Studies on abnormal movement

Abstract

Cerebellar and spinal ataxia are distinguished from one another and from disequilibrium. Disequilibrium affects body musculature as a whole. Locomotion is deviated and lunging, with rolling, swaying and twisting. Tense postures, deviation of the head and nystagmus are usually observed. It is evoked by injury to the vestibular system and to the flocculonodular lobe and its connections. Cerebellar ataxia is characterized by forceful, springy, alternating activity. If the ataxia is of cortical origin, these movements interfere with the active attempt to arrange the limbs and body more particularly than with the effort to hold truncal postures. It can be produced only by damage of the cerebellum or the brachium conjunctivum, before the latter divides after its mesencephalic decussation. Spinal ataxia is a loose, non-repetitive disarrangement which occurs primarily in the lower extremities. It is due to destruction of afferent mechanisms at spinal levels.