Preserved Simple and Impaired Compound Movement After Infarction in the Territory of the Superior Cerebellar Artery

Abstract

ABSTRACT:A patient with an infarct in the distribution of the right superior cerebellar artery was studied with regard to his ability to make simple movements (visually triggered, self-terminated ballistic wrist movements), and compound movements (reaching to a visual target and precision pinch of a seen object). Movements on the right side of the body alone were affected. Control movements were made by the normal left upper extremity. Wrist movement on the right side was normal in reaction time, direction, peak velocity, and end-point position control as compared to the left. By contrast, both reaching and pinching movements on the right were impaired. Reaching movements showed marked decomposition of the compound elbow-shoulder movement into seriatim simple movements made alternately at elbow and shoulder. Pinching movements were not made, and instead winkling movements (a movement of index alone) were substituted. These results are compared to similar results of controlled inactivation of the cerebellar dentate nucleus in monkeys. We conclude that one function of the cerebellum may be to combine elements in the movement repertoires of downstream movement generators. When that ability is lost, a strategy may be voluntarily adopted of using the preserved simple movements in place of the impaired compound movements. RESUME: Preservation des mouvements simples et alteration des mouvements complexes apres un infarctus dans le territoire de 1'artere cerebelleuse superieure. Nous avons etudie un patient ayant un infarctus dans le territoire irrigue par l"artere cerebelleuse superieure droite quant a sa capacite d'executer des mouvements simples (mouvements ballistiques du poignet a declenchement visuel, auto-limites) et des mouvements complexes (atteindre une cible visuelle et pincer avec precision un objet situe dans le champ de vision). Seulement les mouvements du cote droit du corps etaient affectes. Des mouvements controles etaient effectues par le membre superieur gauche normal. Le mouvement du poignet droit etait normal compare au gauche quant au temps de reaction, a la direction, a la velocite maximale et au controle de la position au point d'arrivee. Par ailleurs, les mouvements executes pour atteindre ou pincer du cote droit etaient atteints. Les mouvements pour atteindre une cible manifestaient une decomposition marquee de la composante epaule-coude en des mouvements simples, successifs, faits alternativement au coude et a l'epaule. Les mouvements de pincement n'etaient pas effectues et des mouvements oscillants y etaient substitues (mouvements de l'index seulement). Ces resultats sont compares a des resultats similaires d'inactivation controlee du noyau dentele chez le singe. Nous concluons qu'il est possible qu'une des fonctions du cervelet soit de combiner des elements du mouvement appartenant aux repertoires des generateurs de mouvements situes en aval. Quand cette capacite est perdue, une strategie utilisant des mouvements simples qui sont preserves peut etre substitute volontairement a l'utilisation ...

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