title: Perioperative monitoring of pulsatile and static intracranial pressure in patients with Chiari malformation type 1 undergoing foramen magnum decompression.
abstract: BACKGROUND
  Patients with Chiari malformation type 1 (CMI) often present with elevated pulsatile and static intracranial pressure (ICP). The preferred treatment of CMI, foramen magnum decompression (FMD), is assumed to normalise ICP and craniospinal pressure dissociation. In order to further explore the mechanisms behind FMD, the present study investigated whether or not pulsatile and static ICP normalises immediately after FMD.
  
  
  METHODS
  The study included CMI patients undergoing FMD with perioperative ICP monitoring as a part of clinical management. The pulsatile and static ICP scores were retrieved from the department's ICP database, and the clinical and radiological data from the patient records.
  
  
  RESULTS
  Eleven patients were included in the study. During the first 3 days following FMD, mixed model analysis revealed no significant time-dependent differences of preoperatively elevated either pulsatile (mean wave amplitude, MWA; p = 0.85) and/or static (mean ICP, p = 0.90) ICP. Percentage of mean ICP >15 mmHg increased during days 2 and 3 after FMD. Two patients from the present series had to receive ventriculoperitoneal shunt after FMD in the early postoperative period.
  
  
  CONCLUSIONS
  The present observations suggest that anatomical restoration of cerebrospinal fluid pathways by FMD does not lead to immediate normalisation of preoperatively altered pulsatile and static ICP in patients with CMI. This finding may explain persistent symptoms during the early period after FMD.
authors.affiliation: Department of Neurosurgery, Oslo University Hospital-Rikshospitalet, P.O.Box 4950, Nydalen, 0424, Oslo, Norway. radek.fric@medisin.uio.no.
authors.forename: Radek
authors.initials: R
authors.lastname: Frič
authors.affiliation: Department of Neurosurgery, Oslo University Hospital-Rikshospitalet, P.O.Box 4950, Nydalen, 0424, Oslo, Norway.|Faculty of Medicine, University of Oslo, Oslo, Norway.
authors.forename: Per Kristian
authors.initials: PK
authors.lastname: Eide
mesh_terms: D000328:Adult; D000368:Aged; D001139:Arnold-Chiari Malformation / Q000601:surgery*; D019299:Decompression, Surgical / Q000379:methods*; D005260:Female; D005539:Foramen Magnum / Q000601:surgery*; D006801:Humans; D007427:Intracranial Pressure; D008297:Male; D008875:Middle Aged; D064926:Neurophysiological Monitoring / Q000379:methods*
keywords: Cerebrospinal fluid dynamics; Chiari malformation type I; Foramen magnum; Intracranial pressure; Syringomyelia