Transcranial MR-Guided Focused Ultrasound Used to Treat Patients with Functional Brain Disorders

A feasibility study has been completed assessing the use of noninvasive transcranial MR-guided focused ultrasound surgery (MRgFUS) for the treatment of neuropathic pain. Ten adult patients diagnosed with chronic neuropathic pain successfully underwent noninvasive deep brain ablation surgery (central lateral thalamotomy) with transcranial MRgFUS and showed improvement in pain scores and reduction of pain medication with no adverse effects at three months follow-up. This is the first study in the world to evaluate noninvasive transcranial focused ultrasound as a treatment modality for functional brain disorders.

InSightec, Ltd. (Tirat Carmel, Israel) developed the technology and the study was performed by a team at the University Children's Hospital Zurich (Switzerland). "This study showed that we can perform successful operations in the depth of the brain without opening the cranium or physically penetrating the brain with medical tools, something that appeared to be unimaginable only a few years ago,” said Daniel Jeanmonod, neurosurgeon at the University of Zurich. "By eliminating any physical penetration into the brain, we hope to duplicate the therapeutic effects of invasive deep brain ablation without the side effects for a wider group of patients.”

Neurosurgeons currently treat patients with functional neurologic disorders such as neuropathic pain or Parkinson's disease by inserting a tiny probe through the cranium and brain to reach and ablate damaged tissue. The more traditional invasive treatment works to alleviate pain and other symptoms, however, it exposes the patient to complications, including infections, bleeding, and damage to surrounding brain tissue, Dr. Jeanmonod explained. Moreover, only patients whose target tissue lies in the clear path of the probe are eligible for the invasive procedure, he said.

"We now have early clinical evidence suggesting that transcranial MRgFUS provides a safe and effective way to noninvasively ablate tissue deep within the brain,” said Ernst Martin, M.D., director of the Magnetic Resonance Center at the University Children's Hospital Zurich. "While we need to monitor these patients further, we are very encouraged by the results to date and look forward to continuing our research. A noninvasive treatment that reduces the risk of infection and bleeding will fill an unmet need for many patients who currently have run out of treatment options or are unwilling to undergo invasive brain surgery because of the risks associated with it.”

One patient in the study suffered nerve damage from a spinal tumor that led to severe pain and cramps in his right arm. The pain persisted for years and the patient ultimately reported depression and suicidal thoughts because of his condition. Immediately after receiving transcranial MRgFUS treatment on his brain, he reported that the pain had disappeared. A short time later, he was able to resume normal activities that his neuropathic pain had prevented him from doing, such as gardening and outings in the country with his family.

The Swiss research team is planning a larger study for functional brain disorders and expands its clinical research to movement disorders, such as Parkinson's disease and tremor, and to other functional neurologic disorders later this year. Additional sites in North America are also expected to initiate clinical research programs in functional brain disorders with transcranial MRgFUS later in 2009.

ExAblate is the first system to use the MR guided focused ultrasound technology that combines MRI--to visualize the body anatomy, plan the treatment and monitor treatment outcome in real time--and high intensity focused ultrasound to target brain tissue noninvasively. MR thermometry allows the physician to control and adjust the treatment in real time to ensure that the targeted area is fully treated and surrounding tissue is spared. The ExAblate 4000 is a platform for a variety of transcranial indications, such as brain tumors, functional neurosurgery, stroke, and targeted drug delivery.

The ExAblate 2000, based on the same technology, was approved by the U.S. Food and Drug Administration (FDA) in 2004 as a treatment for symptomatic uterine fibroids; 5,000 women have been treated worldwide to date. ExAblate 2000 received the European CE marking certification for pain palliation of bone metastases in June 2007.

InSightec was founded in 1999 to develop the breakthrough MR-guided focused ultrasound technology and transform it into the next-generation operating room.

Related Links:
InSightec
University Children's Hospital Zurich