Microsurgical outcomes after failed repeated Gamma Knife surgery for refractory trigeminal neuralgia

The results of microsurgery in patients with trigeminal neuralgia (TN) after failure of repeated Gamma Knife surgery (GKS) have not previously been examined. The effects of microvascular decompression (MVD) in patients in whom repeated GKS has failed are reported.

Between 1999 and 2004, eight patients (five women and three men) who underwent repeated GKS and experienced treatment failure subsequently underwent MVD. These patients underwent MVD for recurrent or residual intractable trigeminal pain. The duration of facial pain before MVD ranged from 0.8 to 13 years (mean 5.2 years). The total treatment dose administered ranged from 110 to 140 Gy (mean 129 Gy). The mean age was 59.5 years (range 44-68 years). Seven patients in whom the offending vessel (five arteries and two veins) was located at the nerve entry zone improved with variable pain relief after MVD. One patient in whom the vessel could not be identified did not improve. Intraoperatively, there were no signs in any patient of radiation-induced damage such as thickening of arachnoid membrane. In one patient a segment of atherosclerotic plaque was discovered at the nerve entry zone. Two patients experienced numbness at 1 and 3 months after MVD.

Microvascular decompression is an effective treatment for patients with TN in whom repeated GKS has failed. Previous radiation treatment did not negatively impact operative difficulty or risk to the patient in this small series. Radiosurgery may induce vascular injury and cause pain recurrence.