Anterior Distraction and Reduction with Posterior Stabilization for Basilar Invagination: A Novel Technique

BACKGROUND: Introduction of a posterior spacer Tor atlantoaxial joint distraction followed by posterior stabilization is a commonly performed procedure for irreducible atlantoaxial dislocation. We present a unique case in which posterior distraction was associated with increased risk of injury to the vertebral artery (VA) owing to its anomalous course, and hence a novel anterior distraction technique was used. CASE DESCRIPTION: A 45-year-old woman presented with severe neck pain for 1 month with gait imbalance and history of occipital headache for 1 year. Clinical examination revealed upper motor neuron-type findings. Hoffmann sign was positive bilaterally. Clinically, the patient had Nurick grade 4 cervical myelopathy. Magnetic resonance imaging showed basilar invagination along with Arnold-Chiari malformation and syrinx formation at C3-C4 vertebral levels. CT angiography revealed anomalous VAs directly overlying the atlanto-occipital joint. Owing to the anomalous route of the VA and unfavorable slope of facet joints, a 2-step anterior reduction followed by posterior stabilization surgery was planned. We achieved complete reduction using a 10-mm titanium cage inserted via a retropharyngeal approach. Following anterior reduction, instrumented in situ occipitocervical fusion was performed using a plate and screw construct. At 2-year follow-up, the patient is ambulating independently without gait imbalance and with successful radiologic fusion. CONCLUSIONS: The craniovertebral junction has a unique pathoanatomy, and the course of the vertebral artery is variable. Appropriate investigations, including computed tomography angiography, with adequate surgical planning will provide a desirable long-term outcome. Our novel technique has the potential to add a new dimension to the management of irreducible atlantoaxial dislocation.

Automated summary

A 45-year-old woman presented with severe neck pain and gait imbalance, and was successfully treated with anterior distraction and posterior stabilization surgery for irreducible atlantoaxial dislocation. The patient achieved independence in walking and complete recovery after 2 years of follow-up. Proper investigation and surgical planning are crucial for desirable long-term outcomes in cases involving anomalies of the craniovertebral junction.