Cerebrovascular Disease

What is Trigeminal Neuralgia?

Trigeminal Neuralgia (TN), or tic douloureux, is a neurological condition characterized by paroxysmal episodes of lancinating facial pain lasting a few seconds. This pain is usually triggered by sensory stimuli such as chewing, shaving, smiling, touching the side of your face, or brushing your teeth.

The trigeminal, or fifth cranial nerve, is the largest cranial nerve and it divides into 3 branches once it reaches the face. They are called V1 (forehead area), V2 (upper lip and cheek), and V3 (jaw region). The pain is usually confined to one or more of these branches on only one side of the face.

What causes TN?

Eighty-five percent of the cases of TN are caused by a normal artery near the brain stem which is in an abnormal position. This artery has a loop in it which is pressed up against the trigeminal nerve. With each beat of the heart, blood is forced through this artery which causes the artery to bump up against the nerve. With time, this repeat pressure rubs the insulation off the nerve. This causes the nerve to fire these abnormal painful electrical-like shocks.

Rarely TN can be caused by tumors, less than 0.8% incidence, or multiple sclerosis, 3% incidence. Most of the other causes of TN are unknown.

What type of work-up should be performed in the evaluation of TN?

First of all, a good history and neurological examination should be performed by a neurologist. The exam is usually normal except for the ability to reproduce the pain by touching the trigger point. Imaging studies, such as an mri scan with contrast, should be performed prior to any treatment in order to rule out a tumor as the cause of the pain.

What treatment options are available and what are their risks and benefits?

There are three categories of treatment options available. They include medical, invasive non-surgical, and surgical.

• Medical

  The initial treatment of choice for TN is the medication called Carbamazepine or Tegretol. This drug provides complete or acceptable relief of pain in 69% of patients with TN. Tegretol is not a "pain pill". It is most effective by gradually increasing the dose to where it achieves a level in the blood which provides the maximal relief of the symptoms. The maximum daily dose is 1200 mg. Side effects include drowsiness, staggering, dizziness, depressed white blood cell count, and liver toxicity. Other pharmacologic therapies, which may help with alleviating the painful episodes include baclofen, pimozide, phenytoin, clonazepam, and amitriptyline. These medications can be used in conjunction with Tegretol but must be closely regulated by your physician. The benefits of this medical treatment option include avoiding the risks involved with the invasive non surgical and surgical treatments.

• Invasive Non-Surgical

  1. Peripheral Nerve Block
  This procedure provides temporary relief of pain by injecting either phenol, or alcohol around the trigeminal branch involved.

2. Percutaneous Stereotactic Rhizotomy (PSR)
The goal of PSR is to injure or destroy the trigeminal nerve via different techniques which may include radio- frequency thermocoagulation or glycerol injection.


In radio frequency heating, an electrode is inserted through a spinal needle under radiographic guidance and certain pain fibers of the trigeminal nerve are destroyed by heat. With this technique there is good pain relief in 80-90% of cases. The major complication is called "anesthesia dolorosa" which is a painful condition that is difficult to treat. When this occurs the patient develops a severe constant burning, aching pain which is more disagreeable than the original pain. This occurs approximately 2 -4 % of the time.

With the glycerol injection a rhizotomy or nerve injury is performed by injecting glycerol in this same area instead of using heat. About 85-90% of patients have a good result - that is, significant relief from TN pain. With this procedure there is a lower incidence of "anesthesia dolorosa".


The benefits of these invasive non surgical techniques is that the patient does not have to accept the risks of "major" brain surgery and the general anesthesia associated with it. Another benefit is that recurrences of pain may be treated by repeat procedure, although the results of repeat procedures may be less successful.

The risks include the above mentioned "anesthesia dolorosa", infection, facial weakness, facial numbness, double vision, reduced hearing, and alterations in lacrimation and/or salivation. It is important to remember that with PSR you are treating the symptoms of TN and not the problem itself. Therefore, the chances of the pain returning with PSR is greater than with the surgical treatment option.


• Surgical

  The surgical procedure performed to treat TN is called a microvascular decompression (MVD). The MVD is recommended for patients who have failed medical treatment and are in good health.
  

  With this procedure, the patient is taken to the operating room and a small amount of hair is shaved behind the ear on the affected side. Under general anesthesia, the skin is opened and a small piece of bone is removed. Working under the microscope, the neurosurgeon is able to identify the blood vessel that is pressing against the nerve. The surgeon will then move it out of the way by tacking it up away from the nerve with an insulating sponge. The bone is then replaced and the skin is closed.
  

  The benefits of this procedure involves the fact that the problem itself is treated if in fact the blood vessel is the offending agent. There is an 85-90% initial success rate and 70% at 10 years post operatively. This is compared to the 20% success rate at 12 years post-operatively with the PSR. The incidence of facial numbness is also much less then with PSR, and "anesthesia dolorosa" does not occur.
  

  The mortality for this procedure is 1%. The most common complications include mild facial numbness (25% - usually temporary), hearing loss on the affected side (3%), double vision (usually temporary), spinal fluid leakage (5%), and meningitis (less than 5%).
  

For further information or to schedule an appointment please contact the Neurosurgery Clinical Office at (323) 442-5720