I WAS IN A REAR IMPACT COLLISION IN MY HIGHLANDER. MY VEHICLE WAS STATIONARY ON A HIGHWAY, HAVING STOPPED TO AVOID A COLLISION, AND WAS HIT FROM BEHIND AT A RELATIVELY HIGH RATE OF SPEED (ESTIMATED 55-65 MPH). MY CAR WAS PUSHED INTO THE CAR IN FRONT OF IT WHICH CAUSED A CHAIN REACTION WITH SEVERAL OTHER VEHICLES. IMMEDIATELY AFTER IMPACT I BEGAN TO FEEL NECK AND BACK PAIN AND WAS TRANSPORTED TO THE HOSPITAL. PRIOR TO TRANSPORT, WE NOTICED THAT MY HEADREST HAD BROKEN FREE IN THE IMPACT AND WAS LAYING ON THE BACK FLOORBOARD.