Chiasm gliomas in pediatric patients. Part 1. Сlinical manifestations

Chiasm gliomas are very important heterogeneous group of tumors manifesting in the first and second decades of life and is the second leading cause of blindness in children with neurosurgical pathology. It is a benign, slow-growing piloid astrocytoma, accounting for 1–5% of intracranial gliomas in children. The incidence of neurofibromatosis type 1 among patients with chiasm glioma ranges from 7 to 60%. The location of the tumor is determined based on ophthalmological symptoms, neuroimaging data (MRI), and surgical findings. The initial growth of the tumor occurs in the anterior visual pathway structures (optic nerves, chiasm, optic tracts) and leads to ophthalmological symptoms, which are dominant in the clinical manifestations of the disease. Chiasm damage may occur in one or both optic nerves, in one or both optic tracts. Damage to the chiasm manifests as bitemporal heteronymous hemianopsia. Moreover, the spread of the tumor to the optic nerves is accompanied by decreased visual acuity. Damage to the optic tract is manifested by homonymous hemianopia and normal visual acuity. However, isolated damage to the optic tract is uncommon and usually occurs with chiasm and optic nerve lesions; hence, visual disturbances are more complex. Lesions in the optic nerve fibers in the chiasm and optic nerves/tracts lead to primary descending atrophy of the optic nerves. Papilledema with optic nerve atrophy indicates occlusive hydrocephalus. Delayed diagnosis of the disease affects treatment results.