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Azygos compression and effect of respiratory cycle during CCSVI venography.
Michael Arata Andrew, MD

OBJECTIVE. Chronic Cerebrospinal Venous Insufficiency (CCSVI) is venous
hypertension of the cerebrospinal veins resulting from a flow obstructing lesion in the
jugular and azygos veins. It is most often are result of venous valve malfunction.
Extrinsic venous compression in these veins may also result in flow obstruction. It has
been suggested that the compression of the azygous vein is a result of respiratory
motion rather than a fixed lesion. We retrospectively reviewed the azygous venographic
images obtained during the CCSVI procedure. Azygos venogram technique included
imaging at full inspiration and after complete exhalation. Evaluation of the relative
frequency of azygos vein compression during CCSVI venogram and the effect of
respiratory motion on the degree of compression was undertaken.

MATERIALS AND METHODS. A database search was performed of all CCSVI procedures
performed over a two month period starting July 2011. Review of the
azygos portion of these venograms was undertaken. Determination of the presence of
significant stenosis, defined as 50% or greater was performed. If a significant stenosis
was present the lesion was compared to assess for change associated with respiration.

RESULTS. Over the two month study period, 54 CCSVI procedures were performed
and had azygous imaging performed with full inspiration and complete expiration.
Compression resulting in significant stenosis was identified in 26% (n=14). The
significant stenosis was only present at complete exhalation in 19% (n=10). Stenoses
of greater than 70% did not change with respiration (n=4).

CONCLUSION. Venous compression of the azygos vein can produce flow obstructing
lesions in up to 1/4 of patients. Imaging at full inspiration is helpful to identify fixed flow
limiting lesions. Fixed lesions that do not change with respiration tend to be of a more
significant degree of stenosis