I am having numbness in my left leg and arm. i was in a major car accident about a year ago. could they be related?

Its possible: What was the damage to your body when you were in the car accident? Did you have x-rays and mri? What did they show? Certainly, whiplash and back issues can occur in a car accident. It is entirely possible that initial damage deteriorated and caused the problem you have now. Another words, if you weren't in the accident - would you have the problem.? You ask could they be related. I say yes.

Brain injury: Numbness in the left leg and arm can be caused by a brain injury. When do you think the symptoms started? If they started just after your accident, there is a good chance they are related. If they started recently, it is not likely they are related to the accident one year ago. Numbness covering a large area is an important symptom that should be checked out fast.