title: Postcarotid endarterectomy hyperperfusion or reperfusion syndrome.
abstract: OBJECTIVE
  Hyperperfusion syndrome (HS) after carotid endarterectomy (CEA) has been related to impaired cerebrovascular autoregulation in a chronically hypoperfused hemisphere. Our aim was to provide new insight into the pathophysiology of the HS using magnetic resonance imaging (MRI) studies with diffusion-weighted imaging (DWI) and perfusion-weighted imaging (PWI).
  
  
  METHODS
  Five out of 388 consecutive patients presented 2 to 7 days after CEA, partial seizures (n=5), focal deficits (n=5), and intracerebral hemorrhage (n=3). In 4 patients, using sequential examinations, we identified vasogenic or cytotoxic edema by DWI; we assessed relative interhemispheric difference (RID) of cerebral blood flow (CBF) by PWI; and we measured middle cerebral artery mean flow velocities (MCA Vm) by transcranial Doppler (TCD).
  
  
  RESULTS
  None of the patients presented pathological DWI hyperintensities, consistent with the absence of acute ischemia or cytotoxic edema. In 2 patients, we found an MRI pattern of reversible vasogenic edema similar to that observed in the posterior leukoencephalopathy syndrome. Middle cerebral artery (MCA) mean flow velocities (Vm) were not abnormally increased at any time. PWI documented a 20% to 44% RID of CBF in favor of the ipsilateral to CEA hemisphere.
  
  
  CONCLUSIONS
  HS can occur in the presence of moderate relative hyperperfusion of the ipsilateral hemisphere. MCA Vm values may not accurately reflect RID of CBF over the cortical convexity. We suggest that the hemodynamic pathogenetic mechanisms of the HS are more complicated than hitherto believed and that they may be more accurately described by the term "reperfusion syndrome."
authors.affiliation: Department of Neurology, Centre Hospitalier Universitaire Vaudois, Lausanne, Switzerlandeece. theoneu@otenet.gr
authors.forename: Theodoros
authors.initials: T
authors.lastname: Karapanayiotides
authors.forename: Reto
authors.initials: R
authors.lastname: Meuli
authors.forename: Gerald
authors.initials: G
authors.lastname: Devuyst
authors.forename: Bartlomiej
authors.initials: B
authors.lastname: Piechowski-Jozwiak
authors.forename: Annelise
authors.initials: A
authors.lastname: Dewarrat
authors.forename: Patrick
authors.initials: P
authors.lastname: Ruchat
authors.forename: Ludwig
authors.initials: L
authors.lastname: Von Segesser
authors.forename: Julien
authors.initials: J
authors.lastname: Bogousslavsky
mesh_terms: D000368:Aged; D002543:Cerebral Hemorrhage / Q000209:etiology; D002560:Cerebrovascular Circulation; D002561:Cerebrovascular Disorders / Q000175:diagnosis / Q000209:etiology*; D038524:Diffusion Magnetic Resonance Imaging; D016894:Endarterectomy, Carotid; D005260:Female; D006801:Humans; D018810:Magnetic Resonance Angiography; D008297:Male; D015427:Reperfusion Injury / Q000175:diagnosis / Q000209:etiology*; D012640:Seizures / Q000209:etiology; D013577:Syndrome; D014057:Tomography, X-Ray Computed; D017585:Ultrasonography, Doppler, Transcranial