Connections: Quick relief and low risk with incision-free brain surgery for tremor | Winter 2022

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From the OHSU Brain Institute

Ahmed M.T. Raslan, M.D., headshot

Ahmed M. Raslan, M.D., FAANS, is a neurosurgeon and treats a spectrum of neurological diseases. He focuses on brain mapping in addition to surgery for epilepsy, chronic neurologic pain and movement disorders.

An incisionless neurosurgery is potentially life-changing for patients who have dominant tremor on one side of their bodies and whose disease has progressed to impact daily living. Using MR-guided high-intensity focused ultrasound (MR-HIFU), our surgeons can now perform extremely precise and accurate unilateral thalamotomies without burr holes, craniotomies or radiation.

For patients, this means:

  • Immediate improvement in tremor: Most patients have 70%-80% improvement within the same day of the procedure.
  • Rapid recovery: Most patients return to normal activity within a week.
  • Minimum side effects: These include skin irritation, nausea and vomiting, temporary weakness or imbalance.
  • Discontinuing medical therapy: Medications can be weaned following surgery.

MR-HIFU technology

The procedure combines image-guided, high intensity focused ultrasound ablation with real-time monitoring of temperature change in the brain during the sonication. This treatment takes about three hours and has submillimeter accuracy. OHSU Parkinson Center and Movement Disorders Program is the only resource between San Francisco and Seattle for this treatment option. By expanding our portfolio of services for people with movement disorders, patients in our region who could benefit from MR-HIFU to control tremor will now be able to get treatment closer to home.

Safer procedure for the right patients Many of the standard surgery risks don’t apply with MRHIFU, because there is no incision.

There is:

  • No general anesthesia
  • Low/no postop infection risk
  • Minimal pain/discomfort
  • Discharge same day or next day


  • Patients must meet standard MR protocols
  • Patients must be awake during the surgery.
  • Shaving the entire head is necessary for the procedure.
  • Anticoagulation medications must be stopped for a few days.
  • Tremor may eventually recur in some patients (15%-20%), but the procedure can be repeated. Recurrence rate is based on the first three years of data.

MR-HIFU versus asleep deep brain stimulation

These procedures are complementary. The decision for one treatment over the other is guided by patient presentation and preference.

Generally, asleep deep brain stimulation is the better option for patients with bilateral disorder or tremor in the central core. We know that many patients who are unwilling or unable to pursue DBS will consider MR-HIFU.

MR-guided high-intensity focused ultrasound for the brain

Ultrasound can create physiologic change by depositing heat via multiple beams of sound waves. The Food and Drug Administration approved MR-HIFU for essential tremor in 2016, adding tremor-dominant Parkinson’s disease in 2018. Medicare approved the treatment in 2020.

How it works

During the procedure, the patient wears a helmet that is fixed to the stereotactic frame. To keep the patient motionless, pins secure the helmet. We provide a local anesthetic for the placement of the pins.

Through the helmet, cold water circulates around the scalp. The surgeon uses low energy sonications to pinpoint the target, typically the ventral intermediate nucleus. To ablate the target, the surgeon uses multiple beams of acoustic energy that pass through the scalp and skull to create a tiny, discrete lesion without damaging surrounding tissue.

This is a gradual, stop-start process that requires feedback and testing with the patient (i.e., drawing spirals or raising arms) to assess tremor improvement throughout the treatment. The surgeon also receives real-time feedback about temperature changes in the brain.

When to refer

Our team will evaluate your patients for all options available for tremor, from medication to surgery. Appropriate candidates for MR-HIFU for tremor include:

  • Confirmed diagnosis of medication-refractory essential tremor over age 22
  • Confirmed diagnosis of medication-refractory tremor-dominant Parkinson’s disease over age 30