Congenital hypoplasia of the posterior arch of the atlas accompanied with cervical high-intensity intramedullary lesions: a case report.

Congenital hypoplasia of the posterior arch of the atlas (C1) is uncommon and typically asymptomatic. A 49-year-old woman presented with a 2-year history of recurrent vertigo attacks. One month before admission, she began to have weakness in both lower extremities and unsteady walking, with chest tightness and shortness of breath after walking. She did not have any history of trauma. Cervical spine imaging revealed partial hypoplasia of the posterior arch of C1, midline cleft of the anterior arch, and cervical high-intensity intramedullary lesions. We used a posterior, suboccipital midline approach to resect the posterior arch of C1. This case underscores the importance of differential diagnosis, detailed imaging examinations should be performed to properly assess the stability of the atlantoaxial spine. In patients with neurological symptoms but no severe spinal cord compression, isolated posterior arch should be considered an potential cause of symptoms, and posterior arch resection is effective.