Multiple sclerosis (MS) is a relapsing and progressive disorder of the central 
nervous system. It is characterized most commonly by episodes of clinical 
worsening, followed by clinical improvement. Pathologically, MS is associated 
with focal areas of myelin destruction, inflammation, and axonal transection 
("demyelinating plaques") in the brain and spinal cord. Traditionally, MS has 
been considered an autoimmune disorder, with the primary pathophysiology arising 
from an errant immune system. Recent work has raised the possibility that MS is 
not caused primarily by an immune abnormality but may instead arise from venous 
anomalies affecting the jugular and/or azygos venous systems. This condition has 
been called chronic cerebrospinal venous insufficiency (CCSVI). It has been 
proposed that CCSVI may be pathogenic in MS, causing venous back pressure and 
iron deposition, with a secondary immune response. Some investigators have 
proceeded to unblinded nonrandomized angioplasty and stenting procedures in 
patients with CCSVI, with anecdotal reports of symptom improvement. Because of 
conflicting data on the presence of CCSVI and the absence of controlled trials 
of CCSVI intervention, the current standard of clinical care is neither to 
evaluate multiple sclerosis (MS) patients for CCSVI anomalies, nor to intervene 
with procedures to alter such anomalies. There is intense interest and ongoing 
work to evaluate the presence of venous anomalies in MS patients as well as in 
normal controls and patients with other neurologic conditions; to characterize 
such anomalies, if present; and to further understand whether the concept of a 
"backpressure" pathology is borne out by the evidence. If CCSVI is indeed a 
pathogenic mechanism for some subset of the MS population, this would 
dramatically change the focus of attention for therapeutic endeavors and 
monitoring for this population and would bring MS therapeutics firmly into the 
area of vascular intervention. On the other hand, the history of MS research 
contains many novel and potentially paradigm-shifting ideas that were later 
disproved by other investigators.