A condition called "chronic cerebrospinal venous insufficiency" (CCSVI) has been 
postulated to play a role in the pathogenesis of multiple sclerosis (MS). This 
hypothesis implies that a complex pattern of extracranial venous stenosis 
determines a venous reflux into the brain of MS patients, followed by increased 
intravenous pressure, blood-brain barrier breakdown and iron deposition into the 
brain parenchyma, thus triggering a local inflammatory response. In this review, 
we critically analyze the scientific basis of CCSVI, the current literature on 
the relationship between CCSVI and MS, as well as the ultrasound methodology 
that has been claimed to provide evidence of impaired cerebral venous drainage. 
We show that no piece of the CCSVI theory has a solid supportive scientific 
evidence. The CCSVI appears to be a rather alien condition and its existence 
should be definitely questioned. Finally, no proven (i.e., based on strict 
scientific methodology and on the rules of evidence-based medicine) therapeutic 
effect of the "liberation" procedure (unblocking the extracranial venous 
obstruction using angioplasty) has been shown up to date.