Unilateral MR-guided laser interstitial thermal therapy thalamotomy for refractory multiple sclerosis tremor: 12-month outcomes in four patients

Background Tremor affects many people with multiple sclerosis (MS), is frequently disabling and responds poorly to medication. Deep brain stimulation, gamma-knife radiosurgery and MR-guided focused ultrasound are options, but each has constraints. MR-guided laser interstitial thermal therapy (MRgLITT) is a hardware-free stereotactic thalamotomy providing real-time thermometry, its role in MS tremor is unknown. Objective To describe 12-month clinical, safety and imaging outcomes after unilateral MRgLITT thalamotomy for refractory MS tremor. Methods Single-centre, consecutive case series of four patients with medically refractory MS tremor who underwent robot-assisted unilateral MRgLITT thalamotomy. The primary outcome was the treated-limb Fahn–Tolosa–Marin Tremor Rating Scale (FTM-TRS) at 12 months, scored from standardized videos by a blinded neurologist. Secondary outcomes were patient-reported tremor severity, tremor-related quality of life, adverse events, cognition, mood and MRI lesion characteristics. Analyses were descriptive. Results The cohort comprised three secondary-progressive and one relapsing-remitting patient (median EDSS 5.5; median tremor duration 15.5 years). The mean treated-limb FTM-TRS score fell from 15.8 to 5.5 at 12 months (mean per-patient reduction 65.7%, range 41.2–80.0%). Quality of life improved in three of four patients. Acute adverse events occurred in two patients (transient gait ataxia; transient hemiparesis with dysarthria), both resolving by 3 months, none persisting at 12 months. Cognitive decline in one patient and mood deterioration in two, the causes of these changes remain uncertain. Conclusion Unilateral MRgLITT thalamotomy was feasible and produced meaningful, largely sustained tremor reduction within a narrow therapeutic window. Larger controlled studies are required to establish efficacy, durability, safety and function.