Gait apraxia in normal-pressure hydrocephalus: patterns of movement and muscle activation.

We made gait recordings in 11 patients with normal-pressure hydrocephalus. Sagittal rotations in hip, knee, and ankle joints were determined with intermittent light photography or with polarized light goniometry. In eight patients, gait muscle activation was determined with integrated surface EMG from six leg muscles on one side. We assessed the patterns of movement and muscle activity by averaging data from 20 gait cycles. Reduced speed and range of movements, short steps, small foot-floor clearance, and low swing-to-stance ratio were typical. The activation of the calf muscles was regularly premature and low. In severe disorders, there was continuous activity in the antigravity muscles acting on hip and knee joints. Gait records verified improvement after CSF drainage or shunting.