Clinical signs in functional (psychogenic) gait disorders: a brief survey
© Sokol and Espay. 2016
Received: 24 December 2015
Accepted: 15 January 2016
Published: 12 February 2016
Clinical signs are critical in ascertaining the functional nature of a gait disorder. Four signs of gait impairment have been documented in the course of examining patients with clinically definite functional (psychogenic) movement disorders: “huffing and puffing” during standing and walking, manipulation-resistance dorsiflexion of the first toe, fixed plantar flexion and inversion, and marked discrepancy between ambulation with and without swivel chair assistance. While large studies are needed to ascertain their prevalence, sensitivity, and specificity, the identification of these signs may help elevate the diagnostic certainty of functional gait disorders.
KeywordsPsychogenic gait Functional gait Clinical signs
Patterns, signs, and supportive features in functional gait disorders
Overall functional gait patterns
Incongruent functional gait signs
Supportive additional features
“Huffing and puffing”
Variable resistance of feet or leg to passive manipulation
Fixed toe extension
Fixed plantar flexion/inversion
Associated incongruent neurological findings
Swivel chair signs
Excessive demonstration of effort during gait: “Huffing and puffing” sign
Limited gait with incongruent dystonia (1/2): “Psychogenic toe” sign
The “psychogenic toe” sign (Fig. 1b, Additional file 2: Video 2), derives from a case study  of a 13-year-old male who exhibited a striatal-like toe on neurological examination within the context of clinically definite functional dystonia and weakness . This sign is characterized by resistance to manipulation of an extended first toe, which can be forcibly flexed only at the expense of associated pain or by extending toes 2–5, which are held in tonic flexion. This sign needs to be distinguished from the spontaneous first-toe dorsiflexion seen in focal dystonias or dystonic manifestations of neurodegenerative disorders, including Parkinson disease and multiple system atrophy . The organic striatal toe can be readily displaced with passive manipulation, without pain or resistance, and is not modified by passively extending toes 2–5 . This phenotype is admittedly rare and may be restricted to the pediatric population, whereby dystonia tends to be a more common functional phenotype than tremor . Indeed, our ongoing search in adults with this sign has been negligible in the years since this observation was published.
Limited gait with incongruent dystonia (2/2): Fixed plantar flexion sign
Fixed plantar flexion and inversion of one foot or both feet, that appears suddenly or in rapid sequence, and which cannot be easily overcome with passive manipulation is typical of functional dystonia (Fig. 1c, Additional file 3: Video 3). Although dystonia is the primary phenotype, gait is an immediate casualty. Patients may be able to take a few limping steps while carefully guarding the affected foot by minimizing its weight bearing, when only one limb is affected (wheelchair-bound state is the rule among those with bilateral or severe unilateral leg involvement). In one large study, about 20 % of these patients may also carry the diagnosis of complex regional pain syndrome type 1 (formerly, reflex sympathetic dystrophy), reflecting secondary skin dysautonomia due to limb immobility . This pattern of gait impairment has been well documented among soldiers with “shell shock” or “war neuroses” during World War I and other military conflicts .
Incongruent ambulation: Swivel chair sign
The swivel chair test (Fig. 1d, Additional file 4: Video 4) may afford a means to evaluating the inconsistency of gait by way of comparing two mediums of ambulation . Major gait discrepancies in gait performance between upright versus chair propelling walking has been suggested as an important sign in FGD. Inspired by an earlier observation by Charcot-trained Paul Oscar Blocq (1860 –1896), at the Salpêtrière, Michael Okun and his group formally compared the differential gait performance in patients with FGD before and after asking them to use a swivel chair to propel themselves forward and backward . Compared with no changes in a control group of 9 consecutive organic gait impairment (7 of whom had Parkinson disease) 8/9 patients with FGD, who exhibited a range of bizarre gait patterns at baseline, were able to propel themselves on a swivel chair. Caveats regarding this observation are that the response to a swivel chair has not been examined in other organic gait disorders beyond neurodegenerative parkinsonisms and further studies will be needed to quantify the sign’s prevalence and related clinimetric properties. Also, in the absence of data from ataxic patients (where the sign may conceivably be positive), the reader is cautioned about the likelihood of misclassification when relying on this sign disproportionate to other neurological examination features.
The bizarre nature of certain gait abnormalities, alone, does not suffice to diagnose a presentation as FGD, a pitfall illustrated by the unusual gait of patients with chorea-acanthocytosis and “limp man syndrome” . Identifying previously reported clinical signs, despite the need to further validate their relevance in FGD, could be helpful in ascertaining the diagnosis while explaining the futility of unnecessary additional laboratory evaluations. A clinically definite diagnosis of FGD also serves to steer therapeutic efforts away from pharmacotherapy, and the associated iatrogenic harm, and toward multidisciplinary physical and cognitive behavioral therapies.
Consent for publication of videos was obtained from each of the patients. Patients signed a standard institutional consent form, which includes publication in medical journals.
Functional (psychogenic) gait disorders
The authors thank Danielle Kogan, an animator of over 15 cartoons made widely available on the Internet, for her illustrations.
Full financial disclosures
Mr. Sokol has nothing to disclose.
Dr. Espay is supported by the NIH (K23MH092735) and has received grant support from CleveMed/Great Lakes Neurotechnologies, Davis Phinney Foundation, and Michael J Fox Foundation; personal compensation as a consultant/scientific advisory board member for Solvay, Abbott, Chelsea Therapeutics, TEVA, Impax, Merz, Lundbeck, and Eli Lilly; honoraria from TEVA, UCB, the American Academy of Neurology, and the Movement Disorders Society; and publishing royalties from Lippincott Williams & Wilkins and Cambridge University Press.
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