Mini-invasive surgery for Chiari type I malformation.

Surgical treatment of Chiari I malformation and associated syringomyelia includes several different techniques with various degrees of invasiveness. Most extensive procedures may provide good long-term outcome in a good proportion of cases but are burdened by a quite high risk of postoperative complications. Thirty children operated on by simple bone decompression are retrospectively reviewed to assess the effectiveness of a less invasive technique. The present series comprises 30 children (18 females, 12 males; mean age: 68 months) treated from 1993 to 2005. All patients underwent foramen magnum decompression by means of suboccipital craniectomy and resection of the fibrous band at the level of foramen itself. Twenty-one children also required C1 laminectomy while a dural delamination was performed in 11 cases. The mean current follow-up is 4.3 years (1-12.6 years). Head and/or neck pain was the most frequent preoperative finding (56.7%), followed by upper and lower extremity weakness (20.0%), ataxia (20.0%) and vertigo (27.7%). Syringomyelia was present in 12 patients. A significant improvement of preoperative clinical symptoms and signs was observed in 28 patients (93.3%). Two children required adjunctive surgery. Neuroimaging revealed minor postoperative modifications in most cases regardless of tonsils location, while syringomyelia was reduced in size in 50% of the cases. Complication rate and length of hospital stay were significantly reduced compared with the literature data and our own experience using more invasive techniques. These data, compared with the literature, allow us to conclude that suboccipital craniectomy and Cl laminectomy (possibly integrated by dural delamination) is an effective and safe treatment for symptomatic children with Chiari I malformation and syringomyelia.