Gamma Knife Surgery for Trigeminal Neuralgia

What is Gamma Knife Surgery?

Gamma Knife surgery is one of the more popular treatments for people who suffer from brain tumors. Over the years it has proved itself as an effective treatment for people who suffer from trigeminal neuralgia. It is a non-invasive procedure that can be applied to patients where brain surgery is not an option.

Gamma Knife is the same as neurosurgery, except that it is non-invasive. As a result of this, there is no need for surgical incisions to be made to expose the brain. This reduces one of the risks that can occur from surgical complications. The Gamma Knife is not a knife but it is complex machine that uses cobalt-60 as the energy and is able to focus a precise intersection of 201 beams of these gamma rays to perform radiosurgery. During the treatment the 201 beams of gamma radiation are focused at eliminating the lesion. Once this has been applied, the lesion should reduce in size and eventually disappear. The brain tissue is not over exposed to the gamma beams and only the treated tissue is affected.

Gamma Knife patients are able to enjoy the benefits from this non-invasive form of brain surgery. They have very few risks and a long hospital stay is not required.

The Use of Gamma Knife and Trigeminal Neuralgia

The Gamma Knife has been used for years in the treatment Trigeminal Neuralgia. This type of radiosurgery has become the treatment of choice for people who do not respond to the typical medical therapy. The advancement in imaging as well as the experienced gained from its use has aided in the success of this practice.

The first use of the gamma knife on Trigeminal Neuralgia was in 1951, when the inventor, Lars Leksell used this radiosurgery technique to target the trigeminal ganglion. He used a conventional stereotactic frame and produced an orthovoltage x-ray tube that was used to target the region. The results from this period over the next 40 years were less than stellar; this was due to poor fixation of the target as well as poor imaging. 1996 brought about a study from the University of Pittsburgh, where they decided to revist the use of radiosurgical treatment of trigeminal neuralgia. Aided by the use of High resolution MRI, they were able to target more accurately. They also targeted the the proximal trigeminal nerve near the pons rather than the ganglion, as was done in previous attempts. The study resulted in 94% of patients who participated in the study having a significant reduction in the pain they felt. There were some patients, who experienced complications, but this was mainly limited to facial numbness and this often occurred at a frequency of less than 10%. Gamma Knife surgery for trigeminal neuralgia has become a safe alternative to the more traditional forms of surgery and also one of the major treatments.

How is Gamma Knife Surgery Performed?

For the surgery to be done properly you need to have a multidisciplinary group of assembled. Generally this will include radiation oncologist, neuroradiologist, neurosurgeon and medical physicist. These are needed to achieve an effective and safe treatment.

The use of Gamma Knife surgery to treat Trigeminal Neuralgia is often done in four steps.

In the first step of the treatment a Leksell stereotactic head-frame is placed on the patient. This is done as there needs to be high quality and accurate imaging. To get great results, magnetic resonance imaging often used in the process. From here the trigeminal nerve is identified and the gamma knife and all can be used to eradicate the target. The trigeminal nerve is often targeted at the location of an imaged vascular compression, or at the site of exit of the trigeminal nerve from the pons if no compressing vessel is identified. The success of the treatment at this exit zone is often due to the fact that the proximal nerve is covered by oligodendrocyte myelin, which is usually more radiosensitive than the distal swan-cell myelin. That could be one explanation or it could also be due to the fact that the concomitant irradiation of the dorsal root entry zone in the brainstem.

Great care is taken in this procedure to ensure that the brainstem is not affected by radiation. Because the Gamma knife is very accurate this can be easily accomplished. This process is the often done under local anesthesia.

During the procedure, great care is taken to ensure that the brainstem is protected from radiation exposure. This can be accomplished easily from the precision of the Gamma Knife. The entire procedure is performed under local anesthesia and mild sedation.

Results of Gamma Knife on Trigmenial Neuralgia

Patients who usually have Gamma Knife surgery done on Trigmenial Neuralgia often report an immediate decrease in pain. Attacks still occur, but the pain associated with it is milder than what they were used to. As the weeks progress, many patients reported that they experienced no new attacks. This is probably secondary to delayed demyelination injury to the nerve. There are also some views that the gamma knife irradiation has a differing effect on the myelinated and unmyelinated fibers. This in turn leads for the pain to be controlled, without dysesthesia.

The results from different studies have shown great success in treating the condition.  Ninety percent of patients with trigeminal neuralgia experienced a significant reduction in the pain they felt after around four weeks. The study went on to show that one-third of the patients experienced some amount of numbness in the face, but 80% showed a significant improvement in their quality of life since the numbness was much more tolerable than the facial pain.

In over 30 years, more than 100,000 people have received gamma knife treatment. The use of the gamma knife has clear advantages to open surgery in many cases, and its use will continue to grow.