Introduction: Management of Basilar invagination (BI) and atlanto-axial dislocation (AAD) remains a complex problem. The study describes a new novel technique to reduce both BI and AAD through a single staged posterior approach only

Methods: 65 patients with irreducible BI and AAD (May, 2010 - August, 2012, operated using this technique. Investigations included pre- and postoperative dynamic cervical x-rays, computed tomographic scans, 3-dimensional reconstruction views and MRI. In all patients, reduction of the AAD and BI was achieved using a new innovative method of distraction, spacer placement, followed by compression and extension. A C1 lateral mass/C2 trans-laminar screw was performed in cases where the C1 arch was not assimilated and occipito-C2 trans-laminar screw fixation was performed in cases where the C1 arch was assimilated.

Results: 61/65 (94%) patients improved clinically and 3 patients had stable symptoms (mean Nurick's post op score = 1.4; pre-op score = 3.7). AAD reduced completely in 63/65 patients and >50% in the other 2. One of these patients underwent a trans-oral procedure at a later stage. BI improved significantly in all patients. Solid bone fusion demonstrated in all patients with at least 6 months follow up (54). The duration of surgery ranged from 80-190 minutes, and blood loss ranged from 90-500 mL (mean: 170+/- 35 ml). There was 1 death because of cardiac etiology and 1 morbidity due to wound infection.

Conclusions: Spacer distraction coupled with extension as a treatment for BI and AAD seems to be an effective, simple, and safe method for the treatment of BI with AAD and may prove to be a better alternative than other existing methods.

Patient Care: The procedure as compared to a trans-oral decompression and posterior instrumented fixation -significantly shortens the duration of surgery and blood loss -reduces the hospital stay -reduces significantly the learning curve of this complex procedure

Learning Objectives: To describe the technique, and outcome of a novel new procedure to reduce both BI and AAD through a single posterior approach

References: 1. Chandra PS, Kumar A, Chauhan A, Ansari A, Mishra NK, Sharma BS. Distraction, Compression and Extension Reduction Of Basilar Invagination and Atlanto-Axial Dislocation: A Novel Pilot Technique. Neurosurgery. 2013 Feb 19. [Epub ahead of print] PubMed PMID: 23426148.