title: Cerebral blood flow changes in rhinogenic subdural empyema and the role of hyperaemia in brain swelling.
abstract: BACKGROUND
  Previous studies have demonstrated that rhinogenic subdural empyema (SDE) generally has a good prognosis. Most patients are admitted with an altered level of consciousness or significant neurological deficit, but eventually have a good outcome. It is well known that intra-operative brain swelling may occur with subdural empyema.
  
  
  OBJECTIVE
  To define cerebral blood flow (CBF) dynamics and determine the role of cerebral hyperaemia, if any, in intracranial SDE.
  
  
  METHODS
  CBF dynamics were assessed in five patients (mean age 13.2 +/- 2.2 years) with unilateral rhinogenic convexity SDE documented on computer tomography (CT). Regional cortical blood flow (rCBF) was measured using a thermo-coupled sensor placed on the cortex at the time of surgery. Dynamic CT scans were performed to assess cerebral blood volume (CBV) quantitatively, while transcranial Doppler ultrasonography (TCD) was used to measure cerebral blood flow velocities (CBF velocities) both pre- and post-operatively for 21 days. The opposite 'normal' hemisphere served as a control for each patient.
  
  
  RESULTS
  Post-operative rCBF and CBF velocities in the pathological hemisphere progressively increased to plateau at 96 hours. Cerebral blood volume was increased bilaterally, but to a greater extent in the pathological hemisphere and more so in grey than white matter. These haemodynamic changes, though clinically significant did not reach statistical significance (p>0.05).
  
  
  CONCLUSIONS
  Our results suggest that the accompanying brain swelling in rhinogenic SDE is a complex event, with reactive cerebral hyperaemia possibly playing neuroprotective role. Furthermore, unilateral convexity empyema causes bilateral cerebral haemodynamic changes. Future studies are necessary to define the aetiology of brain swelling in intracranial SDE.
authors.affiliation: Department of Neurosurgery, University of Natal Medical School, Wentworth Hospital and Medical Research Council, Durban, South Africa.
authors.forename: N
authors.initials: N
authors.lastname: Nathoo
authors.forename: S S
authors.initials: SS
authors.lastname: Nadvi
authors.forename: D
authors.initials: D
authors.lastname: Royston
authors.forename: J R
authors.initials: JR
authors.lastname: van Dellen
authors.forename: M
authors.initials: M
authors.lastname: Rana
authors.forename: P K
authors.initials: PK
authors.lastname: Narotam
authors.forename: E
authors.initials: E
authors.lastname: Gouws
mesh_terms: D000293:Adolescent; D002560:Cerebrovascular Circulation / Q000502:physiology*; D002648:Child; D013354:Empyema, Subdural / Q000150:complications* / Q000503:physiopathology*; D004660:Encephalitis / Q000209:etiology* / Q000503:physiopathology*; D005260:Female; D006801:Humans; D006940:Hyperemia / Q000150:complications* / Q000503:physiopathology*; D008297:Male; D009668:Nose Diseases / Q000150:complications* / Q000503:physiopathology*