title: Successful treatment of negative pressure hydrocephalus using timely titrated external ventricular drainage: a case series.
abstract: OBJECTIVE
  Negative-pressure hydrocephalus (NegPH) is a rare clinical entity characterised by enlarged ventricles and symptoms consistent with increased intracranial pressure (ICP) in the setting of negative ICP. Little has been published regarding appropriate treatment and outcomes of negative-pressure hydrocephalus patients, and no data have been published demonstrating successful therapy producing acceptable long-term outcomes. Here we present 8 cases successfully treated by titrated external ventricular drainage (TEVD), including drainage at negative (subatmospheric) pressure, and subsequent low-pressure ventriculoperitoneal shunting.
  
  
  METHODS
  A retrospective audit of all cases of negative-pressure hydrocephalus occurring at a university teaching hospital between 2006 and 2012 was undertaken. The clinical features of these cases, results of radiological investigations, treatment, and outcome were drawn from the patients' records.
  
  
  RESULTS
  Eight cases of NegPH were identified. All patients had at least one preceding intracranial procedure (mean number of procedures 3.0). All cases were treated using TEVD, titrated to produce between 5 and 15 mL per hour of CSF drainage, including drainage under subatmospheric pressure if this was required to maintain CSF flow. Mean delay from first negative ICP to TEVD was 1.8 days. All 8 patients demonstrated clinical improvement. TEVD resulted in improvement in Glasgow Coma Scale (mean increase 4.6, p=0.003), and increases in ICP (mean increase 8.5, p<0.001). Mean length of follow-up was 471.8 days. At follow-up, four patients had returned to pre-morbid functioning, three had a reduction in functioning attributable to their initial presentation (not NegPH), and one had died of unknown cause. Illustrative case descriptions are included.
  
  
  CONCLUSIONS
  Negative-pressure hydrocephalus is a rare but underrecognised syndrome that can be successfully treated by timely external ventricular drainage titrated to maintain CSF flow, and subsequent low-pressure ventriculoperitoneal shunting.
authors.affiliation: Department of Neurosurgery, Royal Hobart Hospital, Hobart, Tasmania, Australia; School of Medicine, University of Tasmania, Hobart, Tasmania, Australia. Electronic address: ben.hunn@utas.edu.au.
authors.forename: Benjamin H M
authors.initials: BH
authors.lastname: Hunn
authors.affiliation: Department of Neurosurgery, Royal Hobart Hospital, Hobart, Tasmania, Australia.
authors.forename: Asim
authors.initials: A
authors.lastname: Mujic
authors.affiliation: Department of Neurosurgery, Royal Hobart Hospital, Hobart, Tasmania, Australia.
authors.forename: Idrees
authors.initials: I
authors.lastname: Sher
authors.affiliation: Department of Neurosurgery, Royal Hobart Hospital, Hobart, Tasmania, Australia; School of Medicine, University of Tasmania, Hobart, Tasmania, Australia.
authors.forename: Arvind K
authors.initials: AK
authors.lastname: Dubey
authors.affiliation: Department of Neurosurgery, Royal Hobart Hospital, Hobart, Tasmania, Australia.
authors.forename: Jens
authors.initials: J
authors.lastname: Peters-Willke
authors.affiliation: Department of Neurosurgery, Royal Hobart Hospital, Hobart, Tasmania, Australia.
authors.forename: Andrew W M
authors.initials: AW
authors.lastname: Hunn
mesh_terms: D000293:Adolescent; D000328:Adult; D002557:Cerebrospinal Fluid Shunts / Q000379:methods; D002648:Child; D004322:Drainage / Q000379:methods; D005260:Female; D006801:Humans; D006849:Hydrocephalus / Q000175:diagnosis / Q000601:surgery*; D007427:Intracranial Pressure / Q000502:physiology*; D008297:Male; D008875:Middle Aged; D011312:Pressure; D012189:Retrospective Studies; D013997:Time Factors; D016896:Treatment Outcome; D055815:Young Adult
keywords: External ventricular drain; Hydrocephalus; Negative-pressure