Letter - full text for Zamboni's response.
I read with interest the article titled “No Cerebrocervical Venous Congestion in Patients with Multiple Sclerosis” by Doepp and coworkers.1 Contrary to their conclusions, I believe that the authors' results are a further validation of venous flow irregularities in multiple sclerosis (MS) patients.
One of the major regulators of cerebral venous outflow is posture, due to the gravitational gradient between the cerebral parenchymal veins and the base of the neck (−30mmHg).2 The authors demonstrate a much larger change in blood flow volume in normal subjects compared to MS patients when the subjects go from a supine to an upright position. They find a change of 128ml/min and 56ml/min for the right and left sides, respectively, for MS patients. But they find a much larger change of 266ml/min and 105ml/min for their normal subjects. This result actually suggests the presence of chronic cerebrospinal venous insufficiency (CCSVI). Possible causes include intraluminal septum, membrane, and immobile valve affecting the hydrostatic pressure gradient in the upright position. The presence of such blockages in the extracranial and extravertebral cerebral veins has been proven also by using catheter venography, the unquestionable gold standard in medicine.3, 4
There was a trend toward significance (0.06) when comparing the mean global cerebral blood flow (CBF) in MS patients with that in controls. However, the level of significance is underestimated by the low control sample, 20 versus 56 patients. The reduction in CBF in MS, meaning in practical terms stasis, might become significant by simply increasing the control sample.
Both the above-reported results correspond with the reduction in CBF and in cerebral blood volume with increased mean transit time, assessed by means of magnetic resonance imaging (MRI) perfusion study.5
The authors failed to demonstrate CCSVI through the assessment of the criteria originally proposed by our group. However, it seems the latter were not precisely assessed. For instance, the authors exchange the parameter for defining stenosis we used in angiographic studies (>50% lumen reduction) with those used in Doppler ultrasonography. In addition, the frequent detection of intraluminal jugular septation is not described by the authors. The latter is the most common cause of flow blockage, and can only be diagnosed with high resolution ultrasonographic probes capable to explore the jugular in the supraclavicular fossa (Fig. 1) 3-4. Clearly, a complete understanding of the system is required before drawing conclusions about the lack of venous abnormalities, and this requires ultrasound, MRI, and catheter venography. This underscores the urgency of establishing an internationally accepted protocol. In the attempt to achieve this cultural osmosis, my group is available to travel to Berlin and rescan with German colleagues the entire series by the means of the proposed methodology.