Blood drainage from brain impaired in MS

Abnormal blood flow into brain tissue (perfusion) has been previously documented in MS -- both higher and lower blood flow into different tissue types have been reported. A new study now shows that blood drainage away from brain tissue is also abnormal in MS (see abstract or
full-text). This study used ultrasound to analyze blood flow through the deep middle cerebral veins and the transverse sinus in 89 people with MS and 60 normal controls. The technique assessed whether blood flowed out only, or both out and in, and how long any inward flow lasted. Only 20% of controls had any inward flow (this was through the transverse sinus only) compared with 65-81% of MS subjects. Furthermore, only 7% of the controls had "reflux" (inward flow lasting > 0.5 second) vs. 38-51% of the MS group.

Blood flow that is turbulent vs. smooth and single-direction can cause an inflammatory reaction in the blood vessel by upregulating adhesion molecules that facilitate the migration of T cells and other cells into the tissue. The authors suggest therefore that the source of this impaired blood flow be examined -- does it start in the brain or is there also reduced blood flow downstream? If reduced flow is found only in the brain, it may be an effect of MS inflammation and neurodegeneration. However, if a reduction in blood flow downstream is in turn causing reflux in the brain, this downstream "back-up" may be a trigger for brain inflammation. The authors also suggest performing this study in subjects with other neurological disease to see whether or not these results are specific to MS.