Walsh & Hoyt: Cysts and Tumors of the Septum Pellucidum

The septum pellucidum is a double membrane that separates the frontal horns of the lateral ventricles. Cysts or ""caves"" occur between its laminae in many instances. Most cysts or caves in the region of the septum pellucidum are asymptomatic and are usually discovered at autopsy or during the performance of neuroimaging studies for some other condition. When the cysts become large, however, they may compromise the foramina of Monro, producing hydrocephalus and symptoms and signs of increased ICP. Although visual symptoms and signs are rare (except for those associated with increased ICP), Kansu and Bertan described an 8-year-old boy with a 4-month history of headaches and decreased vision in both eyes who was found to have a bitemporal hemianopia associated with signs of a bilateral optic neuropathy. A subsequent evaluation revealed a large cyst of the septum pellucidum that was compressing the intracranial portion of both optic nerves and the optic chiasm. There was no evidence of hydrocephalus. The patient had minimal improvement after incision and drainage of the cyst.