Bony decompression vs duraplasty for Chiari I malformation: does the eternal dilemma matter?

The management of Chiari I malformation (CIM) still raises the problem of the optimal surgical treatment, with special regard to the "eternal dilemma" of the posterior fossa bony decompression alone (PFBD) or with duraplasty (PFBDD). The goal of the present review is to update the results (outcome and complications) of both techniques to better understand the correct indication for each of them. A review of the literature has been performed, focusing on the articles and the meta-analyses specifically addressing the problem of PFBD vs PFBDD. Also, the personal authors' experience is briefly discussed. PFBD (usually with C1 laminectomy, often with delamination of the external dural layer) is the most commonly used technique in children, especially if syringomyelia is absent. It ensures a high success rate, with > 80% clinical improvement and about 75% reduction of the syringomyelia, and a very low risk of complications, hospital stay, and costs. A certain risk of recurrence is present (2-12%). PFBDD (with autologous tissues or dural substitutes), on the other hand, is mostly used not only in adults but also in children with large syringomyelia. It is burdened by a higher risk of complications (namely, the CSF-related ones), longer hospital stay, and higher costs; however, it warrants a better clinical improvement (> 85%) and a lower risk of reoperation (2-3.5%). Eight meta-analyses of the literature (three on pediatric series and five in adult series) and one prospective study in children, published in the last decade, largely confirm these findings. PFBD and PFBDD are different techniques that are indicated for different types of patients. In children, PFBD has been demonstrated to represent the best choice, although some patients may require a more aggressive treatment. Therefore, the success in the management of CIM, with or without syringomyelia, depends on the correct indication to surgery and on a patient-tailored choice rather than on the surgical technique.