What Causes Numbness And Tingling In Arms?

I m a 58 y/o man. My symptoms are: numbness starting in my left arm above the elbow running down to the ring and pinky finger. Tingling and numbness down my left leg including my left foot. Right leg now perceives any cool touch as pain. Bowell function has decreased. Stool is now produced in thin strips rather than well formed. Balance has been negatively affected. Right eyelid seems to stick closed momentarily now when I open it...but not always. MRI s are all normal to include: brain/cervical/lumbar and thoracic. Xrays are normal.CAT scan normal. Any thought?