Hemi-parkinsonism and return of essential tremors after MRgFUS thalamotomy: Case report and review of procedural complications affecting ventral thalamic nuclei

• Published in: eNeurologicalSci 2021-06, Vol.23, p.100339, Article 100339
• Main Authors: Varma-Doyle, Aditi Vian, Villemarette-Pittman, Nicole R., Copeland, Brian J.
• Format: Article
• Language: English
• Subjects: Case Report; Dysarthria; Essential tremors; MRgFUS thalamotomy; Parkinsonism; Ventrolateral thalamic nucleus; VIM nucleus
• ISSN: 2405-6502; 2405-6502
• DOI: 10.1016/j.ensci.2021.100339

Magnetic resonance guided focused ultrasound (MRgFUS) thalamotomy targets the ventral intermediate nucleus of the thalamus and has been shown to be safe and effective to treat medication-resistant essential tremors. Improvement in tremor scores, posture and action scores, disability scores and quality of life scores have been reported in patients treated with this procedure. Adverse events are usually transient and non-severe. We present a patient who underwent MRgFUS thalamotomy of the left VIM and developed new-onset parkinsonian features predominantly on the right side and return of essential tremors a few years after the procedure. Changes in speech (hypophonia and dysarthria), gait imbalance and postural instability, bradykinesia, and cogwheeling rigidity occurred, likely due to involvement of the fiber tracts through the ventrolateral subnuclei and the adjacent ventral anterior thalamic nuclei and other surrounding structures. We describe side effects of MRgFUS thalamotomy in our patient compared to previous reports and review the thalamic nuclei and surrounding structures that can be affected during procedure, causing these effects. •We describe parkinsonism and return of ET as side effects post-MRgFUS thalamotomy.•We review thalamic nuclei that can be affected during MRgFUS thalamotomy.•Role of afferent/efferent connections of ventral thalamic nuclei are discussed.