Gamma Knife Radiosurgery for Thalamotomy in Parkinsonian Tremor: Preliminary Report

Kim, Jeong Eun; Paek, Sun Ha; Chung, Hyun Tai; Kim, Dong Gyu

Abstract

OBJECTIVE
The authors present a retrospective analysis of gamma knife radiosurgery for thalamotomy for Parkinsonian tremor to determine the efficacy of the procedure, to review radiological findings of radiosurgical lesioning and to assess the risk of complications. METHODS: Radiosurgical thalamotomy with gamma knife was performed in one men and nine women. The target was nucleus ventralis intermedius following classic anatomical landmarks. The median age of the patients was 68 years(range 53-85). A mean radiation dose of 148Gy(range 140-168) was delivered using a 4-mm collimator. Patients were followed for a mean of 35 months(range 21-47). Independent neurological evaluation of tremor was based on the change in the Unified Parkinson's Disease Rating Scale tremor score(UPDRS, question 16, 20, 21) and the subjective satisfaction. The radiological follow-up period of the available five cases ranged from 6 to 13 months(mean 6). RESULTS: Nine patients(90%) showed the decrease in the sum of UPDRS. In the patient's subjective satisfaction, five(50%) showed excellent improvement, three(30%) good improvement and one(10%) mild improvement respectively. No response was observed in one patient. The mean time to onset of improvement was 3.5 months (range 1-14). There were no neurological complications. Follow-up magnetic resonance image showed the target-shaped lesion with a ring enhancement, of which location was matched to that of gamma knife planning. CONCLUSION: Gamma knife radiosurgery for thalamotomy offers acceptable tremor control with minimal risk to patients unsuited for open surgery, however, larger consecutive series and long-term follow-up are mandatory.