Etiological studies have shown that the causes of facial myoclonus can be broadly divided into two categories: 1. Vascular factors It is known that about 80% to 90% of facial myoclonus is due to the presence of vascular compression in the brainstem area of the facial nerve. Clinical data show that the anterior inferior cerebellar artery and posterior inferior cerebellar artery are the main vascular factors leading to facial spasm, while the superior cerebellar artery is the second. This is because the superior cerebellar artery originates from the junction of the basilar artery and the posterior cerebral artery, which is higher and has the most constant course. The posterior inferior cerebellar artery and the anterior inferior cerebellar artery are relatively more variable, and thus are prone to form vascular loops or ectopic compression of the facial nerve. In addition, the superior vagus artery and other major arterial variants such as the vertebral artery and basilar artery may also compress the facial nerve and cause facial spasm. It was thought that facial spasm was due to pulsatile compression of the arteries, but recent studies have shown that compression of the facial nerve by a single venous vessel can also lead to facial spasm. And the above-mentioned vessels can be two or more to form a joint compression of the facial nerve. 2, non-vascular factors Non-vascular occupying lesions of the pontocerebellar angle such as granulomas, tumors and cysts can also produce facial muscle spasm. The reasons may be due to (1) displacement of normal vessels due to the occupancy. (2) Direct compression of the facial nerve by the occupancy. (3) The influence of abnormal blood vessels of the occupancy itself, such as arteriovenous malformation, meningioma, aneurysm, etc. In addition some occupying lesions in the posterior cranial fossa can also lead to facial spasm. For example, a rare case of a Chewang’s cell tumor of the median nerve compressing the facial nerve leads to facial muscle spasm. In young patients, localized arachnoid thickening may be one of the main causes of facial myoclonus. 3, high-risk groups Anyone can develop the disease, but the middle-aged and elderly are the most common, and women are more common. The incidence is higher in people with hypertension. The most confusing symptom of facial muscle spasm is facial muscle hypertonia, which is caused by a “short circuit” injury of nerve fibers. For example, if the home power control system is short-circuited, when the kitchen light is turned on, the toilet light will come on as well. And vice versa. However, the cause of the “short circuit” can be arterial vascular compression or the sequelae of viral facial neuritis. The difference in treatment is determined by the cause.