1497. Atlantoaxial fixation for failed foramen magnum decompression for Chiari formation

Authors: Atul Goel, MD, IFAANS (Mumbai, India)

Introduction:

Outcome of 26 patients who had failed conventional treatment for Chiari formation that included foramen magnum decompression surgery and were treated by atlantoaxial fixation is analyzed.

Methods:

During the period January 2010 to December 2017, we treated 26 patients who had undergone conventionally described surgical procedures; all included foramen magnum decompression for Chiari formation.Seven patients had associated basilar invagination and all patients had syringomyelia. All patients worsened in their neurological condition either in the immediate or in the delayed postoperative phase. Atlantoaxial instability was diagnosed on the basis of facetal alignment and on the basis of direct observation of joint status by bone manipulation during surgery. The patients were treated by atlantoaxial fixation. Goel clinical grading scale and JOA scores assessed the clinical status both before and after surgery.

Results:

Following surgery, all patients improved in the clinical condition. The improvement began in the immediate postoperative period and progressed. During the follow-up period that ranged from 4 to 96 months,‘significant’ neurological recovery and amelioration of presenting symptoms was observed. During the period of follow-up, reduction in the size of syrinx was observed in 12 out of 16 cases where post-operative MRI was possible.

Conclusion:

Clinical results reinforce the belief that atlantoaxial instability is nodal point of pathogenesis of Chiari formation in cases with or without bone malformations in the craniovertebral junction. Atlantoaxial fixation is the treatment. In patients who have failed foramen magnum decompression surgery, atlantoaxial fixation can be an effective mode of treatment.