MVD Bests Gamma Knife for Pain in Trigeminal Neuralgia

Meg Barbor

October 05, 2015

NEW ORLEANS — Microvascular decompression (MVD) is more effective than gamma knife surgery (GKS) for the treatment of pain associated with trigeminal neuralgia (TN), a new systematic review and meta-analysis shows.

"Microvascular decompression may be a more effective intervention than gamma knife surgery due to higher rates of initial pain-free outcomes, long-term pain-free outcomes, and lower rates of pain-free recurrences," said lead author Jayant Velagala, a student in the Department of Neurological Surgery at Rutgers New Jersey Medical School in Newark, New Jersey.

He presented the results here at the Congress of Neurological Surgeons (CNS) 2015 Annual Meeting.

No Current Consensus for Treatment of TN

To better evaluate the differences between the two interventions, 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.

The most common surgical treatment options for TN are MVD and GKS. MVD relieves neurovascular compression at the root entry zone of the trigeminal nerve, while GKS is a "destructive procedure" that relies on partially or totally damaging the trigeminal nerve in order to relieve symptoms.

GKS has gained popularity because of its appeal as a minimally invasive alternative, but it is associated with a longer time interval between treatment and pain improvement and lower rates of long-term pain relief. This modality is considered destructive but noninvasive and is associated with postoperative numbness and motor dysfunction.

MVD is unique in that it is a nondestructive, but invasive, surgical intervention that preserves the trigeminal nerve and the surrounding neurovascular structures while allowing for excellent visualization of the vascular structures related to the root entry zone of the trigeminal nerve. This method also allows for the ability to identify and reposition any compressing vessels, which leads to rapid and long-lasting pain relief.

While MVD is nondestructive, it is the only surgical treatment for TN that requires a craniotomy; potential adverse effects include facial nerve dysfunction and hearing loss.

Currently there is no definitive consensus as to which of the two options is more effective at providing immediate and long-lasting pain relief, said Velagala.

Cases were selected by using a MEDLINE/PubMED search, and data were extracted regarding rates of complete pain relief (pain-free without the use of medication — Barrow Neurological Institute [BNI] grade 1) and pain-free recurrence (initially experiencing complete pain relief — BNI grade 1, with a subsequent recurrence of pain).

Included were 18 articles with a total of 2650 patients for the MVD group and 25 articles with a total of 2846 patients for the GKS group.

"We found statistically significant differences between the two groups in favor of MVD for all four of the parameters," said Velagala.

MVD had a significantly higher rate of initial pain-free outcomes (BNI grade 1) and a significantly lower pain-free recurrence rate when compared with GKS. Additionally, MVD was found to have a significantly higher rate of long-term pain-free outcomes at last follow-up as compared with GKS.

Table. Outcomes with MVD vs GKS for TN

Variable GKS (%) MVD (%) P Value
Initially pain-free 61.45 92.22 <.05
Never pain-free 44.14 8.88 <.05
Pain-free recurrence 19.38 14.93 <.05
Pain-free on last follow-up 41.62 79.37 <.05

 

The investigators also used Forest plots to determine the consistency of the studies between the two groups. According to Velagala, "MVD was far more consistent in terms of its results when compared to GKS, and this is true for initial pain free, never pain free and BNI 1 at last follow-up."

According to the investigators, the optimal radiation dose and location in GKS continues to be a subject of debate, "and this is likely an explanation as to why there is increased variability in the results in the GKS group," he said.

"This is an ongoing debate as to which should be a frontline therapy," said session moderator Ashwin Viswanathan, MD, Clinical assistant professor of neurosurgery at The University of Texas MD Anderson Cancer Center in Houston.

"Some centers are beginning to advocate gamma knife, or more broadly, radiosurgery, as a first-line therapy for trigeminal neuralgia, but I think this study highlights again that MVD is the nondestructive option that provides the best initial and long-term benefit for patients with neurovascular conflict," he told Medscape Medical News.

On the basis of the evaluation of these parameters, the investigators concluded that MVD may be a more effective intervention than GKS for the treatment of trigeminal neuralgia. The data also highlight the need for determination of optimal GKS radiation dosage and location of delivery, which may provide more consistent and better long-term outcomes.

Mr Velagala and Dr Viswanathan have disclosed no relevant financial relationships.

Congress of Neurological Surgeons (CNS) 2015 Annual Meeting. Presented September 29, 2015.

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