Targeted detection and repair of a spinal dural defect associated with successful biochemical resolution of subarachnoid bleeding in classical infratentorial superficial siderosis

Background and importance Classical infratentorial superficial siderosis (iSS) is characterised by repeated insidious bleeding into the subarachnoid space, leading to haemosiderin deposition within the subpial layers of the brainstem, cerebellum and spinal cord, sometimes with supratentorial involvement. Although nearly always associated with a dural defect (usually from previous trauma or neurosurgery) there is little evidence to support definitive investigation and management strategies. Here, we present a novel investigation strategy to identify a dural defect and subsequent successful surgical repair with biochemical resolution of subarachnoid bleeding. Clinical presentation A 55-year-old gentleman presented with a 15-year progressive history of sensorineural deafness, followed by a slowly worsening gait ataxia. He had previously sustained cranio-spinal trauma. On examination there were features of myelopathy and ataxia. MRI demonstrated classical iSS, affecting cerebellum and cerebral cortices, with a cervicothoracic epidural CSF collection. Lumbar puncture (LP) revealed elevated ferritin 413 ng/mL and red cell count of 4160. Reverse CT myelography, a novel technique involving contrast injection into the collection, delineated a dural defect at the T9/T10 level that was not present on conventional myelography. Following surgical repair, repeat LP twelve months later demonstrated biochemical improvement (ferritin 18 ng/mL, red cells < 1). There was no further neurological deterioration in symptoms during eighteen months follow-up. Conclusion We show the value of a rational targeted investigation pathway in identifying a surgically reparable dural defect underlying classical iSS. We also provide proof of concept that surgical repair can facilitate biochemical resolution of subarachnoid bleeding and might prevent progression of neurological disability.