title: Pathophysiology of shunt dysfunction in shunt treated hydrocephalus.
abstract: BACKGROUND
  We hypothesized that shunt dysfunction in the ventricular catheter and the shunt valve is caused by different cellular responses. We also hypothesized that the cellular responses depend on different pathophysiological mechanisms.
  
  
  METHODS
  Removed shunt material was collected. Macroscopic tissue in the catheters was paraffin-embedded and HE-stained. Valves were incubated with trypsin-EDTA in order to detach macroscopically invisible biomaterial, which was then cytospinned and HE-stained. Associated aetiological and surgical data were collected by reviewing patient files, and ventricular catheter position was examined using preoperative radiology (CT scans).
  
  
  RESULTS
  We examined eleven ventricular catheters and ten shunt valves. Catheters: 6/11 catheters contained intraluminal tissue consisting of vascularised glial tissue and inflammatory cells (macrophages/giant cells and a few eosinophils). Catheter adherence correlated with the presence of intraluminal tissue, and all tissue containing catheters had some degree of ventricle wall contact. All obstructed catheters contained intraluminal tissue, except one catheter that was dysfunctional because of lost ventricular contact. Valves: Regardless of intraoperative confirmation of valve obstruction, all ten valves contained an almost uniform cellular response of glial cells (most likely ependymal cells), macrophages/giant cells, and lymphomonocytic cells. Some degree of ventricle wall catheter contact was present in all examined valves with available radiology (9/10).
  
  
  CONCLUSIONS
  The same cellular responses (i.e., glial cells and inflammatory cells) cause both catheter obstruction and valve obstruction. We propose two synergistic pathophysiological mechanisms. (1) Ventricle wall/parenchymal contact by the catheter causes mechanical irritation of the parenchyma including ependymal exfoliation. (2) The shunt material provokes an inflammatory reaction, either nonspecific or specific. In combination, these mechanisms cause obstructive tissue ingrowth (glial and inflammatory) in the catheter and clogging of the valve by exfoliated glial cells and reactive inflammatory cells.
authors: University Clinic of Neurosurgery 2092, Copenhagen University Hospital, Rigshospitalet, Blegdamsvej 9, 2100, Copenhagen Ø, Denmark. christoffer.blegvad@gmail.com
authors: C
authors: C
authors: Blegvad
authors: A D
authors: AD
authors: Skjolding
authors: H
authors: H
authors: Broholm
authors: H
authors: H
authors: Laursen
authors: M
authors: M
authors: Juhler
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D057785:Catheters; D002552:Cerebral Ventricles / Q000601:surgery*; D002557:Cerebrospinal Fluid Shunts / Q000295:instrumentation / Q000379:methods; D002648:Child; D004868:Equipment Failure; D006801:Humans; D006849:Hydrocephalus / Q000503:physiopathology* / Q000601:surgery; D008875:Middle Aged; D009457:Neuroglia / Q000166:cytology; D055815:Young Adult