Complete Atlantooccipital Assimilation with Basilar Invagination and Atlantoaxial Subluxation Treated Non-Surgically: A Case Report

Atlantooccipital assimilation is a partial or complete congenital fusion between the atlas and the base of the occiput. Most patients with atlas assimilation are asymptomatic, but some may present with neurological problems such as myelopathy. We present the case of a 37-year-old woman who presented with neck and occipital pain, episodic neck stiffness, and dizziness. Medical imaging revealed complete atlantooccipital assimilation associated with basilar invagination, atlantoaxial subluxation, and predisposing anterior spinal cord compression. The patient was treated non-operatively with medications, cervical interferential therapy, and a rigid cervical orthosis.