Preoperative predictors of foramen magnum decompression with dural splitting for amelioration of syringomyelia associated with Chiari type 1 malformation

Soichiro Takamiya; Ikuma Echizenya; Kazuyoshi Yamazaki; Motoyuki Iwasaki; Syunsuke Yano; Toshitaka Seki; Kazutoshi Hida; Miki Fujimura

doi:10.1016/j.wneu.2024.08.167

Preoperative predictors of foramen magnum decompression with dural splitting for amelioration of syringomyelia associated with Chiari type 1 malformation

World Neurosurg. 2024 Sep 6:S1878-8750(24)01536-5. doi: 10.1016/j.wneu.2024.08.167. Online ahead of print.

Authors

Soichiro Takamiya¹, Ikuma Echizenya², Kazuyoshi Yamazaki³, Motoyuki Iwasaki⁴, Syunsuke Yano⁵, Toshitaka Seki⁶, Kazutoshi Hida⁵, Miki Fujimura⁴

Affiliations

¹ Department of Neurosurgery, Faculty of Medicine and Graduate School of Medicine, Hokkaido University, Sapporo, Hokkaido, Japan. Electronic address: soichiro.tkmy@med.hokudai.ac.jp.
² Department of Neurosurgery, Faculty of Medicine and Graduate School of Medicine, Hokkaido University, Sapporo, Hokkaido, Japan; Department of Neurosurgery, Sapporo Azabu Neurosurgical Hospital, Sapporo, Hokkaido, Japan.
³ Department of Neurosurgery, Otaru General Hospital, Otaru, Hokkaido, Japan.
⁴ Department of Neurosurgery, Faculty of Medicine and Graduate School of Medicine, Hokkaido University, Sapporo, Hokkaido, Japan.
⁵ Department of Neurosurgery, Sapporo Azabu Neurosurgical Hospital, Sapporo, Hokkaido, Japan.
⁶ Department of Spinal cord surgery, Doutou Forest Hospital, Kitami, Hokkaido, Japan.

PMID: 39245134
DOI: 10.1016/j.wneu.2024.08.167

Abstract

Objective: Among several procedures for syringomyelia associated with Chiari type 1 malformation (CM-1), foramen magnum decompression (FMD) with dural splitting is one of the treatment choices with low complication rates. However, some meta-analyses have suggested that FMD with dural splitting may be inferior to FMD with duraplasty based on clinical outcomes; therefore, a predictor of a good surgical outcome with dural splitting is essential. This study aimed to clarify the preoperative parameters for good outcomes in patients with FMD with dural splitting, including the volumetric perspective.

Methods: We reviewed the cases of patients diagnosed with CM-1 and syringomyelia who underwent FMD with dural splitting at our institution. We included patients who underwent magnetic resonance imaging (MRI) from 6 months to 1 year after surgery, and measured radiological parameters using preoperative computed tomography and preoperative/follow-up MRI.

Results: Thirty-one patients were enrolled. Among all radiological parameters, the volume of the herniated tonsils (V_tonsil) and the difference between the expected volume-increment and V_tonsil (V_incr-V_tonsil) in improved groups were significantly smaller than those in non-improved groups. To predict the improvement of the syrinx, V_incr-V_tonsil of 0.77 mL was the optimal cutoff value, and yielded 100% sensitivity and 48.0% specificity.

Conclusions: V_tonsil and V_incr-V_tonsil, which are novel predictors based on the volumetric perspective, might be the optimal predictors for improvement of the syrinx associated with CM-1 by 1 year after surgery.

Keywords: Chiari malformation; dural splitting; foramen magnum decompression; syringomyelia.