title: Three-day CSF drainage barely reduces ventricular size in normal pressure hydrocephalus.
abstract: OBJECTIVE
  External lumbar drainage (ELD) of CSF is a test to determine the suitability of a shunt for patients with normal pressure hydrocephalus (NPH), but its effect on ventricular volume is not known. This study investigates the effect of 3-day ELD of 500 mL on ventricular size and clinical features in patients with idiopathic NPH.
  
  
  METHODS
  Fifteen patients were investigated in a 1.5-T MRI scanner before and after ELD. Ventricular volume was measured manually. Clinical features involved motor and cognitive functions, testing primarily gait and attention. Reduction in ventricular volume was correlated to total drain volume and clinical parameters. Statistical tests were nonparametric, and p < 0.05 was required for significance.
  
  
  RESULTS
  Drain volume was 415 mL (median 470 mL, range 160-510 mL). Ventricular size was reduced in all patients, averaging 3.7 mL (SD 2.2 mL, p < 0.001), which corresponded to a 4.2% contraction. The ratio of volume contraction to drain volume was only 0.9%. Seven patients improved in gait and 6 in attention. Ventricular reduction and total drain volume correlated neither with improvement nor with each other. The 7 patients with the largest drain volumes (close to 500 mL), had ventricular changes varying from 1.3 to 7.5 mL.
  
  
  CONCLUSIONS
  Clinical improvement occurs in patients with NPH after ELD despite unaltered ventricles, suggesting that ventricular size is of little relevance for postshunt improvement or determining shunt function. The clinical effect provided by ELD, mimicking shunting, is probably related to the recurring CSF extractions rather than to the cumulative effect of the drainage on ventricular volume.
authors: Department of Clinical Neuroscience, Centre for Biomedical Engineering and Physics, Umeå University, Umeå, Sweden. niklas.lenfeldt@neuro.umu.se
authors: Niklas
authors: N
authors: Lenfeldt
authors: William
authors: W
authors: Hansson
authors: Anne
authors: A
authors: Larsson
authors: Richard
authors: R
authors: Birgander
authors: Anders
authors: A
authors: Eklund
authors: Jan
authors: J
authors: Malm
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D002404:Catheterization; D002552:Cerebral Ventricles / Q000473:pathology*; D004322:Drainage; D005260:Female; D005684:Gait / Q000502:physiology; D006801:Humans; D006850:Hydrocephalus, Normal Pressure / Q000134:cerebrospinal fluid* / Q000473:pathology*; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009483:Neuropsychological Tests; D017287:Ventriculoperitoneal Shunt; D016138:Walking / Q000502:physiology; D051598:Whole Body Imaging