title: Delayed posthypoxic leukoencephalopathy: a case series and review of the literature.
abstract: BACKGROUND
  Delayed posthypoxic leukoencephalopathy (DPHL) is a rare and underrecognized entity where patients manifest a neurological relapse after initial recovery from an acute hypoxic episode. We sought to describe the magnetic resonance imaging (MRI) findings in a group of patients with DPHL and review the available literature.
  
  
  METHODS
  Retrospective case series including patients who presented with neurological and/or psychiatric symptoms after recovery from an acute hypoxic episode. The history and clinical presentation were reviewed from the electronic medical records. MRI scans were evaluated from the picture archiving and communication system. We performed a comprehensive review of the English medical literature for prior published cases of DPHL and describe the key imaging findings that have been reported related to this condition.
  
  
  RESULTS
  A total of five patients were identified, including four patients with respiratory failure due to drug overdoses from benzodiazepines, opioids, and/or barbiturates, and one patient who presented after cardiopulmonary arrest due to pulmonary embolism. All patients showed diffuse, extensive, and confluent white matter signal abnormalities including prominent restricted diffusion, extending to the subcortical white matter and respecting the U-fibers. There was no gyral edema or contrast enhancement. In one case histopathology was available, which highlighted patchy subcortical myelin loss with sparing of U-fibers and demonstrated prominent macrophage/microglial inflammation with extensive axonal damage. Of the other four patients, two were at their neurological baselines and two had persistent neurological deficits at the time of discharge.
  
  
  CONCLUSIONS
  The described constellation of MRI findings is highly suggestive of DPHL in the appropriate clinical setting.
authors.affiliation: Division of Neuroradiology, The Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine 601 N Caroline St, Baltimore, MD, 21287.
authors.forename: Carlos A
authors.initials: CA
authors.lastname: Zamora
authors.affiliation: Department of Pathology, Johns Hopkins University School of Medicine 600 N Caroline St, Baltimore, MD, 21287.
authors.forename: David
authors.initials: D
authors.lastname: Nauen
authors.affiliation: Division of Neuroradiology, The Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine 601 N Caroline St, Baltimore, MD, 21287.
authors.forename: Robert
authors.initials: R
authors.lastname: Hynecek
authors.affiliation: Division of Neuroradiology, The Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine 601 N Caroline St, Baltimore, MD, 21287.
authors.forename: Ahmet T
authors.initials: AT
authors.lastname: Ilica
authors.affiliation: Division of Neuroradiology, The Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine 601 N Caroline St, Baltimore, MD, 21287.
authors.forename: Izlem
authors.initials: I
authors.lastname: Izbudak
authors.affiliation: Division of Neuroradiology, The Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine 601 N Caroline St, Baltimore, MD, 21287.
authors.forename: Haris I
authors.initials: HI
authors.lastname: Sair
authors.affiliation: Division of Neuroradiology, The Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine 601 N Caroline St, Baltimore, MD, 21287.
authors.forename: Sachin K
authors.initials: SK
authors.lastname: Gujar
authors.affiliation: Division of Neuroradiology, The Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine 601 N Caroline St, Baltimore, MD, 21287.
authors.forename: Jay J
authors.initials: JJ
authors.lastname: Pillai
mesh_terms: D001921:Brain / Q000000981:diagnostic imaging / Q000473:pathology; D005260:Female; D006801:Humans; D056784:Leukoencephalopathies / Q000175:diagnosis* / Q000473:pathology; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D011859:Radiography; D012189:Retrospective Studies; D066127:White Matter / Q000000981:diagnostic imaging / Q000473:pathology
keywords: Hypoxia; MRI; leukoencephalopathy; myelin; white matter