Brainstem gliomas are tumors that predominantly occur in children. They are usually thought to account for 10-20% of CNS tumors. Historically, brainstem gliomas were considered a single disease and treated by radiation therapy alone, usually without a morphologic diagnosis. This treatment approach was not wise, and its five-year survival rate was typically 20-30%. In the last decade, due to advances in neuroradiology, the wide variety of brainstem gliomas has become clear, and some scholars have identified important subgroups that have different clinical presentations, sites, and growth patterns. The increased awareness of tumor diversity has led to improved patient survival rates. One classification of brainstem gliomas is based on the “old-fashioned” growth pattern of the tumor on magnetic resonance imaging. Two authors have classified gliomas into four types: limited, diffuse, cervical medullary, and dorsolateral growth. A confined tumor is one that is less than 2 cm in diameter, has clear borders on MRI and shows no signs of cerebral edema or exudation. It can occur at any level of the brainstem, but the midbrain and medulla oblongata are usually considered to be the most frequent sites. Clinically, patients present with focal cranial nerve deficits and contralateral hemiparesis. Hydrocephalus rarely occurs unless the tumor originates in the cerebrospinal region and causes narrowing of the conduits. The diffuse form accounts for approximately 80% of all brainstem gliomas and usually originates in the pons and causes enlargement of the pons. Two-thirds of cases are axial and external growths. This type of tumor usually has a short latency period that includes compound, symmetric cranial nerve deficits, long MRI signals and neurological dysfunction. Hydrocephalus occurs rarely, with an incidence of approximately 10%. The cervical medullary type originates from the high cervical medulla and its typical growth pattern is described as a rostral growth into the cervical medullary junction. The main body of the rostral tumor is confined to the anterior aspect of the conus interpositus; therefore, the tumor expands posteriorly at the level of the foramen magnum and may break into the fourth ventricle. Posteriorly, the tumor is thought to be intramedullary. These tumors usually present with mild cranial nerve deficits, long MRI signals and neurological deficits, and occasionally a sloping neck. Lateral spinal growth type brainstem gliomas account for approximately 20% of brainstem gliomas. They originate at the base of the fourth ventricle and often fill the fourth ventricle, but are usually clearly demarcated from the surrounding neurological structures. In young patients, the clinical presentation is marked by insidious neurological deficits and signs and symptoms of increased intracranial pressure. Approximately half of the patients have cranial nerve deficits, while functional impairment is rare. Radiological imaging and histopathological features Modern classification criteria and treatment of brainstem gliomas are closely related to the invention of MRI. Routine application of fine-scale neuroradiology and correlation with clinical presentation, location, and growth pattern allows identification of different brainstem gliomas. Although the gadolinium signal is variable on MRI and has little significance for tissue grading, MRI provides the necessary anatomical detail to help understand the fine clinical interrelationships. Focal brainstem tumors are small, well-defined, and without edema or exudate. These tumors may include cysts and have a larger cystic component than a substantial component.Vardertop and his associates examined the neuroradiologic and pathologic histologic characteristics of 12 children with limited midbrain tumors. The tumors were confined to the dorsal or parietal region of the midbrain and may grow rostrally toward the thalamus or posteriorly into the pons. These tumors were well-defined, smooth, ring-like, and sometimes uniformly enhancing in contrast. All 12 tumors examined were non-fibroblastic, low-grade astrocytomas. Extrinsic spinal growth tumors are usually large, originate at the base of the fourth ventricle, and extensively fill the fourth ventricle, but without local infiltration of brain tissue. Typical extraspinal growth tumors are hyposignal on T1-weighted images and hypersignal on T2-weighted images, with uniform enhancement on gadolinium-DTPA-enhanced scans. A large number of limited or extrinsic spinal growth tumors are found to be low-grade astrocytomas. Two-thirds of the tumors described as limited or extradural growth were low-grade astrocytomas. The remaining tumors were either undifferentiated astrocytomas (25%) or gangliogliomas. Diffuse brainstem gliomas account for the majority of brainstem tumors. Unlike the confined and extrinsic spinal growth types, the diffuse type is a high-grade astrocytoma that includes fibrous astrocytes. 20 cases of diffuse tumors reported by Epstein and Farmer were all undifferentiated astrocytomas. On MRI, most diffuse tumors are low signal on T1-weighted images and high signal on T2-weighted images.Acbright and his colleagues worked out the MRI diagnostic criteria for diffuse brainstem gliomas. They concluded that extensive biological diagnosis is not necessary because MRI provides a high degree of accuracy. Cervical medullary brainstem gliomas are slow-growing, low-grade, originating in the cervical medulla and extending upward until confined by conus interscriptio. Posterior growth of the tumor causes expansion of the medullary spine and extension into the fourth ventricle. The cervical medullary type is most commonly a low-grade astrocytoma. Other rare pathological types in the cervical medulla are undifferentiated astrocytomas, gangliogliomas, and ventricular meningiomas.