Microvascular decompression after failed Gamma Knife surgery for trigeminal neuralgia: a safe and effective rescue therapy?

OBJECT: Stereotactic radiosurgical rhizolysis using Gamma Knife surgery (GKS) is an increasingly popular treatment for medically refractory trigeminal neuralgia. Because of the increasing use of GKS for trigeminal neuralgia, clinicians are faced with the problem of choosing a subsequent treatment plan if GKS fails. This study was conducted to identify whether microvascular decompression (MVD) is a safe and effective treatment for patients who experience trigeminal neuralgia symptoms after GKS.

METHODS: From their records, the authors identified 29 consecutive patients who, over a 2-year period, underwent MVD following failed GKS. During MVD, data regarding thickened arachnoid, adhesions between vessels and the trigeminal nerve, and trigeminal nerve atrophy/discoloration were noted. Outcome and complication data were also recorded.

RESULTS: The MVD procedure was completed in 28 patients (97%). Trigeminal nerve atrophy was noted in 14 patients (48%). A thickened arachnoid was noted in 1 patient (3%). Adhesions between vessels and the trigeminal nerve were noted in 6 patients (21%) and prevented MVD in 1 patient. At last follow-up, 15 patients (54%) reported an excellent outcome after MVD, 1 (4%) reported a good outcome, 2 (7%) reported a fair outcome, and 10 patients (36%) reported a poor outcome. After MVD, new or worsened facial numbness occurred in 6 patients (21%). Additionally, 3 patients (11%) developed new or worsened troubling dysesthesias.

CONCLUSIONS: Thickened arachnoid, adhesions between vessels and the trigeminal nerve, and trigeminal nerve atrophy/discoloration due to GKS did not prevent completion of MVD. An MVD is an appropriate and safe "rescue" therapy following GKS, although the risks of numbness and troubling dysesthesias appear to be higher than with MVD alone.