In my case, the worst initial GBS symptoms during onset were severe, for me off-the-chart, unmanageable low-back pain, accompanied by an onset of ascending paralysis (numbness) starting in the feet, & gradual numbness that ascends towards the knees. Unchecked, the numbness may continue to the point of affecting chest muscles & the ability to breathe, potentially leading to respiratory failure. Timely diagnosis & treatment are key to trying to stop the progressive paralysis before it reaches a life-threatening stage.