Chronic cerebrospinal venous insufficiency (CCSVI) and Multiple sclerosis
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What is CCSVI and why might it be important?
Chronic cerebrospinal insufficiency (CCSVI) is thought to occur when narrowing in veins draining blood from the brain lead to high pressures in the veins and subsequent damage to to the brain. Recent studies from Italy by Zamboni et al (2009) have examined the possible role of CCSVI in multiple sclerosis (MS). In the most recent report 65 consecutive patients with CCSVI and multiple sclerosis were identified. There were three different types of MS patients - relapsing remitting (RR, 35), secondary progressive (SP, 20) and primary progressive (PP, 10). Patients were screened for CCSVI using colour flow ultrasound then patients underwent selective venography to examine evidence of narrowing (stenosis) in the internal jugular or or azygos veins in the neck and chest respectively. Stenosis of the veins was treated by balloon angioplasty.
Following screening it appears that every patient of the original 65 patients was found to have evidence of significant CCSVI. In these patients, 4 different patterns of narrowing in the veins were identified (Type A, B, C, D). The stenoses were all treated safely by angioplasty. In measures of quality of life and disability there was no improvement for the SP and PP types of MS patients at 18 months meaning that 46% (30 of 65) of the original group of patients showed no benefit from the treatment.
At 18 months following treatment in the RR group 50% (17 or 18 of 35) of patients were free of relapse in the preceding year compared with 27% (9 or 10 of 35) in the year prior to treatment. However, the annualised rate of relapse was unchanged suggestive of no benefit. Even with the most positive spin on the results, only about 8-9 of the original 65 MS patients (12%) benefited from treatment.
Unfortunately, following angioplasty of the veins there is a significant risk of further narrowing in the veins especially in the internal jugular veins with a rate of restenosis of 47% at 18 months.
Does the Zamboni paper prove the benefit of treatment for CCSVI?
NO. Absolutely not. This is a pilot study and although the findings may give some MS sufferers hope these results are far from clear cut. There is no information given on how many patients in total were screened and how many were excluded from the study because they did not fit the exclusion criteria. If every patient with MS has significant venous stenoses this is important, but this study has not proved that treating these stenoses is helpful. The authors acknowledge this fact.
The major flaw of this study is that there is no comparable control group with similar disease in the veins and with a similar severity of MS not undergoing treatment. This is particularly important in a condition such as MS which typically will have a fluctuating clinical course. In these circumstances it can be difficult to determine what is genuine improvement due to the treatment and what is merely part of the normal fluctuation that occurs in this disease. Without a control group and randomisation of patients into treatment or no treatment groups it is impossible to tell how much of the effects of treatment could be due to a placebo effect and not due to genuine improvement because of treatment. There is no information on all the other treatments that patients may have been taking at the same time. Unless these treatments are equal between the groups there is a possibility that patients undergoing successful angioplasty were also more likely to be taking other medications
The study is not blinded. In other words the researchers were aware of which patients received which treatments. This is especially important in this study because the investigations and invasive treatments performed, including the extra attention the patients will have been afforded by the researchers, have a huge potential for introducing a significant bias as well as a placebo effect.
There are also other groups of patients that develop similar types of venous stenoses (eg patients on haemodialysis) but there is no known association with MS or neurological impairment.
These limitations of the study make it impossible to draw all but the most preliminary and tentative of conclusions based on the information provided. The possible role of CCSVI still awaits a properly conducted randomised trial to determine whether any effects are truly genuine effects related to angioplasty of narrowed veins. However there are many people who feel this treatment may have no basis whatsoever see http://medicalmyths.wordpress.com/
Further information here and http://www.nationalmssociety.org/news/news-detail/index.aspx?nid=2206
Zamboni P, Galeotti R, Menegatti E, Malagoni AM, Gianesini S, Bartolomei I, Mascoli F, Slavi F. A prospective open-label study of endovascular treatment of chronic cerebrospinal venous insufficiency. J Vasc Surg 2009; 50: 1348-58.
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Last updated 26 May, 2010