What Is the Trigeminal Nerve?

The trigeminal nerve is a large, three-part nerve in the head that is responsible for us being able to feel sensations like touch and pain in our faces. We each have two trigeminal nerves, one on each side of the head. Each one starts in the brain and then splits into three different branches that extend out across the face like the branches of a tree, and that have different roles:

• One branch travels to the lower part of your face and is involved in the lower jaw’s functions (biting, chewing, and swallowing). It’s also involved in feeling sensations with your lower lip and gums.
• A second branch is involved in the upper lip and gums feeling sensation, and also the cheeks, nose, and lower eyelids.
• The final branch covers the scalp and the upper part of the face, including the eyes, upper eyelids, and forehead.

What Is Trigeminal Neuralgia?

Like the skin, nerves can sometimes become damaged or bruised. Although the trigeminal nerve can recover over time if it becomes damaged, some people experience numbness or facial pain in the area that the damaged branch of the trigeminal nerve serves (this is known as “trigeminal neuropathy”).

Trigeminal neuralgia (also called “tic douloureux”) is a type of trigeminal neuropathy that causes intense pain, usually on one side of the face, that some people describe as being like severe stabbing, burning, or electric shock-like pain. People with trigeminal neuralgia often have attacks of pain that get worse over time, with shorter pain-free periods. It can be caused by compression of or pressure on the trigeminal nerve (for example as the result of the growth of a tumor or cyst), a facial injury, and disorders that affect the myelin sheaths of nerve cells (these act to insulate the signal-sending parts of the nerve cells, a bit like the covering of an electrical wire) like multiple sclerosis. Essentially, the trigeminal nerve keeps sending signals of intense pain to the brain, whether or not anything is actually happening to that part of the face.

How Is Trigeminal Neuropathy Treated?

Trigeminal neuropathy can be treated in different ways according to the individual needs of patients. A number of medications can be effective, but some patients find that their pain is not significantly reduced by medication and surgery is offered instead. Nucleotractotomy is a type of surgery that involves the selective cutting or damaging of a region of the trigeminal nerve called the nucleus caudalis. This is the area where the different signals from the branches extending out to the rest of the face are brought together. The technique works by stopping the intense pain signals from reaching the brain, but importantly does not stop the person from being able to sense that the affected region of the face is being touched.

How Is Nucleotractotomy Done?

There are two main ways that nucleotractotomy can be done:

1. The first is an “open” technique under general anesthesia. A portion of the patient’s skull is removed and an electrode is inserted and used to “thermolesion” (damage part of the trigeminal nerve using heat) the part of the nerve that is causing the intense pain signals, so that they are no longer received.
2. The second technique is done under local anesthetic while the patient is awake and involves an electrode being inserted through the skin (“percutaneous”) and guided by computed tomography scanning to the location that will be damaged.

What Did This Study Investigate?

The aim of this study was to review how effective nucleotractotomy is at stopping patients from experiencing severe facial pain in the long term. The authors of the study assessed the amount of pain that 13 patients (7 who underwent the open procedure and 6 that underwent the percutaneous one) experienced before and after surgery using a pain intensity score questionnaire (which rates pain from 0 to 10). They found that before surgery, patients’ pain was rated on average as 9.3. Not long after surgery, this had decreased to on average 1.57 for patients who underwent open nucleotractotomy and 2.66 for patients who underwent the percutaneous technique.

Although there was some evidence that there was a higher rate of pain getting worse again with the percutaneous method, the smaller area of tissue that is affected by this technique seems to be linked to it having a lower chance of patients experiencing severe complications after surgery. The patients were followed up for an average of 40 months (range 1 to 71 months), and at the end of this period the pain scores across the two groups were on average 2.6. Although severe facial pain developed again in 3 patients after percutaneous surgery and in 1 patient after open surgery, the authors of the study judged the techniques to be safe overall and to be equal in terms of how well they relieve severe facial pain in the long term.