Recurrent trigeminal neuralgia: long term outcome of repeat gamma knife radiosurgery

Objective: To date, the efficacy and safety of repeat radiosurgery (RS) for trigeminal neuralgia (TN) is based mainly on short term results. Methods: Between 1994 and 2006, 93 patients were treated by RS for TN at the Department of Neurosurgery, Graz, Austria. 22 patients underwent repeat gamma knife radiosurgery (GKRS) a mean of 18.8 months after the initial treatment. The mean dose for repeat treatment was 74.3 Gy. Pain outcome was rated using the Barrow Neurological Institute (BNI) Pain Intensity Scale and facial numbness according to the BNI Facial Numbness Scale. Results: Mean follow-up after repeat RS was 5.4 years. Pain relief was noted in 72.7% (16/22) of patients; six patients had a second pain recurrence after a mean of 9.3 months and underwent medical, alternative and/or further RS. One patient was lost to follow-up. BNI pain scale evaluation for 21 patients indicated improvement in 76.2% (16/21) of cases without medication (BNI I and II). Facial numbness was recorded in 73.7% (14/19) but in only one was it classified as bothersome. Conclusions: Long term observation of repeat GKRS for TN showed good pain relief in more than two-thirds of patients. Despite a high percentage of facial numbness, most likely attributable to the higher delivered dose, repeat RS can still be regarded as safe. However, further studies are needed to determine an optimised treatment protocol.