Fig. 1

Shows the examination results of a 43-year-old female with basilar invagination, atlantoaxial dislocation and neurofibromatosis. She was treated with transoral atlantoaxial reduction, antogenous iliac bone-grafting and internal fixation with the help of transoral atlantoaxial reduction plate. As shown in a and b, the X-rays reflect obvious anterior atlantoaxial dislocation. The sagittal CT (see c) further shows that odontoid tip is 2.5 mm higher than the Chamberlain line, which can be considered as basilar invagination. According to d and e, the sagittal and axial CTs (near the left lateral mass) show callus hyperplasia in the atlanto-dental interval (ADI) space, leading to the irreducible atlantoaxial dislocation. MRI results (see f and g) show significant compression of cervical medulla at atlantoaxial level and partial degeneration of spinal cord. The postoperative X-rays (see h and i) immediately show that the atlantoaxial vertebra has been completely reducible, and the internal fixation is in good position. According to j, k and l, the postoperative CTs immediately show good position of the atlantoaxial screw path, no invasion of vertebral artery and spinal canal, and the bony callus in the ADI space is removed. The postoperative MRI results (see m and n) demonstrate that there is no significant compression of cervical spinal cord at atlantoaxial level, and no significant changes in partial degeneration of spinal cord. X-rays (see o and p) conducted 3 months after the operation show that the internal screw fixed in the atlantoaxial segment is in place without obvious loosening or displacement. The CT (see q) shows callus formation in the ADI, and initial osseous fusion of the atlantoaxial segment. The MRI (see r) shows that there is no significant compression of cervical spinal cord and no significant change in partial degeneration of spinal cord. X-rays which were conducted 6 months (see s and t) and 17 months (see w and x) after the operation demonstrate that the atlantoaxial internal fixation is firm without any obvious dislocation. In addition, the physiological curve of cervical spine is good, and there is no instability of adjacent segments. The CTs conducted 6 months (see u) and 17 months after operation (see y) show further callus formation in the ADI space, and firm osseous fusion. The MRIs conducted 6 months (see v) and 17 months (see z) after operation show no significant compression of cervical spinal cord. In addition, partial degeneration of spinal cord shows some improvement