I had back surgery on 1/15/13 and left hospital feeling ok. now i have some level of numbness from my face to my toes. what could be the cause of this?

Paresthesias: Back surgery sequellae usually cause problems in the surgical site and distally. For problems running the entire body, i think it would be difficult to place the blame on the surgery. I would return to my surgeon and explain the situation. A visit to a neurologist may be in order, since various scenarios, not excluding guillian-barre syndrome, need to be considered.