Yasuda Taketoshi, Suzuki Kayo, Kawaguchi Yoshiharu, Seki Shoji, Makino Hiroto, Watanabe Kenta, Hori Takeshi, Yamagami Tohru, Kanamori Masahiko, Kimura Tomoatsu
Department of Orthopaedic Surgery, Faculty of Medicine, University of Toyama, 2630 Sugitani, Toyama, Toyama, 930-0194, Japan.
Department of Orthopaedic Surgery, Nippon Koukan Hospital, 1-2-1 Kokandori, Kawasaki, Kanagawa, 210-0852, Japan.
BMC Musculoskelet Disord. 2018 Mar 1;19(1):66. doi: 10.1186/s12891-018-1988-8.
Lumbar epidural lipomatosis (LEL) is characterized by abnormal accumulation of unencapsulated adipose tissue in the spinal epidural space. Such accumulation compresses the dural sac and nerve roots, and results in various neurological findings. However, the pathophysiology of LEL remains unclear. This study examined the associations between imaging and clinical findings in detail, and investigated the mechanisms underlying symptom onset by measuring intraoperative epidural pressures in LEL.
Sixteen patients (all men; mean age, 68.8 years) were enrolled between 2011 and 2015. Mean body mass index was 26.5 kg/m. Four cases were steroid-induced, and the remaining 12 cases were idiopathic. All patients presented with neurological deficits in the lower extremities. Cauda equina syndrome (CES) alone was seen in 8 patients, radiculopathy alone in 4, and both radiculopathy and CES (mixed CES) in 4. All patients subsequently underwent laminectomy with epidural lipomatosis resection and were followed-up for more than 1 year. We investigated the clinical course and imaging and measured epidural pressures during surgery.
Subjective symptoms improved within 1 week after surgery. Mean Japanese Orthopaedic Association (JOA) score was 15.2 ± 2.8 before surgery, improving to 25.4 ± 2.5 at 1 year after surgery. On magnetic resonance imaging, all lipomatosis lesions included the L4-5 level. On preoperative computed tomography, saucerization of the laminae was not observed in radiculopathy cases, whereas saucerization of the posterior vertebral body was observed in all radiculopathy or mixed CES cases. Intraoperative epidural pressures were significantly higher than preoperative subarachnoid pressures. The results suggest that high epidural pressure resulting from the proliferation of adipose tissue leads to saucerization of the lumbar spine and subsequent symptoms.
Clinical courses were satisfactory after laminectomy. In LEL, epidural pressure increases and symptoms develop through the abnormal proliferation of adipose tissue. Higher epidural pressures induce saucerization of the laminae and/or posterior vertebral body. Furthermore, the direction of proliferative adipose tissue (i.e., site of saucerization) might be related to the types of neurological symptoms.
腰椎硬膜外脂肪增多症（LEL）的特征是未包裹的脂肪组织在脊髓硬膜外间隙异常蓄积。这种蓄积会压迫硬膜囊和神经根，并导致各种神经学表现。然而，LEL的病理生理学仍不清楚。本研究详细检查了影像学与临床发现之间的关联，并通过测量LEL患者术中硬膜外压力来探究症状发作的潜在机制。
2011年至2015年间纳入了16例患者（均为男性；平均年龄68.8岁）。平均体重指数为26.5kg/m²。4例为类固醇诱导型，其余12例为特发型。所有患者均表现为下肢神经功能缺损。仅马尾综合征（CES）8例，仅神经根病4例，神经根病和CES均有（混合性CES）4例。所有患者随后均接受了椎板切除术及硬膜外脂肪切除术，并进行了超过1年的随访。我们调查了临床病程、影像学表现，并测量了手术期间的硬膜外压力。
主观症状在术后1周内改善。术前日本骨科协会（JOA）平均评分为15.2±2.8，术后1年提高至25.4±2.5。在磁共振成像上，所有脂肪增多症病变均累及L4 - 5节段。在术前计算机断层扫描中，神经根病病例未观察到椎板碟形化，而在所有神经根病或混合性CES病例中均观察到椎体后缘碟形化。术中硬膜外压力显著高于术前蛛网膜下腔压力。结果表明，脂肪组织增生导致的高硬膜外压力会导致腰椎碟形化及随后的症状。
椎板切除术后临床病程令人满意。在LEL中，硬膜外压力升高且症状通过脂肪组织的异常增生而出现。较高的硬膜外压力会导致椎板和/或椎体后缘碟形化。此外，增生性脂肪组织的方向（即碟形化部位）可能与神经症状的类型有关。
