Pseudohypoxic brain swelling

Last revised by Henry Knipe on 24 Nov 2022

Pseudohypoxic brain swelling, also known as postoperative intracranial hypotension-associated venous congestion, is a rare condition with restricted diffusion on MRI in the basal ganglia and thalami following surgery. This can mimic cerebral hypoxic changes in the absence of vascular pathology.

Clinical presentation

Patients will have unexpected hypotension, cardiac arrest and/or Delayed gain of consciousness after uneventful surgery e.g. burr hole, lumbar discectomy, cranioplasty 1-4.

Radiographic features


Hypodensity of thalami and basal ganglia.


The basal ganglia and thalami will demonstrate edema and restricted diffusion. No stenosis or occlusion of cerebral arteries.

Signal characteristics
  • T2: high signal

  • FLAIR: high signal

  • DWI: high signal

  • ADC: low signal

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