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Cervical venous reflux in dynamic brain scintigraphy.

Cervical venous reflux, shown by dynamic brain scintigraphy, was investigated through three avenues of approach: (A) by reviewing 371 randomly chosen routine dynamic intracerebral bloodflow studies to estimate its incidence; (B) by correlative positive-contrast superior venacavography in patients with characteristic cervical venous reflux; and (C) by performing dynamic brain scintigraphy while utilizing various positional and physiologic maneuvers to attempt to produce cervical venous reflux in patients who did not exhibit this phenomenon on earlier examination. Although any obstruction of the superior vena cava or a properly timed Valsalva maneuver in selected patients can produce the scintigraphic picture of cervical venous reflux, in most cases it is a normal phenomenon due to incompetent or absent cervical venous valves.