Ankylosing spondylitis of occipito-atlanto-axial region

This code describes a specific form of ankylosing spondylitis, a chronic inflammatory disease primarily affecting the spine, when it impacts the occipito-atlanto-axial region. This area encompasses the joints connecting the skull (occiput) to the first cervical vertebra (atlas) and the second cervical vertebra (axis). Inflammation in this region can lead to pain, stiffness, and progressive fusion of these critical upper cervical joints.

Use this code when documentation clearly indicates a diagnosis of ankylosing spondylitis with specific involvement of the occipito-atlanto-axial complex. This diagnosis is typically supported by imaging studies (e.g., X-rays, MRI) showing characteristic inflammatory changes or fusion in this area, along with clinical findings consistent with ankylosing spondylitis. It is appropriate for both initial diagnoses and exacerbations affecting this specific spinal segment.

• Ensure the documentation explicitly states involvement of the "occipito-atlanto-axial region" or similar anatomical specificity (e.g., C0-C2).
• Do not use this code if the ankylosing spondylitis is generalized or affects other spinal regions without specific mention of the occipito-atlanto-axial area.
• Consider sequencing this code as a primary diagnosis if the occipito-atlanto-axial involvement is the primary reason for the encounter, otherwise, it may be a secondary diagnosis.