title: Default Mode Network Perfusion in Aneurysmal Subarachnoid Hemorrhage.
abstract: The etiology of altered consciousness in patients with high-grade aneurysmal subarachnoid hemorrhage (SAH) is not thoroughly understood. We hypothesized that decreased cerebral blood flow (CBF) in brain regions critical to consciousness may contribute.
  
  
  
  We retrospectively evaluated arterial-spin labeled (ASL) perfusion magnetic resonance imaging (MRI) measurements of CBF in 12 patients with aneurysmal SAH admitted to our neurocritical care unit. CBF values were analyzed within gray matter nodes of the default mode network (DMN), whose functional integrity has been shown to be necessary for consciousness. DMN nodes studied were the bilateral medial prefrontal cortices, thalami, and posterior cingulate cortices. Correlations between nodal CBF and admission Glasgow Coma Scale (GCS) score, admission Hunt and Hess (HH) class, and GCS score at the time of MRI (MRI GCS) were tested.
  
  
  
  Spearman's correlation coefficients were not significant when comparing admission GCS, admission HH, and MRI GCS versus nodal CBF (p > 0.05). However, inter-rater reliability for nodal CBF was high (r = 0.71, p = 0.01).
  
  
  
  In this retrospective pilot study, we did not identify significant correlations between CBF and admission GCS, admission HH class, or MRI GCS for any DMN node. Potential explanations for these findings include small sample size, ASL data acquisition at variable times after SAH onset, and CBF analysis in DMN nodes that may not reflect the functional integrity of the entire network. High inter-rater reliability suggests ASL measurements of CBF within DMN nodes are reproducible. Larger prospective studies are needed to elucidate whether decreased cerebral perfusion contributes to altered consciousness in SAH.
authors.affiliation: Department of Neurology, Massachusetts General Hospital, 55 Fruit Street, Boston, MA, USA. senelson13@gmail.com.
authors.forename: Sarah
authors.identifier: 0000-0002-6026-2251
authors.initials: S
authors.lastname: Nelson
authors.affiliation: Department of Neurology, Massachusetts General Hospital, 55 Fruit Street, Boston, MA, USA.|Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Charlestown, MA, USA.
authors.forename: Brian L
authors.initials: BL
authors.lastname: Edlow
authors.affiliation: Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Charlestown, MA, USA.|Department of Radiology, Massachusetts General Hospital, Boston, MA, USA.
authors.forename: Ona
authors.initials: O
authors.lastname: Wu
authors.affiliation: Department of Neurology, Massachusetts General Hospital, 55 Fruit Street, Boston, MA, USA.
authors.forename: Eric S
authors.initials: ES
authors.lastname: Rosenthal
authors.affiliation: Department of Neurology, Massachusetts General Hospital, 55 Fruit Street, Boston, MA, USA.
authors.forename: M Brandon
authors.initials: MB
authors.lastname: Westover
authors.affiliation: Department of Neurology, Massachusetts General Hospital, 55 Fruit Street, Boston, MA, USA.
authors.forename: Guy
authors.initials: G
authors.lastname: Rordorf
mesh_terms: D000328:Adult; D000368:Aged; D002560:Cerebrovascular Circulation / Q000502:physiology*; D003244:Consciousness Disorders / Q000000981:diagnostic imaging / Q000503:physiopathology*; D005260:Female; D066128:Gray Matter / Q000098:blood supply* / Q000000981:diagnostic imaging; D006801:Humans; D018810:Magnetic Resonance Angiography / Q000379:methods*; D008297:Male; D008875:Middle Aged; D009415:Nerve Net / Q000098:blood supply* / Q000000981:diagnostic imaging; D010865:Pilot Projects; D012189:Retrospective Studies; D013113:Spin Labels; D013345:Subarachnoid Hemorrhage / Q000000981:diagnostic imaging / Q000503:physiopathology*
chemical_list: D013113:Spin Labels
keywords: Arterial-spin labeling (ASL); Cerebral blood flow; Default mode network; Disorders of consciousness; Magnetic resonance imaging; Subarachnoid hemorrhage