A Rare Case of Cervical Myelopathy Caused by an Anomaly of the Axis: A Case Report and a Review of Current Comprehensive Literature

INTRODUCTION: Cervical myelopathy due to anomalies of the posterior elements of the axis is rare, and limited cases have been reported. This study reports such a unique case of congenital anomaly of the laminae of the axis, which is treated by partial removal of the anomalous bony structure surgically, and provides a comprehensive review of the present literature on this pathological condition. CASE PRESENTATION: A 65-year-old man presented with a 3-year history of numbness in both arms with a sensory change in the right arm. Six months before admission, he noticed weakness in his right upper extremities and stiffness of the right lower extremity. Magnetic resonance imaging (MRI) showed a bilaterally compressed spinal cord with an anomalous bony structure at the C2-3 level. Computed tomography (CT) showed an invaginated abnormal bony structure at the C2-3 level and an abnormal lateral mass on the right side at the C2-3 level. The patient underwent posterior decompression surgery using the conventional open approach. One year after surgery, his myelopathy partially ameliorated, with his cervical radiograph showing no signs of the secondary instability and MRI showing sufficient decompression of the spinal cord. The age of onset, symptoms, and surgical treatment in our case was similar to those in the 14 previously reported cases; however, the morphology of the anomaly had variations. CONCLUSION: This is a report of a rare anomaly in the laminae of the axis. MRI and reconstructed CT scans were useful for the treatment of this case. Partial surgical removal was an appropriate treatment for this patient, resulting in a satisfactory outcome.