When we give injections, sometimes the needle will actually hit the nerve. We can't see it when we give an injection so its always a possibility that it can occur. Sometimes during the injection, you'll feel an electrical shock pain if it makes contact with the nerve. Sometimes this trauma can cause what we call paraesthesia or numbness. It can take upwards of 6 months to heal although there's no telling how long it'll actually take. I don't imagine it'll take 6 months, but a few weeks may not be unusual.