a. Except as otherwise provided by law, every action at law for an injury to the person caused by the wrongful act, neglect or default of any person within this State shall be commenced within two years next after the cause of any such action shall have accrued; except that an action by or on behalf of a minor that has accrued for medical malpractice for injuries sustained at birth shall be commenced prior to the minor's 13th birthday.
b. In the event that an action by or on behalf of a minor that has accrued for medical malpractice for injuries sustained at birth is not commenced by the minor's parent or guardian prior to the minor's 12th birthday, the minor or a person 18 years of age or older designated by the minor to act on the minor's behalf may commence such an action. For this purpose, the minor or designated person may petition the court for the appointment of a guardian ad litem to act on the minor's behalf.