Effects of Suboccipital Craniectomy with and without Duraplasty on Chiari Type-one Malformation

Background: Chiari Malformation type 1 (CM-I) is a congenital disease characterized by downward decent of the cerebellar tonsil and crowding in the craniocervical junction area. There are still obvious controversies for the optimum surgical strategy for Chiari malformation type 1 especially if associated with syringomylia. Objectives: to determine the results of bony decompression with and without duraplasty on treatment of Chiari type 1 malformation patients. Patients and Methods: a retrospective study was undertaken on the medical records and magnetic resonance imaging (MRI) scans of 20 surgical corrections of Chiari malformation type I performed at our institution from 2007 to 2011. The age and sex of the patient, the presence of syringomyelia, the type of surgery (duraplasty or non duraplasty), and the clinical outcome were determined. Results: Of the eight patients who did not undergo duraplasty, four patients without syringomyelia showed improvement postoperatively; of the four patients with syringomyelia, three showed improvement, including two with a decrease in the cavity size. One patient showed improvement in symptoms but the syringomyelia was unchanged. The cavity size increased in the one patient who did not show improvement. Among the 12 patients who underwent duraplasty, improvements were noted in four of the five patients without syringomyelia and in all of the seven with syringomyelia. Conclusion: Suboccipital craniectomy, C1 laminectomy, and duraplasty for the treatment of Chiari I malformation may lead to a more reliable reduction in the volume of concomitant syringomyelia, compared with Suboccipital craniectomy and C1 laminectomy alone. However, there seems to be a subset of patients whose symptoms will resolve and whose syringomyelic cavity will decrease with the removal of bone only. Further studies are needed to better characterize these patients, to determine which patients with Chiari I malformation are better served with bony decompression only, and which will require duraplasty to resolve their syringomyelia.