I'm not sure what you mean by signs of paralysis. If their back legs are paralyzed this means they cannot use them...generally they drag their back legs.
If you are wanting to know what causes the hind legs to become paralyzed, it is usually one of two things. One being an impaction, which means they have an obstruction in their digestional tract. If the impaction pushes on the spinal cord it will cause them to drag their back legs, due to paralysis.
The other one is MBD(Metabolic Bone Disease) which is caused by a lack of vitamins.... primarly calcium and vitamin D or lack of uvb.
Are your beardies back legs paralyzed?
If so....how old is your beardie?
What are you feeding him?
When was the last time he pooped?