Superficial siderosis is a rare condition caused by hemosiderin deposits in the central nervous system (CNS). Classical type of superficial siderosis primarily affects the infratentorial regions and spinal cord, and typically presents with slowly progressive sensorineural hearing impairment, cerebellar ataxia, and myelopathy. Hemosiderin deposition results from chronic intermittent or continuous minor bleeding into the subarachnoid space. The bleeding is caused by various pathologies, including tumors, meningocele and pseudomeningocele, vascular malformations, and trauma. But only less than 50% of cases have a definite bleeding source identified. A second type of brain siderosis restricted to the part of the cerebral hemispheres, has been identified and referred to as cortical superficial siderosis (CSS). CSS has a different range of potential causes and clinical presentation to classical type, but in older individuals is emerging as a key feature of cerebral amyloid angiopathy.
