Hypercapnia and hypoxaemia due to impaired venous blood draining and significant improvement after endovascular treatment in patients with chronic cerebrospinal venous insufficiency

Objectives: The aim of this prospective study was to investigate if venous blood coming from the brain and spinal cord in multiple sclerosis patients contains abnormal concentrations of oxygen and carbon dioxide and whether blood gas parameters normalise after successful endovascular angioplasty of abnormal veins.

Material and methods: In this study 178 multiple sclerosis patients with sonographically-proven chronic cerebrospinal venous insufficiency and 50 controls without multiple sclerosis and venous abnormalities were included. We obtained blood samples from the femoral, internal jugular, and azygous veins and measured: partial pressure of oxygen (pO₂), partial pressure of carbon dioxide (pCO₂), and oxygen saturation (SatO₂). In multiple sclerosis patients these blood gas parameters were evaluated before and after endovascular treatment for chronic cerebrospinal venous insufficiency.

Results: Blood samples obtained from the internal jugular veins in multiple sclerosis patients revealed significant hypercapnia and hypoxaemia. Blood from the azygous veins in these patients revealed hypercapnia, but not hypoxaemia. After endovascular treatment of the stenoses most of the abnormal blood gas parameters improved significantly: in the internal jugular veins – all parameters studied, while in the azygous vein – pCO₂ and pO₂ improved but SatO₂ remained unchanged.

Conclusions: We demonstrated hypercapnia and hypoxaemia in the veins draining the brain and spinal cord in multiple sclerosis patients, and improvement of blood gas parameters after endovascular treatment for chronic cerebrospinal venous insufficiency. Nevertheless, it is unclear if this beneficial effect is long lasting and has any influence on the natural course of multiple sclerosis.