Several structures or conditions can cause damage to, or irritate the trigeminal nerve resulting in trigeminal neuralgia (TN). When a nerve is injured—from any potential cause—it becomes overly sensitive or hyperexcited. These sensitive nerves tend to fire off pain signals at the slightest provocation.
Trigeminal Neuralgia Causes
Some of the potential causes of TN are discussed below.
- Compression from near-by blood vessels. Majority of TN cases occur due to compression of the trigeminal nerve by one or more arteries and/or veins.1 Large or small blood vessels can grow over, wrap themselves around, or combine together to squeeze the nerve. A constant irritation to the nerve can also occur from the pulsating action of blood vessels. The exact mechanism of how or why blood vessels end up pressing against the trigeminal nerve is not understood.
- Multiple sclerosis (MS). MS is a neurodegenerative and inflammatory condition that causes breakdown of the myelin sheath around the nerves. This loss of protective coating around the trigeminal nerve can cause irritability to the nerve, resulting in TN as potentially an early symptom of MS.
- Tumors and cysts. Tumors such as meningiomas and neuromas in the brain can either compress the trigeminal nerve directly, or push blood vessels against the nerve causing TN.
- Blood vessel abnormalities. Aneurysms (weak blood vessels with a bulge) and arteriovenous malformations (abnormal blood vessels that grow randomly) in the brain can cause compression and injury to the trigeminal nerve’s myelin sheath, resulting in TN. These are life-threatening abnormalities and require immediate medical attention.
- Virus. Like many other neurological disorders, viruses may be a cause for TN.
- Other causes. Abnormally thickened arachnoid tissue layer of the brain, trauma, and nutritional deficiencies may cause damage to the trigeminal nerve resulting in TN. Inflammatory conditions such as sarcoidosis and Lyme disease or vascular diseases such as scleroderma and systemic lupus erythematosus may also cause TN. It is possible that certain dental procedures or fillings may trigger an already developing TN to suddenly become fully noticeable.
- Unknown cause. When the cause of TN cannot be identified by clinical or diagnostic tests, it is called idiopathic trigeminal neuralgia, meaning there is no identifiable cause.
Atypical TN is presumed to be caused by tumors or cysts. Typical TN with symptoms on both sides of the face is also believed to commonly have a cancerous origin.
Risk Factors of Trigeminal Neuralgia
Common risk factors associated with trigeminal neuralgia include:
- Advanced age. The risk of TN is higher among older people, especially between 50 to 60 years of age.2 Age related changes, such as hardening and elongation of blood vessels and sagging of the brain (just like aged skin) can cause blood vessel-nerve contact where there was none before—resulting in irritable and sensitive nerves. Advancement of age also causes degenerative changes in nerves resulting in loss of myelin sheath, making the nerves susceptible to irritation.
- Female sex. Women are at a higher risk than men to be affected by TN.2,3
- Multiple sclerosis. TN is known to be associated with multiple sclerosis, a condition that causes degeneration of the myelin sheath of nerves.
While the presence of these risk factors increases the likelihood of developing TN, it is also possible for younger people or children to have TN. In rare cases, trigeminal neuralgia occurring in people below 50 years of age typically involves the ophthalmic division of the trigeminal nerve (the branch that is least involved in TN) and may cause loss of vision.4