Motor symptomatology of the thalamus

: Muscular deficit, voluntary movement disorders, abnormal movements, and global disturbance of movements are considered. A muscular deficit is part of the Dejerine-Roussy syndrome. It appears as hemiparesis, regressive within days or weeks. A juxta-thalamic capsular involvement can be considered as the origin of this deficit in most cases, especially in hemorrhagic processes even if these are located within the thalamus, on account of mass effect. The occurrence of paresis or paralysis in ischemic processes strictly situated in the thalamus, however, is discussed: the deficit may be limited to parts of limbs; most often, it is not associated with pyramidal symptomatology; recovery is observed in the hand before the inferior limb. To these anatomoclinical facts some data from animal experiments or thalamic stereotaxic surgical procedures in humans must be added. A deafferentiation from the cortex seems to be the main cause of these motor disturbances. Three types of voluntary movement disorders may be encountered: contralateral cerebellar incoordination due to the involvement of the nucleus ventrooralis posterior where the superior cerebellar peduncle ends; homolateral imitative syncinesias, not confined to thalamic lesions, but frequently observed in this location with a particular aspect; contracture. Abnormal movements include choreoathetosic movements, and exceptionally intention and action tremor, and asterixis. They primarily involve the superior limb, but reported cases are not associated with thalamic limited lesions. Global disturbance of movements is observed in the hand or gait. "Thalamic hand" consists of incessant finger movements in the vertical and horizontal planes. They are associated with thalamic dystonia and deep sensibility disorder.(ABSTRACT TRUNCATED AT 250 WORDS)