Regression of retroodontoid pseudotumors following C-1 laminoplasty. Report of three cases.

The authors report a new technique for C-1 laminoplasty without fusion in the treatment of cervical myelopathy associated with a retroodontoid pseudotumor (also known as a phantom tumor). The authors review the cases of three patients who underwent C-1 laminoplasty in which hydroxyapatite was used and fusion was not performed. All patients suffered from severe progressive myelopathy before surgery. Magnetic resonance imaging revealed a retroodontoid pseudotumor compressing the spinal cord at the C-1 level in all cases. Computed tomography was performed to examine the extent of bone erosion at the atlantoaxial joint and dens. Clinical parameters included neurological function, measured using the Japanese Orthopaedic Association score, and neck pain. Imaging parameters included pre- and postoperative atlas-dens intervals; the space available for the spinal cord; instability of the atlantoaxial joints; osteoarthritic changes of the atlantoaxial joint; postoperative changes in T2 high-intensity signal; and postoperative alteration in the size of the pseudotumor. Magnetic resonance imaging demonstrated complete disappearance of the pseudotumor in two cases and partial reduction in one case. In all three cases sufficient neurological recovery was observed. The mean recovery rate was 87.0%. This new technique is less invasive than standard procedures, preserves the cervical range of motion, and avoids the morbidity of obtaining a bone graft and placing instrumentation. The authors conclude that C-1 laminoplasty without fusion is an option in the surgical management of cervical myelopathy associated with a retroodontoid pseudotumor, either without C1-2 instability or with slight, but reducible, C1-2 instability.