Loss of left-sided volitional movements caused by a combined lesion of thecorpus callosum and right hemisphere: 'Initiation pseudohemiakinesia'

We report a right-handed patient who showed a marked loss of unilateral vol itional movements of the left limbs after the onset of a cerebral infarctio n in the combined territories of the right anterior and middle cerebral art eries. The same limbs retained their mobility in acts requiring bilateral s ides of the body. This left-sided abnormal behavior resembled motor neglect resulting from lateralized brain damage. Behavioral and neuroradiological findings presented by this patient, however, suggested that callosal discon nection was definitely involved in this symptomatology, We postulate that i n this patient, the diseased right hemisphere could no longer initiate move ments of the left limbs despite its potential ability to realize them, and that the injured callosum prevented the intact left hemisphere from initiat ing unilateral voluntary movements of the left limbs. We suggest that this so far undescribed symptomatology be called 'initiation pseudohemiakinesia' in order to be distinguished from other rare forms of unilateral voluntary movements like motor neglect, extinction or directional hypokinesia, Copyr ight (C) 2000 S. Karger AG. Basel.