Brain stem tumors account for 1.4% of intracranial tumors. They are mainly gliomas, among which astrocytomas and polar glioblastomas are more common, followed by oligodendrogliomas, ventricular meningeal gliomas, medulloblastomas, in addition to hemangiomas (including vascular reticulocytomas), cysts, teratomas, tuberculomas, metastatic tumors and so on. They are more prevalent in children and adolescents, with the highest incidence especially in children aged 5 to 9 years. Poorly differentiated polar glioblastoma, medulloblastoma, and ventricular meningioma are more common in children, while astrocytoma is more common in adults. In pediatric patients, the disease duration is short and progresses rapidly; it often causes severe brainstem symptoms within a short period of time (weeks to months); in adult patients, the disease duration is long and progresses slowly, and severe brainstem symptoms may occur within months or even a year. The distribution of various tumors in the brainstem varies slightly, from astrocytomas in all parts of the brainstem to medulloblastomas and ventricular meningiomas in the perineurium of the aqueduct and the floor of the fourth ventricle. The symptoms of brainstem tumors (brainstem glioma) can be divided into two categories: general symptoms and focal symptoms. General symptoms include posterior occipital headache. Children often have personality changes, and many patients have difficulty urinating. Increased intracranial pressure is often not the first symptom of brainstem tumors. Therefore, for progressive crossed palsy or multiple cranial nerve palsy combined with cone bundle damage, the possibility of brainstem tumor should be considered first, regardless of the presence of increased intracranial pressure. The focal symptoms of brainstem tumors vary according to the location of the tumor. Due to the infiltrative growth of the tumor, it is practically difficult to clearly delineate the specific location such as midbrain or pontine brain. Brainstem tumor (brainstem glioma) symptoms: 1. Midbrain tumor: Because the tumor can easily block the conduit, so the symptoms of increased intracranial pressure can appear in early stage. There are also first symptoms of mental and intellectual changes, which may be related to the involvement of reticular structures. Depending on the site of tumor invasion, it often manifests as follows: (1) Actinic nerve crossed hemiplegia syndrome – Weber syndrome, in which the lesion is located at the base of the cerebral peduncle, with paralysis of the actinic nerve on the diseased side and central paralysis of the upper and lower limbs and facial and tongue muscles on the opposite side. (2) Tetrahymena syndrome – Parrnaud syndrome, showing ptosis, epiphora, fixed pupil, loss of response to light, inability to converge, etc. (3) Benedikt syndrome, manifesting as deafness, etc., articulatory nerve palsy on the diseased side, increased muscle tone of the contralateral limb, tremor, etc. 2. Pontine brain tumor: accounting for more than half of all brainstem tumors, mostly seen in children. More than 90% of patients have symptoms of cranial nerve palsy, about 40% of patients have abducens nerve palsy as the first symptom, with the development of tumor, cranial nerve damage such as facial nerve and trigeminal nerve and motor sensory disorders of limbs. If the lesion is located in the lower half of the pontine brain, it causes peripheral facial palsy and hemiparesis of the opposite limb. 3. Medullary tumor: The first symptom is often vomiting, which is easily misdiagnosed as neurological vomiting or neurosis, especially in adult patients. Patients may have different degrees of dizziness and headache, and then the symptoms of posterior group cranial nerve palsy may appear earlier, such as difficulty in swallowing, choking and coughing, nasal speech and inability to extend the tongue. If the tumor involves both sides, the patient will have true medullary paralysis syndrome, accompanied by bilateral motor and sensory impairment of limbs and spastic paraplegia of varying degrees, and irregular breathing in the early stage of the disease, and respiratory distress or failure in the late stage. The following hemiplegic impairments of the medulla oblongata are commonly seen: (1) hypoglossal crossed nerve palsy (Jackson syndrome); (2) swallowing and vagal crossed palsy (Avellis syndrome); (3) Schmidt syndrome – cranial nerve palsy and contralateral hemiplegia on the side of the disease; (4) dorsolateral medulla oblongata syndrome (Wallenberg syndrome) (Wallenberg syndrome), etc.