Superficial siderosis is a rare condition characterized by deposition of hemosiderin in the leptomeninges and in the subpial layers of the brain and spinal cord. It is associated with cerebrospinal fluid abnormalities consistent with recurrent bleeding into the subarachnoid space. The usual symptoms are hearing loss, ataxia, spastic paraparesis, sensory and sphincter deficits, and mental deterioration. A case is presented of severe superficial siderosis of the central nervous system in a 51-year-old man who had suffered a brachial plexus injury at the age of 20 years. The diagnosis was made by means of magnetic resonance imaging 16 years after the initial symptoms, which comprised bilateral hearing loss and anosmia. Subarachnoid bleeding was due to traumatic pseudomeningocele of the brachial plexus, a very unusual cause of superficial siderosis. This case is interesting insofar as the surgical treatment prevented further bleeding and possibly progression of the disease.