Radiosurgery has emerged as an important primary treatment means of typical trigeminal neuralgia. Despite its high safety and efficacy, the likelihood of recurrence is significant, potentially requiring salvage treatment. Posterior fossa exploration and microvascular decompression is an option for salvage treatment.

     Results are presented regarding a single surgeon experience and a grading scale is proposed for post-irradiation surgical findings.

     A retrospective analysis of the author''s experience with 109 consecutive trigeminal nerve posterior fossa explorations for typical trigeminal performed over a period of 8 years is included in this analysis. There were 42 patients undergoing microvascular decompression following recurrence of pain after radiosurgery and 67 patients underwent microvascular decompression without prior radiosurgery.

      Operative findings were reviewed and categorized. A four category typing system is proposed. The Barrow Neurological Institute Pain Scale Score was used to categorize post-MVD outcomes.

     Within the post-radiosurgery group, 41 of 42 patients had initial treatment success (BNI=1-3), comparing favorably to the non-irradiated group where 59 of 67 patients had initial successful treatment. Findings of conflicting vessel atherosclerosis and adhesions between conflicting vessel and nerve were only seen in the post radiosurgery group while arachnoidal thickening requiring sharp dissection was seen in both post-radiosurgery and non-irradiated groups. Increased difficulty of dissection in either the radiosurgery or non-irradiated groups did not appear to affect likelihood of satisfactory outcome.

     This is a retrospective study.

     Microvascular decompression can be performed in the post-radiosurgery setting safely with high efficacy.

     Dissection typically was not significantly more difficult in comparison to procedures performed without prior history of radiosurgery intervention.