Microvascular decompression for trigeminal neuralgia in patients with failed gamma knife surgery: Analysis of efficacy and safety

Though it is usually successful, failure or delayed pain recurrence may occur after gamma knife surgery (GKS) in patients with trigeminal neuralgia (TN), and additional intervention may be required. This study aimed to investigate whether the safety and efficacy of microvascular decompression (MVD) were influenced by prior GKS.

The authors retrospectively evaluated 36 consecutive TN patients who underwent MVD after failed GKS from January 2012 to June 2013. The clinical features, operative findings and surgical outcomes were reviewed and statistically analyzed, and the operation results were further compared with a cohort of 60 patients with no prior GKS.

At surgery, atrophy of the trigeminal nerve was observed in 13 patients (36.1%), arachnoid thickening in 6 patients (16.7%), adhesions between vessels and the trigeminal nerve in 8 patients (22.2%), and atherosclerotic plaque in the offending vessels in 3 patients (8.3%). The complete pain relief rates were 83.3% immediately after MVD and 72.2% at last follow-up, which showed no statistical difference when compared with patients without GKS. New or worsened facial numbness occurred in 7 patients (19.4%), which was significantly higher than those without GKS (p=0.02). Univariate analysis suggested that a positive pain response to the prior GKS correlated with better long-term outcome (p=0.015), and the existence of arachnoid adhesions correlated with higher risk of facial numbness (p=0.03).

MVD remains an appropriate and effective alternative therapy for patients with failed GKS, with no added technical difficulty. However, the risk of facial numbness seems to be higher than those with MVD alone.