What is the treatment for atlantoaxial instability?

Treatment of Atlantoaxial Instability

Atlantoaxial instability requires prompt surgical stabilization in patients with neurological compromise, progressive instability, or failed conservative management, with posterior fusion techniques being the primary surgical approach. 1

Initial Assessment and Risk Stratification

When evaluating atlantoaxial instability, immediately assess for:

• Neurological deficits (myelopathy, radiculopathy, or cord compression signs) 2
• Mechanism of injury (trauma, congenital anomalies, inflammatory conditions, or tumor invasion) 1
• Degree of instability using imaging criteria: >3mm displacement of adjacent vertebrae or >11° of angulation 3
• Presence of torticollis or neck pain following trauma, which warrants urgent diagnostic evaluation 3

Critical pitfall: Vertebral artery dissection can present 12-24 hours after neck injury and may cause devastating neurological complications. Any neck pain after trauma requires prompt medical evaluation. 3

Conservative Management

Non-operative treatment is appropriate for 60.9% of pediatric cases without neurological compromise or severe instability 1:

• Cervical halo immobilization for 3 months in select cases (mean patient age 72.6 months) 1
• External immobilization with rigid cervical collar for stable injuries without neural compression 1
• Close monitoring with serial imaging to detect progression 1

Conservative management should never be attempted in patients with:

• Active neurological deterioration 2
• Significant spinal cord compression 2
• Progressive anterior displacement of atlas 4

Surgical Intervention

Indications for Surgery

Surgical stabilization is mandatory for 1:

• Neurological compromise or myelopathy 2
• Progressive instability despite conservative treatment 1
• Atlantooccipital dislocation (requires immediate fusion) 1
• Tumor invasion destroying bony elements 5
• Congenital anomalies with instability (os odontoideum, transverse ligament agenesis) 4

Surgical Techniques

Posterior fusion is the primary surgical approach 6, 1:

• Transarticular screw fixation with sublaminar wiring for standard atlantoaxial instability 1
• Atlas translaminar fixation when lateral masses are destroyed by pathology or tumor 5
• Occipital-cervical fusion (Locksley technique with Steinmann pins) for atlantooccipital dislocation 1
• Posterior plating following transoral decompression when anterior pathology requires removal 1

Important technical consideration: Surgeons should only perform procedures with which they have direct "hands-on" cadaver or model experience. Traditional wiring techniques remain satisfactory if the surgeon is experienced with them. 6

Anterior Approach

Transoral decompression may be required when:

• Anterior compression from odontoid pathology exists 1
• Posterior-only approach cannot adequately decompress neural elements 6
• This is typically followed by posterior stabilization 1

Special Populations

Down Syndrome Patients

• Up to 50% have atlantoaxial instability due to anomalous axis formation or transverse ligament laxity 4
• Surgical fusion is standard treatment for symptomatic instability 4
• Cervical manipulation is potentially fatal and should be avoided 4

Cervical Dystonia

• Early-onset cervical dystonia can cause cord complications at the craniovertebral junction, including os odontoideum and rotational malalignment 2
• Multidisciplinary management including botulinum toxin, deep brain stimulation, and surgical fusion when indicated 2
• Outcome depends on timing: irreversible cord damage occurs if treatment is delayed 2

Tumor-Related Instability

• Atlas translaminar fixation provides immediate stability when lateral masses are destroyed by metastatic lesions 5
• Utilize contralateral hemilamina for screw fixation when one lateral mass is compromised 5

Outcomes

Surgical stabilization provides good results when performed before irreversible cord damage 2, 1:

• Marked neurological improvement in atlantooccipital dislocation with immediate fusion 1
• Partial recovery possible even with established myelopathy if intervention is timely 2
• Poor outcomes occur when cord damage is irreversible prior to surgery 2

Key prognostic factor: Early recognition and intervention before permanent neurological injury occurs is essential for optimal outcomes. 2, 1