Stereotactic Radiosurgery for Essential Tremor and Parkinsonian Tremor

The purpose of this study is to determine the changes in quality of life and degree of tremor for patients with essential tremor or Parkinsonian tremor who are treated by stereotactic radiosurgery (SRS).

Tremor is the most common of all movement disorders. Patients with essential tremor (ET) or Parkinsonian tremor (PT) may be severely disabled by their tremor. When the tremor is inadequately controlled by medications, surgical options are often offered. However, some patients may prefer a noninvasive treatment approach and some patients are not surgical candidates for medical reasons.

Stereotactic radiosurgery (SRS) is a treatment that uses high-energy highly-focused radiation (X-rays) to destroy a tiny region in the brain that causes tremor to occur. This region is known as the ventral intermedius nucleus of the thalamus and is the same area targeted by surgical deep brain stimulator (DBS) treatment or neurosurgical operation (thalamotomy). Multiple case series publications using Gamma Knife stereotactic radiation have been reported that show stereotactic radiosurgery is safe and effective treatment for ET and PT, making it a standard treatment for inoperable and inadequately controlled tremor patients. However, radiation treatment by linear accelerator machines are much more common than Gamma Knife treatment machines in the United States, and there are no reports of large series of ET and PT patients treated using linear accelerator-based SRS using a noninvasive mask-based targeting system.

This clinical trial asks the question of whether linear accelerator-based SRS is as safe and effective as that reported for Gamma Knife procedures, and whether it is a valid alternative to surgical thalamotomy or implantation of a deep brain stimulator (DBS) device. The primary measurements are quality of life related to tremor before and after stereotactic radiosurgery treatment, and secondary measurements are degree of tremor severity and usage of tremor-related medications.

All patients interested in this clinical trial must have consultations with both neurology (Dr. Peter Hedera or Dr. Fenna Phibbs) and radiation oncology (Dr. Anthony Cmelak). At the time of the consultations, baseline assessments of the patient's tremor-related quality of life (a questionnaire filled out by the patient) and severity of tremor will be determined (a questionnaire filled out by the neurologist). In preparation for the single stereotactic radiation treatment, a tight-fitting thermal plastic mask will be custom made and a thin-cut CT scan of the head will be performed in the radiation department. In addition, a thin-cut MRI of the brain will be done for treatment planning. Approximately 1 week after obtaining the imaging for planning, the single stereotactic radiation treatment will be performed. Afterwards at 3 month intervals for up to 1 year, the quality of life questionnaire and severity of tremor will be assessed.

All patients interested in this clinical trial should feel free to call the contact phone numbers listed below or have their physician refer the patient for consultation with Dr. Anthony Cmelak in the radiation oncology department at Vanderbilt, as well as Dr. Peter Hedera or Dr. Fenna Phibbs in the neurology department at Vanderbilt.

This trial enrolls persons with essential tremor or Parkinsonian tremor that is inadequately controlled by medications.

• Tremor
• Essential Tremor
• Parkinson Disease
• Radiosurgery
• Quality of Life

Inclusion Criteria:

• Must be certified by a neurologist as having essential tremor or Parkinsonian tremor that is insufficiently controlled by medication alone.
• Preference to receive radiation treatment for tremor treatment, rather than surgical DBS implantation or surgical thalamotomy
• At least 18 years old

Exclusion Criteria:

• Contraindications to cranial radiation (such as prior radiation to the thalamus)
• Inability to have a MRI of the brain
• Taking an anticoagulant (except aspirin)
• Prior surgical thalamotomy treatment (but contralateral deep brain stimulator [DBS] is permitted)
• Estimated life expectancy less than 1 year