Diagnostic Performance of the “Huffing and Puffing” Sign in Functional (Psychogenic) Movement Disorders

The diagnosis of psychogenic (functional) movement disorders (PMD) can be challenging given the phenotypic overlap with organic disorders and the poor diagnostic agreement by clinicians using currently available diagnostic criteria.1 Diagnostic delays result in larger accrual of disability and poor prognosis.2 In order to formulate a positive rather than exclusionary diagnosis of PMD, signs and symptoms unique to these disorders, inconsistent or incongruent with their organic counterparts, are needed.3 We have observed that PMD patients with primary or associated involvement of gait and/or balance tend to exhibit verbal and physical behaviors of effort disproportionate to their disability, particularly when standing or walking. These behaviors appear to be much less prevalent among those with organic gait disorders of comparable or greater severity, such as in advanced Parkinson disease, spinocerebellar ataxia or motor neuron disease. We sought to examine the prevalence, phenotypic range, and diagnostic performance of such a “huffing and puffing” spectrum of behaviors in consecutively examined patients with clinically definite PMD as compared with organic gait disorders.