Noninvasive functional neurosurgery using transcranial MR imaging-guided focused ultrasound.

Transcranial magnetic resonance imaging-guided focused ultrasound (tcMRgFUS) is a novel technique to supplement the spectrum of established neurosurgical interventions. In contrast to traditional ablative procedures, tcMRgFUS is noninvasive and entirely imaging-guided with continuous temperature measurements at and around the target in real time. It has no trajectory restrictions and does not involve ionizing radiation. Since no device is implanted into the brain or the body, there is no restriction to future diagnostic work-up with MR imaging. The ability to treat a variety of chronic, therapy-resistant neurological diseases by precisely focusing ultrasound energy to desired targets in the thalamus, subthalamus and basal ganglia while avoiding collateral tissue damage is certainly attractive. Ongoing clinical studies on over 130 patients with neuropathic pain, essential tremor, Parkinson's disease and obsessive-compulsive disorder are very promising and demonstrate that ultrasound energy can precisely be focused through the intact skull, without overheating it. Varying the ultrasound parameters allows not only to ablate pathological tissue, or silence dysfunctional neuronal circuits, but also to modulate neural functions, as shown in preclinical studies. Transcranial magnetic resonance imaging-guided focused ultrasound is a novel, noninvasive, alternative treatment option for patients with therapy-resistant movement disorders, such as essential tremor and Parkinson's disease.