Superficial Siderosis Following Posterior Fossa Exploration

A 70 year old lady presented with symptoms and signs suggesting lesions in the vestibulocochlear nerve, the cerebellum and brainstem. Features on magnetic resonance imaging of the brain led to the diagnosis of superficial siderosis. This condition is a very rare neurodegenerative disorder characterised by deposition of haemosiderin in several areas of the nervous system. This occurs a result of recurrent bleeding in the subarachnoid space. Various sources of chronic bleeding have been implicated, including dural defects, neoplasms or arterio-venous malformations. Whilst presenting symptoms depend on the site of haemosiderin deposition, there is a predilection for the eight cranial nerve, the cerebellum and brainstem. The investigation of choice is magnetic resonance imaging of the brain, and linear hypointensity is pathognomonic. Early identification of this condition will obviate the need for further, extensive investigation of the patient’s symptoms. It will also enable the physician to search for an underlying, potentially treatable cause. Our patient gave a history of posterior fossa exploration half a century prior to her current presentation, suggesting the presence of a dural defect as the cause of this disorder.