Case Report: Jerky Dystonic Unsteady Hand Following High Frequency Focused Ultrasound Thalamotomy
Abdalmalik Bin Khunayfir1, Stewart Factor1, Nicholas Au Yong2, Richa Tripathi1
1Jean & Paul Amos PD & Movement Disorders Program, Department of Neurology, Emory University School of Medicine, 2Department of Neurosurgery, Emory University School of Medicine
Background:
MRI-guided focused ultrasound (MRgFUS) thalamotomy, targeting the ventralis intermedius (Vim) nucleus, has emerged as an effective treatment for refractory tremors in essential tremor (ET). While it improves tremor symptoms significantly, it has been associated with adverse effects such as disturbances in strength, speech, swallowing, balance, and sensation. Rarely, it can lead to abnormal movements, such as dystonia, asterixis, and hemi-parkinsonism. This case highlights the emergence of post-procedural jerky dystonic unsteady hand previously reported with thalamic strokes/lesions. This has not been associated with MRgFUS thalamotomy so far.
Design/Methods:
An 82-year-old right-handed male with ET underwent MRgFUS targeting the left Vim to alleviate severe postural and kinetic tremors. He had been intolerant to first-line medications. The procedure was performed with the lesion on target, at standard coordinates, and of reasonable size, with no immediate complications. MRI performed immediately following MRgFUS demonstrated the expected left VIM ultrasound ablation. While his examination post-procedurally showed tremor improvement, he developed involuntary, insuppressible movements in his right hand on post-procedure day one. These abnormal hand movements were primarily jerky, choreiform, and exacerbated by voluntary activity, and asterixis in the proximal right arm muscles. No changes in speech or swallowing were observed. Although the patient had pre-existing sensory abnormalities due to neuropathy, these remained unchanged post-procedure. Delayed MRI imaging at 4 months postoperatively showed the same finding as above, without other explanatory findings. On the six months follow up, the abnormal movements did not change significantly, while the tremor continues to be suppressed.
Conclusions:
This case presents a rare instance of "jerky dystonic unsteady hand" following MRgFUS thalamotomy, resembling hyperkinetic movement disorders seen in thalamic infarction. It suggests that Vim lesioning may alter function in adjacent thalamic nuclei, contributing to hyperkinetic complications. Further research is needed to understand the underlying mechanisms.
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