Surgical management of Chiari I malformation based on different cerebrospinal fluid flow patterns at the cranial-vertebral junction

Abstract

Chiari I malformation has been shown to present different cerebrospinal fluid (CSF) flow patterns at the cranial-vertebral junction (CVJ). Posterior fossa decompression is the first-line treatment for symptomatic Chiari I malformation. However, there is still controversy on the indication and selection of decompression procedures. This research aims to investigate the clinical indications, outcomes, and complications of the decompression procedures as alternative treatments for Chiari I malformation, based on the different CSF flow patterns at the cranial-vertebral junction. In this study, 126 Chiari I malformation patients treated with the two decompression procedures were analyzed. According to the preoperative findings obtained by using cine phase-contrast MRI (cine PC-MRI), the abnormal CSF flow dynamics at the CVJ in Chiari I malformation was classified into three patterns. After a preoperative evaluation and an intraoperative ultrasound after craniectomy, the two procedures were alternatively selected to treat the Chiari I malformation. The indication and selection of the two surgical procedures, as well as their outcomes and complications, are reported in detail in this work. Forty-eight patients underwent subdural decompression (SDD), and 78 received subarachnoid manipulation (SAM). Ninety patients were diagnosed as having Chiari I malformation with a syrinx. Two weeks after the operation, the modified Japanese Orthopedic Association (mJOA) scores increased from the preoperative value of 10.67 ± 1.61 to 12.74 ± 2.01 (P < 0.01). The mean duration of follow-up was 24.8 months; the mJOA scores increased from the postoperative value of 12.74 ± 2.01 to 12.79 ± 1.91 at the end of follow-up (P = 0.48). More complications occurred in the patients who underwent SAM than in those who received SDD (SAM 11 of 78 (9.5%) vs SDD 2 of 48 (3.5%)). The abnormal CSF flow dynamics at the CVJ in Chiari I malformation can be classified into three patterns. A SAM procedure is more feasible in Chiari I malformation (CM1) patients with pattern III CSF flow dynamics, whereas a SDD procedure is more suitable for CM1 patients with pattern I CSF flow dynamics. In CM1 patients with pattern II CSF flow dynamics, an intraoperative ultrasound after craniectomy could play an important role in the selection of an effective decompression procedure.

Potential association among posterior fossa bony volume and crowdedness, tonsillar hernia, syringomyelia, and CSF dynamics at the craniocervical junction in Chiari malformation type I

“…In previous studies, we described the underdeveloped clivus and occipital bone as well as a reduction of the volume of bony PCF in adults with CMI ( 4 ). We also first divided CMI into three different degrees of CSF circulation disorders in the anterior, middle, and posterior spaces ( 32 ). Here, we quantitatively analyzed the CSF dynamics at CVJ.…”

Basilar invagination without atlantoaxial dislocation: treatment by correction of clivus canal angle with interfacet distraction and fixation

“…In our group of 13 cases with syringomyelia, improvement of the CCA without posterior fossa and subdural decompression was achieved, and there was significant relief of syringomyelia in 10 cases at the postoperative follow-up. The improvement of syringomyelia may be because of the relief of the ventral brainstem compression, which subsequently improves the cerebrospinal fluid flow patterns at the craniovertebral junction [ 24 ]. The absence of relief of the cavity in individual cases may be explained by insufficient ventral decompression.…”

Basilar invagination without atlantoaxial dislocation: treatment by correction of clivus canal angle with interfacet distraction and fixation

“…The improvement of syringomyelia may be due to the relief of the ventral brainstem compression, which subsequently improves the cerebrospinal uid ow patterns at the craniovertebral junction. [4] The absence of relief of the cavity in individual cases may be explained by insu cient ventral decompression.…”