title: Blood pressure fluctuations in posterior reversible encephalopathy syndrome.
abstract: BACKGROUND
  Posterior reversible encephalopathy syndrome (PRES) can be a consequence of hypertensive crisis and is often associated with rapid fluctuations in blood pressure (BP). However, the role of these BP changes in the pathogenesis of PRES has not been formally studied. Our objective was to analyze the relationship between BP fluctuations and the occurrence of PRES.
  
  
  METHODS
  We identified consecutive patients who developed PRES in the hospital and compared them with randomly selected controls matched for age, gender, and history of hypertension (HTN). Systolic BP (SBP) and diastolic BP (DBP) were collected at 2-hour intervals over a 48-hour window before the onset of PRES symptoms. A profile of changes in the values of SBP, DBP, mean arterial pressure (MAP), and pulse pressure (PP) over the 48-hour window was summarized for each individual by calculating a single number (M value) using the approach by Service et al. Comparisons of these summary numbers between the 2 groups (cases and controls) were made with the Wilcoxon signed rank test because of the smaller sample size and paired nature of the data. All tests were 2-sided, and P < .05 was considered statistically significant.
  
  
  RESULTS
  We analyzed the BP profiles in 25 cases of PRES and 25 controls. The median age of PRES patients was 54 years (range 31-72). Fourteen of them (56%) had a history of HTN. Hypertensive encephalopathy was considered the underlying cause of PRES in 13 patients (52%). At the time of the first symptoms of PRES, the mean SBP was 182 ± 20 mm Hg (range 218-145), DBP 95 ± 16 mm Hg (range 134-62), MAP 124 ± 15 (range 152-93), and PP 87 ± 18 (range 123-46). While BP was higher in PRES cases, the severity of HTN was variable and BP fluctuations were not significantly more common than in controls (P = .38 for SBP, .79 for DBP, .25 for MAP, and .73 for PP, respectively).
  
  
  CONCLUSIONS
  Although acute HTN is frequent in patients with PRES, BP fluctuations do not appear to be more common in hospitalized patients who develop PRES compared with controls matched for age and history of HTN. Other predisposing factors must therefore contribute to the development of PRES.
authors.affiliation: Department of Neurology, Mayo Clinic, Rochester, MN 55905, USA. rabinstein.alejandro@mayo.edu
authors.forename: Alejandro A
authors.initials: AA
authors.lastname: Rabinstein
authors.forename: Jay
authors.initials: J
authors.lastname: Mandrekar
authors.forename: Ryan
authors.initials: R
authors.lastname: Merrell
authors.forename: Osman S
authors.initials: OS
authors.lastname: Kozak
authors.forename: Olayemi
authors.initials: O
authors.lastname: Durosaro
authors.forename: Jennifer E
authors.initials: JE
authors.lastname: Fugate
mesh_terms: D000328:Adult; D000368:Aged; D001794:Blood Pressure / Q000502:physiology*; D001795:Blood Pressure Determination / Q000379:methods; D016022:Case-Control Studies; D015897:Comorbidity; D005260:Female; D006801:Humans; D006973:Hypertension / Q000175:diagnosis / Q000453:epidemiology / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D054038:Posterior Leukoencephalopathy Syndrome / Q000175:diagnosis / Q000453:epidemiology / Q000503:physiopathology*