title: Temporal bone thickness and texture are major determinants of the high rate of insonation failures of transcranial Doppler in Amerindians (the Atahualpa Project).
abstract: OBJECTIVE
  To assess the role of temporal bone characteristics in transcranial Doppler (TCD) insonation failures in Amerindians living in rural Ecuador.
  
  
  METHODS
  We evaluated thickness and texture of temporal bones in community-dwelling Amerindians ≥65 years old undergoing TCD. Using receiver operator characteristics curve analysis and generalized estimating equations, we investigated factors associated with insonation failures.
  
  
  RESULTS
  Of 65 participants (mean age 74.7 ± 6.7 years, 60% women), 32 (49%) had uni- or bilateral insonation failure through temporal windows. Considering temporal bones independently, 57 of 130 (44%) had poor insonation. Mean thickness was higher (4.7 ± 1.2 versus 2.7 ± 0.9, p < 0.0001), and texture more often heterogeneous (93% versus 22%, p < 0.0001) in bones with poor acoustic windows. Thickness, better predicting poor insonation, was ≥3.6 mm if used alone, and ≥2.7 mm if used together with heterogeneous texture. For every millimeter of increase in thickness, subjects were 2.9 times more likely to have insonation failures. Per se, heterogeneous texture increased by 3.2 times the odds for poor insonation. In all models, being woman increased the odds for poor insonation by six to nine times.
  
  
  CONCLUSIONS
  Temporal bone thickness and texture are independent predictors of TCD insonation failure in Amerindians.
authors.affiliation: School of Medicine, Universidad Espíritu Santo-Ecuador, Guayaquil, Ecuador.
authors.forename: Oscar H
authors.initials: OH
authors.lastname: Del Brutto
authors.affiliation: Gastroenterology Department, Vanderbilt University, Nashville, TN.
authors.forename: Robertino M
authors.initials: RM
authors.lastname: Mera
authors.affiliation: Department of Neurology, Hospital Medica Sur, Mexico City, Mexico.
authors.forename: María
authors.initials: M
authors.lastname: de la Luz Andrade
authors.affiliation: Department of Imaging, Hospital Medica Sur, Mexico City, Mexico.
authors.forename: Verónica
authors.initials: V
authors.lastname: Espinosa
authors.affiliation: Sleep Disorders Center, Mayo Clinic College of Medicine, Jacksonville, FL.
authors.forename: Pablo R
authors.initials: PR
authors.lastname: Castillo
authors.affiliation: Community Center, the Atahualpa Project, Atahualpa, Ecuador.
authors.forename: Mauricio
authors.initials: M
authors.lastname: Zambrano
authors.affiliation: Department of Neurology, Hospital Medica Sur, Mexico City, Mexico.
authors.forename: Juan A
authors.initials: JA
authors.lastname: Nader
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D015519:Bone Density; D004484:Ecuador / Q000208:ethnology; D005260:Female; D006801:Humans; D007197:Indians, Central American / Q000208:ethnology*; D008297:Male; D012372:ROC Curve; D012107:Research Design; D012737:Sex Factors; D013701:Temporal Bone / Q000737:chemistry / Q000000981:diagnostic imaging*; D017585:Ultrasonography, Doppler, Transcranial
keywords: Amerindians; insonation failure; temporal bone; transcranial Doppler