From the earliest pathological studies the perivenular localization of the 
demyelination in multiple sclerosis (MS) has been observed. It has recently been 
suggested that obstructions to venous flow or inadequate venous valves in the 
great veins in the neck, thorax and abdomen can cause damaging backflow into the 
cerebral and spinal cord circulations. Paolo Zamboni and colleagues have 
demonstrated abnormal venous circulation in some multiple sclerosis patients 
using non-invasive sonography and invasive venography. Furthermore, they have 
obtained apparent clinical improvement or stabilization by endovascular 
ballooning of points of obstruction in the great veins in some, at least 
temporarily. If non-invasive observations by others validate their initial 
observations of a significantly increased prevalence of venous obstructions in 
MS then trials of angioplasty/stenting would be justified in selected cases in 
view of the biological plausibility of the concept.