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Assessment of cerebral venous return by a novel plethysmography method
Paolo Zamboni, MD, Erica Menegatti, PhD, Paolo Conforti, MD, Simon Shepherd, PhD, Mirko Tessari, VT, Clive Beggs, PhD
Background
Magnetic resonance imaging and echo color Doppler (ECD) scan techniques do not accurately assess the cerebral venous return. This generated considerable scientific controversy linked with the diagnosis of a vascular syndrome known as chronic cerebrospinal venous insufficiency (CCSVI) characterized by restricted venous outflow from the brain. The purpose of this study was to assess the cerebral venous return in relation to the change in position by means of a novel cervical plethysmography method.
Methods
This was a single-center, cross-sectional, blinded case-control study conducted at the Vascular Diseases Center, University of Ferrara, Italy. The study involved 40 healthy controls (HCs; 18 women and 22 men) with a mean age of 41.5 ± 14.4 years, and 44 patients with multiple sclerosis (MS; 25 women and 19 men) with a mean age of 41.0 ± 12.1 years. All participants were previously scanned using ECD sonography, and further subset in HC (CCSVI negative at ECD) and CCSVI groups. Subjects blindly underwent cervical plethysmography, tipping them from the upright (90°) to supine position (0°) in a chair. Once the blood volume stabilized, they were returned to the upright position, allowing blood to drain from the neck. We measured venous volume (VV), filling time (FT), filling gradient (FG) required to achieve 90% of VV, residual volume (RV), emptying time (ET), emptying gradient (EG) required to achieve 90% of emptying volume (EV) where EV = VV-RV, also analyzing the considered parameters by receiver operating characteristic (ROC) curves and principal component mathematical analysis.
Results
The rate at which venous blood discharged in the vertical position (EG) was significantly faster in the controls (2.73 mL/second ± 1.63) compared with the patients with CCSVI (1.73 mL/second ± 0.94; P = .001). In addition, respectively, in controls and in patients with CCSVI, the following parameters were highly significantly different: FT 5.81 ± 1.99 seconds vs 4.45 ± 2.16 seconds (P = .003); FG 0.92 ± 0.45 mL/second vs 1.50 ± 0.85 mL/second (P < .001); RV 0.54 ± 1.31 mL vs 1.37 ± 1.34 mL (P = .005); ET 1.84 ± 0.54 seconds vs 2.66 ± 0.95 seconds (P < .001). Mathematical analysis demonstrated a higher variability of the dynamic process of cerebral venous return in CCSVI. Finally, ROC analysis demonstrated a good sensitivity of the proposed test with a percent concordant 83.8, discordant 16.0, tied 0.2 (C = 0.839).
Conclusions
Cerebral venous return characteristics of the patients with CCSVI were markedly different from those of the controls. In addition, our results suggest that cervical plethysmography has great potential as an inexpensive screening device and as a postoperative monitoring tool.
Love it!
Dr. Simka is working on a comparison of plethysmography, MRV and doppler but I would also like to see academic research on plethysmography in CCSVI. It is too good to ignore or go sloooooow in getting this replicated. We could also use research on patients after their treatment for CCSVI, to see if we achieve normal measurements, and if plethysmography is a good detector of restenosis. Dr. Sclafani mentioned that plethysmography could even be of use during the procedure!
This could be the technique that ends the controversy about whether or not MS patients have impaired cerebrospinal drainage. Then the researchers can get on to doing something about it!
Let's break down the study somewhat:
It's a blinded study. It was done on MS patients and on healthy controls. All the patients were scanned using doppler ultrasound and divided into a CCSVI group and a non-CCSVI group. So there could be nonMS patients in the CCSVI group? Or MS patients in the healthy control group if doppler was negative for CCSVI?
All patients underwent plethysmography. They were tipped flat so that they were lying down, then given some time for blood flow to stabilize in that position, and then they were abruptly raised up to a sitting position.
Many measurements were made. The emptying gradient was the rate at which venous blood emptied when the patients were raised to the sitting position. In the healthy controls, the veins emptied at a rate of 2.73 mL/second and in patients with CCSVI, the veins emptied at a rate of 1.73 mL/second. Statistically this had a p-value of P = .001 which is very significant.
In addition, filling time and filling gradient and residual volume and emptying time were all significantly different between the two groups.
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