A simple technique for expansive suboccipital cranioplasty following foramen magnum decompression for the treatment of syringomyelia associated with Chiari I malformation

The benefits of osteoplastic suboccipital craniotomies over the traditional suboccipital craniectomies have been recognized. We describe a simple method of expansive suboccipital cranioplastic craniotomy using a free bone flap and report satisfactory clinical results in 16 patients with syringomyelia associated with Chiari I malformation. A free suboccipital bone flap is created from the rostral part of the occiput by placing two to four burr holes and connecting them with a craniotome. The posterior bony margin of the foramen magnum and the posterior arch of C1 are removed thereafter. Then dural plasty using a patch graft of dural substitutes is performed. The expansive suboccipital cranioplasty is performed by positioning the free bone flap caudal to the original location and fixing it with titanium miniplates to construct a bony frame to cover the foramen magnum. The rostral part of the cranial defect is filled with bone chips created during the craniotomy. Sixteen patients underwent this procedure. There was no operative mortality and no major complication, such as persistent pseudomeningocele. Preoperative symptoms improved significantly in all patients except for one who had persistent dysesthetic pain. Our simple method of expansive suboccipital cranioplasty for the treatment of syringomyelia associated with Chiari I malformation proved useful and achieved satisfactory long-term results.