I had a double fusion at L4/5 and L5/S! and have sustained permnanent damage. I have lossed sensation in varius parts of my legs and feet but not enough to prevent me from being able to function normally. The extent of long term damage is dependent on the pressure on the nerve ad the lenghth of time this level of pressure is sustained.
As Coco has stated, if you begin to experience a loss of bladdre control etc you need to contact your dr.