Motor neglect associated with a discrete parietal lesion.

The syndrome of motor neglect may follow brain lesions affecting frontal, subcortical, and parietal structures. However, pure motor neglect has not been previously associated with a lesion confined to the parietal lobe. We observed a 79-year-old right-handed man with right-sided limb akinesia and motor neglect without concomitant sensory or visuospatial neglect. MRI showed a left posterior parietal infarct sparing the primary sensorimotor cortex. Transcranial magnetic stimulation showed comparable thresholds for electromyographic activation of the muscles of the right and left arm and normal central motor conduction times, indicating functional integrity of the motor cortex. This case demonstrates that a discrete parietal lesion can produce a pure intentional disorder, independent of sensory or visuospatial neglect.