• Basilar invagination (BI) is associated with instability of the craniovertebral junction, mainly atlantoaxial dislocation (AAD), and causes brainstem and upper cervical spinal cord compression.
• Many approaches have been utilized in the past, targeting mainly anterior and posterior resection, decompression, and circumferential fusion.
• Recently, a single posterior approach has been introduced with better results in decompression and fusion in addition to gaining odontoid reduction instead of resection. This approach is named DCER (distraction, compression, extension, and reduction) due to posterior craniocervical decompression followed by “distraction” of the C1-C2 joint with spacer materials, fixing craniocervical construct with “extension” and “compression” in order to gain anatomic
lordosis, and “reduction” of the odontoid process.