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.