Introduction
The trigeminal or fifth cranial nerve originates from the brain stem and runs toward the structures of the face and head to supply sensation to the skin and other structures. The trigeminal nerve has 3 divisions… 1) the ophthalmic division supplies sensation to the upper face, 2) the maxillary division supplies the mid-face and 3) the mandibular division supplies the lower face.
Neuralgia refers to intense pain within the distribution of a specific nerve, so trigeminal neuralgia refers to pain within the territory of the trigeminal nerve.
Trigeminal Neuralgia (or simply 'TN') is understood to affect 0.1-0.2% of the population and seems to particularly affect women and people over 50 years of age. Rather than improve, in most cases the condition gets worse over time. It is considered a chronic pain condition.
Causes
The direct cause of trigeminal neuralgia is some form of dysfunction in the nerve, often caused by an artery or vein near the base of the brain putting pressure on the nerve. It may also be related to the protective layer around the nerve – the 'myelin sheath' - being damaged in some way.
Factors that are linked to trigeminal neuralgia include…
- The ageing process.
- Multiple sclerosis.
- A tumour putting pressure on the nerve.
- Brain lesion.
- Facial surgical injury.
- Other injury to the face.
- Stroke.
- Vitamin deficiency (especially B1 and B12).
- Diabetes (which is known to cause nerve damage).
- High levels of alcohol consumption.
There are also some known 'triggers' which precede a painful episode. These include for example…
- Brushing teeth.
- Chewing.
- Drinking.
- Talking.
- Smiling.
- Washing the face.
- Shaving.
- Applying makeup.
Even simply touching the face or feeling air movement on the face can be a trigger.
Symptoms
The primary symptom of trigeminal neuralgia is an intense shooting, stabbing pain affecting one or more parts of the face supplied by the nerve – the cheeks, jaw, lips, gums and teeth particularly, and in some cases the scalp, forehead or eyes.
The pain episodes can last anything from seconds to many minutes, and attacks (where there are multiple episodes in a period of time) can last for days, weeks or in severe cases, months.
These intermittent attacks also mean that TN can disappear as well for sometimes long periods, although in the long-term episodes tend to get longer, happen more frequently and become more intense. In some cases, a bout of intense pain is preceded by a general ache or burning sensation.
Trigeminal neuralgia generally only affects one side of the face at any one time.
Tests / Diagnosis
The first step in the diagnosis of trigeminal neuralgia is a review of symptoms and medical history. Certain tests, such as blood tests, may be recommended to check whether any known risk factors are present. Other tests that may be recommended include a nerve conduction study and CT and/or MRI scan.