title: Retinal Vessel Analysis (RVA) in the Context of Subarachnoid Hemorrhage - A Proof of Concept Study.
abstract: BACKGROUND
  Timely detection of impending delayed cerebral ischemia after subarachnoid hemorrhage (SAH) is essential to improve outcome, but poses a diagnostic challenge. Retinal vessels as an embryological part of the intracranial vasculature are easily accessible for analysis and may hold the key to a new and non-invasive monitoring technique. This investigation aims to determine the feasibility of standardized retinal vessel analysis (RVA) in the context of SAH.
  
  
  METHODS
  In a prospective pilot study, we performed RVA in six patients awake and cooperative with SAH in the acute phase (day 2-14) and eight patients at the time of follow-up (mean 4.6±1.7months after SAH), and included 33 age-matched healthy controls. Data was acquired using a manoeuvrable Dynamic Vessel Analyzer (Imedos Systems UG, Jena) for examination of retinal vessel dimension and neurovascular coupling.
  
  
  RESULTS
  Image quality was satisfactory in the majority of cases (93.3%). In the acute phase after SAH, retinal arteries were significantly dilated when compared to the control group (124.2±4.3MU vs 110.9±11.4MU, p<0.01), a difference that persisted to a lesser extent in the later stage of the disease (122.7±17.2MU, p<0.05). Testing for neurovascular coupling showed a trend towards impaired primary vasodilation and secondary vasoconstriction (p = 0.08, p = 0.09 resp.) initially and partial recovery at the time of follow-up, indicating a relative improvement in a time-dependent fashion.
  
  
  CONCLUSIONS
  RVA is technically feasible in patients with SAH and can detect fluctuations in vessel diameter and autoregulation even in less severely affected patients. Preliminary data suggests potential for RVA as a new and non-invasive tool for advanced SAH monitoring, but clinical relevance and prognostic value will have to be determined in a larger cohort.
authors.affiliation: Department of Neurosurgery, RWTH Aachen University, Aachen, Germany.
authors.forename: Walid
authors.initials: W
authors.lastname: Albanna
authors.affiliation: Department of Neurosurgery, RWTH Aachen University, Aachen, Germany.
authors.forename: Catharina
authors.initials: C
authors.lastname: Conzen
authors.affiliation: Department of Neurosurgery, RWTH Aachen University, Aachen, Germany.
authors.forename: Miriam
authors.initials: M
authors.lastname: Weiss
authors.affiliation: Department of Neurosurgery, RWTH Aachen University, Aachen, Germany.
authors.forename: Hans
authors.initials: H
authors.lastname: Clusmann
authors.affiliation: Department of Ophthalmology, RWTH Aachen University, Aachen, Germany.
authors.forename: Matthias
authors.initials: M
authors.lastname: Fuest
authors.affiliation: Department of Diagnostic and Interventional Neuroradiology, RWTH Aachen University, Aachen, Germany.
authors.forename: Marguerite
authors.initials: M
authors.lastname: Mueller
authors.affiliation: Department of Diagnostic and Interventional Neuroradiology, RWTH Aachen University, Aachen, Germany.
authors.forename: Marc Alexander
authors.initials: MA
authors.lastname: Brockmann
authors.affiliation: IMEDOS Systems UG, Jena, Germany.
authors.forename: Walthard
authors.initials: W
authors.lastname: Vilser
authors.affiliation: Department of Exercise and Health Sciences, University of Basel, Basel, Switzerland.
authors.forename: Arno
authors.initials: A
authors.lastname: Schmidt-Trucksäss
authors.affiliation: Department of Neurosurgery, RWTH Aachen University, Aachen, Germany.
authors.forename: Anke
authors.initials: A
authors.lastname: Hoellig
authors.affiliation: Department of Neurosurgery, Universitätsmedizin Mannheim, University of Heidelberg, Mannheim, Germany.
authors.forename: Marcel
authors.initials: M
authors.lastname: Seiz
authors.affiliation: Department of Neurosurgery, Medical University Innsbruck, Innsbruck, Austria.
authors.forename: Claudius
authors.initials: C
authors.lastname: Thomé
authors.affiliation: Department of Medical Engineering and Technomathematics, FH Aachen University of Applied Sciences, Aachen, Germany.
authors.forename: Konstantin
authors.initials: K
authors.lastname: Kotliar
authors.affiliation: Department of Neurosurgery, RWTH Aachen University, Aachen, Germany.
authors.forename: Gerrit Alexander
authors.initials: GA
authors.lastname: Schubert
mesh_terms: D000328:Adult; D000368:Aged; D000783:Aneurysm / Q000150:complications / Q000503:physiopathology*; D002545:Brain Ischemia / Q000150:complications / Q000175:diagnosis*; D016022:Case-Control Studies; D002560:Cerebrovascular Circulation; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D008991:Monitoring, Physiologic / Q000379:methods; D009553:Nimodipine / Q000627:therapeutic use; D010865:Pilot Projects; D011446:Prospective Studies; D012171:Retinal Vessels / Q000000981:diagnostic imaging* / Q000503:physiopathology; D013345:Subarachnoid Hemorrhage / Q000150:complications / Q000000981:diagnostic imaging / Q000503:physiopathology*; D016896:Treatment Outcome; D014661:Vasoconstriction; D020301:Vasospasm, Intracranial / Q000150:complications
chemical_list: D009553:Nimodipine