title: Flow velocity and pulsatility of the ocular circulation in chronic intracranial hypertension.
abstract: OBJECTIVE
  The aim of this study is to examine the relationship of ocular blood flow velocities and pulsatility to intracranial pressure (ICP).
  
  
  METHODS
  We measured arterial and venous flow velocities using color Doppler imaging (CDI) and calculated resistance indices for the central retinal (CRA) and the ophthalmic (OA) arteries from 16 patients (32 eyes) with chronic intracranial hypertension (ICH) and varying degrees of ICP and papilledema. The results were compared with normal data from 16 age-matched, healthy subjects.
  
  
  RESULTS
  Arterial flow velocities were significantly decreased for the aggregate subject group compared with controls. A corresponding rise in arterial resistance with increasing ICP in the mild-moderate range was noted. Unexpectedly, with more severe elevations of ICP these trends reversed.
  
  
  CONCLUSIONS
  In mild-moderate increased cerebrospinal fluid (CSF) pressure, a reduction of flow velocities may result because of increased vascular resistance. Paradoxically, in more severe chronic ICH, we hypothesize that local autoregulatory vascular changes and/or diversion of cerebral blood flow into the ophthalmic circulation may normalize these parameters. This phenomenon may partially underlie the relative sparing of visual function early in the course of pseudotumor cerebri (PTC), regardless of actual ICP levels.
authors.affiliation: Division of Neurology, St Elizabeth's Medical Center and Tufts University, Boston 02135, USA. hquerfur@opal.tufts.edu
authors.forename: H W
authors.initials: HW
authors.lastname: Querfurth
authors.forename: W-D A
authors.initials: WD
authors.lastname: Lagrèze
authors.forename: T R
authors.initials: TR
authors.lastname: Hedges
authors.forename: P A
authors.initials: PA
authors.lastname: Heggerick
mesh_terms: D000328:Adult; D001783:Blood Flow Velocity; D002908:Chronic Disease; D005123:Eye / Q000098:blood supply*; D005260:Female; D006801:Humans; D007427:Intracranial Pressure; D017078:Laser-Doppler Flowmetry; D008297:Male; D008875:Middle Aged; D009880:Ophthalmic Artery / Q000502:physiology; D010211:Papilledema / Q000175:diagnosis / Q000503:physiopathology; D011559:Pseudotumor Cerebri / Q000175:diagnosis* / Q000503:physiopathology*; D011673:Pulsatile Flow; D012161:Retinal Artery / Q000502:physiology; D014655:Vascular Resistance; D014794:Visual Fields