Department of Neurosurgery, Rhode Island Hospital, The Warren Alpert Medical School of Brown University, Providence, Rhode Island, USA.
Center for Biomedical Engineering and School of Engineering, Brown University, Providence, Rhode Island, USA.
World Neurosurg. 2022 Jun;162:e492-e502. doi: 10.1016/j.wneu.2022.03.038. Epub 2022 Mar 17.
Patients with hypermobile Ehlers-Danlos syndrome (hEDS), a heritable connective tissue disorder, present frequently with symptoms of tethered cord syndrome (TCS) but without a low-lying conus. Currently, surgical treatment of such cases is controversial. Because connective tissue disorder affects fibrous structures, we hypothesized that a diseased filum terminale (FT) might cause TCS in hEDS, justifying surgical transection for treatment.
We investigated FT pathology, FT biomechanics, clinical presentation, and outcome following FT excision in 78 radiologically occult hEDS-TCS cases and for comparison in 38 typical TCS cases with low-lying conus and/or fatty FT infiltration but without hEDS.
In hEDS-TCS, electron microscopy revealed inherited collagen fibril abnormalities and acquired fibril damage. Biomechanical tension tests revealed elastic properties of the FT in both study groups, but they were impaired in the hEDS TCS. Follow-up examinations at 3 and 12 months after FT excision showed statistically significant improvement of urinary, bowel, and neurologic symptoms in both study groups; intergroup comparison revealed no differences in outcome except more pronounced neurologic improvement in the hEDS-TCS group.
Both morphologic findings and biomechanical tests indicate limited elastic properties of the FT in hEDS, which is no more able to dampen but still transmitting spine movement-related stretch forces. That mechanism exposes the conus medullaris to unphysiologic stretch forces, causing TCS, especially when considering the hypermobile spine in hEDS. This notion is supported by the observed clinical improvement following FT resection in hEDS-TCS cases without a low-lying conus.
患有可动性埃勒斯-当洛斯综合征（hEDS）的患者，一种遗传性结缔组织疾病，经常出现脊髓栓系综合征（TCS）的症状，但没有低位圆锥。目前，此类病例的手术治疗存在争议。因为结缔组织疾病会影响纤维结构，我们假设病变的终丝（FT）可能会导致 hEDS 中的 TCS，从而证明手术横断是合理的治疗方法。
我们研究了 78 例影像学隐匿性 hEDS-TCS 病例和 38 例典型 TCS 病例（低位圆锥和/或脂肪性 FT 浸润，但无 hEDS）的 FT 病理学、FT 生物力学、临床表现和 FT 切除后的结果。
在 hEDS-TCS 中，电子显微镜显示存在遗传性胶原纤维异常和获得性纤维损伤。生物力学张力测试显示两组 FT 都具有弹性特性，但 hEDS-TCS 组的弹性特性受损。FT 切除后 3 个月和 12 个月的随访检查显示，两组患者的尿、肠和神经症状均有统计学显著改善；组间比较显示，除 hEDS-TCS 组的神经症状改善更为明显外，两组结果无差异。
形态学发现和生物力学测试均表明 hEDS 中的 FT 弹性特性有限，无法减震，但仍能传递与脊柱运动相关的拉伸力。这种机制使圆锥暴露在非生理性的拉伸力下，导致 TCS，特别是在考虑到 hEDS 中的可动性脊柱时。这一观点得到了 hEDS-TCS 病例中无低位圆锥的 FT 切除后观察到的临床改善的支持。
