Can an already settled accident case be re-opened due to additional injuries appearing at a later time?

I am a lawyer in CT and practice in this area of the law.  Once you settle a personal injury case with an insurance company you give up your right to sue for any injuries that subsequently arise.  In most PI cases, lawyers have you treat for over a year to make sure that all the injuries that you had inthe accident can be revealed so that you may seek compensation.  The injury that you are referring to, if it arose out of the accident, is going to be barred as a result of the settlement agreement.