Comparison of the Surgical Results for Foramen Magnum Decompression with and without Duraplasty in Chiari Malformation Type 1.

Abstract

The surgical results for foramen magnum decompression (FMD) with and without duraplasty in Chiari Malformation type 1 (CM-1) were compared retrospectively. Thirty-nine cases of CM-1 with and without syringomyelia (SM) were included. There were 18 patients in the nonduraplasty and 21 in the duraplasty group. Syringomyelia, tonsillar herniation (TH), preoperative symptom duration, and postoperative SM size were compared. No significant difference was found between improvement in the duraplasty group (81%) and the non-duraplasty group (61.1%). In cases whose symptom duration was 0-36 months, improvement in the duraplasty group (93%) was significantly better than in the nonduraplasty group (50%) (p < 0.01). The rate of syrinx regression was 92.3% in the duraplasty group and 12.5% in the non-duraplasty group (p < 0.05). In cases with SM, the improvement was 21.4% in the non-duraplasty group compared to 78.6% in the duraplasty group (p=0.056). In cases with TH greater than 10 mm, the improvement was 66.7% in the non-duraplasty group, whereas all six cases (100%) in the duraplasty group had improved. In SM associated cases, cases with TH greater than 10 mm, and whose symptom duration is less than 36 months, duraplasty is a more reliable choice despite a slightly higher rate of complications.