The Food and Drug Administration (FDA) has recently approved a first of its kind focused ultrasound device to treat essential tremor in patients who have not responded to medication. Insightec’s Exabalate Neuro uses magnetic resonance images taken during the procedure to deliver focused ultrasound waves to destroy brain cells in a tiny region that is believed to induce tremors. A trial was conducted to test the effectiveness of the treatment with results showing nearly 50% improvement in tremor reduction.
Essential tremors, also known as benign essential tremors, are the most common form of tremors. According to the National Institute of Neurological Disorders and Stroke, several million Americans, usually those over age 40, are affected by the condition. Essential tremor may be treated with beta blockers or anticonvulsant drugs. If medications fail to control symptoms, the condition may also be treated with surgery, known as thalamotomy or a deep brain stimulation device to destroy the tiny part of the brain (thalamus) that controls some involuntary movements, and important functions such as sleeping, consciousness and sensory interpretation. Thalamotomy usually carries a risk of inducing hemorrhage, resulting in stroke and even death.
To test the efficacy of ExAblate Neuro treatment in a patient, patients should first have MR scans and computerized tomography (CT) scans. The patients who are eligible to undergo treatment with the MRI-guided device lie in an MRI scanner that takes images to help a doctor identify the targeted area in the brain’s thalamus for treatment. Treatment with transcranial focused ultrasound energy is administered with incremental increases in energy until patients achieve a reduction of tremor. Patients are conscious and responsive throughout the whole treatment. Real-time thermal feedback allows the physician to control and adjust the treatment, ensuring that the targeted tissue is completely ablated without impacting adjacent healthy tissue.
The trial was conducted in a double-blind setting involving 76 patients with essential tremor who had not responded to medication therapy, 56 of which received the ExAblate Neuro treatment, while 20 served as control, receiving pseudo treatment. Patients in the control group were able to cross over into the treatment group three months later.
Patients treated with ExAblate Neuro showed nearly 50% improvement in their tremors and motor function (composite tremor/motor function score) three months after treatment compared to their baseline score. Patients in the control group had no improvement, and some experienced a slight worsening after the sham procedure before they crossed over into the treatment group. At 12-month post-procedure, the treatment group retained a 40 percent improvement in these scores compared to baseline.
Adverse events for the ExAblate Neuro are consistent with those reported for thalamotomy surgery, including numbness or tingling sensation of the fingers, headaches, nausea, imbalance/unsteadiness, loss of control of body movements, known as ataxia or gait disturbance. Other side effects identified as possibly related to treatment with magnetic resonance-guided focused ultrasound treatments include tissue damage in a nearby region to the target area, hemorrhage in the target area requiring emergency treatment, skin burns with ulceration of the skin, skin retraction, scar formation and blood clots.
The ExAblate Neuro treatment is not recommended for patients who cannot have MR imaging, including those who have a non-MRI compatible implanted metallic device, such as a cardiac pacemaker, or metallic hip joint, those with allergies to MR contrast agents or those with body size limitations for MR machines.
The treatment should also not be used in women who are expecting, patients with advanced kidney disease or on dialysis treatment, those with unstable heart conditions or severe hypertension, patients exhibiting any behavior consistent with ethanol or substance abuse or patients with a history of abnormal bleeding, hemorrhage and/or blood clotting disorders (coagulopathy). Patients currently taking anticoagulant drugs or drugs known to elevate the risk of hemorrhage, patients with a history of cerebrovascular disease (strokes) or brain tumors and patients who are not able to tolerate the prolonged stationary position during treatment also should avoid the procedure.
The significant advantages of this treatment is that it gives immediate result in a single session without any invasive surgery in a single treatment without the use of anesthesia, or any implant hardware. “Patients with essential tremor who have not seen improvement with medication now have a new treatment option that could help them avoid more invasive surgical treatments,” said Carlos Peña, PhD, MS, Director of the Division of Neurological and Physical Medicine Devices in the FDA’s Center for Devices and Radiological Health. “As with other treatments for essential tremor, this new device is not a cure but could help patients enjoy a better quality of life.”
Insightec was founded in 1999 and develops Exablate platform which provides non-invasive treatments for a variety of oncology and gynecology indications. The Exablate platform uses revolutionary MRgFUS technology which combines high intensity focused ultrasound guided by magnetic resonance imaging (MRI).