Evaluation of outcomes in Gamma Knife stereotactic radio surgery treatment of essential and Parkinsonian tremor

Alyssa Zemanek1, Peter Shin2, Herbert Wang3, Michael McDonough3, Kenneth Bergman3, Kevin Sanders3, Nathan Bittner3, Ann Pittier3, Dean Mastras3

1Tacoma, United States 2South Sound Gamma Knife, Tacoma, USA 3Tacoma/Valley Radiation Oncology Centers, Tacoma, USA

Keywords: tremor, thalamotomy, gamma knife, outcome, Parkinson's Disease

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     Disabling tremor can be improved with thalamotomy.
The purpose of this study was to examine the outcomes of 39 patients (40 cases) with essential or Parkinsonian tremor who were treated with Gamma Knife stereotactic radiosurgery (GKSRS) via ventralis intermedius (Vim) thalamotomy.
     In total, 39 patients with a median age of 77.5 years, received GKSRS for tremor.
     A total of 40 cases of tremor were treated at our institution, 35 essential tremor, three Parkinsonian tremor, and two with both types of tremor. Using magnetic resonance imaging, the Vim was located and treated, receiving a single isocenter exposure of 130Gy with a 4-mm collimator. These patients were followed by their radiation oncologist or neurosurgeon. A retrospective review of medical records, in combination with patient phone interviews, was conducted to obtain data on treatment outcomes.
      They had a median pre-treatment tremor duration of 13 years (range, 1.5-70). With a median follow-up period of 15.5 months (range, 3-64), a total of 33 patients (82.5%) responded to the treatment, as evidenced by lessening in their tremor severity. Of these patients, 24% had a complete response, with no residual tremor. The median time to response was 3.5 months (range, 0.1-12). One patient developed unilateral weakness in his lower extremity with evidence of significantly more edema than what is considered normal. He had steroid and physical therapy that resolved this weakness.
     This was a retrospective series.
     GKSRS Vim thalamotomy at our institution was shown to provide relief from tremor at rates similar to other studies on this topic. 
     This is a viable, safe and effect treatment option that is an alternative to deep brain stimulation in patients refractory to medication.


Project Roles:

A. Zemanek (), P. Shin (), H. Wang (), M. McDonough (), K. Bergman (), K. Sanders (), N. Bittner (), A. Pittier (), D. Mastras ()