title: Elastance correlates with outcome after endoscopic third ventriculostomy in adults with hydrocephalus caused by primary aqueductal stenosis.
abstract: OBJECTIVE
  To study prospectively the correlation between clinical outcome after endoscopic third ventriculostomy (ETV) and resistance to the outflow of cerebrospinal fluid (R(out)) and elastance in adults with hydrocephalus caused by primary aqueductal stenosis (AS).
  
  
  METHODS
  R(out) and elastance were measured in the subarachnoid space and intraventricularly before ETV in 15 consecutive patients. Three months after the ETV, the clinical effect was evaluated by standardized indices, and R(out) and elastance were measured. If symptoms persisted and the ETV was patent, shunt surgery was offered. The effect of the shunt operation and R(out) were measured after 3 months.
  
  
  RESULTS
  Four patients experienced excellent improvement, six improved slightly, and five had unchanged or deteriorated symptoms after ETV. R(out) before ETV did not correlate with outcome. R(out) decreased after ETV with correlation to the clinical effect; in the six patients who had shunt surgery, R(out) decreased further. High preoperative elastance correlated strongly with a good outcome and reduction of ventricle size. Elastance did not change after ETV.
  
  
  CONCLUSIONS
  R(out) intraventricularly and in the subarachnoid space could not predict the outcome of the ETV, but the reduction in R(out) correlated positively with clinical improvement. Preoperative elastance correlated positively with clinical improvement, and elastance was unchanged after ETV. Clinical improvement correlated positively with reduction in ventricle size.
authors.affiliation: Hydrocephalus Research Unit, Institute of Clinical Neuroscience, Sahlgrenska University Hospital, Göteborg University, SE-413 45 Göteborg, Sweden. Magnus.Tisell@vgregion.se
authors.forename: Magnus
authors.initials: M
authors.lastname: Tisell
authors.forename: Mikael
authors.initials: M
authors.lastname: Edsbagge
authors.forename: Hannes
authors.initials: H
authors.lastname: Stephensen
authors.forename: Marek
authors.initials: M
authors.lastname: Czosnyka
authors.forename: Carsten
authors.initials: C
authors.lastname: Wikkelsø
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D002535:Cerebral Aqueduct / Q000503:physiopathology; D015170:Cerebrospinal Fluid Pressure / Q000502:physiology; D003251:Constriction, Pathologic / Q000503:physiopathology / Q000601:surgery; D004548:Elasticity; D004724:Endoscopy; D005260:Female; D006801:Humans; D006849:Hydrocephalus / Q000503:physiopathology / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D009460:Neurologic Examination; D016896:Treatment Outcome; D014696:Ventriculostomy