Neurosurg Focus. 2023 Mar;54(3):E10. doi: 10.3171/2022.12.FOCUS22633.
Syringomyelia (syrinx) associated with Chiari malformation type I (CM-I) is commonly managed with posterior fossa decompression, which can lead to resolution in most cases. A persistent syrinx postdecompression is therefore uncommon and challenging to address. In the setting of radiographically adequate decompression with persistent syrinx, the authors prefer placing fourth ventricular subarachnoid stents that span the craniocervical junction particularly when intraoperative observation reveals arachnoid plane scarring. The objective of this study was to evaluate the safety and efficacy of a fourth ventricle stent for CM-I-associated persistent syringomyelia, assess dynamic changes in syrinx dimensions, and report stent-reduction durability, clinical outcomes, and procedure-associated complications.
The authors performed a single-institution, retrospective review of patients who underwent fourth ventricular subarachnoid stent placement for persistent CM-I-associated syringomyelia following a prior posterior fossa decompression. The authors' institutional Chiari database contains 600 cases with 149 decompressions for CM-I-associated syringomyelia, of which 13 met criteria for inclusion. Data on patient demographics, clinical presentation and outcomes, and MRI findings were collected. The maximal syrinx diameter was estimated by calculating the area of an elliptical cross-section in the largest axial plane from preoperative, immediately postoperative, and late postoperative T2-weighted MR images.
All 13 patients experienced a significant decrease in mean syrinx area from the preoperative to the late postoperative MRI (mean syrinx diameter 114.1 ± 81.8 mm2 vs 24.5 ± 23.8 mm2, p < 0.001). The mean time until late postoperative MRI was 19.7 months (range 2.0-70.7 months). The syrinx area reduced on average by 75.0% ± 23.9% at the time of the last postoperative scan. Syrinx resolution was variable, with 4 patients (30.8%) achieving near-complete resolution (> 90%, grade III reduction), 7 patients (50%) having 50%-90% reduction (grade II), and 2 patients (14.3%) having < 50% decrease (grade I). One patient experienced catheter migration into the left brachium pontis with an associated cyst at the tip of the catheter that decreased in size on follow-up imaging.
Placement of fourth ventricular subarachnoid stents spanning the craniocervical junction in patients with persistent CM-I-associated syringomyelia after posterior fossa decompression is a safe therapeutic option and significantly reduced the mean syrinx area, with a greater reductive effect seen over longer follow-up periods.
与 Chiari 畸形 I 型（CM-I）相关的脊髓空洞症（空洞）通常通过后颅窝减压进行治疗，大多数情况下可以解决。因此，减压后持续存在的脊髓空洞症并不常见，也难以解决。在减压后影像学显示充分且仍存在脊髓空洞症的情况下，作者倾向于放置第四脑室蛛网膜下腔支架，该支架跨越颅颈交界区，尤其是当术中观察到蛛网膜平面瘢痕时。本研究的目的是评估第四脑室支架治疗 CM-I 相关持续性脊髓空洞症的安全性和有效性，评估脊髓空洞症尺寸的动态变化，并报告支架缩小的持久性、临床结果和与手术相关的并发症。
作者对在先前的后颅窝减压后因持续性 CM-I 相关脊髓空洞症而行第四脑室蛛网膜下腔支架置入术的患者进行了单中心回顾性研究。作者所在机构的 Chiari 数据库包含 600 例患者，其中 149 例因 CM-I 相关脊髓空洞症行减压术，其中 13 例符合纳入标准。收集了患者的人口统计学、临床表现和结果以及 MRI 结果的数据。最大脊髓空洞症直径通过计算术前、术后即刻和术后晚期 T2 加权 MRI 中最大轴位的椭圆形截面面积来估计。
所有 13 例患者的平均脊髓空洞症面积均从术前显著减少到术后晚期 MRI（平均脊髓空洞症直径 114.1 ± 81.8 mm2 比 24.5 ± 23.8 mm2，p < 0.001）。直到术后晚期 MRI 的平均时间为 19.7 个月（范围 2.0-70.7 个月）。最后一次术后扫描时，脊髓空洞症面积平均缩小了 75.0% ± 23.9%。脊髓空洞症的缓解程度不同，4 例（30.8%）患者几乎完全缓解（> 90%，分级 III 级），7 例（50%）患者缓解 50%-90%（分级 II 级），2 例（14.3%）患者缓解 < 50%（分级 I 级）。1 例患者发生导管迁移至左侧脑桥臂，导管尖端出现相关囊肿，随时间推移囊肿体积减小。
在接受后颅窝减压术治疗的 CM-I 相关持续性脊髓空洞症患者中，放置跨越颅颈交界区的第四脑室蛛网膜下腔支架是一种安全的治疗选择，可显著缩小平均脊髓空洞症面积，且在更长的随访期内具有更大的缩小效果。
