Kohara Kotaro, Maegawa Tatsuya, Okumura Eitaro, Hashimoto Ryo, Kubota Motoo
Department of Spine Surgery, Kameda Medical Center, Kamogawa, Chiba, Japan.
NMC Case Rep J. 2025 Jun 30;12:283-288. doi: 10.2176/jns-nmc.2025-0052. eCollection 2025.
Foramen magnum decompression is an established surgical method for the treatment of Chiari type 1 malformation with syringomyelia. However, in some cases, neurologic symptoms that improve only after foramen magnum decompression may deteriorate again, and it has been suspected that increased instability of the craniocervical junction may be a factor. We report a case of Chiari type 1 malformation accompanied by basilar invagination and syringomyelia in which atlantoaxial facet joint distraction and fixation was performed as a revision surgery for deteriorating neurologic symptoms after foramen magnum decompression. The patient was a 16-year-old boy with chief complaints of gait disturbance and repeated falls. He was diagnosed with Chiari type 1 malformation accompanied by basilar invagination and syringomyelia. The clivo-axial angle was narrow at 105.8°. Initially, only foramen magnum decompression was performed, and the symptoms were relieved after the procedure but re-exacerbated within 2 weeks. The condition was speculated to have worsened instability at the atlantoaxial segment and ventral medullary compression; then, atlantoaxial facet joint distraction and fixation was performed secondarily, and symptoms improved. There is no clear surgical standard for performing foramen magnum decompression, atlantoaxial facet joint distraction and fixation, or a combination of both for Chiari type 1 malformation. Foramen magnum decompression provides horizontal decompression at the craniocervical junction, and atlantoaxial facet joint distraction and fixation achieves vertical indirect decompression of the ventral medulla and stabilization of the atlantoaxial segment in case with basilar invagination. Our experience suggests that combined foramen magnum decompression and atlantoaxial facet joint distraction and fixation may be particularly beneficial in Chiari type 1 malformation cases with basilar invagination and narrow clivo-axial angle.
枕骨大孔减压术是治疗伴有脊髓空洞症的Chiari I型畸形的一种成熟手术方法。然而，在某些情况下，仅在枕骨大孔减压术后改善的神经症状可能会再次恶化，有人怀疑颅颈交界区稳定性增加可能是一个因素。我们报告一例伴有基底凹陷和脊髓空洞症的Chiari I型畸形病例，该病例在枕骨大孔减压术后因神经症状恶化而进行了寰枢关节撑开固定术作为翻修手术。患者为一名16岁男孩，主要症状为步态障碍和反复跌倒。他被诊断为伴有基底凹陷和脊髓空洞症的Chiari I型畸形。斜坡-枢椎角狭窄，为105.8°。最初仅进行了枕骨大孔减压术，术后症状缓解，但在2周内再次加重。推测病情在寰枢段不稳定加剧和延髓腹侧受压方面有所恶化；随后，二期进行了寰枢关节撑开固定术，症状得到改善。对于Chiari I型畸形，进行枕骨大孔减压术、寰枢关节撑开固定术或两者联合手术，目前尚无明确的手术标准。枕骨大孔减压术在颅颈交界区提供水平减压，而寰枢关节撑开固定术可实现延髓腹侧的垂直间接减压，并在存在基底凹陷的情况下稳定寰枢段。我们的经验表明，对于伴有基底凹陷和斜坡-枢椎角狭窄的Chiari I型畸形病例，联合枕骨大孔减压术和寰枢关节撑开固定术可能特别有益。
