Jugular venous reflux in cerebral radionuclide angiography.

Jugular venous reflux was observed in six routine cerebral radionuclide angiograms. Repeat studies during a Valsalva maneuver failed to reproduce the reflux. In one case the reflux appeared to be related to the arm position; but in the other five cases, the cause remains unknown. Such reflux may be mistaken for superior vena cava syndrome or asymmetric carotid blood flow.