Zhang Justin K, Javeed Saad, Greenberg Jacob K, Yakdan Salim, Noroozi Gilandehi Sama, Shah Lubdha M, Iyer Rajiv R, Dailey Andrew T, Bisson Erica F, Mahan Mark A, Mazur Marcus D, Song Sheng-Kwei, Ray Wilson Z
Department of Neurological Surgery, Washington University School of Medicine, Saint Louis, MO.
Department of Neurosurgery, Clinical Neurosciences Center.
Clin Spine Surg. 2025 May 1;38(4):204-212. doi: 10.1097/BSD.0000000000001763. Epub 2025 Feb 28.
STUDY DESIGN: Prospective cohort study. OBJECTIVE: To provide a primer of the glymphatic system, discuss its potential relevance in evaluating spinal diseases like cervical spondylotic myelopathy (CSM), and describe possible imaging markers of the glymphatic system derived from advanced diffusion-weighted imaging (dMRI), namely diffusion tensor imaging (DTI) and diffusion basis spectrum imaging (DBSI). SUMMARY OF BACKGROUND DATA: The glymphatic system is a recently described physiological process that plays an integral role in macroscopic waste clearance in the CNS through cerebrospinal fluid (CSF)-interstitial fluid (ISF) exchange. Chronic spinal cord compression in CSM leads to pathophysiological consequences that theoretically affect the glymphatic system, and advanced dMRI may be well positioned to characterize these changes. METHODS: This single-center study enrolled participants (control and CSM) from 2018 through 2020. All participants underwent clinical assessments and dMRI, followed by DTI and DBSI analyses, preoperatively and 2 years postoperatively. CSF flow was characterized by DTI-derived apparent diffusion coefficient (ADC) and ISF flow by DBSI-derived extra-axonal axial diffusivity (EA-AD) and radial diffusivity (EA-RD). Imaging parameters were compared among participants. RESULTS: Forty-two patients with CSM [23 (55%) mild, 9 (24%) moderate, 10 (21%) severe] and 20 control patients were included. Preoperatively, ADC was significantly lower in CSM (2.59±0.4 µm 2 /ms) than control (3.08±0.34 µm 2 /ms) patients ( P <0.01). Conversely, EA-AD and EA-RD were significantly higher in CSM (2.53±0.33; 0.48±0.13 µm 2 /ms) compared with control (2.27±0.2; 0.40±0.04 µm 2 /ms) patients (both P <0.01). Two years postoperatively, only EA-RD significantly decreased for CSM patients (Δ-0.04±0.12 µm 2 /ms, P <0.01). More severe CSM preoperatively was associated with lower baseline ADC (ρ=0.49, P <0.001) and higher baseline EA-RD (ρ=-0.35, P =0.005). CONCLUSIONS: The pathophysiology of CSM may affect the glymphatic system because of chronic spinal cord compression that decreases CSF bulk flow, leading to compensatory increases in ISF flow. Although research in this topic remains nascent, greater glymphatic system function observed on dMRI may correspond with greater disease burden. Future studies examining the role of the glymphatic system in spinal cord pathology are critical to better understanding how these noninvasive imaging biomarkers can improve patient outcomes in CSM. LEVEL OF EVIDENCE: Level II.
研究设计：前瞻性队列研究。 目的：介绍淋巴系统，讨论其在评估颈椎病性脊髓病（CSM）等脊柱疾病中的潜在相关性，并描述源自先进扩散加权成像（dMRI）的淋巴系统可能的成像标志物，即扩散张量成像（DTI）和扩散基谱成像（DBSI）。 背景数据总结：淋巴系统是最近描述的一种生理过程，通过脑脊液（CSF）-组织间液（ISF）交换在中枢神经系统的宏观废物清除中起不可或缺的作用。CSM中的慢性脊髓压迫会导致病理生理后果，理论上会影响淋巴系统，先进的dMRI可能非常适合表征这些变化。 方法：这项单中心研究在2018年至2020年招募了参与者（对照组和CSM组）。所有参与者在术前和术后2年均接受了临床评估和dMRI检查，随后进行DTI和DBSI分析。CSF流动通过DTI衍生的表观扩散系数（ADC）来表征，ISF流动通过DBSI衍生的轴外轴向扩散率（EA-AD）和径向扩散率（EA-RD）来表征。对参与者的成像参数进行了比较。 结果：纳入了42例CSM患者[23例（55%）轻度，9例（24%）中度，10例（21%）重度]和20例对照患者。术前，CSM患者的ADC（2.59±0.4 µm²/ms）显著低于对照患者（3.08±0.34 µm²/ms）（P<0.01）。相反，与对照患者（2.27±0.2；0.40±0.04 µm²/ms）相比，CSM患者的EA-AD和EA-RD显著更高（2.53±0.33；0.48±0.13 µm²/ms）（均P<0.01）。术后2年，CSM患者仅EA-RD显著降低（Δ-0.04±0.12 µm²/ms，P<0.01）。术前病情越严重的CSM与较低的基线ADC（ρ=0.49，P<0.001）和较高的基线EA-RD（ρ=-0.35, P=0.005）相关。 结论：CSM的病理生理学可能由于慢性脊髓压迫导致CSF总体流量减少，从而影响淋巴系统，导致ISF流量代偿性增加。尽管该主题的研究仍处于初期阶段，但在dMRI上观察到的更强的淋巴系统功能可能与更大的疾病负担相对应。未来研究淋巴系统在脊髓病理学中的作用对于更好地理解这些非侵入性成像生物标志物如何改善CSM患者的预后至关重要。 证据级别：二级。
J Neurosci. 2021-9-15
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