Thalamic ataxia refers to the incoordination that develops due to a lesion involving the thalamus, particularly VL and VPL/VPM, probably because of involvement of the dentatorubrothalamic tract and ascending sensory pathways as they enter the thalamus. Thalamic ataxia usually occurs after ischemic lesions, primarily infarction involving the distribution of the thalamogeniculate artery. Patients develop "cerebellar" findings, but these are associated with sensory loss (hemiataxia-hypesthesia syndrome) and sometimes pain. Involvement of the immediately adjacent posterior limb of the internal capsule may cause weakness. In addition to ataxia and tremor, posterior thalamic infarction may cause dystonia, myoclonus and chorea. When these involve the hand, the condition is referred to as “thalamic hand.”
This patient presented with an enhancing mass lesion in the left thalamus with vasogenic edema. Biopsy findings suggested lymphoma but review of the pathological material at referral centers, ultimately Memorial Sloan Kettering, favored sarcoidosis. Significant improvement followed steroid therapy but the patient was left with a mild right hemiparesis, worse in the upper extremity, accompanied by dystonia of the hand, ataxia and dense sensory loss. This combination of findings is consistent with “thalamic hand.” The findings are similar to those in case 3 of Ghika, et al in their paper on the "jerky dystonic unsteady hand."(4)
1. Campbell WW. DeJong's the neurologic examination, 7th ed. Philadelphia: Wolters Kluwer Health/Lippincott Williams & Wilkins, 2013. 2. Deleu D, Lagopoulos M, Louon A. Thalamic hand dystonia: an MRI anatomoclinical study. Acta Neurol Belg. 2000 Dec;100(4):237-41.
3. Franzini A, Ferroli P, Servello D, Broggi G. Reversal of thalamic hand syndrome by long-term motor cortex stimulation. J Neurosurg. 2000 Nov;93(5):873-5.
4: Ghika J, Bogousslavsky J, Henderson J, et al. The "jerky dystonic unsteady hand": a delayed motor syndrome in posterior thalamic infarctions. J Neurol. 1994 Aug;241(9):537-42.