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Focused Ultrasound for Essential Tremor (ET) and Tremor Dominant Parkinson’s Disease (TDPD)

What is Focused Ultrasound?

OVERVIEW

Focused Ultrasound Set-up

Focused Ultrasound is an incisionless treatment for patients with Essential Tremor (ET) and Tremor Dominant Parkinson’s Disease (TDPD) who have not responded to medication. It uses high intensity ultrasound waves guided by MRI to treat deep areas in the brain associated with tremor, with no permanent implants or general anesthesia. There is little to no risk of infection and patients usually return home the same day with immediate tremor improvements.

Focused ultrasound targets a small brain area called the ventral intermediate nucleus, which is a crucial relay station for tremor-related signals. This precise targeting is a crucial aspect of its efficacy in reducing tremors. During the procedure, the patient is lying on a table and moves in and out through an MRI. The MRI enables the physician to visualize a patient’s brain anatomy, plan, and target the area for treatment. It also acts like a thermometer, providing continuous temperature monitoring to verify that only the targeted tissue is destroyed. As the temperature at the brain target rises, it creates a small ablation or burn, providing a therapeutic effect.

While treatment of hand tremors is the goal of focused ultrasound, it may also provide some degree of tremor relief for the head and voice.

Medical Indications

  • Medication-Refractory Tremor: Patients with ET or TDPD who have not adequately responded to medication may be considered.
  • Severe Tremor Impacting Quality of Life: Candidates typically have tremors that significantly affect their daily activities, work, and social interactions, thereby impairing their quality of life
  • Patient Preference: Particularly suitable for patients who prefer less invasive procedures and patients who want to avoid the upkeep of an implantable device.
  • Contraindications for Surgery: Patients who cannot undergo surgical procedures due to medical contraindications may be eligible, as it avoids surgical risks such as infection and bleeding.
  • Treatment of Unilateral Symptoms: The treatment is FDA approved for staged unilateral treatment – treating one side at a time with at least 9 months between treatments for eligible patients and without significant clinical events from the first treatment.
  • Assessment and Diagnosis: Patients are typically assessed to ensure that their tremor symptoms are primarily caused by ET or TDPD and no other neurological conditions, ensuring accurate diagnosis and treatment.

Benefits & Expected Outcomes

Incisionless Focused ultrasound does not require incisions, general anesthesia, nor surgical implants, reducing some of the risks inherent to more invasive procedures.

  • Outpatient Setting: The procedure is usually performed in an outpatient setting, eliminating the need for hospital stays.
  • Precision: The technology allows for precise targeting, minimizing damage to surrounding tissues.
  • Safety Profile: Focused ultrasound generally has a favorable safety profile with relatively few serious adverse effects.
  • Rapid Recovery: Patients often experience a rapid recovery with minimal downtime, sometimes resuming normal activities within days.
  • No Permanent Implants: Unlike deep brain stimulation, which involves placing permanent electrodes in the brain, focused ultrasound does not leave any implants, thus avoiding long-term maintenance issues and the need for device programming.
  • Immediate Effects: Many patients experience an immediate reduction in tremor severity following the procedure, providing rapid symptomatic relief.
  • Improvement in Quality of Life: By alleviating tremor symptoms, patients often report improved quality of life, including better social interaction and reduced dependency on others for daily tasks.
  • Sustained Benefits: Clinical studies have shown that many patients maintain the benefits of tremor reduction for a prolonged period following treatment, although ongoing monitoring is recommended.

Potential Side Effects & Complications

While focused ultrasound is generally safe, there are potential side effects and complications that patients should be aware of:

  • Temporary Side Effects: Some patients may experience temporary effects such as numbness, tingling, imbalance, headache, nausea, or discomfort in treated areas. These symptoms usually resolve after a few days to weeks.
  • Permanent Side Effects: A small percentage of patients are at risk of permanent side effects, which may include numbness, tingling, balance issues, or other neurological changes
  • Uncommon Serious Complications: Although rare, there is a potential for severe complications such as scalp burn, brain hemorrhage, and speech or swallowing changes. Each patient’s risk of side effects and complications can vary based on their medical history, condition severity, and other health factors.
  • Long-Term Monitoring: Ongoing follow-up is necessary to assess the durability of tremor reduction and manage any emerging side effects.
  • Failure to Achieve Desired Tremor Reduction: Some patients may not experience the anticipated level of tremor improvement, necessitating additional interventions.

Alternative Treatments to Focused Ultrasound

The choice of treatment depends on the severity of symptoms, patient preference, and individual health considerations. Here are some of the primary alternatives.

Pharmacological Treatments

  • Medications for Essential Tremor:
    • Beta Blockers: Propranolol is commonly prescribed to reduce tremor severity.
    • Anti-seizure Medications: Drugs like primidone can be effective for ET.
  • Medications for Parkinson’s Disease:
    • Levodopa/Carbidopa: The most effective medication for treating Parkinson’s symptoms, including tremor.
    • Dopamine Agonists: Such as pramipexole and ropinirole, mimic dopamine effects in the brain.
    • MAO-B Inhibitors: Rasagiline and selegiline can help increase dopamine levels

Surgical and Interventional Treatments

  • Deep Brain Stimulation (DBS): DBS involves implanting electrodes in specific brain areas (usually the thalamus for ET and the subthalamic nucleus for TDPD) to regulate abnormal activity and reduce tremor. It is a reversible and adjustable treatment, offering sustained tremor relief for many patients.
  • Radiofrequency Thalamotomy: A surgical procedure that involves lesioning a small area of the thalamus responsible for tremor, typically used when other treatments fail.
  • Botox Injections: Botulinum toxin injections can be effective for localized tremors, such as hand tremors in ET.

Lifestyle and Complementary Approaches

  • Physical and Occupational Therapy: Therapists can help patients develop strategies to manage daily activities affected by tremor and maintain functional mobility.
  • Lifestyle Modifications: Reducing caffeine intake, using adaptive devices, and stress management can help minimize tremor severity.
  • Diet and Exercise: Regular exercise and a balanced diet can improve overall health and help manage symptoms indirectly.
  • Alternative Medicine: Techniques such as acupuncture, meditation, and yoga can provide additional relief and improve quality of life.

Considerations

  • Individualized Treatment: It’s crucial for patients to work closely with healthcare providers to tailor treatment plans to their specific needs and preferences.
  • Combination Therapy: Often, a combination of treatments provides the best symptom control, requiring a multidisciplinary approach.
  • Evaluation and Monitoring: Continuous evaluation is important to assess the effectiveness and adjust treatments as needed.

HOW IT WORKS

Procedure Description

  1. The patient’s head is shaved to ensure efficient transmission of ultrasound waves.
  2. The patient undergoes an MRI to identify the specific brain area responsible for tremor.
  3. The patient’s head is secured in a frame to ensure precise targeting.
  4. The patient is positioned in a focused ultrasound machine, similar to an MRI scanner.
  5. Ultrasound waves are directed at the target area in the brain through the intact skin and skull.
  6. The energy from the ultrasound waves heats and ablates the targeted brain tissue, altering its activity to reduce tremor.
  7. Throughout the procedure, MRI imaging is used to monitor the effects and adjust the ultrasound beam as needed.
  8. The patient may be asked to perform tasks or movements during the procedure to evaluate tremor improvement.
  9. The entire procedure usually lasts between 3 to 4 hours. This includes preparation, imaging, treatment, and immediate post-procedure monitoring.
  10. The procedure is completed, and the patient is typically monitored for a short period before being discharged.

FAQS

The FDA approved the Exablate Neuro device for treating essential tremor at the end of 2016 and for treating patient’s second side essential tremor in 2022.

The limitation is based on the FDA approval that is based on the clinical study that was performed and its criteria.

The treatment is FDA approved to treat hand tremor. Patients with head or voice tremor may experience relief of their tremor.

The treatment is FDA approved for staged unilateral treatment – treating one side at a time with at least 9 months between treatments for eligible patients and without significant clinical events from the first treatment.

The ultrasound waves pass through the rest of the brain. Only where they converge in the thalamus does the temperature rise, heating and creating a lesion that helps disrupt what is causing the tremor.

The possibility is rare, because MR imaging allows the treating physician to continuously see the treatment area and monitor the temperatures.

Yes, you need to have a definitive diagnosis of essential tremor, often done by your healthcare provider, primary care physician, a neurologist, or a movement disorder specialist. Other criteria are described below and should be discussed with your physician.

To be a candidate for the incisionless treatment, you must have a confirmed diagnosis of essential tremor that does not respond or are ineligible for at least two standard of care medications.

The focused ultrasound treatment (also known as Magnetic Resonance guided Focused Ultrasound (MRgFUS) for treatment of essential tremor) is covered 80% under Medicare Part B.

Coverage may vary depending upon benefits, although most commercial insurances do offer coverage. Contact your health plan’s Member Service department by calling the phone number listed on the back of your insurance ID card. Ask whether MR-guided Focused Ultrasound for treating essential tremor (CPT code 61715) is a covered benefit in an outpatient setting based on your health plan.

Yes, you will need to get a specialized CT scan, and you may be asked to get an MRI scan as well.

Everyone’s skull is different, and a CT scan is done to determine if the shape and thickness of your skull are suitable for the incisionless treatment. Certain skull shapes and thickness may make it impossible for ultrasound waves to reach the temperature at the target required for treatment.

Most often, a patient will meet with the treating physician at least two times. At the first consultation, the physician will evaluate your CT scans to determine whether you are a candidate for the treatment. The second is on treatment day. In some instances, you may meet a third time for follow-up imaging on the day after treatment. The treating team will also discuss any additional follow up visits needed as well as information that will be relayed back to your referring physician.

The frame is a standard stereotactic frame that helps ensure your head does not move during the treatment.

No, from about your mid-torso up will be placed inside the scanner.

No, the treatment bed will move in and out of the MRI scanner. After each application of energy, your tremor will be assessed by doing various tasks such as drawing a spiral.

Ultrasound waves do not travel well through air. In this treatment, water is used as a conductive medium. A smooth scalp covered by a silicone cap enables a tight interface with the ultrasound transducer. Secondly, air bubbles could get trapped in the hair, blocking the ultrasound waves and absorbing energy. A smooth scalp covered by a silicone cap prevents skin burns. Some patients also consider the use of wigs as hair growth returns.

Your feedback during the treatment is necessary as you will be asked to do different neurological tasks such as drawing spirals. This is so the physician can evaluate the improvement of your tremor by addressing any potential side effects that you may be experiencing during the treatment.

The treatment time is a few hours on average and performed on an outpatient basis. However, the treating physician will decide when you can return home.

The most recent data shows hand tremor improvement of the study subjects was mostly maintained at three years. There is the possibility that your tremor may return months or even years after the treatment, or that the tremor may not improve at all. And while the treatment may improve your tremor, it is important to understand that it does not treat the underlying disease nor prevent its progression.

Most patients may return to work after a week, but the timing may vary based on your occupation.

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