Left unilateral melokinetic apraxia and left dynamic apraxia following partial callosal infarction.

A 69 year-old right-handed man suffered from an infarct in the left anterio r cerebral territory's artery, involving the anterior and middle parts of t he corpus callosum, and the cingulum. He had a right crural hemiparesis wit h a grasp reflex of the right hand, and ipsilaterally a melokinetic and a d ynamic apraxia. Agility of the left fingers was lost : fast and nimble move ments of theses fingers, and repetitive gestures of the left hand were defe ctive. Execution of motor sequences with the left hand was disrupted by a l ack of litheness in gesture series. By analogy with unilateral left ideomot or apraxia, we suggest melokinetic and dynamic apraxia could be symptomatic of an interhemispheric disconnection. Premotor cortex could have a dominan ce for both digital movements and programmation of gestual sequences. As a general rule, the left cortex could be preferentially activated by the natu re of some tasks, particularly the execution of complex gestual series, whi ch implie an internal speech. In theses conditions, an interhemispheric dis connection could lead some difficulties to make theses gestures with the le ft hand.