MRI patterns of global hypoxic-ischemic injury in adults

Background and purpose: To assess MRI patterns and associated clinical outcome in adults with global hypoxic-ischemic injury. Materials and methods: In order to identify the patients with evidence of global hypoxic-ischemic injury, we retrospectively searched our radiology information system for reports of brain MRI studies from 01/01/2004 to 12/31/2010, containing the keywords -"hypoxia", "hypoxic", "anoxia" and "anoxic". A board certified neuroradiologist visually inspected the corresponding MR images for the presence, location and extent (focal versus diffuse) of ischemic findings. Clinical data for these patients was collected from the electronic medical records, including mechanism of the hypoxic-ischemic injury, and clinical outcome was measured using modified Rankin Scale (mRS). Results: Review of radiology reports identified 151cases, of which 64patients remained after exclusion of normal studies ("no hypoxia" in the report), pediatric patients and patients with remote perinatal hypoxia. Five patients had relatively favorable clinical outcome (mRS of 1 to 3) and 59 had poor outcome (mRS of 4 to 6). Patterns associated with relatively favorable clinical outcome were: a) watershed pattern and b) basal ganglia without cortical involvement. Patterns associated with poor clinical outcome were: a) diffuse cortical and deep grey matter pattern, with and without perirolandic sparing; (b) medial occipital with perirolandic involvement; c) precentral gyrus involvement; d) diffuse white matter involvement; e) brainstem involvement; f) cerebellar involvement and g) hippocampal involvement. Conclusion: The vast majority of patients with MRI patterns of hypoxic-anoxic injury have a poor clinical outcome, independently of the observed pattern, with the only relative exception being the watershed pattern and the basal ganglia pattern without cortical involvement.