Microvascular decompression and facial spasm Idiopathic hemifacial spasm (HFS) refers to paroxysmal, involuntary muscle spasms on one side of the face. Foreign epidemiological findings show that its incidence is 1 1 million. The cause of idiopathic HFS has been identified as a demyelinating lesion of the facial nerve roots in the pontocerebellar angle (CPA) due to compression of the responsible vessels, which short-circuits the impulses between the afferent and efferent nerve fibers. MVD was rapidly spread in the clinic because of its safety and effectiveness. Half a century has passed, but MVD, which is the most effective treatment in the field of functional neurosurgery, is still not popular in China, and there is a great imbalance in the development between regions, and the treatment level needs to be improved. MVD is the only method known to cure idiopathic HFS, especially because of its characteristic of completely preserving vascular and neurological functions, thus becoming the most effective treatment of choice. For physicians with extensive experience in MVD surgery, the cure rate of HFS MVD can reach 95-98%. The high cure rate of MVD is only for idiopathic HFS with vascular compression as the underlying cause. Secondary HFS is very rare and is most often caused by CPA cholesteatoma. In addition. The diagnosis of idiopathic HFS must be differentiated from the following disorders: habitual ophthalmoplegia, hysterical ophthalmoplegia, limited motor epilepsy, spasticity after facial nerve palsy, myoclonus behind facial nerve trauma, oculomotor syndrome (Maggie’s disease), chorea and facial twitching associated with tardive dyskinesia, and facial myoclonus due to motor neuron disease. For idiopathic HFS with a clear diagnosis, vascular compression is the only etiology. Preoperative MRA with the primary aim of identifying the responsible vessels near the facial nerve root is completely unnecessary. During MVD for HFS, it should be remembered that there must be a vessel at the root of the facial nerve that constitutes the compression and the only task of the surgeon is to find and push it away from the nerve root. Every surgeon who performs MVD surgery must be well versed in the anatomy of the local vessels, cerebral nerves, brain tissue, and brain pools of CPA. Many of the MVD deaths in China and abroad have been performed by renowned neurosurgeons. In fact. For an experienced surgeon. The whole CPA area can be well exposed by using the posterior locking hole of the sigmoid sinus with a diameter of 2.0-2.5 cm, and all kinds of CPA tumors can be safely and effectively resected. There is no need to force a locked-hole approach for first-time MVD surgeons. The key to this type of foraminal approach is the correct positioning of the surgical body, the accurate positioning of the micro-osseous foramen, and the slow release of cerebrospinal fluid by dissecting the cerebral pool to obtain sufficient operating space. Of course, familiarity with local microscopic anatomy. The mastery of microsurgical skills and the accumulation of rich surgical experience are the key to ensure the safety and effectiveness of the foraminal surgery. It is a prerequisite to ensure the safety and effectiveness of lockhole surgery. The root exit zone (REZ) of the facial nerve is compressed by the responsible vessels. It is most prone to demyelinating lesions and symptoms. In addition, some scholars, represented by Ishikawa, have studied the electrophysiology of facial muscle in the perioperative period of MVD for HFS and concluded that the abnormal increase of excitability of the motor nucleus of the facial nerve caused by vascular compression is also one of the causes of HFS. This theory not only enriches the theory of vascular compression etiology, but also has certain guiding significance for clinical practice. Therefore. In MVD, the importance of REZ decompression in MVD surgery should be fully recognized, and adequate decompression of the REZ should be the first priority. the responsible vessel for HFS is almost always located in the REZ, while the free vessels located in the lateral pool of the pons distal to the facial nerve, which are only in contact with or parallel to the facial nerve trunk, are not the responsible vessels. When multiple vessels are present in the REZ. The responsible vessel is often located on the deep side of the vascular plexus. After the responsible vessel is fully free, it is pushed away from the REZ and a decompression pad is placed between the responsible vessel and the brainstem. Placement of the pad between the responsible vessel and the REZ or facial nerve should be avoided. So-called “peri-herpetic” decompression and facial nerve “commissures” should be discarded. It is often seen in clinical practice that for various reasons the responsible artery cannot be satisfactorily pushed away from the REZ, thus compromising the decompression effect or predisposing to recurrence. In cases where the responsible artery cannot be pushed out of the REZ satisfactorily for various reasons, which may affect the decompression effect or may be prone to recurrence, or in cases where the responsible artery can barely be pushed out and cause complications that are difficult to recover. In this case, Teflon cotton can be used to wrap around the responsible artery and then pushed to the cranial wall or the dura of the canopy, the local dura is roughened by electrocoagulation, and the responsible artery or the Teflon cotton wrapped around the artery and the dura are fixed with a small amount of _medical ear cerebral glue. Thus, the responsible artery is suspended away from the REZ and satisfactory decompression is achieved. In recent years. With the advancement of neuroendoscopic technology. There have been reports of successful use in MVD surgery. The local magnification, good illumination, and multi-angle observation of the endoscope can compensate for the lack of tubular view of the operating microscope and avoid missing the responsible vessel. The ability to clearly visualize the facial nerve REZ and place pads without excessive stretching and stripping of nerve tissue has clinical implications for improving the outcome of MVD. A basic principle of functional neurosurgery is to relieve pain without causing serious complications that are unacceptable to the patient. For neurosurgeons who are new to MVD, one of the major concerns is the occurrence of serious complications. Intraoperative rock vein hemorrhage, brainstem dissection, postoperative cerebellar hemorrhage and infarction, and brainstem infarction. The responsible artery (mostly the main stem of the anterior inferior cerebellar artery or posterior inferior cerebellar artery) is often seen to emanate from the brainstem during HFS MVD, where it is anatomically and physiologically a terminal branch with little collateral circulation and must be carefully preserved. Injury may result in serious consequences. The number of penetrating arteries, their short stroke, or the complexity of their course. often make the operation of pushing the responsible artery and placing the pad cotton difficult and dangerous. Avoiding facial nerve REZ and brainstem penetrating artery injuries. Can reduce the incidence of postoperative facial palsy to less than 3%. Hearing impairment remains the most common complication after HFS MVD. For physicians with extensive experience in MVD. Permanent hearing loss on the sick side can still be 2% to 7%, and the main reason for this is not direct mechanical damage to the auditory nerve. The main reason for this is not direct mechanical damage to the auditory nerve, but rather the ischemia of the internal auditory artery caused by the treatment of the responsible vessel. Intraoperative brainstem auditory evoked potential monitoring plays an important role in reducing auditory nerve injury for physicians who are new to MVD. In conclusion, long-term surgical practice has shown that almost all idiopathic HFS is caused by compression of the facial nerve root at the CPA site by the responsible vessel. The study of the etiology of HFS, the causes of delayed healing after MVD, and the causes of postoperative delayed facial palsy will further enhance our understanding of the nature of HFS, and a 100% cure rate will be the goal of every neurosurgeon performing MVD surgery for HFS. Permanent loss of hearing on the diseased side is the greatest possible disadvantage after this surgery, and how to minimize its incidence is also an important issue. As a class of functional neurosurgery with a very high degree of delicacy, the standardization of its operation needs to be promoted. The standardization of its operation needs to be promoted urgently, and serious complications that are unacceptable to the patient should be avoided as much as possible. The responsible arterial suspension method and endoscopic application are useful supplements and improvements to the traditional MVD procedure, which deserve further improvement and promotion.