Journal of Neurological Sciences 151 (1997) 71–77 Dissociation in the neural control of single-joint and multi-joint movements in the thalamic ataxia syndrome a a,b, c a * N. van Blercom , M. Manto , J. Jacquy , J. Hildebrand a ˆ Service de Neurologie, Hopital Erasme, 808 Route de Lennik, 1070 Brussels, Belgium b ˆ Fonds National de la Recherche Scientifique, Hopital Erasme, 808 Route de Lennik, 1070 Brussels, Belgium c ˆ Hopital Civil de Charleroi, 6000 Charleroi, Belgium Received 18 July 1996; revised 8 January 1997; accepted 29 March 1997 Abstract We report a patient presenting with a right thalamic ataxia syndrome following a hemorrhage located in the left lateral and posterior thalamus.We investigated the fast goal-directed movements of the wrists (single-joint movements) and the fast pointing movements in the upper limbs (multi-joint movements). On the right side, single-joint movements were markedly hypermetric and characterized by an asymmetry in kinematics, an abnormality of ballistic movements which is considered to be a fundamental cerebellar disorder. By contrast, rapid multi-joint movements were only very slightly impaired. These results suggest that ballistic movements of the wrist are under the strong influence of the cerebello-thalamo-cortical pathway, while rapid pointing multi-joint movements in upper limb are mostly influenced by another pathway emerging from the lateral cerebellum, possibly the dentato-rubral or the dentato-reticular projections in the brainstem. The roles of these neuroanatomical pathways in the control of fast single-joint and multi-joint movements are discussed.  1997 Elsevier Science B.V. Keywords: Ataxia; Ballistic movements; Cerebello-thalamic projections 1. Introduction al., 1981; Manto et al., 1994). This classical sign of a lesion in the lateral cerebellum is known as hypermetria. Lesions in the ventrolateral and posterior nuclei of the Such movements made as rapidly as possible have been thalamus can produce a contralateral cerebellar-like ataxia, called ‘ballistic’ movements (Hallett, 1979), and are associated or not with a sensory loss (Solomon et al., characterized by high firing rates and brief contraction 1994). This clinical picture called ‘thalamic ataxia times (Zehr and Sale, 1994). One of the fundamental syndrome’ (TAS) was first described by Garcin in 1955 kinematic features of cerebellar hypermetria is the who reported a hemiataxia and hemisensory loss in a asymmetry in kinematics: compared with normal move- patient with a lesion of the ventrolateral nucleus (Garcin, ments of similar peak velocities, the acceleration peaks are 1955). By contrast to ataxic hemiparesis in which the decreased while the deceleration peaks are increased (Hore pyramidal tract is primarily involved (Fisher and Cole, et al., 1991). The cerebellum plays also a major role in the 1965; Iragui and McCutchen, 1981), weakness is either control of the trajectories during coordination tasks requir- absent or mild in the TAS (Solomon et al., 1994). ing synchronous shoulder and elbow movements (Mas- Patients with cerebellar disease performing proximal or saquoi and Hallett, 1996). In particular, the cerebellum is distal fast goal-directed movements at the level of a single responsible for a prediction, an accommodation and a joint often overshoot the target (Holmes, 1917; Gilman et compensation for the dynamic interaction torques which occur at one joint as a result of a movement of another * Corresponding author. Tel.: 132 2 5556747; fax: 132 2 5553942. joint linked (Bastian et al., 1996). 0022-510X / 97 / $17.00  1997 Elsevier Science B.V. All rights reserved PII S0022-510X(97)00096-8