Lost in space, lost in time: A clinician's proposed approach to the diagnosis of multiple sclerosis.

Current McDonald criteria for multiple sclerosis (MS) rely on complex statistical metaphors-dissemination in space and time-that are prone to clinical misapplication. This manuscript proposes a clinician-centred approach that simplifies diagnosis by focusing on four fundamental immunobiological pillars: confirming the condition is a chronic, inflammatory, demyelinating disease of the CNS. By reclassifying existing markers-such as the central vein sign, paramagnetic rim lesions, and neurofilaments-into these intuitive categories, the model provides clinicians greater flexibility to triangulate evidence based on available data. Crucially, this framework introduces Immunobiological MS (IBMS) (formerly Radiologically Isolated Syndrome) and Non-active CDMS as distinct diagnostic entities. These categories acknowledge the disease's biological diversity and accommodate variable treatment decisions.