Demyelination of the trigeminal nerve is the main cause of trigeminal neuralgia. The cause of demyelination of the trigeminal nerve is due to limited, acute or chronic inflammation or compression of a segment of the trigeminal nerve fibers, resulting in severe degeneration and necrosis of the sensory fibers of the trigeminal nerve, and then the myelin sheath is repaired, thickened and adhered, resulting in compression of the nutrient vessels that normally supply the trigeminal nerve, which reduces the blood supply to the sensory roots, and The result is that the blood supply to the sensory roots is reduced, resulting in disorders of myelin metabolism and nutrition. The short-circuiting of efferent fibers and nociceptive afferent fibers, or the loss of large myelinated fibers and the loss of inhibition of conduction in the caudal nucleus and anterolateral nerve tracts, sensitize the damaged nerve tracts to self-excitation and repetition of spinal trigeminal root reflexes, resulting in painful episodes caused by afferent impulses that normally cause only tactile sensation. Therefore, it can be assumed that inflammation or some kind of compression stimulating the sensory roots of the trigeminal nerve is the main factor causing sensory root demyelination. In animal tests, local demyelination of the posterior root of the trigeminal nerve was found to produce repetitive action potentials, sometimes lasting several minutes, independent of the brainstem, which increased during hyperventilation and disappeared after administration of phenytoin sodium, suggesting that primary demyelinating disease causing demyelination of large nerve fibers is the cause of trigeminal neuralgia. Demyelination of the trigeminal nerve is the main cause of trigeminal neuralgia, and mechanical compression of ischemia and disturbance of myelin nutrient metabolism may be the precipitating factors of myelin loss. The degeneration of nerve fibers may be the basis of nerve function changes, but the exact cause of nerve fiber degeneration still needs further exploration and in-depth study.