Background:
In June 2010, the National MS Society (USA) and the MS Society of Canada committed over $2.4 million to support seven new research projects that would gain further insight into the relationship between chronic cerebrospinal venous insufficiency (CCSVI) and MS. One of these studies was led by Dr. Fiona Costello at the Hotchkiss Brain Institute at the University of Calgary. This study, published in the Canadian Medical Association Journal, explored the validity of the CCSVI hypothesis by comparing venous anatomy and blood flow in people with MS compared to healthy individuals.
The Study:
Dr. Costello and colleagues conducted a cross-sectional study involving 180 subjects, of which 120 had MS and 60 were healthy controls. The researchers used ultrasound and magnetic resonance venography (MRV), a procedure that generates detailed images and observes blood flow in the head and neck veins, in order to compare the proportion of venous abnormalities between the two groups. They hypothesized that if CCSVI is associated with MS, there would be significant evidence of obstruction of venous flow in the MS group. The radiologists who interpreted the imaging results were blinded to the clinical status of the person and results from the other imaging procedure to avoid bias in analysis. The presence of altered venous flow was interpreted using four out of the five diagnostic criteria for CCSVI as defined by Dr. Paolo Zamboni in 2009; one criterion was excluded because the study did not include a specific type of ultrasound.
Results:
58% of the individuals with MS and 63% of the controls fulfilled one or more of the criteria for CCSVI diagnosis, while 20% of the MS patients and 10% of the controls met two or more of the criteria. The research team did not find any differences in the proportion of abnormalities in venous flow between the MS patients and healthy controls. The researchers also noted that there was significant variability in vein anatomy and venous flow both the MS and healthy groups.
Comment:
An association between CCSVI and MS was not detected. Researchers who conducted the study noted concerns relating to study methodology and diagnostic criteria for CCSVI. Dr. Costello challenges the criteria outlined by Dr. Zamboni by stating that the outcomes are dependent on several factors. These factors include patient posture, the imaging techniques used, and the subjective interpretation of the results. It is due to these factors that results vary across studies and the findings produced by Dr. Zamboni are unreproducible by many researchers. The variance in venous anatomy seen in this study also did not reflect the absence or presence of MS disease.
The MS Society of Canada continues to support a Canadian CCSVI trial led by Dr. Anthony Traboulsee from Vancouver Coastal Health that is investigating whether venous dilation procedures could be beneficial for the treatment of MS symptoms. The MS Society is committed to funding research that will provide answers to people living with the disease.
Source:
Costello F et al. Validity of the diagnostic criteria for chronic cerebrospinal venous insufficiency and association with multiple sclerosis. Canadian Medical Association Journal 2014 June 2 [Epub ahead of print]