Blow-out fracture. Multiprojection CT findings in three cases and their relation to postoperative recovery of impaired eye movements

We reviewed three recent cases of blow-out fracture of the orbit with special reference to multiprojection CT findings of axial, modified coronal, Towne and semisagittal sections, and investigated their relation to postoperative recovery of impaired eye movements. Especially, Towne and semisagittal sections provided more precise informations about the correlation among inferior rectus muscle, orbittal floor, entrapped orbital contents with bony fragment and maxillary sinus. Towne section performed in the 4th day after injury a 7-year-old boy showed the 'tear drop' sign of the soft tissue density, irregular high density thickening of the left orbital floor and the obscure inferior rectus muscle suggesting periorbital hemorrhage and edema in the soft tissue around the fracture. The operation was performed by transorbital approach on the 12th day after injury. Eight months later limitation of upward gaze remained, which seemed to be due to direct injury to the orbital contents involving the inferior rectus muscle. In the second case, a 17-year-old boy, axial CT showed no evident defect in the left maxillary sinus, however, Towne section performed on the 2nd day after injury clearly showed the 'tear drop' sign of the soft tissue density with bony fragment hanging into the maxillary sinus. The inferior rectus muscle was kept intact. The recovery of impaired upward gaze was not obtained until the operation on the 11th day after injury. Following the operation his eye movements improved rapidly and became normal two months later. Impaired upward gaze this case seemed to be due to the secondary effect of herniated orbital contents attaching the inferior rectus muscle. In the last case of a 8-year-old boy, Towne section performed on the 25th day after injury showed the bone discontinuity in the right orbital floor and soft tissue density hanging into the maxillary sinus with entrapment of the inferior rectus muscle. Semisagittal section clearly showed the entrapment of the inferior rectus muscle. The operation was performed on the 35th day after injury. He slowly recovered the limitation of eye movements but still had double vision 6 months later. It has been discussed whether the treatment of the blow-out fracture should be early operative or conservative; however, no mention has been made of early pathological findings by multiprojection CT scanning and their movements. In the last case, postoperative recovery seemed to be influenced by delayed operative stage. But in the first and second case, the recovery was different whereas they received operation at the same early stage. It seemed to depend upon the degree of injury to the orbital contents with or without involvement of inferior rectus muscle suggested by early multiprojection CT findings as mentioned above. It is concluded that early and precise diagnosis by multiprojection CT scanning will be important for the treatment of blow-out fracture.