Pros and Cons of C2 Nerve Sectioning/Preservation in Posterior Fusion for Congenital Atlantoaxial Dislocation

OBJECTIVE: Deliberate C2 nerve root sectioning and its preservation have been described during posterior fusion for atlantoaxial dislocation (AAD). However, the associated outcomes have been less studied, especially in congenital AAD. Our objective was to study the clinical outcomes after C2 nerve root sectioning and the feasibility of C2 preservation in these patients. METHODS: The data from 190 patients were retrospectively studied. The decision to cut or preserve the C2 nerve root was determined by the preoperative radiologic findings and intraoperative suitability of its preservation. During follow-up, the patients were questioned about C2 nerve-related dysfunction. The pros and cons of sectioning or preservation of the C2 nerve root and the related feasibility factors are also described. RESULTS: Complex C1-C2 anatomy that required extensive dissection and drilling was seen in 139 patients. After C2 nerve root sectioning in 178 patients, none reported bothersome hypoesthesia, paresthesia, or dysesthesia that required medication. However, 9 patients (5.1%) developed nonhealing occipital ulcers and most required flap coverage or a skin graft. C2 nerve root preservation is feasible with an adequate inferior C1 lateral mass and normal-size ganglion. In patients with C1-occipital condyle hypoplasia, extremely oblique joints, spondyloptosis, incurved occiput, pseudofacets, and anomalous vertebral artery, preservation of the C2 nerve root is difficult. CONCLUSIONS: The advantages of sectioning the C2 nerve root are many. However, a subset of patients is prone to morbid occipital neuropathic ulcers. After C2 nerve sectioning, one should be cautious of such complications. C2 nerve root preservation should be strongly considered for patients with favorable anatomy.