The trigeminal nerve is the fifth of 12 nerves that exit from the brain through openings in the skull rather than through the spinal column, as other nerves do. These 12 nerves are known as cranial nerves. The trigeminal nerve is named for its three-pronged structure. It supplies nervous impulses to three nerves that branch from its main root: the ophthalmic, maxillary and mandibular nerves. These nerves sense pain, temperature and pressure over much of the face.
Arterial Pressure
Trigeminal neuralgia, also known as Tic Douloureux, refers to pain caused by irritation of the trigeminal nerve. The Merck Manual explains that trigeminal neuralgia is most often cause by pressure from an artery, or sometimes a vein, in the skull. Two arteries are suggested as possible sources of pressure on the trigeminal nerve: the anterior cerebellar artery and the ectatic basilar artery. The area where the trigeminal nerve exits the base of the brain is suspected as the location where the blood vessels are most likely to put pressure on the trigeminal nerve.
Multiple Sclerosis
A thin membrane called the myelin sheath covers nerves. This sheath protects the nerves, insulating them and causing signals to travel more efficiently along the nerve cells. Multiple sclerosis is the most common disease that causes damage to the myelin sheath. The immune systems of patients with multiple sclerosis mistakenly attack and destroy myelin, leaving the nerve uncovered and vulnerable. Demyelination of the trigeminal nerve is common in multiple sclerosis. Patients often experience what the Mayo Clinic describes as "electric shock-like sensations that occur with head movements," which occur in the areas of the face supplied by the trigeminal nerve.
Postherpetic Neuralgia
When chickenpox is contracted during childhood, the virus that causes it, herpes zoster, can remain dormant for decades in the nerve bundles near the spine. The virus will sometimes reactivate, causing the condition known as postherpetic neuralgia, or more commonly, shingles.
In cases of postherpetic neuralgia, the reactivated virus travels around the affected nerve, causing pain. The herpes virus can affect the trigeminal nerve, resulting in postherpetic neuralgia, or pain, in the facial areas supplied by the trigeminal nerve.
