Superficial siderosis of the central nervous system: an unusual cause of sensorineural hearing loss.

Neurology Service, State University of Rio de Janeiro (UERJ), Rio de Janeiro RJ, Brazil; Laboratory of Panic & Respiration, Institute of Psychiatry, Federal University of Rio de Janeiro (UFRJ), INCT Translational Medicine, Rio de Janeiro RJ, Brazil. Superficial siderosis (SS) of the central nervous system (CNS) is a rare disorder characterized by a classic triad of symptoms consisting of sensorineural hearing loss, cerebellar ataxia, and myelopathy. Less frequently, it is also associated with bladder disturbance, anosmia, extraocular palsies, anisocoria, dementia, and Parkinsonism. SS is caused by chronic or recurrent haemorrhage into the subaracnoid space with haemossiderin deposition in the subpial layers of brain and spinal cord, which leads to progressive and irreversible neurological dysfunction. There are many causes for it, including aneurysms, vascular malformations, and CNS tumours. However, in most cases despite extensive investigations, the cause of bleeding is often not apparent. Magnetic resonance imaging (MRI) of the brain is the main laboratory screening exam to confirm the diagnosis, which shows a characteristic rim of hypointensity seen on T2weighted around the brain, brainstem and spinal cord. Sensorineural hearing loss may be the first symptom of the disease, and early diagnosis is extremely important, because this progressive disorder may lead to deafness, dementia and confinement. We present a case study related to the possibility of superficial siderosis of the CNS in patients presenting sensorineural hearing loss, will be discussed.