What Causes Numbness In Fingers?

I just like 5 hours ago got 3 interior stitches and 10 superficial stitches in my left wrist, my hand from my ring finger to thumb is completely numb. Judging by the pain the medicine has worn off. Why am I numb? The doctor in the er who stitched me up said I completely missed everything despite the depth of the laceration. Is this permanent?