[Motor neglect]

Abstract

The core symptom of motor neglect is under-utilization of contralesional limbs without hemiparesis, ataxia, extrapyramidal symptoms, or sensory neglects. This under-utilization is characterized by marked reversibility when the examiner strongly encouraged the patient to use the limbs. Besides the core symptom the three following signs can be observed frequently: 1) abnormal "placing reaction", 2) lack of automatic withdrawal reaction to painful stimulation, and 3) so-called hypometria, a sort of completion deficits of gesture (Fig. 1). In many cases tumors are found to cause motor neglect, and this tends to make the symptoms transient. It has been noticed that unilateral neglect is not a unitary symptom but has some underlying composant factors. It was very difficult, however, to separate these factors practically. Recently some investigators succeeded to uncouple perceptual and premotor factors of unilateral neglect, and the premotor factor, directional hypokinesia, was found direction-specific and visual hemifield-specific, but regardless of used limbs. These features of directional hypokinesia are quite different from those of motor neglect which appears regardless of the cerebral dominance.