Intravascular Ultrasound in the diagnosis and treatment of chronic cerebrospinal venous insufficiency

Justification for IVUS in CCSVI

IVUS is indicated as a primary evaluation of intraluminal venous pathology, as a tool for stenosis analysis, as a method of detecting pressure gradients, as an aid for assessing inconstant or atypical narrowings and as a post-angioplasty exam. In unusual circumstances, IVUS can allow the procedure without use of iodinated contrast media in patients who have had potentially life-threatening allergic reactions to contrast media or who have severe renal insufficiency but do not yet require chronic hemodialysis. IVUS can provide sufficient information to perform this procedure without venography although venography does make this procedure easier.

A recent presentation of a joint meeting of the European Committee on Research in MS (ECTRIMS) and the American Committee on Research in MS (ACTRIMS) reported on a comparison of jugular venous pathology from specimens obtained at autopsy from cadavers of patients with multiple sclerosis and of people who died of unrelated illness. (22) The authors discovered that stenoses were common in both group. What distinguished the MS group from the non-MS group was a preponderance of intraluminal lesions, such as immobile or inverted valves and other valvular deformities, septum, webs, membranes and duplications. This is consistent with the theory that CCSVI is the result of malformation of the maturation of the fetal cardinal system of cerebrospinal veins into the adult system (23).

The preponderance of intraluminal lesions suggests that an intraluminal study is appropriate for the complete diagnosis of this pathology. Venography can demonstrate the major stenotic lesions. However superimposition of valvular cusps and reflux opacification of the vessel distal to a stenosis may obscure them. Moreover, venography cannot distinguish the various etiologies of such stenoses. Strictures, hypoplasia, and valvular stenosis can look identical on venography which provides a simple lumenogram. Endoluminal studies are superior to contrast studies that obscure such pathology by the necessary density of the contrast media. Negen and Raju have shown evidence that such venous pathology in the iliac vein is unrecognized by venography and yet well seen by IVUS. (21)

IVUS is also valuable in evaluating transient narrowings that are not fixed and may be physiological. Moreover veins often have irregular circumference; compressed by surrounding muscles, arteries and bones they may take varied and unusual contours that make it difficult to determine their diameter. As such, stenosis analysis may be extraordinarily difficult and inaccurate. Simple diameter measurements rarely provide a good maker of stenosis. Nor are such diameter measurements sufficient to choose an appropriate balloon size for angioplasty. Finally IVUS provides an excellent methodology of evaluating the effectiveness of venoplasty and valvuloplasty. The elimination of immobile valves is particularly well seen on IVUS. Complications of angioplasty are also better visualized by IVUS. Thrombus and dissections are readily seen on IVUS.