Retro-odontoid mass without atlantoaxial instability causing cervical myelopathy: a case report of transdural surgical resection

Abstract

Introduction: Retro-odontoid mass rarely occur in patients with noninflammatory retro-odontoid lesions without atlantoaxial instability. We describe a rare case of retro-odontoid mass without atlantoaxial instability operated on by a transdural approach.

Case presentation: The patient was an 83-year-old man who presented with a retro-odontoid mass causing symptomatic cervical myelopathy. Preoperative magnetic resonance imaging (MRI) revealed that the mass was severely compressing the spinal cord. We operated on it via a C1 laminectomy and performed tumor resection by a transdural approach. Pathological findings from the operative specimen confirmed the diagnosis; histopathological examination revealed that the mass contained fibrinoid material, and collagenous tissue with myxoid changes, but no granulation or a granulomatous lesion. Postoperative MRI confirmed spinal cord decompression. The patient's symptoms were alleviated, and he has not had a recurrence or cervical instability in the 7 years since his surgery.

Discussion: We successfully used a transdural approach in the present case and have observed no recurrence for 7 years postoperatively. C1 laminectomy is reportedly beneficial, especially for elderly patients, given the risk of other surgical options using an anterior transoral approach or posterior fusion. However, most tumors do not attenuate after C1 laminectomy alone; hence, we think that tumor resection by the transdural approach is one effective method to perform enucleation of the tumor after C1 laminectomy.

Keywords: Bone; Spinal cord diseases.

Figure 1

Preoperative imaging of the cervical spine. Dynamic radiography in (a) flexion, and (b) distraction. Radiography showed osteoarthritis at the C1/2 joint with sclerotic change in the odontoid process. Dynamic radiography revealed no instability at the C1/2 level. MRI: (c) sagittal view of T2-weighted image, (d) sagittal view of T1-weighted image, (e) sagittal view of T1-weighted image with gadolinium enhancement. Note that there was peripheral enhancement of the mass (e) and edematous changes in the spinal cord (c).

Figure 2

Laminectomy of C1 was performed, followed by a posterolateral transdural approach to the mass. (a) Photograph and representative diagram of the pseudotumor before removal. The specimen consisted of many small pieces of yellowish white and partially myxoid soft tissue. (b) A microscopic view of a section of the pseudotumor stained with hematoxylin and eosin showing fibrinoid, degenerated material or collagenous tissue with myxoid changes. (c) Cartilaginous metaplasia and fibrinoid degeneration were also seen. There was some inflammatory cell infiltration, but no granulation or granulomatous lesion. No amyloidosis was observed with Congo red staining. There was no evidence of malignancy or neoplasm.

Figure 3

Postoperative imaging of the cervical spine. (a) Sagittal view, T2-weighted MRI. (b) Dynamic radiography in flexion. Decompression of the spinal cord was confirmed. There has been no recurrence and no instability of cervical spine 7 years after the operation.