What is the role of gamma knife surgery in the treatment of trigeminal neuralgia (TN)?

Updated: Jul 11, 2019
  • Author: Manish K Singh, MD; Chief Editor: Robert A Egan, MD  more...
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Answer

In 1953, Leksell irradiated the trigeminal nerve in 2 patients with good initial success but did not publish this data until 1971. [62] Progress really began when, in the 1990s, surgeons learned to target the nerve precisely with stereotactic magnetic resonance imaging (MRI), determine the proper radiation dose to quickly relieve pain without incurring facial sensory loss, and ascertain the length of nerve to be radiated. [63]

Gamma knife surgery (GKS) has become more widely available since 2000. This surgery is less technically demanding, less operator-dependent, and less invasive than the percutaneous procedures. It is among the newer techniques for treating trigeminal neuralgia and has fewer complications. Gamma knife surgery appears to be about as effective (80% of patients) as the percutaneous procedures but takes weeks to months to bring relief, which may be too long for some patients, and costs slightly more.

This procedure consists of multiple rays (>200) of high-energy photons concentrated with high accuracy on the target (ie, trigeminal nerve root), [64, 65] destroying specific components of the nerve. Of those treated, 60% of patients are immediately free of pain, and more than 75% of patients have greater than 50% relief after 1.5 years. Recurrence rates are around 25 % between 1 and 3 years. The device contains a stable source of radiation (60-Co) that frees this technique from requiring an external source of radioactivity (eg, cyclotron). See the image below.

Magnetic resonance image (MRI) with high resolutio Magnetic resonance image (MRI) with high resolution on the pons demonstrating the trigeminal nerve root. In this case, the patient with trigeminal neuralgia has undergone gamma-knife therapy, and the left-sided treated nerve (arrow) is enhanced by gadolinium.

The pain recurrence rate is low for patients who initially attain complete relief. Gamma knife surgery is generally effective, even in patients in whom previous surgery or medication trials failed.

In one study, most patients already had no relief with either microvascular decompression or glycerol rhizotomy, whereas following gamma knife surgery, at a median follow-up point of 18 months, 60% of patients were pain free, 17% were moderately improved, and 23% were minimally or not improved. [64] The investigators concluded that this technique is minimally invasive, is associated with a low risk (10%) of facial paresthesias or sensory loss, and offers a high rate (86%) of significant, initial pain relief. [64]

New facial numbness or paresthesias develop slowly over the first 12-15 months after gamma knife surgery, reaching bothersome levels in 9-20% of patients.

Also see Trigeminal Neuralgia Surgery.


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