title: The predictive value of external continuous lumbar drainage, with cerebrospinal fluid outflow controlled by medium pressure valve, in normal pressure hydrocephalus.
abstract: BACKGROUND
  Although sporadic studies have described temporary external cerebrospinal fluid (CSF) lumbar drainage as a highly accurate test for predicting the outcome after ventricular shunting in normal pressure hydrocephalus (NPH) patients, a more recent study reports that the positive predictive value of external lumbar drainage (ELD) is high but the negative predictive value is deceptively low. Therefore, we conducted a prospective study in order to evaluate the predictive value of a continuous ELD, with CSF outflow controlled by medium pressure valve, in NPH patients.
  
  
  METHODS
  Twenty-seven patients with presumed NPH were admitted to our department and CSF drainage was carried out by a temporary (ELD) with CSF outflow controlled by a medium pressure valve for five days. All patients received a ventriculoperitoneal shunt using a medium pressure valve based upon preoperative clinical and radiographic criteria of NPH, regardless of ELD outcome. Clinical evaluation of gait disturbances, urinary incontinence and mental status, and radiological evaluation with brain CT was performed prior to and after ELD test, as well as three months after shunting.
  
  
  RESULTS
  Twenty-two patients were finally shunted and included in this study. In a three-month follow-up, using a previously validated score system, overall improvement after permanent shunting correlated well to improvement after ELD test (Spearman's rho = 0.462, p = 0.03). When considering any degree of improvement as a positive response, ELD test yielded high positive predictive values for all individual parameters (gait disturbances 94%, 95% CI 71%-100%, urinary incontinence 100%, 95% CI 66%-100%, and mental status 100%, 95% CI 66%-100%) but negative predictive values were low (< 50%) except for cognitive impairment (85%, 95% CI 55%-98%).
  
  
  CONCLUSIONS
  This study suggests that a positive ELD-valve system test should be considered a reliable criterion for preoperative selection of shunt-responsive NPH patients. In case of a negative ELD-valve system test, further investigation of the presumed NPH patients with additional tests should be performed.
authors.affiliation: Department of Neurosurgery, University Hospital of Patras, Rion of Patras, Greece. panagiotopoulos2000@yahoo.com
authors.forename: V
authors.initials: V
authors.lastname: Panagiotopoulos
authors.forename: D
authors.initials: D
authors.lastname: Konstantinou
authors.forename: A
authors.initials: A
authors.lastname: Kalogeropoulos
authors.forename: T
authors.initials: T
authors.lastname: Maraziotis
mesh_terms: D000328:Adult; D000368:Aged; D015170:Cerebrospinal Fluid Pressure / Q000502:physiology*; D002557:Cerebrospinal Fluid Shunts / Q000592:standards*; D003072:Cognition Disorders / Q000209:etiology / Q000503:physiopathology / Q000601:surgery; D004322:Drainage / Q000295:instrumentation / Q000379:methods; D020233:Gait Disorders, Neurologic / Q000209:etiology / Q000503:physiopathology / Q000601:surgery; D006801:Humans; D006850:Hydrocephalus, Normal Pressure / Q000175:diagnosis* / Q000503:physiopathology / Q000601:surgery*; D008159:Lumbar Vertebrae; D008875:Middle Aged; D018579:Patient Selection; D011237:Predictive Value of Tests; D011446:Prospective Studies; D013129:Spinal Puncture / Q000592:standards* / Q000706:statistics & numerical data; D013346:Subarachnoid Space / Q000502:physiology; D013525:Surgical Instruments / Q000592:standards* / Q000706:statistics & numerical data; D014057:Tomography, X-Ray Computed; D014555:Urination Disorders / Q000209:etiology / Q000503:physiopathology / Q000601:surgery; D017287:Ventriculoperitoneal Shunt / Q000592:standards / Q000706:statistics & numerical data