Brainstem glioma is a collective term for gliomas that occur in the pontine brain, midbrain and medulla oblongata. There are statistically two peaks in the age of onset, the first at 5-10 years of age and the second at 40-50 years of age, so they can be divided into pediatric and adult types. Children are relatively more common, accounting for 10%-20% of all central nervous system tumors in children and 30% of posterior cranial recess tumors in children. Classification Brainstem glioma is divided into four categories 1. diffuse endogenous type: mostly located in the pontine brain, it is the most typical brainstem glioma, accounting for 80% of the cases, and is also the type with the worst prognosis. 2.Focal type: accounting for 5%-10% of brainstem tumors, with limited tumors, clear boundaries, no infiltration and edema. 3.Ventral exophytic type: accounting for 10%-20% of brainstem glioma, the tumor originates from the subventricular glial tissue at the base of the four ventricles, the main body is located in the four ventricles, rarely invades the brainstem, and the symptoms occur late. 4.Cervical medullary junction type: It accounts for 5%-10% of brainstem tumors, similar to glioma of medullary or spinal cord origin. The center of the tumor may be located in the medulla oblongata or cervical medulla. Histopathology More than 95% of brainstem gliomas are of astrocytic origin. Most diffuse types are high-grade astrocytomas that progress rapidly and may have cystic changes, hemorrhage, or necrosis. The focal and ventral exophytic types are of lower histologic grade, mostly fibrous or hairy cell astrocytomas, and progress relatively slowly. The cervical medullary type is mostly low-grade astrocytoma with slow growth, and high proliferation and infiltrative behavior are rare. On diffuse MR images, they show diffuse infiltration and expansion centered on the pontine brain, mostly with equal, long Tl-long T2 signal, inconsistent enhancement situation, and may have more obvious peritumoral edema. MR images can accurately describe the location of the tumor and the degree of infiltration and expansion, and whether it is accompanied by obstructive hydrocephalus. Focal and ventral exophytic MR shows long T1 and long T2 abnormal signals, which can have uniform and consistent enhancement with relatively clear borders and distinguish from normal tissues. Clinical manifestations The location and growth pattern of the tumor determine the different clinical manifestations. The focal and ventral exophytic types are relatively slow progressing and insidious in origin. In addition to the common symptoms of CNS diseases, such as high cranial pressure symptoms, cognitive and behavioral changes, there are three other types of manifestations of brainstem occupying lesions: neurological nuclei and cranial nerve signs, such as swallowing disorder, facial palsy and eyelid ptosis; long bundle signs, such as hemiparesis and hemianopsia; and ataxia signs. Most patients show increased intracranial pressure and occipital and cervical discomfort. Treatment Surgical treatment: focal and ventral exophytic brainstem gliomas should be pursued for surgical treatment. According to Wang Loyalty et al, surgery can be considered in the following cases: (1) exogenous brainstem glioma protruding into the four ventricles, the pontocerebellar horn or cerebellar hemisphere; (2) focal non-exogenous tumors; (3) large cystic lesions or hemorrhagic necrotic lesions. The purpose of surgery is to remove the tumor under the surgical microscope as much as possible while preserving neurological function, providing better conditions for radiation and chemotherapy. Glioma in the parietal region of the midbrain with a long natural history is only suitable for bypass surgery and regular observation. The brainstem is the site where the nuclei, nerve conduction bundles and reticular structures of the brain are concentrated, and it is also the location of the heartbeat and respiratory center. After brainstem injury, in addition to the manifestation of local cranial nerve damage, the manifestation of impaired consciousness and motor sensory impairment is often more severe. In addition, there may be respiratory and circulatory failure. Therefore, we must be careful and gentle when removing the tumor and closely observe the changes of vital signs during the operation. Radiation therapy: Radiation therapy is one of the main means of brainstem tumor treatment. For tumors with clear boundary and protruding brainstem, surgical resection plus radiotherapy is preferable; for tumors with diffuse growth that are not suitable for surgical resection, radiotherapy is first. Conventional external radiation radiotherapy is the commonly used method at present, which is effective, simple and economical. 50-60 Gy is the appropriate dose of radiotherapy; a few brainstem tumors with limited lesions and small size can be treated with r-knife or X-knife. Chemotherapy: Chemotherapy is not yet uniform in the field of brainstem glioma treatment. Some research teams have combined the use of irinotecan and cisplatin in the treatment of pediatric brainstem glioma and achieved significant therapeutic effects, resulting in a reduction in tumor size. There is no consensus on the efficacy of temozolomide and other targeted therapeutic agents such as bevacizumab in the treatment of brainstem glioma. Prognosis In terms of tumor site, lesions in the midbrain and medulla have a relatively good prognosis, while lesions in the pontine brain (>80%) have the worst prognosis because most are diffuse, with most children dying within 1 to 8 months, and only a small proportion of focal pontine tumors have a better prognosis because they are limited and resectable. Focal brainstem tumors can be treated surgically to obtain a good prognosis. In patients with diffuse brainstem glioma, radiotherapy and/or chemotherapy are the main treatment options today.