Microvascular decompression better than gamma knife for pain in trigeminal neuralgia
The new systematic and meta-analysis shows that microvascular decompression (MVD) is more effective than gamma knife surgery (GKS) for the treatment of pain associated with trigeminal neuralgia (TN).
According to the lead author, jayant velagala, a student in the department of neurological surgery at Rutgers New Jersey medical school in Newark, New Jersey, MVD shows better effectiveness due to higher rates of initial pain-free outcomes, long-term pain-free outcomes, and lower rates of pain-free recurrences as compare to GKF. The results of this study were presented at the Congress of Neurological Surgeons (CNS) 2015 Annual Meeting.
No Current Consensus for Treatment of TN
Velagala and his colleagues performed a systematic review and meta-analysis on published studies of MVD and GKS for the treatment of TN from 2004 to 2014 in order to better evaluate the differences between the two interventions. MVD and GKS are the most common surgical treatment options for TN. The mechanism of MVD relates to neurovascular compression at the root entry zone of the trigeminal nerve while GKS involves partial or total damage of the trigeminal nerve in order to relieve symptoms.
GKS is minimal invasive technique and that is the reason for its popularity. There is a longer time interval between treatment and pain improvement and also does not provide long-term pain relief. This modality is considered destructive but noninvasive and causes postoperative numbness and motor dysfunction.
MVD is non destructive but invasive in nature. This treatment conserves trigeminal nerve and surrounding neurovascular structures while allowing for excellent visualization of the vascular structures related to the root entry zone of the trigeminal nerve. This method lead to rapid and long term relief as it allows the identification and relocation of any compressed vessels.
MVD is the only surgical treatment for TN that requires a craniotomy and the main adverse effects involves facial nerve dysfunction and hearing loss.
According to Velagala, there is no definitive proof at present which may help in concluding the one as better treatment.
Medline/PubMED search was used to select the cases and data were extracted regarding rates of complete pain relief and pain-free recurrence. From 18 articles, a total of 2650 patients were included in MVD group and from 25 articles, 2846 patients in GKS group.
Velagala and his colleagues found statistically significant differences between the two groups in favor of MVD for all four of the parameters. MVD had a significantly higher rate of initial pain-free outcomes, higher rate of long-term pain-free outcomes at last follow-up and a significantly lower pain-free recurrence rate when compared with GKS. Forest plots were also used to determine the consistency of the studies between the two groups and MVD was far more consistent in results as compared to GKS.
The investigators felt that the optimal radiation dose and location in GKS continues to be the topic of debate and that becomes the reason for the variability in results of GKS group.
According to the session moderator, Ashwin Viswanathan, MD, clinical assistant professor of neurosurgery at the University of Texas MD Anderson Cancer Center in Houston, there is an ongoing debate as to which should be a frontline therapy. He told Medscape Medical News that some centers have started to support GKS or more specifically radiosurgery as first-line therapy for TN, but according to this study, MVD is the nondestructive option that provides the best initial and long-term benefit for patients with neurovascular conflict.
Finally the investigators concluded that MVD is an effective intervention than GKS for the treatment of TN. The results also emphasize the need for evaluating optimal GKS radiation dosage and delivery location which may give more consistent and better long-term outcomes.