Foramen magnum herniation

Foramen magnum herniation is a secondary brain injury caused by the cerebellar tonsils herniating through the posterior margin of the foramen magnum into the spinal canal, compressing the medulla oblongata and upper cervical spinal cord. This occurs in the late stages of posterior fossa space-occupying lesions or severe supratentorial space-occupying lesions. Based on the onset, it can be divided into two types: acute foramen magnum herniation and chronic foramen magnum herniation. It mostly occurs in middle-aged and elderly patients, presenting with suboccipital headache, nausea, vomiting, and other symptoms.