Brain Bleeding Associated With Cavitation During Focused Ultrasound Ablation.

Magnetic resonance-guided focused ultrasound (MRgFUS) ablation is a new therapeutic tool for movement disorders. Side effects after treatment are mild to moderate, and treatment-related severe complications are rare. Technical intraprocedural hurdles such as inertial cavitation can be associated with adverse events. We describe 2 patients who developed symptomatic brain bleeding during MRgFUS ablation associated with the presence of cavitation. This complication has not been reported thus far. Two female patients aged 74 and 68 years were treated with MRgFUS ablation for medically refractory essential tremor and Parkinson disease, respectively. The treatment progressed uneventfully, and clinical improvement was seen; however, cavitation occurred before we achieved satisfactory benefit. To mitigate cavitation, sonication power was decreased in both patients, but cavitation activity persisted. After the last sonication, both patients showed contralateral motor weakness, and the treatment was terminated. Post-treatment brain computed tomography scans in both patients showed a brain hematoma in the targeted area. One patient improved progressively within a few months, but the second remained disabled. These two cases represent 0.4% of our over 500 patients treated with MRgFUS ablation, and, thus, brain bleeding should be considered a rare complication of the therapy. However, it cannot be ruled out, particularly if uncontrollable cavitation occurs. A conservative approach should be taken in such cases to avoid it.