title: Dual-task related gait changes after CSF tapping: a new way to identify idiopathic normal pressure hydrocephalus.
abstract: BACKGROUND
  Gait disturbances found in patients with idiopathic normal pressure hydrocephalus (iNPH) are unspecific to the diagnosis and commonly occur in neurodegenerative or vascular conditions (iNPH-like conditions). This current retrospective pre-post intervention study aims to determine whether changes in quantitative gait parameters during dual task condition differed between iNPH and iNPH-like conditions before and after cerebrospinal fluid (CSF) tapping.
  
  
  METHODS
  49 patients assessed before and after CSF tapping were included in this study (27 with iNPH and 22 with iNPH-like conditions). Gait analysis during single and dual task conditions (walking and backward counting) was performed before and after a CSF spinal tap of 40 ml. Gait parameters were compared between iNPH and iNPH-like conditions patients. Logistic regressions were used to examine the association between iNPH and gait parameters.
  
  
  RESULTS
  Improvements of step width (-9.03 (20.75)% for iNPH group; +0.28 (21.76)% for iNPH-like conditions group), stride length (+7.82 (20.71)% for iNPH group; -0.62 (19.22)% for iNPH-like conditions group), walking speed (+12.20 (29.79)% for iNPH group; +2.38 (32.50)% for iNPH-like conditions group) and stance duration (-1.23 (4.03)% for iNPH group; +0.49 (5.12)% for iNPH-like conditions group) during dual task, after CSF spinal tapping, were significant in patients with iNPH compared to patients with iNPH-like conditions. No between group difference was observed for the single walking task evaluation. The multiple logistic regression revealed that among these four gait parameters, only the improvement in step width was associated with the diagnosis of iNPH.
  
  
  CONCLUSIONS
  Dual-task related changes in spatio-temporal gait parameters before and after CSF tapping might be a novel and discriminative method of identifying iNPH patients from other similar conditions.
authors.affiliation: Department of Clinical Neurosciences, Division of Neurology, Geneva University Hospitals and University of Geneva, 4 rue Gabrielle-Perret-Gentil, Geneva 1211, Switzerland. gilles.allali@hcuge.ch.
authors.forename: Gilles
authors.initials: G
authors.lastname: Allali
authors.forename: Magali
authors.initials: M
authors.lastname: Laidet
authors.forename: Olivier
authors.initials: O
authors.lastname: Beauchet
authors.forename: Francois R
authors.initials: FR
authors.lastname: Herrmann
authors.forename: Frederic
authors.initials: F
authors.lastname: Assal
authors.forename: Stephane
authors.initials: S
authors.lastname: Armand
mesh_terms: D000368:Aged; D005260:Female; D020233:Gait Disorders, Neurologic / Q000209:etiology*; D006801:Humans; D006850:Hydrocephalus, Normal Pressure / Q000150:complications* / Q000175:diagnosis*; D008297:Male; D012189:Retrospective Studies; D013129:Spinal Puncture; D013850:Thinking / Q000502:physiology