Retrograde jugular flow associated with idiopathic normal pressure hydrocephalus.

To clarify the relation between the drainage pathway of cerebrospinal fluid and the development of idiopathic normal pressure hydrocephalus (iNPH), we examined flow patterns of internal jugular veins in 20 patients with iNPH and 13 control patients using air-contrast ultrasound venography during the Valsalva maneuver. The iNPH group had a significantly greater frequency of retrograde jugular venous flow (19/20, 95%) than the control group (3/13, 23%) (chi(2) test, p < 0.001). Our results suggest that retrograde jugular venous flow may be associated with the development of iNPH; therefore, the analysis of retrograde jugular venous flow could be a useful element in the diagnosis of iNPH.