By Michael H. Brisman MD, FACS, Attending Neurosurgeon at NSPC Brain & Spine Surgery

Trigeminal neuralgia (TN) is a very specific type of facial pain condition. TN causes patients to suffer from recurring episodes of sudden, brief, severe, sharp pains on one side of the face. The pain is described as electric shock or stabbing in nature, and patients will experience spontaneous remissions over time. Rarely, patients will experience pain on both sides of the face, but not at the same time. The pain is usually triggered by light touch to the face, and usually responds to anti-seizure medicines, in particular, carbamazepine (Tegretol). Sometimes there can be some “atypical” features such as a dull or constant pain as well. Trigeminal neuralgia can be caused by multiple sclerosis (MS), or compression on the trigeminal nerve root by a blood vessel or other mass. But often the cause is not known. Treatments include medicines (primarily anti-seizure medicines), nerve injuring procedures (such as percutaneous trigeminal rhizotomy/PTR and stereotactic radiosurgery/SRS) and nerve decompression (such as microvascular decompression/MVD). There are many other chronic craniofacial pain syndromes besides TN, and these are generally not treated with surgical procedures.

There are several current areas of investigation underway to try to offer better treatments for people with trigeminal neuralgia. For one, there are increased efforts being made to correctly diagnose TN as quickly as possible. Part of this involves educating doctors, dentists, and the public. But there are frequently instances in which a diagnosis is uncertain even for the experienced professional. To address this, better efforts are underway to determine exactly which constellation of symptoms can most definitively establish the diagnosis of TN. Efforts are also ongoing to determine the optimal medical regimens for patients. Furthermore, different types of patients may do best with different medical routines. For example, older patients generally require lower doses of medicines than younger patients. Investigations are also underway to better establish which patients will do best with which surgical procedures.

Current thinking is that vascular causes of TN are usually arterial (such as the superior cerebellar artery/SCA, the anterior inferior cerebellar artery/ AICA, or the basilar artery) and that a vascular compression is more likely to be causative than a mere vascular contact. As such, it seems that the best candidates for MVD will be healthy patients with trigeminal nerve compression from smaller vessels such as the SCA or AICA vessels — the basilar artery is larger and much more difficult to mobilize from the nerve at surgery. Many surgeons are now considering using materials besides the traditional Teflon felt for the actual decompression, including muscle and fibrin glue. The Teflon felt can cause a chemical meningitis as well as delayed granuloma formation, that may itself contribute to recurrences. There is also a much stronger preference being expressed for “transpositional” MVD procedures over “interpositional” procedures, that is, procedures that move the blood vessel away without leaving the foreign body contacting the nerve itself. For MVDs there is also a trend towards using smaller incisions, smaller bone openings, and incorporation of the surgical endoscope into the procedure for better viewing of distal nerve segments that might be hard to see with the microscope alone. There is also a trend towards sending patients home the day after surgery.

The percutaneous trigeminal rhizotomy (PTR) remains an excellent procedure for trigeminal neuralgia as well. This procedure involves placing a needle in the cheek, under sedation, into the trigeminal nerve close to where it exits the brain and producing a small injury in the nerve. It is outpatient, low risk, provides quick pain relief, and usually allows for a quick tapering off of anti-seizure medicines. It can also be repeated an unlimited number of times. There are three methods for this procedure—a radiofrequency, glycerol, and a balloon technique. Each variation has its advantages and disadvantages. Surgeons are looking at ways to optimize the results of these techniques. Considerations include set ups to perform any of the three variations at the same sitting, using different times and temperatures for the radiofrequency procedure (which may vary by the type of needle and machine used), using different volume glycerol injections and different times seated upright for the glycerol procedure, using different balloon inflation times and pressures for the balloon procedure, and using combinations of two variations at the same sitting. Ongoing assessments are also continuing as to which patients might be best for which rhizotomy procedure, or another procedure entirely.

Stereotactic radiosurgery/SRS (such as Gamma Knife), a one day, outpatient, super-focused radiation procedure, is the least invasive of the procedures to treat TN. This technique can also be very effective at controlling TN pain. It is the preferred procedure for patients who cannot come off blood thinners. Repeat procedures can be performed, but only after long waiting periods, and ideally at least 2 years from the first procedure. Radiosurgery is also usually the preferred method for treating masses that may be causing TN, such as acoustic neuromas and meningiomas. Considerations for optimizing these treatments include consideration of the dose given, the time for the dose (which may be related to the age of the radiation sources), the proximity of the treatment to the brainstem, the shape/contour of the treatment, and the particulars of the patient’s nerve anatomy. Again, studies continue on which patients will do best with this versus other treatments.

A final topic of study is which treatments (MVD, PTR, SRS) might interact in what ways with other treatments, and how such treatments might be optimized for particular patients. Again, TN patients are quite varied, in age, health, cause of the TN (MS, tumor, large vessel, small vessel, unknown), presence of only typical versus some atypical features, history of prior procedures, presence of facial numbness from prior procedures, tolerance of medicines, etc.

It should also be mentioned that we are constantly learning more about medical treatments for TN and other types of chronic facial pain, so as best to treat our patients. Exciting new developments are rapidly evolving to help patients with cranio-facial pain live more comfortable and better lives.