Basilar invagination and atlantoaxial dislocation as a complication of severe dystrophic cervical kyphosis correction in neurofibromatosis type 1: Report of a rare case and review of literature

Introduction and importance: Neurofibromatosis type 1 (NF1) affects the musculoskeletal system as well as the cervical spine. It is associated with severe, progressive cervical kyphosis. Surgical intervention is the treatment of choice to avoid neurological impairment and malalignment. Case presentation: We herein report an 11-year-old NF-1 patient with severe cervical kyphosis and intact neurological status. We applied five days of cervical traction followed by surgery utilizing the combined cervical approach (posterior release, anterior corpectomy and reconstruction, and posterior cervicothoracic instrumentation). In one-year follow-up, atlantoaxial dislocation (AAD) and basilar invagination (BI) were detected in neuroimagings. The complication was corrected by adding C1 to the previous construct via unilateral C1 lateral mass screw, contralateral C1 sublaminar hook, unilateral C3 and contralateral C4 sublaminar hook insertion, fixed with contoured rods medial to previous rods. This led to the correction of the AAD and the BI and the patients remained neurologically intact. Clinical discussion: Severe cervical kyphosis in the setting of NF-1 is progressive and carries a considerable risk of neurologic compromise. Surgical intervention is thus necessary. Conclusion: The combined approach with complete spinal column reconstruction is the surgical approach of choice. However, complete curve correction to near-normal lordosis carries the risk of proximal junctional failure (PJF).