title: Raised intracranial pressure and hydrocephalus following hindbrain decompression for Chiari I malformation: a case series and review of the literature.
abstract: OBJECTIVE
  Chiari-syringomyelia is a heterogeneous condition that may be treated by decompression of the foramen magnum. Raised intracranial pressure (ICP) and/or hydrocephalus is a rare complication of this treatment. We aim to describe the incidence, clinical presentation, radiographic findings, management and outcome of patients developing raised ICP and/or hydrocephalus after hindbrain decompression for Chiari I malformation.
  
  
  METHODS
  Retrospective analysis of 138 consecutive adult and paediatric patients with Chiari I malformation who underwent foramen magnum decompression.
  
  
  RESULTS
  The incidence of post-operative symptomatic raised ICP and/or hydrocephalus in this series was 8.7%. Overall, 9 of 12 patients developing raised ICP or hydrocephalus required a VP shunt, an overall incidence of 6.5%. However, 3 of 12 patients were successfully managed with external ventricular drainage or conservatively. Presentation was with headache or CSF wound leak at a median of 13 days post-operatively. Subdural hygromata were observed in five cases in association with hydrocephalus and urgent drainage to relieve mass effect was required in two cases. At a mean follow up of 36 months, 9 of 12 patients were asymptomatic.
  
  
  CONCLUSIONS
  There is a risk of requiring a permanent VP shunt associated with decompression for Chiari I even in the absence of ventriculomegaly or signs of raised ICP pre-operatively. Patients presenting with new symptoms or CSF wound leak following FMD mandate investigation to exclude hydrocephalus, raised ICP or subdural hygroma.
authors.affiliation: Department of Neurosurgery, The Walton Centre NHS Foundation Trust, Lower Lane, Fazakerley, Liverpool, UK. rzakaria@nhs.net
authors.forename: Rasheed
authors.initials: R
authors.lastname: Zakaria
authors.forename: Jothy
authors.initials: J
authors.lastname: Kandasamy
authors.forename: Yousaf
authors.initials: Y
authors.lastname: Khan
authors.forename: Michael D
authors.initials: MD
authors.lastname: Jenkinson
authors.forename: Sam R
authors.initials: SR
authors.lastname: Hall
authors.forename: Andrew
authors.initials: A
authors.lastname: Brodbelt
authors.forename: Tim
authors.initials: T
authors.lastname: Pigott
authors.forename: Conor L
authors.initials: CL
authors.lastname: Mallucci
mesh_terms: D000328:Adult; D001139:Arnold-Chiari Malformation / Q000601:surgery*; D002648:Child; D002675:Child, Preschool; D019299:Decompression, Surgical / Q000009:adverse effects*; D005260:Female; D020773:Headache Disorders / Q000209:etiology; D006801:Humans; D006849:Hydrocephalus / Q000209:etiology* / Q000601:surgery; D007223:Infant; D019586:Intracranial Hypertension / Q000209:etiology* / Q000601:surgery; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D012249:Rhombencephalon / Q000601:surgery*; D024162:Second-Look Surgery; D013353:Subdural Effusion / Q000209:etiology; D016896:Treatment Outcome; D055815:Young Adult