Features: recurrent episodes of sudden, transient, severe pain in the trigeminal nerve division area. Epidemiology: It is mainly seen in middle-aged and elderly people, with peak incidence at the age of 50-70 years, and there is a tendency for the incidence to increase with age. The annual incidence is about 3.4/100,000 in men and 5.9/100,000 in women, slightly more than in men. Classification: primary and secondary, the latter mostly due to tumors in the CPA area, arachnoiditis, vascular malformations, aneurysms, multiple sclerosis and other disorders. 1. Peripheral pathogenesis: Any lesion from the end of the trigeminal nerve to the nucleus accumbens of the brainstem may cause this disease. Cushing (1920) found that mechanical compression of the tumor could cause trigeminal neuralgia during surgery. Jennetta (1966) suggested that more than 90% of the bridging entrances to the trigeminal nerve have heterogeneous twisted vessels compressing the posterior trigeminal roots, resulting in localized demyelinating changes in the nerve roots. Gardner suggested that a short circuit is created between adjacent fibers in the demyelinated area, through which minor tactile stimuli can be transmitted to the center, and the impulses from the center are converted into afferent impulses by this “short circuit”, which are superimposed to reach above-threshold intensity and produce symptoms. The symptoms are produced when the intensity reaches above the threshold. There are many similarities between trigeminal neuralgia and focal epilepsy: there are some phenomena that cannot be explained by peripheral pathogenesis, such as autopsy finding that many normal people have nerve-vascular contact, and some patients with trigeminal neuralgia have no vascular compression. Trigeminal neuralgia may be a sensory seizure. The idea that the seizures of trigeminal neuralgia have trigger points, sudden onset, short duration, and effective antiepileptic drugs supports this view. This doctrine cannot explain the vast majority of cases that are unilateral, pain is confined to a certain two-branch range for a long time without development, and brainstem lesions do not produce trigeminal neuralgia, among other phenomena. Clinical manifestations 1, the characteristics of pain: aura: before the onset of the attack mostly without aura, the pain comes suddenly by the sudden stop, the interictal period without pain. Nature: electric shock-like, lightning-like, knife-like; the face can be distorted or frozen when the pain attack is severe. Duration: each attack usually does not exceed 2 minutes, but after the attack the patient may have a residual dull pain or burning sensation in the face. Frequency: Early attacks are less frequent and may occur once every few days, but later they may gradually worsen, even once every few minutes. The course of the disease may be periodic, with a cycle of several weeks to several months. Painful twitching: reflex twitching of facial muscles with the corners of the mouth drawn to the side. Concomitant symptoms: facial flushing, increased skin temperature, conjunctival congestion, lacrimation, increased salivation, nasal mucosa congestion, and runny nose. 2. Trigger point and trigger: Also known as trigger point, it is often located somewhere in the trigeminal nerve distribution area on the diseased side, such as upper and lower lip, nasal flank, corner of the mouth, incisors, palate, buccal mucosa, etc. Pain in the mandibular branch is mostly caused by jaw movements (chewing, talking, yawning), and direct stimulation of skin trigger points to induce pain is rare. The maxillary branch is mostly caused by stimulation of trigger points (outer 1/3 of the upper lip, upper incisors, cheeks, inner part of the eye), and can be caused by washing the face, brushing the teeth, shaving, and blowing the nose. 3, pain site: side: mostly limited to one side, slightly more on the right side, 4% of patients have bilateral pain, mostly seen in patients with multiple sclerosis. Branch: most commonly the 2nd and 3rd branches are involved at the same time, followed by the 2nd and 3rd branches alone, the ophthalmic branch is the least common.