MR-guided focused ultrasound used to treat first U.S. patient with Parkinson’s disease
The University of Maryland’s Center for Metabolic Imaging and Image-Guided Therapeutics (CMIT) in Baltimore performed the first MRI-guided focused ultrasound procedure to treat dyskinesia in an American patient with Parkinson’s disease. The patient is one of 40 being recruited to participate in an international clinical pilot study to assess the feasibility, safety, and preliminary efficacy of MR-guided focused ultrasound pallidotomy for dyskinesia (abnormal distorted movement).
Researchers from the Departments of Diagnostic Radiology and Nuclear Medicine, Neurosurgery and Neurology at CMIT used MRI to guide ultrasound waves through the intact skin and skull to reach the global pallidus. The global pallidus contributes to the regulation of voluntary movements and is targeted with medications and deep brain stimulation using implanted micro-electrodes to treat motor symptoms of tremor, rigidity, and dyskinesia in patients with Parkinson’s. Dyskinesia is a common complication of the medical treatment of Parkinson’s disease using drugs such as levodopa.
These functional imaging and noninvasive ultrasound procedures are performed on an outpatient basis in the CMIT MRI suite. After being fitted with a head-immobilizing frame fitted with a transducer helmet, a patient lies in a MRI scanner. Ultrasonic energy is targeted through the skull to the globus pallidus of the brain (ExAblate Neuro System, Insightec, Tirat Carmel, Israel) and images acquired during the procedure give physicians real-time images of the area being treatment.
“We are raising the temperature in a very restricted area of the brain to destroy tissue. The ultrasound waves create a heat lesion that we can monitor through MRI,” explained principal investigator Howard M. Eisenberg, MD, chair of neurosurgery.
The entire procedure takes 2 to 4 hours. Patients are awake and able to interact with the treatment team, allowing physicians to monitor the immediate effects of treatment and make adjustments.
As of September 2015, 7 patients in Korea and 1 patient in Canada have also received treatment. Enrollment is still open for more patients to be treated at the University of Maryland Medical Center. Eligible patients include individuals whose medication has failed to satisfactorily control dyskinesia and who are not candidates for surgery. If clinical trials are successful, a large study is planned in advance of seeking U.S. Food and Drug Administration approval.
This clinical study follows a pilot study of focused ultrasound thalamotomy for essential tremor performed in 2011 at the University of Virginia Health Sciences Center in Charlottesville. Fifteen patients with severe, medication-refractory essential tremor were followed for one year. All patients experienced “significant improvement”, with scores for hand tremor improving from 20.4 at baseline to 5.2 one year after treatment, according to principal investigator and neurosurgeon W. Jeffrey Elias, M.D. and colleagues1. None of these patients had Parkinson’s disease.
The Michael J. Fox Foundation for Parkinson’s Research and the Focused Ultrasound Foundation are funding the Parkinson’s study.
REFERENCE
- Elias, WJ, Huss D, Voss T et al. A pilot study of focused ultrasound thalamotomy for essential tremor. 2013 N Engl J. Med. 369;7: 640-648.