Chronic cerebrospinal venous insufficiency and multiple sclerosis.

Chronic cerebrospinal venous insufficiency has recently been proposed to be etiologic to multiple sclerosis. Independent investigation into this theory during the past 2 years has not succeeded in verifying this relationship. A critical analysis of the scientific methods used in the original studies of chronic cerebrospinal venous insufficiency in multiple sclerosis reveals several methodological problems with regard to potential bias and confounding. The current evidence calls into question whether chronic cerebrospinal venous insufficiency in multiple sclerosis exists at all.