Meta-analysis of gamma knife treatment for trigeminal neuralgia

Jose Lorenzoni1, Adrián Zárate2, Raúl De Ramón3, Leonardo Badinez3, Francisco Bova3, Claudio Lühr3

1La Reina, Chile 2Departamento de Neurocirugía, Pontificia Universidad Católica de Chile 3Centro Gamma Knife Santiago, Gamma Knife Chile

Keywords: pain, gamma knife, trigeminal neuralgia, outcome, review

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     Trigeminal neuralgia radiosurgery is commonly performed.
     Our purpose was to analyze the results published in the literature concerning Gamma Knife treatment for trigeminal neuralgia focused on pain outcome, side effects and prognostic factors.
     A search in PubMed and Medline was performed looking for publications meeting the keywords: trigeminal neuralgia, radiosurgery and Gamma Knife. Only clinical series were selected, excluding systematic reviews. When many publications from the same center were found, only the most recent was considered. The data studied were the latency for pain improvement, the initial pain response, the long-term pain control, treatment-related morbidity and prognostic factors for pain outcome. Pain control was assessed by the Barrow Neurological Institute Pain Scale (BNI) and long term pain control was evaluated considering actuarial m-ethods. Prognostic factors associated with pain outcome were classed as clinical, anatomo-radiological and dosimetric. Only significant prognostic factors in multivariate analysis were considered. For each variable three studies were done. First, a study of the number of publications supporting the positive, neutral or negative influence on pain outcome, then, a study considering the number of patients included in such studies and finally an integrated analysis of the hazard ratios.
     Sixty one manuscripts published between 1997 and August 2011 were selected for the purpose of this study. The mean latency period for pain control was 4.5 weeks (range 1.5 to 10), the mean initial pain control for BNI I to BNI III (pain well controlled with or without medications) was 86%. At five years the mean actuarial pain control was 54%. The average of sensory disturbances was communicated in 21.5%, (6.7% numbness or bothersome). Sensory dysfunction was more frequent after repeated Gamma Knife treatment. The most consistent prognostic factors for better pain control were: absence of previous treatments, typical trigeminal neuralgia, absence of multiple sclerosis, irradiation dose > 80 Gy, and post-treatment hypoesthesia.
     This was a retrospective review of published literature.
     Gamma knife treatment is a safe and useful modality for the treatment of trigeminal neuralgia with an initial adequate response in 86% and long-term pain control in one half of patients, comparable to other ablative treatments.
     We identified several prognostic factors for pain outcome after radiosurgery.


Project Roles:

J. Lorenzoni (), A. Zárate (), R. Ramón (), L. Badinez (), F. Bova (), C. Lühr ()