Prevalence of extracranial venous abnormalities: results from a sample of 586 multiple sclerosis patients.

The aim of this study was to assess the prevalence of chronic cerebrospinal venous insufficiency in an unselected cohort of multiple sclerosis (MS) patients. A total of 586 patients with clinically defined MS underwent catheter venography of the internal jugular veins, brachiocephalic veins and azygos vein. The following findings were regarded as pathologic: no outflow, slowed outflow, reversal of flow direction, prestenotic dilation accompanied by impaired outflow, outflow through collaterals, intraluminal structures obstructing the vein, hypoplasia, agenesia or significant narrowing of the vein. Venous abnormalities were found in 563 patients (96.1%). Lesions in one vein were found in 43.5%, in two veins in 49.5%, and in three veins in 3.1% of patients. Venous pathologies in the right internal jugular vein were found in 64.0% of patients, in the left internal jugular vein in 81.7%, in the left brachiocephalic vein in 1.0%, and in the azygos vein in 4.9%. Venous pathologies were found to be highly associated with MS, yet the clinical relevance of this phenomenon remains to be established.