A prospective randomized control study of Gamma Knife radiosurgery for trigeminal neuralgia with one or two isocenters: the preliminary result of 26 patients

Keywords: trigeminal neuralgia, pain, gamma knife, outcome, randomized trial

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     There are different techniques for trigeminal neuralgia radiosugery.
A prospective randomized control study of Gamma Knife radiosurgery for trigeminal neuralgia was carried out to investigate the different results between one isocenter and two isocenters.
     Twenty-six patients were followed up with an average time of 6.3 months (4 days to 16 months). There were 14 patients in Group I and 12 patients in Group II. The average age of Group I patients was 64.5 years (56-77) and 65.3 years (43-87) of Group II. The average carbamazepine dose was 600mg/d (100-1800mg/d) of Group I patients and 688.9mg/d (200-1500mg/d) of Group II patients before treatment.
     Between June 2010 and August 2011, 26 patients were included in this study. The patients were divided into two groups based on the randomized rule. Single isocenter was delivered to patients of Group I and two isocenters to Group II patients. The central dose was limited to 85Gy or 90Gy for each patient of both groups. Follow-up was established through the telephone visit. The effect was classified to complete pain relief (pain free with or without medication), partial pain relief (pain frequency reduction superior to 50%) and no effect (pain frequency reduction less than 50%).
      At last follow-up, the number of complete pain relief, partial pain relief and no effect was 8 (57.2%), 6 (42.8%) and 0 in Group I, and 4 (33.3%), 5 (41.7%), 3 (25%) in Group II respectively. The mean time to pain relief was 4.72 weeks (1 day – 24 weeks) of Group I patients and 4.65 weeks (1 day -12 weeks) of Group II patients. Radiation induced brain injury was observed in two patients of Group I to whom the central dose of 90Gy had been delivered. Facial numbness was reported by one Group I patient and two Group II patients. No pain recurrence was reported.
     Although this was a prospective trial, more subjects would have provided greater study power.
     There is not enough evidence for the benefit with two isocenters based on the initial result of this study. A central radiation dose of 90 Gy might increase the risk of radiation induced brain injury. 
     However, the preliminary result of these 26 patients was limited. More cases and longer follow-up are needed.


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