Delayed restricted diffusion in carbon monoxide leukoencephalopathy.

to a wide range of neurological symptoms, ranging from headaches, dizziness and altered mental status to coma. The basis for this is thought to be hypoxia. Carbon monoxide competes with oxygen for binding to hemoglobin (Hb) and once bound, shifts the oxyhemoglobin dissociation curve to the left, thus impairing off-loading of oxygen molecules, leading to hypoxia . A sizable minority of CO poisoning cases also develop a delayed neuropsychiatric syndrome (DNS) following a lucid interval of 2-40 days . The underlying pathophysiology of DNS is much less well understood and only recently, with the advent of advanced neuroimaging techniques, have we been able to draw distinctions between DNS and other forms of cellular injury1. We present a case of delayed neuropsychiatric syndrome following CO poisoning for whom diffusion weighted imaging (DWI) magnetic resonance imaging (MRI) revealed restricted diffusion but in a temporal pattern distinct from ischemia.