Unilateral open-door laminoplasty involving C1 for developmental atlantal canal stenosis combined with multilevel cervical stenosis: a case report.

BACKGROUND: Developmental atlantal canal stenosis is a rare cause of high cervical myelopathy. When combined with multilevel subaxial cervical stenosis, even minor trauma may result in severe neurological deficits. Surgical management remains challenging, particularly when C1 is involved, as laminoplasty is conventionally limited to C3-C7. CASE PRESENTATION: A 55-year-old male presented with acute cervical pain accompanied by quadriparesis following a low-energy fall. Neurological examination revealed severe cervical myelopathy with an ASIA grade C injury. Preoperative imaging demonstrated developmental atlantal canal stenosis combined with multilevel cervical stenosis from C1 to C5, without atlantoaxial instability. The preoperative Japanese Orthopaedic Association (JOA) score was 4 points. A unilateral open-door laminoplasty extending from C1 to C5, including the C1 level which is rarely incorporated in laminoplasty procedures, was performed. Postoperatively, the sagittal diameter of the atlantal canal increased from 0.93 cm to 1.35 cm, and the Pavlov ratio improved from 0.39 to 0.92. At 2 months, the JOA score improved to 15 points, corresponding to a recovery rate of 84.6%, and the patient maintained stable neurological function without cervical instability during a 4-year follow-up. CONCLUSION: For carefully selected patients with preserved atlantoaxial stability, unilateral open-door laminoplasty involving C1 may provide effective decompression and durable neurological recovery while preserving cervical stability and motion.