1290. C1-C2 Facet Joint Distraction with Allograft in Occipitocervical Fusion for An Iatrogenic Basilar Invagination in Chiari II

Authors: Muhammad Burhan Ud Din Janjua, MD; Dale Swift, MD; Bruno Braga, MD (Dallas, TX)

Introduction: Iatrogenic occipitocervical kyphosis associated with basilar invagination can be a complication of suboccipital decompression surgery. Manual reduction with occipitocervical instrumented fusion has been described in Chiari I malformation in children. Reduction techniques for basilar invagination in Chiari II, however, can be challenging. Methods: A 12-year-old boy with history of Chiari II malformation, myelomeningocele repair, shunted hydrocephalus, previous C1, C2 laminectomies with consequent C2C3 kyphosis and C2-3 posterior fusion developed significant occipitocervical kyphosis and ventral brain stem compression (VBSC) over the years. Clinical presentation, radiographic details, indications, and surgical technique are discussed. Results: Patient’s preoperative imaging studies showed anacute clivocanal angle of 104 degrees with C1-C2 anterolisthesis and kyphosis. Retroflexion of odontoid and basilar invagination were evidenced by dens well posterior to Wackenheim’s line and above McGregor’s and McRae's lines despite a previous suboccipital decompressionAuthors describe a unique technique of reduction of basilar invagination with the use of C1-2 facet joint distraction with interarticular allografts followed by an extension of occipitocervical instrumented fusion. Postoperative images showed marked reduction of basilar invagination and resolution of C1C2 kyphosis. Patient had no vascular, neurological or infectious complications. Conclusion: C1-2 facet joint distraction with allograft insertion followed by posterior instrumented occipitocervical fusion is safe, feasible and an effective surgical technique for de novo or iatrogenic basilar invagination and occipitocervical kyphosis associated with Chiari II in children.