A rare case of cervical myelopathy due to a bipartite atlas: degenerative complications and surgical outcome. Illustrative case.

backgroundA bipartite atlas is a rare congenital anomaly characterized by incomplete fusion of the anterior and posterior arches of the first cervical vertebra (C1). While typically asymptomatic, this condition can result in cervical myelopathy when accompanied by degenerative changes. This report presents a rare case of cervical myelopathy caused by a bipartite atlas in an older patient that required surgical intervention. OBSERVATIONS: A 63-year-old male presented with progressive neurological symptoms, including impaired fine motor skills, pain, and paresthesias in both the upper and lower extremities. Imaging revealed a bipartite atlas accompanied by degenerative changes, resulting in significant spinal cord compression. The patient underwent a posterior decompression via C1 laminectomy and duraplasty, resulting in significant clinical improvement and a resolution of symptoms. LESSONS: This case highlights the importance of recognizing a bipartite atlas as a potential cause of cervical myelopathy, particularly in older patients with degenerative changes. This is a rare case in which congenital and degenerative factors are intertwined, underscoring the importance of a comprehensive pathological analysis and the development of a personalized treatment strategy. Prompt diagnosis and appropriate surgical intervention are essential for favorable outcomes. https://thejns.org/doi/10.3171/CASE24688.