[Diagnosis and treatment of superficial siderosis]

Superficial siderosis (SS) is a rare condition in which hemosiderin is deposited on the pial surface of the brain and/or spinal cord. Hemosiderin deposition is the consequence of recurrent or persistent hemorrhage in the subarachnoid space. There are two types of SS. In "classical"-type SS, hypointense MRI signals are observed in the brainstem and cerebellum with diffuse and symmetrical margins. Causes of hemorrhage in the "classical" type include tumor, vascular abnormality, injury, and dural defect. The source of hemorrhage is not apparent in approximately 50% of patients despite extensive examination. In "localized"-type SS, hypointense MRI signals are localized in the cerebral cortex. The most common causes of hemorrhage in the "localized" type are cerebral amyloid angiopathy and/or Alzheimer's disease. Patients with SS usually present with slowly progressive and irreversible cerebellar ataxia, sensorineural hearing loss, and/or myelopathy due to involvement of the acoustic nerve, cerebellum, and spinal cord. T2-weighted imaging (WI) or T2* WI demonstrates characteristic linear low-intensity signals along the surface of the brain and spinal cord. Treatment of SS involves identification and surgical correction of the bleeding source. Deferiprone, which is a lipid-soluble iron chelator that can penetrate the blood-brain barrier, is reportedly effective at improving the clinical symptoms and deposition of hemosiderin. It is thus a hopeful treatment option for SS.