What Is The Time Required For Sore In Back Area To Heal?

Hi, my son just went yesterday to have a lumbar puncture done. He is very sore in his back area, also says his legs are very weak. The doctor filled a form for him to go see a physiotherapist. It takes a couple of weeks just to get an appointment to assess him for physio. How long does it regularly take a patient who has had this done to feel better. Do you think he will be able to go back to school before physio, I'm hoping he will be able to go back after the long weekend of Easter.