For safety purpose: A prior distribution of the success rate with regard to severe adverse effect (SAE) will be set as 75%. The investigators will consider severe sepsis due to CLABSI and venous thrombosis related to CVC use as SAE. If >5 patients had SAE at or before completion of SVPE in 20 GBS patients; the study will be stopped. Otherwise an RCT will be planned subsequently to evaluate the neurological efficacy of the SVPE procedure.