The trigeminal nerve provides innervation (nerve supply) to many different parts of the face. It carries sensory impulses, including heat and pain signals, to the brain. If the nerve gets damaged or pinched, this can lead to the development of a phenomenon called trigeminal neuralgia, which is marked by a burning pain being present in affected parts of the face.
Blood Vessels
The Mayo Clinic explains that one of the most common causes of trigeminal neuralgia is it getting pinched by a blood vessel, such as an artery. This typically happens when the trigeminal nerve is coming out of the brain stem on the way to supplying innervation to the face. When a blood vessel is pressing on the trigeminal nerve, the pulsation of the blood through the artery puts additional pressure on the nerve. This pinching leads to abnormal electrical activity. Because one of the functions of the trigeminal nerve is to transmit pain signals, it is thought that this abnormal electrical activity is interpreted by the brain as pain, leading to the neuralgia. One of the more common procedures for treating trigeminal neuralgia, according to the National Pain Foundation, is to move the nerve and the blood vessels away from each other to avoid this phenomenon.
Multiple Sclerosis
Multiple sclerosis is a condition that can also cause trigeminal neuralgia. Patients with multiple sclerosis have an abnormally activated immune system that attacks the outer covering of nerves, which is called myelin. Myelin works to make nerve impulses spread much faster. If the myelin sheath that covers the trigeminal nerve gets affected by this autoimmune disorder, the nerve can become inflamed and damaged. Inflammation and damage to the nerve alters its electrical activity, which can cause nerve pain (neuralgia).
Tumor
The Mayo Clinic notes that tumors are a potential (though rare) cause of trigeminal neuralgia. When a tumor grows near the trigeminal nerve it can cause the nerve to get compressed or pinched, leading to nerve dysfunction and pain. The tumor may also lead to damage of the myelin sheath that surrounds the nerve. Either one of these mechanisms can cause nerve dysfunction and aberrant electrical signaling which can result in pain sensations being transmitted to the brain.
