Brain Surgery-TGN

Trigeminal neuralgia is an intermittent, lancinating face pain in one or more divisions of the trigeminal nerve. Characteristically, trigeminal neuralgia has an acute, memorable onset with periods of exacerbation and remission. Trigeminal neuralgia is often triggered by light touch, pressure, or facial sensory stimulation. Typical exacerbating triggers described by patients include brushing the teeth, chewing, cold wind, shaving, and talking. Typical trigeminal neuralgia tends to respond favorably to treatment with carbamazepine (Tegretol). Over time the pain becomes more intense. The periods of remission become fewer, with a shorter duration. While the rate of progression is variable, symptoms often progress over time.

Various etiologies of trigeminal neuralgia have been recognized. In many patients, trigeminal neuralgia is caused by vascular compression of the trigeminal nerve, most often by the superior cerebellar artery. It is postulated that with the development of atherosclerosis, the intracranial arteries elongate and become more tortuous, compressing the trigeminal nerve. Segmental demyelination has been shown in the trigeminal nerve. The demyelinated fibers are thought to be responsible for the intermittent pain. In multiple sclerosis patients a demyelinating plaque in the brainstem may lead to the development of typical trigeminal neuralgia.

The annual incidence of trigeminal neuralgia is estimated as 4/100,000 persons, affecting men slightly more often than women (1.2:1). Trigeminal neuralgia is usually unilateral, but may be bilateral. Up to 2% of patients with multiple sclerosis (MS) will develop trigeminal neuralgia. Most patients with trigeminal neuralgia do not have MS. Of the patients with bilateral trigeminal neuralgia, 18% have MS. Trigeminal neuralgia usually affects adults older than 40 years of age, but may affect even children.

The first line treatment of trigeminal neuralgia is medical management with Tegretol (carbamazepine). Many patients achieve long term relief from medical management alone. Although many other medicines have been tried, we are not aware of any other drug that works as well as Tegretol. Additional medications that also may provide relief include Trileptal, phenytoin (Dilantin), baclofen, gabapentin (Neurontin), and clonazepam (Klonopin). When medical management fails due to a lack of efficacy or side effects, surgical options may be considered.

There is no absolute guideline for selecting the best procedure. Procedure selection should consider the patient's medical condition, prior procedures, and the patient's willingness to accept the associated risks and benefits of each procedure. The currently available surgical options include microvascular decompression, percutaneous retrogasserian glycerol rhizotomy, radiofrequency rhizotomy, balloon compression, partial neurolysis and Gamma Knife radiosurgery.

Surgical candidates, patients who have did not obtain satisfactory relief with medicines or suffer from the side effects of the medicines fall into one of three groups; idiopathic trigeminal neuralgia, multiple sclerosis with associated trigeminal neuralgia , or trigeminal neuralgia caused by a tumor. Tumor resection may be desirable in such patients, but is not always necessary. Should a craniotomy fail to relieve the trigeminal neuralgia due to a tumor, patients may be considered for a glycerol rhizotomy or Gamma Knife procedure. Patients with unresectable brain tumors may also be considered for both of these treatments. Patients with multiple sclerosis associated trigeminal neuralgia are not considered for microvascular decompression as the outcomes have not been favorable. Glycerol rhizotomy and Gamma Knife are recommended as adjunct surgical options for multiple sclerosis patients.

Those patients with typical trigeminal neuralgia, likely due to a microvascular compression syndrome are candidates for a number of procedures. For typical trigeminal neuralgia in older patients (>65 years old), or those with complicating medical conditions, glycerol rhizotomy and Gamma Knife are often recommended. Patients with typical trigeminal neuralgia who undergo microvascular decompression and do not obtain relief of symptoms remain candidates for the Gamma Knife or a glycerol rhizotomy. Patients with all etiologies of trigeminal neuralgia who obtain symptomatic relief with a glycerol rhizotomy or Gamma Knife but subsequently suffer a recurrence are considered for repeat procedure.

The addition of the Gamma Knife to the surgical armamentarium has made the decision algorithm slightly more sophisticated. Of the patients who were previously candidates for a glycerol rhizotomy, the, Gamma Knife also is available. The Gamma Knife is also a valid option for many patients who might otherwise elect to undergo microvascular decompression. In our current treatment algorithm, patients who fail to obtain relief of symptoms with either Gamma Knife or glycerol rhizotomy are considered for the other procedure.

During my seven years at the University of Pittsburgh, Dr. Thompson learned the necessary clinical skills to manage trigeminal neuralgia. He was privileged to work closely with Drs. P.J. Jannetta, and Dade Lunsford, pioneers in the management of trigeminal neuralgia. He also studied under Dr. Kondziolka. As a neurosurgical referral center, Dr. Thompson offers percutaneous rhizotomy, microvascular decompression, and Gamma Knife radiosurgery options to patients.

TREATMENTS

Microvascular Decompression
Glycerol Rhizotomy, and Radiofrequency Rhizotomy
Gamma Knife Radiosurgery

PUBLICATIONS:

Thompson TP, Jannetta PJ, Lovely TJ, Ochs M. Unilateral trismus and microvascular decompression. Journal of Oral Maxillofacial Surgery 57(1):90-92, 1999

Thompson TP, Lunsford LD. Trigeminal Neuralgia-Percutaneous Glycerol Rhizotomy pp 219-226 in Follett KA (ed), Neurosurgical Pain Management, Elsevier Inc., Philadelphia, 2004