disorders

We aimed at determining the diagnostic value of effort‐associated behaviors (“huffing and puffing” spectrum) in patients with psychogenic movement disorders. Three blinded clinicians rated presence, severity, and duration of effort‐associated features during standing and walking tasks on edited videos of 131 patients with psychogenic gait disorders and 37 with organic gait disorders. Huffing, grunting, grimacing, and breath holding were the most common effort‐associated behaviors in patients with psychogenic gait disorders, with a combined prevalence of 44% and disproportionate to the severity of gait impairment, compared to organic gait disorders. The presence of huffing and puffing–type behaviors yielded a relatively low sensitivity, but high specificity, for the diagnosis of psychogenic movement disorders, increasing the odds of diagnosis 13‐fold (95% confidence interval: 4.2–43.8), compared to organic gait disorders. Demonstration of effort‐associated behaviors during standing and walking strongly supports the psychogenic nature of disorders when gait is involved.