ObjectiveMultiple sclerosis (MS) is a chronic neurodegenerative disease of the CNS. Recently a controversial vascular hypothesis for MS, termed chronic cerebrospinal venous insufficiency (CCSVI), has been advanced. The objective of this study was to evaluate the relative prevalence of the venous abnormalities that define CCSVI.MethodsA case-control study was conducted in which 100 MS patients aged between 18–65 y meeting the revised McDonald criteria were randomly selected and stratified into one of four MS subtypes: relapsing/remitting, secondary progressive, primary progressive and benign. Control subjects (16–70 y) with no known history of MS or other neurological condition were matched with the MS cases. All cases and controls underwent ultrasound imaging of the veins of the neck plus the deep cerebral veins, and magnetic resonance imaging of the neck veins and brain. These procedures were performed on each participant on the same day.ResultsOn ultrasound we found no evidence of reflux, stenosis or blockage in the internal jugular veins (IJV) or vertebral veins (VV) in any study participant. Similarly, there was no evidence of either reflux or cessation of flow in the deep cerebral veins in any subject. Flow was detected in the IJV and VV in all study participants. Amongst 199 participants there was one MS subject who fulfilled the minimum two ultrasound criteria for CCSVI. Using MRI we found no significant differences in either the intra- or extra-cranial venous flow velocity or venous architecture between cases and controls.ConclusionThis case-control study provides compelling evidence against the involvement of CCSVI in multiple sclerosis.

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Surfer's myelopathy is an emergent medical condition, representing a rare type of nontraumatic injury of the spinal cord, triggered by continued hyperextension of the back in inexperienced surfers. Subsequent acute spinal cord ischemia is the main pathological "substrate" for extensive cord myelopathy, determining potential neurological damage and thus predicting a patient's outcome. Awareness of the regional vascular anatomy and correct interpretation of the radiological findings are essential in making a precise diagnosis. Magnetic resonance imaging is an accurate and sensitive modality to identify early ischemic changes, particularly if diffusion-weighted images are initially performed. We report a case of 23-year-old male in whom the diagnosis of surfer's myelopathy was made based on an appropriate clinical history and imaging findings compatible with acute spinal cord ischemia. We also discuss miscellaneous pathological conditions, causing acute myelopathy, which can mimic clinical signs or/and imaging appearance of this rare, but potentially disabling disorder.

(ANTTILA) FRANCHETTO. Can. J. Chem. 54,2953 (1976.The Falkenhagen-Leist-Kelbg equation for the conductivity of electrolyte solutions has been extended to include the effect of solvation on the concentration of the salt. Two equations have been derived, both of which have only two freely adjustable parameters at any temperature: A, the molar conductance of the salt at infinite dilution and H,, a solvation number parameter for the salt. In one of these equations H, is assumed to be independent of concentration. In the other, H, is assumed to be dependent on concentration and an explicit concentration dependent formula is derived for H,. Conductance data for the alkali halide salts in the 0.5 to 10 m concentration range and 0 to 60 "C temperature range were found to be adequately reproduced by both these equations, but with the variable hydration parameter equation yielding better fits to the data. The H, parameters from the fixed hydration parameter equation are found to be similar to those obtained from the analysis of activity coefficient and other data whereas the variable hydration parameter equation yields H, parameters which are much larger. [Traduit par le journal]