Gait Disorders—Differential Diagnosis (Continued)

Basal Ganglia. Extrapyramidal movement disorders affect gait, depending on the interplay of inhibition and disinhibition within the basal ganglia circuitry. Parkinsonian syndromes characteristically have small shuffling steps at initiation of stride and through all gait phases, stooped posture, and festination, with the anteriorly displaced center of gravity pulling the patient forward. The patient festinates from one stationery object to another to prevent escalation of speed. Resting tremor occurs in Parkinson disease (see Plate 7-4), anteflexed neck in multiple system atrophy, absent vertical gaze in progressive supranuclear palsy (see Plate 7-7), and limb apraxia in corticobasal degeneration (see Plate 7-7). Chorea, dystonia, and athetosis characterize Huntington disease (see Plate 7-13); dyskinesias occur with dopaminergic excess in treated Parkinson patients; hemiballism is seen after subthalamic lesions and in Tourette syndrome.

Cerebral Cortex and White Matter. Frontal lobe gait disorders (gait apraxia) secondary to subcortical small vessel lacunar disease are characterized by a magnetic quality, as if glued to the floor, or slipping clutch. Patients have difficulty initiating stride, taking small repetitive steps before launching a gait that looks almost normal. After stopping, the attempt to restart reproduces the pattern. Confined spaces are particularly troublesome.

Normal-Pressure Hydrocephalus (see Plate 8-17). Normal-pressure hydrocephalus produces a similar gait disorder, together with urinary dysfunction, cognitive decline, and ventriculomegaly on imaging. Hemiparesis from upper motor neuron lesions produces increased tone in the contralateral limbs, with the leg maintained in extension and the arm in flexion. The leg circumducts because of poor flexion at the hip and knees. The plantar-flexed foot may have clonus, producing a bouncing quality to the gait.

Non-neurologic Disorders. Elderly persons sometimes have a slow cautious gait, reflecting slowing of neural conduction and concern to prevent falls. Non-neurologic disorders producing limp or insecure gait include arthritis, trochanteric bursitis, lumbosacral spine or disc disease, and podiatric conditions (bunions, tenosynovitis, neuromas).

Gait is sometimes irregular in primary psychiatric disorders, with stereotypies and mannerisms or extrapyramidal features from chronic psychotropic medications. Psychogenic gait disorders (astasia-abasia) are varying and inconstant, contravening recognized neurologic patterns; this diagnosis is best made by neurologists after careful investigation.

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