Introduction: Traditional stereotactic RF thalamotomy has been used with success in medication refractory tremor-dominant Parkinson’s disease. Recently, transcranial MR guided focused ultrasound (MRgFUS) has been used to successfully perform thalamotomy for essential tremor. We designed a double blinded, randomized controlled trial to investigate the effectiveness of MRgFUS thalamotomy in tremor-dominant PD.
Methods: Patients with medication refractory, tremor-dominant Parkinson’s disease were enrolled in the two center study and randomized 1:2 to receive either a sham procedure or treatment. After the 3 month blinded phase, the sham group was offered treatment. Outcome was measured with blinded CRST and UPDRS ratings. The primary outcome compared improvement in hand tremor between the treatment and sham procedure at 3 months. Secondary outcomes were measured with UPDRS and hand tremor at 12 months. Safety was assessed with MRI, adverse events, and comprehensive Neurocognitive assessment.
Results: Twenty-seven patients were enrolled and six were randomized to a sham procedure. For the primary outcome assessment, there was a mean 50% improvement in hand tremor from MRgFUS thalamotomy at 3 months compared to a 22% improvement from the sham procedures (p=0.088). The 1yr tremor scores for all 19 patients treated with 1yr follow up data (blinded and unblinded) showed a reduction in tremor scores of 40.6% (p=0.0154) and a mean reduction in medicated UPDRS motor scores of 3.7 (32%, p=0.0326). Sham patients had a notable placebo effect with a mean 21.5% improvement in tremor scores at 3 months. Twenty seven patients completed the primary analysis, 19 patients completed the 12 months assessment, 3 patients opted for DBS, 3 were lost to follow up, 1 patient opted for no treatment, and 1 is pending 12m evaluation.
Conclusions: Transcranial MRgFUS demonstrates a trend towards improvement in hand tremor, and a clinically significant reduction in mean UPDRS. A significant placebo response was noted in the randomized trial.
Patient Care: This research investigates the feasibility and durability of using MR guided focused ultrasound to produce unilateral thalamotomies in medication-refractory, tremor-dominant Parkinson’s disease patients, possibly providing an alternative to more invasive stereotactic techniques.
Learning Objectives: To understand the potential role of MR guided focused ultrasound thalamotomy in the treatment of medication-refractory, tremor-dominant Parkinson’s disease