Neocortical capillary flow pulsatility is not elevated in experimental communicating hydrocephalus

Shams Rashid, James P. McAllister, Yiting Yu, Mark E. Wagshul

Research output: Contribution to journalArticlepeer-review

13 Scopus citations


While communicating hydrocephalus (CH) is often characterized by increased pulsatile flow of cerebrospinal fluid (CSF) in the cerebral aqueduct, a clear-cut explanation for this phenomenon is lacking. Increased pulsatility of the entire cerebral vasculature including the cortical capillaries has been suggested as a causative mechanism. To test this theory, we used two-photon microscopy to measure flow pulsatility in neocortical capillaries 40 to 500 m below the pial surface in adult rats with CH at 5 to 7 days (acute, n=8) and 3 to 5 weeks (chronic, n=5) after induction compared with intact controls (n=9). Averaging over all cortical depths, no increase in capillary pulsatility occurred in acute (pulsatility index (PI): 0.15±0.06) or chronic (0.14±0.05) CH animals compared with controls (0.18±0.07; P=0.07). More specifically, PI increased significantly with cortical depth in controls (r=0.35, P<0.001), but no such increase occurred in acute (r=0.06, P=0.3) or chronic (r=0.05, P=0.5) CH. Pulsatile CSF aqueductal flow, in contrast, was elevated 10-to 500-fold compared with controls. We conclude that even in the presence of markedly elevated pulsatile CSF flow in the aqueduct, there is no concurrent increase in microvascular pulsatile flow.

Original languageEnglish (US)
Pages (from-to)318-329
Number of pages12
JournalJournal of Cerebral Blood Flow and Metabolism
Issue number2
StatePublished - Feb 2012


  • animal studies
  • brain imaging
  • capillaries
  • cerebral blood flow measurement
  • two-photon microscopy

ASJC Scopus subject areas

  • Neurology
  • Clinical Neurology
  • Cardiology and Cardiovascular Medicine


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