Abstract

Background: Our institution has previously reported on effectiveness and side effects of Gamma Knife Thalomotomy (GKT) for treatment resistant essential tremor(ET) and Parkinsonian tremor(PT).

Objective: Examine the functional outcomes and side effect profile of patients with Essential and Parkinsonian tremor, resistant to medical therapy, treated with GKT.

Methods: Fifteen-year review of our experience with medically refractory patients treated with GKT for disabling ET and PT.  Previous treatments included DBS (1/91) and medications (58/91). Utilizing the Leksell treatment planning system, gamma knife was utilized to target the ventralis inter-medius (VIM), target dose ranged from 125-130Cy, utilizing a single 4mm shot.  Effectiveness of therapy and evaluation of side effects was evaluated utilizing the Archimedes spiral test, in combination with patient follow ups.

Results: Complete resolution or significant improvement of tremor symptoms occurred in 85% of patients (77/91) at an average of 6 months post treatment. Archimedes tremor score pre and post op was utilized for analysis of therapeutic benefit.  Median post-operative follow-up for evaluation was 16 months (duration 1-64). Side effect symptoms were evaluated clinically and radiographically utilizing MRI.  Radiographically confirmed edema was noted on the side of treatment in 15% of patients (14/91). Major side effects included extremity weakness in 13% of patients. Unsteady gait developed in 5% (5/91), with 2% requiring a cane or wheelchair.  Visual change in 2% (2/91), this manifested as blurriness.  Verbal change 1% (1/91) manifested as expressive aphasia.

Conclusion: Gamma Knife Thalamotmy provides effective relief from tremors, comparable to that of other standard of care treatment options. Persistent side effects were noted in 15% of patients, of which 50% diminished in time.