Hypertrophic Posterior Arch of Atlas Causing Cervical Myelopathy
A 26-year-old female presented with complaints of posterior cervical headaches for many years with on and off tingling and numbness involving right arm, trunk, and leg. There was no history of bowel or bladder dysfunction. There was no significant past medical history or preceding trauma. The general physical examination was within normal limits. Neurological examination revealed presence of subtle spastic hemiparesis on the right side (Medical Research Council grade 4+/5) with exaggerated deep tendon reflexes as compared to left. She has positive right Hoffmann's sign. Computed tomography scan of the cervical spine revealed slight kyphosis and degenerative changes within the subaxial cervical spine with an expanded hyperostotic right posterior arch of C1 (). Magnetic resonance imaging of the cervical spine showed constriction of the dural sac with presence of possible right posterior arch of C1 lesion which was hypointense on T1 and T2W images and no contrast enhancement with a small area of increased signal within the spinal cord on the T2 weighted imagesb (). The patient was referred to us with a diagnosis of a benign bony tumor of C1 and a surgical removal was performed. Tc-labeled bisphosphonate nuclear bone scan performed did not reveal any abnormal focal uptake by the lesion which has been described in osteoid osteomas of the spine. Considering the dubious nature of the lesion with equivocal diagnosis, surgical resection was planned. Posterior exposure of the cervical spine in the C1-C2 regions was performed. There was no obvious anomaly seen externally with a normal appearing ligamentum flavum. The right posterior arch of the atlas was hypertrophied with no other abnormality suggestive of neoplastic lesion. The lesion was excised with performance of right hemilaminectomy of the atlas carefully preserving the C1/C2 joint. Final histopathology of the lesion showed the presence of normal bone tissue with no evidence of tumor confirming the diagnosis of hypertrophied posterior arch of atlas. Patient had an uneventful postoperative course with CT showing good decompression and excellent clinical outcome which was maintained at 3 months follow-up.