Stereotactic radiation therapy Technical introduction: With the development of imaging technologies such as CT and MRI, the localization and qualitative diagnosis of auditory neuroma has become more accurate, which has provided a guarantee for the application of stereotactic radiation neurosurgery in the treatment of auditory neuroma, making it gradually become another treatment method following microneurosurgery. At present, the main treatment devices of stereotactic radiation therapy are X-knife, γ-knife and proton knife, etc. X-knife is less expensive and easy to apply, but there is the disadvantage of mechanical loss to the offset of the positioning target; γ-knife has accurate positioning without mechanical loss to the offset of the target, but there is the disadvantage of expensive equipment and long pre-preparation, etc. Therefore, when choosing the treatment plan, we need to make individual choice according to the patient’s condition and the hospital’s own situation. In the current clinical study of stereotactic radiation therapy for auditory neuroma, the tumor growth control rate in long-term follow-up can reach about 90%, the preservation rate of vestibular nerve is 38%-71%, and the preservation rate of facial nerve grade I-II (according to House-Brack-man classification) is 90%-100%. With high tumor control rate and few complications, it has certain advantages in preserving hearing and reducing facial nerve damage. However, stereotactic radiotherapy also has its disadvantages that cannot be ignored, such as the inaccurate effect of radiotherapy for large tumors. Therefore, the indications for radiotherapy should be strictly controlled. Evaluation of advantages and disadvantages: Currently, there are two main methods of treatment for auditory neuroma: one is surgery and the other is gamma knife. Many people believe that gamma knife treatment can be the best treatment without craniotomy, no pain and low risk, so they go for gamma knife treatment regardless of the size of the tumor. In fact, there are strict surgical indications for the treatment of auditory neuroma, and only tumors under three centimeters can be treated with Gamma Knife. Typical case: a case of trigeminal neuralgia secondary to gamma knife treatment of residual auditory neuroma Clinical data: male, 47 years old, due to hearing loss and tinnitus in the left ear for six months, diagnosed as auditory neuroma in an outside hospital, and operated on January 12, 2004 for near total resection, postoperative pathological diagnosis: auditory nerve sheath tumor. There was a residual tumor of about 1.2×1.2×2cm3 in size. On February 13, 2004, the patient underwent gamma knife treatment for residual tumor in a hospital in Chengdu, with a 40% isodose curve, a peripheral dose of 12 Gy and a central dose of 30 Gy. On September 10, 2004, a repeat MRI showed that the residual tumor had basically disappeared. On June 10, 2005, he underwent gamma knife treatment for trigeminal neuralgia and took oral carbamazepine (dosage unknown), but the effect was poor and gradually worsened, manifested as severe pain, with each attack lasting about 30 minutes, and the dosage of carbamazepine reached more than 10 capsules per day, but the effect was still poor. On September 7, 2005, he was admitted to our neurosurgery department. He was admitted to our neurosurgery department on September 7, 2005. He was clear, had mild facial palsy on the left side of the face (caused by the first auditory neuroma resection), and had episodic pain in the 2nd and 3rd branches of the left trigeminal nerve. In the process of separation and release, there was brainstem pulling, and the heart rate dropped to 30-40 times/ (recovered when the operation was stopped) several times, and in a very difficult situation, the trigeminal nerve was separated and the adhesions were completely released, no vascular compression was seen, and no tumor tissue was seen. Conclusion: Secondary trigeminal neuralgia is often caused by compression by tumors of the pontocerebellar horn, such as cholangiocerebellar tumors. The patient in this case did not have trigeminal neuralgia before tumor resection and before the residual tumor was treated with gamma knife, indicating that the patient’s trigeminal neuralgia was not caused by tumor compression, which was found intraoperatively to be caused by severe adhesions to the pontocerebellar horn and compression of the trigeminal nerve. Gamma knife treatment of auditory neuroma in 5%-6% of cases after treatment found that there is a temporary increase in tumor size or swelling, followed by necrosis, that is, the tumor in the process of enlargement, necrosis produced adhesions, compression of the trigeminal nerve, triggering trigeminal neuralgia attack. Expert comment: Gamma knife is not a panacea for auditory neuroma treatment means to choose the right Gamma knife treatment of small and medium-sized auditory neuroma or large auditory neuroma postoperative residual tumor is a common clinical modality, complications for facial nerve, trigeminal nerve injury, and trigeminal nerve injury is mainly manifested as facial sensory loss, there are reports of local adhesions, compression can induce trigeminal neuralgia This patient is precisely in the 7 months after gamma knife treatment residual tumor During the process of tumor necrosis and disappearance, the connective tissue adhesions compressed the trigeminal nerve, which led to the symptoms. Surgery to release the adhesions and free the trigeminal nerve to make it completely decompressed is the fundamental and effective method of treatment. In this case, the patient’s trigeminal neuralgia was aggravated and the Gamma Knife treatment for trigeminal neuralgia was ineffective, and it may further aggravate the local adhesions and worsen the patient’s symptoms. When the residual tumor of gamma knife treatment is close to the location of the trigeminal nerve, the dose should be controlled to achieve only the purpose of controlling further growth of the tumor, which can prevent the occurrence of trigeminal neuralgia.