Multiple sclerosis: cerebral circulation time

Purpose: To assess cerebral circulation times (CCTs) in patients with multiple sclerosis (MS) and control subjects by using contrast material-enhanced ultrasonography (US) to determine whether vascular abnormalities can be detected in this disease.

Materials and methods: This study was approved by the local ethics committee, and informed consent was obtained from all subjects. One hundred three patients with MS and 42 control subjects underwent extracranial and transcranial venous echo-color Doppler ultrasonography (US) and contrast-enhanced US. CCT was defined as the difference in arrival time of the US contrast agent bolus between the carotid artery and the internal jugular vein. The presence of chronic cerebrospinal venous insufficiency (CCSVI) was defined according to previously reported criteria for the extracranial and transcranial US techniques. Nonparametric statistics, including the Mann-Whitney U test and the Kruskal-Wallis analysis of variance, were used to compare contrast-enhanced US parameters between groups.

Results: The longest and average CCTs were substantially prolonged in patients with MS compared with those in control subjects (median longest CCT in patients with MS, 6.47 seconds [range, 3.29-29.24 seconds]; that in control subjects, 5.54 seconds [range, 2.57-7.63 seconds]; P < .001; median average CCT in patients with MS, 5.76 seconds [range, 2.64-17.51 seconds]; that in control subjects, 5.01 seconds [range, 2.57-7.06 seconds]; P < .002). No correlation was found between CCTs and clinical parameters. The prevalence of CCSVI was higher in patients with MS than in control subjects (77% vs 28%, P < .0001). CCT was not significantly different between patients with MS who had CCSVI and patients with MS who did not (P = .182).

Conclusion: These results suggest that contrast-enhanced US with CCT assessment may have a role in the evaluation of cerebral blood flow in patients with MS and that a vascular impairment could be associated with MS. The finding of a prolonged CCT at contrast-enhanced US does not result from outflow impairment. Further studies are required to verify these observations and to clarify if CCT and CCSVI have any physiologic and clinical relevance in MS.