Classical infratentorial superficial siderosis of the central nervous system: pathophysiology, clinical features and...

The term superficial siderosis (SS) is derived from the Greek word 'sideros', meaning iron. It includes two subtypes, distinguished by their anatomical distribution, causes and clinical features: 'classical' infratentorial SS (iSS, which sometimes also affects supratentorial regions) and cortical SS (cSS, which affects only supratentorial regions). This paper considers iSS, a potentially disabling disorder usually associated with very slow persistent or intermittent subarachnoid bleeding from a dural defect, and characterised by progressive hearing and vestibular impairment, ataxia, myelopathy and cognitive dysfunction. The causal dural defect-most often spinal but sometimes in the posterior fossa-typically follows trauma or neurosurgery occurring decades before diagnosis. Increasing recognition of iSS with paramagnetic-sensitive MRI is leading to an unmet clinical need. Given the diagnostic challenges and complex neurological impairments in iSS, we have developed a multidisciplinary approach involving key teams. We discuss pathophysiology, diagnosis and management of iSS, including a proposed clinical care pathway.