title: Aqueductal Stroke Volume: Comparisons with Intracranial Pressure Scores in Idiopathic Normal Pressure Hydrocephalus.
abstract: OBJECTIVE
  Aqueductal stroke volume from phase-contrast MR imaging has been proposed for predicting shunt response in normal pressure hydrocephalus. However, this biomarker has remained controversial in use and has a lack of validation with invasive intracranial monitoring. We studied how aqueductal stroke volume compares with intracranial pressure scores in the presurgical work-up and clinical score, ventricular volume, and aqueduct area and assessed the patient's response to shunting.
  
  
  METHODS
  Phase-contrast MR imaging was performed in 21 patients with probable idiopathic normal pressure hydrocephalus. Patients were selected for shunting on the basis of pathologically increased intracranial pressure pulsatility. Patients with shunts were offered a second MR imaging after 12 months. Ventricular volume and transverse aqueductal area were calculated, as well as clinical symptom score.
  
  
  RESULTS
  No correlations between aqueductal stroke volume and preoperative scores of mean intracranial pressure or mean wave amplitudes were observed. Preoperative aqueductal stroke volume was not different between patients with shunts and conservatively treated patients (P = .69) but was correlated with ventricular volume (R = 0.60, P = .004) and aqueductal area (R = 0.58, P = .006) but not with the severity or duration of clinical symptoms. After shunting, aqueductal stroke volume (P = .006) and ventricular volume (P = .002) were reduced. A clinical improvement was seen in 16 of 17 patients who had shunts (94%).
  
  
  CONCLUSIONS
  Aqueductal stroke volume does not reflect intracranial pressure pulsatility or symptom score, but rather aqueduct area and ventricular volume. The results do not support the use of aqueductal stroke volume for selecting patients for shunting.
authors.affiliation: From the Department of Radiology and Nuclear Medicine (G.R.) gringsta@ous-hf.no.
authors.forename: G
authors.identifier: http://orcid.org/0000-0003-0919-4510
authors.initials: G
authors.lastname: Ringstad
authors.affiliation: Intervention Centre (K.E.E., O.G.), Oslo University Hospital-Rikshospitalet, Oslo, Norway.
authors.forename: K E
authors.initials: KE
authors.lastname: Emblem
authors.affiliation: Intervention Centre (K.E.E., O.G.), Oslo University Hospital-Rikshospitalet, Oslo, Norway.
authors.forename: O
authors.initials: O
authors.lastname: Geier
authors.affiliation: Department of Radiology (N.A.), University of Miami Miller School of Medicine, Miami, Florida.
authors.forename: N
authors.initials: N
authors.lastname: Alperin
authors.affiliation: Department of Neurosurgery (P.K.E.), Oslo University Hospital, Oslo, Norway Faculty of Medicine (P.K.E.), University of Oslo, Oslo, Norway.
authors.forename: P K
authors.initials: PK
authors.lastname: Eide
mesh_terms: D000328:Adult; D000368:Aged; D002535:Cerebral Aqueduct / Q000503:physiopathology; D002557:Cerebrospinal Fluid Shunts; D005260:Female; D006801:Humans; D006850:Hydrocephalus, Normal Pressure / Q000175:diagnosis* / Q000503:physiopathology* / Q000601:surgery*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D018579:Patient Selection