Psychogenic movement disorders (PMDs) are diagnostically challenging.[1, 2] An early diagnosis appears crucial for the outcome. Typical clues from history include sudden onset, spontaneous remissions, psychiatric comorbidity, and secondary gain. Clues from the examination include variability, distractibility, suggestibility, false neurological signs, and entrainment. However, the main plank of the clinical diagnosis is reliance on incongruity of the presentation with a recognized organic movement disorder. For example, leg onset dystonia in an adult or fixed limb dystonia at disease onset would be incongruous to typical organic primary dystonia. However, it requires considerable expertise to adequately recognize the various clues that signal a PMD. We propose that, often, an incongruity of the gait disorder (either in relation to the presenting movement disorder or incongruity with any type of organic gait disorder) is a useful, often recognizable, but perhaps underutilized, clue in diagnosing PMDs. To illustrate this, we present six examples where gait examination was one of the revealing diagnostic clues.
Case 1: The right-sided rest tremor without signs of entrainment or distractibility suggested Parkinson's disease (PD) in this 60-year-old gentleman. Yet, stance and gait examination—with marked truncal flexion and extension as well as exaggerated uplifting of the affected leg—were inconsistent with a parkinsonian gait (see Video 1, segment A).
Case 2: This patient presented at age 60 with rest and postural tremor predominantly on the left hand. This could have easily been diagnosed as PD, because there was no clear entrainment or distractibility. Yet, when walking, he displayed a cautious, tremulous ataxic gait, swaying from side to side, but with a narrow base (see Video 1, segment B).
Case 3: For 4 years, this 56-year-old woman had suffered constant choreiform involuntary movements of her right arm and leg. There was no MRI lesion. Examination revealed choreodystonic movements, but also an unexpected slow, cautious gait with limping. On tandem walking, she would sway from side to side at a spot, but not fall (see Video 2, segment A).
Case 4: This 32-year-old woman acutely developed lower-trunk jerks and shaking movements of her legs, which spread to her upper trunk when trying to suppress them. The inconsistency of the involuntary movements, with a varying pattern of involved muscles and entrainment, suggested a functional etiology. Any remaining doubts were dispelled by the highly uneconomical gait, with uplifting of the feet and marked swaying without falling (see Video 2, segment B).
Case 5: This 55-year-old gentleman presented with dystonic type of symptoms. Clinical examination showed variable spasm of eye closing, mouth opening, and side-to-side head movements, which were unusual for typical craniocervial dystonia. His trepidant, jerky, and staggering gait was clearly incongruent to adult-onset dystonia (see Video 3, segment A).
Case 6: This 19-year-old woman complained of episodes of involuntary movement of her right hand, which spread in a few days to the left hand and the legs. The episodes and the limbs involved were fluctuating. Entrainment of the movements was not convincing, but the uneconomical gait helped to conclude that it was a functional movement disorder (see Video 3, segment B).
These cases illustrate that incongruity of gait to the presenting movement disorder can be a useful supportive clue to the diagnosis of PMD. In each case, the main presentation had features resembling an organic movement disorder (e.g., cases 1 and 2 had a rest tremor, suggesting a parkinsonian condition). Yet, gait was clearly incongruent with the presenting movement disorder in all of them.
It remains difficult to diagnose PMDs, in particular, when the seated presentation alone is deceptively similar to an organic movement disorder. In our experience, most patients with PMDs present with an odd gait pattern that is hard to reconcile with an organic gait disorder or that is incongruent to the presenting movement disorder. The incongruent gait pattern can often be recognized more readily than the other PMDs that present during seated examination.
Gait disturbance as a feature in PMD is common.[2, 5, 6] In a large group of PMD patients, 37% had an additional abnormal gait, usually including slowness, a dystonic or bizarre appearance, or astasia-abasia. In another study, 97% of patients had one or more of the following characteristic features of a psychogenic gait: fluctuation; excessive slowness; psychogenic Romberg; walking on ice; uneconomic postures; or sudden knee buckling. Despite their complaint to the contrary, patients with psychogenic gait usually show a superior motor control when balancing. Bearing in mind that some organic conditions can feature a bizarre-looking gait (e.g., Huntington's disease), we emphasize the importance of gait evaluation during clinical examination in every patient suspected to have a PMD. When in doubt, based upon the seated examination alone, an incongruent gait might be the key, pointing to a psychogenic etiology.