Overview
The First Decision: Central or Peripheral Demyelination?
One bedside question organizes this topic: is the lesion in the central nervous system (CNS) or the peripheral nervous system (PNS)?
CNPLE
CNPLE
One bedside question organizes this topic: is the lesion in the central nervous system (CNS) or the peripheral nervous system (PNS)? A patient with previous optic neuritis, brisk leg reflexes, and a relapsing history follows an MS pathway. A patient whose leg weakness is progressing upward over several days with absent reflexes follows a GBS pathway and needs immediate airway and autonomic surveillance. Both disorders reflect immune-mediated injury to myelin or its associated axons, but their time course, investigations, treatment, and immediate threats differ. Localize first; then let the trajectory determine urgency.
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