title: Outcome of Surgery for Idiopathic Normal Pressure Hydrocephalus: Role of Preoperative Static and Pulsatile Intracranial Pressure.
abstract: OBJECTIVE
  To examine the outcome of surgery for idiopathic normal-pressure hydrocephalus (iNPH) and how outcome relates to the preoperative static and pulsatile intracranial pressure (ICP).
  
  
  METHODS
  An observational cohort study included all patients with iNPH managed at our department during the years 2002-2012 in whom overnight ICP monitoring was part of the preoperative work-up. Clinical data were retrieved from a quality registry and ICP scores from a pressure database.
  
  
  RESULTS
  The study included 472 patients, 316 in the surgery group and 156 in the nonsurgery group. Among those treated surgically, 278 (90%) showed clinical improvement (Responders) whereas 32 (10%) had no improvement (Nonresponders). Among Responders, only about one third reached the best clinical scores; moreover, the difference in clinical score between Responders and Nonresponders declined with time after surgery, particularly after 3-4 years. The surgery was accompanied by acute intracranial hematomas in 11 patients (3.5%), of whom 4 (1.3%) died. Survival (age at death) was significantly greater among the Responders than in Nonresponders. Although the static ICP was normal in all patients, the pulsatile ICP was significantly greater in Responders than in Non-responders.
  
  
  CONCLUSIONS
  The pulsatile ICP was greater in shunt Responders than Nonresponders. Although the clinical improvement declined over time and the majority did not experience complete relief of symptoms, shunt Responders lived significantly longer than Nonresponders. The present observations suggest that the current surgical treatment regimens for iNPH (primarily shunt surgery) address only some aspects of the disease process, in particular the aspect of brain water disturbance.
authors.affiliation: Department of Neurosurgery, Oslo University Hospital, Rikshospitalet, Oslo, Norway; Faculty of Medicine, University of Oslo, Oslo, Norway. Electronic address: peide@ous-hf.no.
authors.forename: Per Kristian
authors.initials: PK
authors.lastname: Eide
authors.affiliation: Department of Neurosurgery, Oslo University Hospital, Rikshospitalet, Oslo, Norway.
authors.forename: Wilhelm
authors.initials: W
authors.lastname: Sorteberg
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002557:Cerebrospinal Fluid Shunts; D015331:Cohort Studies; D005260:Female; D006801:Humans; D006850:Hydrocephalus, Normal Pressure / Q000401:mortality / Q000503:physiopathology* / Q000601:surgery*; D007427:Intracranial Pressure / Q000502:physiology*; D008297:Male; D008875:Middle Aged; D018579:Patient Selection; D011300:Preoperative Care; D011673:Pulsatile Flow / Q000502:physiology; D020127:Recovery of Function; D015996:Survival Rate; D016896:Treatment Outcome
keywords: Complications; Intracranial pressure; Normal-pressure hydrocephalus; Outcome; Shunt surgery