Prevalence of amyloid in ligamentum flavum of patients with lumbar spinal stenosis

Transthyretin (ATTR) amyloidosis is often diagnosed in an advanced stage, when irreversible cardiac damage has occurred. Lumbar spinal stenosis (LSS) may precede cardiac ATTR amyloidosis by many years, offering the opportunity to detect ATTR already at the time of LSS surgery. We prospectively assessed the prevalence of ATTR in the ligamentum flavum by tissue biopsy in patients aged &gt;50 years undergoing surgery for LSS. Ligamentum flavum thickness was assessed pre-operatively on axial T2 magnetic resonance imaging (MRI) slices. Tissue samples from ligamentum flavum were screened centrally by Congo red staining and immunohistochemistry (IHC). Amyloid in the ligamentum flavum was detected in 74/94 patients (78.7%). IHC revealed ATTR in 61 (64.9%), whereas amyloid subtyping was inconclusive in 13 (13.8%). Mean thickness of ligamentum flavum was significantly higher at all levels in patients with amyloid (<i>p</i> &lt; .05). Patients with amyloid deposits were older (73.1 ± 9.2 vs. 64.6 ± 10.1 years, <i>p</i> = .01). No differences in sex, comorbidities, previous surgery for carpal tunnel syndrome or LSS were observed. Amyloid, mostly of the ATTR subtype, was found in four out of five patients with LSS and is associated with age and ligamentum flavum thickness. Histopathological work-up of ligamentum flavum might inform future decision making.

转甲状腺素蛋白（Transthyretin, ATTR）淀粉样变性通常在出现不可逆心脏损害的晚期才得以确诊。腰椎管狭窄症（Lumbar spinal stenosis, LSS）可能早于心脏ATTR淀粉样变性多年出现，这为在腰椎管狭窄症手术期间即检测到ATTR提供了契机。我们前瞻性评估了年龄＞50岁、因腰椎管狭窄症接受手术治疗的患者中，黄韧带组织活检检出ATTR的患病率。术前通过轴位T2磁共振成像（MRI）切片评估黄韧带厚度。对黄韧带组织标本采用刚果红染色及免疫组织化学染色（immunohistochemistry, IHC）进行中心实验室筛查。在94例患者中的74例（78.7%）检出黄韧带内淀粉样物质。免疫组织化学染色证实61例（64.9%）为ATTR型淀粉样变性，13例（13.8%）的淀粉样物质分型结果不明确。存在淀粉样物质的患者，其各节段黄韧带厚度均显著更高（*p* < 0.05）。存在淀粉样沉积的患者年龄更大（73.1 ± 9.2 vs. 64.6 ± 10.1岁，*p* = .01）。两组在性别、合并症、既往腕管综合征手术史或腰椎管狭窄症手术史方面均无显著差异。每5例腰椎管狭窄症患者中即有4例检出以ATTR亚型为主的淀粉样物质，且该现象与患者年龄及黄韧带厚度相关。对黄韧带进行组织病理学检测可为未来的临床决策提供参考依据。