Objective: To describe two patients with disabling tremor secondary to multiple sclerosis (MS) treated with magnetic resonance-guided focused ultrasounds (MRgFUS) thalamotomy.

Background: MRgFUS thalamotomy improves refractory tremor in essential tremor and Parkinson’s disease.  Tremor associated to other neurological conditions could also benefit from this technique.

Method: A right-handed 52-year-old woman was diagnosed with relapsing-remitting MS (RRMS) at 36-years-old, being currently in a secondary progressive form (Expanded Disability Status Scale (EDSS) of 8.0.) At the age of 38, bilateral action tremor appeared, being disabling for daily living activities. The Fahn-Tolosa-Marin (FTM) total score was 82 (part A: 21, B: 35, and C: 26). The second patient was a right-handed 34-year-old man diagnosed with RRMS at the age of 25 (EDSS 6.0). A progressive and disabling upper extremities action tremor started 6 years after disease onset. The FTM total score was 88 (part A : 28, B: 36, and C: 24). In both cases tremor was refractory to drugs, and were assessed in a multidisciplinary meeting, and were selected for out of label use of MRgFUS.

Results: Both patients underwent MRgFUS left thalamotomy. Stereotactic planning was performed for the left VIM and tractography was used to localize the adjacent anatomical structures. A significant improvement of the tremor was observed in both patients, remaining stable at 3 months (Patient 1: FTM-treated side: baseline: 28, post-procedure: 12, 3-months: 12; Patient 2: baseline: 28, post-procedure: 18, 3-months: 18). Patient 1 reported a patient-global impression of improvement (PGI-I) of  “much better”. Patient 2 reported a subjective improvement of 40%, being able to perform daily activities such as eating alone, carrying a mobile phone or help with transfers.  As side effects, transient worsening of basal dysarthria and right upper limb dysmetria, as well as transient paresthesia in the tongue were observed.

Conclusion: MRgFUS thalamotomy was a safe and effective treatment for disabling refractory tremor associated to MS in our two cases. Although the improvement of the tremor was partial, its impact in the quality of life of patients is significant. However, more studies are needed to assess definite criteria, and patients should be selected based on MS clinical picture.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/magnetic-resonance-guided-focused-ultrasounds-mrgfus-thalamotomy-for-disabling-tremor-secondary-to-multiple-sclerosis/