Tochigi Satoru, Isoshima Akira, Ohashi Hiroki, Kawamura Daichi, Karagiozov Kostadin, Hatano Keisuke, Ohashi So, Nagashima Hiroyasu, Murayama Yuichi, Abe Toshiaki
1Department of Neurosurgery, The Jikei University Kashiwa Hospital, Kashiwa, Chiba.
2Department of Neurosurgery, Omori Red Cross Hospital, Tokyo.
J Neurosurg. 2022 Jul 8;138(2):540-549. doi: 10.3171/2022.5.JNS212973. Print 2023 Feb 1.
The surgical treatment of Chiari malformation type I (CM-I) frequently involves dural incision at the posterior cranial fossa. In cases of persistent patent occipital sinus (OS), the sinus is usually obliterated and divided. However, there are some patients whose OS is prominent and requires crucial modification of the operative planning to avoid potentially life-threatening massive hemorrhage and disturbance of cerebral venous circulation. In the present study, the anatomical variations of the dominant OS in patients with CM-I were analyzed and the authors attempted to develop treatment recommendations for patients with CM-I with dominant OS.
The study included 213 patients with CM-I who underwent MR venography (MRV) prior to surgical treatment. OS dominance was assessed using 2D time-of-flight MRV or 3D phase-contrast MRV. Particular attention was paid to the pattern of venous outflow channels. The characteristics of the patients with dominant OS and the surgical outcomes were retrospectively reviewed.
Dominant OS was identified in 7 patients (3.3%). The age in those with dominant OS was significantly younger than in those without (p = 0.0202). The incidence of concurrent scoliosis in the patients with dominant OS was significantly higher than in those without (p = 0.0366). All the dominant OSs were found to be of the oblique type. Unilateral oblique OS (OOS) with normal ipsilateral transverse sinus (TS) and hypoplastic contralateral TS was found in 2 patients (0.9%). The authors found 1 patient each (0.5%) who had unilateral OOS with hypoplastic ipsilateral TS and normal contralateral TS, unilateral OOS with bilateral hypoplastic TSs, and bilateral OOSs with bilateral normal TSs. Bilateral OOSs with bilateral hypoplastic TSs were found in 2 patients (0.9%). All these patients had syringomyelia. Instead of performing Y-shaped dural incision and duraplasty, surgical procedures were modified depending on the types of the OOSs to preserve their venous drainage routes. Although massive bleeding from the dominant OS during dural incision occurred in 1 patient, none suffered neurological deterioration. The syrinx volume decreased in all but 1 of the patients postoperatively.
Assessment of the venous drainage pattern using MRV is indispensable for safe surgical treatment in patients with CM-I. The surgical procedure should be modified based on the type of dominant OS to minimize the surgical risks.
I型Chiari畸形（CM-I）的外科治疗通常需要在后颅窝进行硬脑膜切开。在存在持续性枕窦（OS）的情况下，通常会闭塞并切断该窦。然而，有些患者的枕窦较为突出，需要对手术计划进行关键调整，以避免可能危及生命的大出血和脑静脉循环紊乱。在本研究中，分析了CM-I患者中优势枕窦的解剖变异情况，作者试图为伴有优势枕窦的CM-I患者制定治疗建议。
该研究纳入了213例在手术治疗前行磁共振静脉血管造影（MRV）的CM-I患者。使用二维时间飞跃MRV或三维相位对比MRV评估枕窦优势情况。特别关注静脉流出道的模式。对伴有优势枕窦患者的特征及手术结果进行回顾性分析。
7例（3.3%）患者发现有优势枕窦。伴有优势枕窦患者的年龄显著低于无优势枕窦者（p = 0.0202）。伴有优势枕窦患者的脊柱侧弯并发率显著高于无优势枕窦者（p = 0.0366）。所有优势枕窦均为斜型。2例（0.9%）患者为单侧斜行枕窦（OOS），同侧横窦（TS）正常，对侧横窦发育不全。作者分别发现1例（0.5%）患者为单侧OOS，同侧TS发育不全，对侧TS正常；1例单侧OOS，双侧TS发育不全；1例双侧OOS，双侧TS正常。2例（0.9%）患者为双侧OOS，双侧TS发育不全。所有这些患者均患有脊髓空洞症。手术未采用Y形硬脑膜切开和硬脑膜成形术，而是根据OOS的类型调整手术操作，以保留其静脉引流途径。尽管1例患者在硬脑膜切开时优势枕窦发生大出血，但无一例出现神经功能恶化。除1例患者外，所有患者术后脊髓空洞体积均减小。
对于CM-I患者的安全手术治疗，使用MRV评估静脉引流模式是必不可少的。应根据优势枕窦的类型调整手术操作，以将手术风险降至最低。
