title: Posterior Circulation Evaluation in Patients with Sickle Cell Anemia.
abstract: BACKGROUND
  The role of transcranial Doppler (TCD) ultrasonography in identifying children with sickle cell anemia (SCA) at risk for stroke is well known; however, the major studies that evaluated TCD velocities in children with SCA did not report posterior circulation evaluation data. The objective of our study was to describe the pattern of blood flow velocities in the posterior circulation of patients with SCA and to examine their relationship with findings on magnetic resonance imaging (MRI)/magnetic resonance angiography (MRA).
  
  
  METHODS
  All adult patients with SCA followed in the outpatient clinic of our hospital were evaluated with TCD and MRI/MRA. The highest velocities of the middle cerebral arteries or internal carotid arteries were taken as the time-averaged maximum mean (TAMM) velocity for each patient and the maximum mean flow velocities in the posterior circulation (TAMMpost) were recorded.
  
  
  RESULTS
  Fifty-six patients with SCA and 56 healthy nonanemic volunteers were evaluated. The mean TAMMpost in the basilar, vertebral, and posterior cerebral arteries (PCAs) were significantly higher among cases than controls (P < .01). In patients with SCA, the TAMMpost in all posterior circulation arteries had a positive correlation with TAMM. Only 1 patient with stenosis in the posterior circulation (right PCA) was identified.
  
  
  CONCLUSIONS
  We found a low frequency of stenosis but high blood flow velocities in the posterior circulation in patients with SCA. The role of increased TCD velocities in the posterior circulation upon stroke risk in patients with SCA should be further examined.
authors.affiliation: Department of Pediatrics and Child Health, Obafemi Awolowo University, Ile-Ife, Nigeria; Department of Hematology, UNIFESP, São Paulo, SP, Brazil.
authors.forename: Samuel Ademola
authors.initials: SA
authors.lastname: Adegoke
authors.affiliation: Department of Hematology, UNIFESP, São Paulo, SP, Brazil.
authors.forename: Maria Stella
authors.initials: MS
authors.lastname: Figueiredo
authors.affiliation: Department of Hematology, UNIFESP, São Paulo, SP, Brazil.
authors.forename: Perla
authors.initials: P
authors.lastname: Vicari
authors.affiliation: Department of Radiology, UNIFESP, São Paulo, SP, Brazil.
authors.forename: Henrique
authors.initials: H
authors.lastname: Carrete
authors.affiliation: Department of Radiology, UNIFESP, São Paulo, SP, Brazil.
authors.forename: Marcos Hideki
authors.initials: MH
authors.lastname: Idagawa
authors.affiliation: Hospital Sírio-Libanês, São Paulo, SP, Brazil.
authors.forename: Ayrton Roberto
authors.initials: AR
authors.lastname: Massaro
authors.affiliation: Department of Neurology and Neurosurgery, UNIFESP, São Paulo, SP, Brazil; Programa Integrado de Neurologia, Hospital Israelita Albert Einstein, São Paulo, SP, Brazil. Electronic address: giselesampaio@hotmail.com.
authors.forename: Gisele Sampaio
authors.initials: GS
authors.lastname: Silva
mesh_terms: D000293:Adolescent; D000328:Adult; D000755:Anemia, Sickle Cell / Q000000981:diagnostic imaging / Q000503:physiopathology*; D001783:Blood Flow Velocity / Q000502:physiology; D016022:Case-Control Studies; D002560:Cerebrovascular Circulation / Q000502:physiology*; D005260:Female; D006801:Humans; D018810:Magnetic Resonance Angiography; D008279:Magnetic Resonance Imaging; D008297:Male; D010045:Outpatients; D013223:Statistics as Topic; D017585:Ultrasonography, Doppler, Transcranial; D055815:Young Adult
keywords: Sickle cell anemia; intracranial stenoses; magnetic resonance imaging; posterior circulation; stroke; transcranial Doppler