Department of Neurosurgery, University of Cincinnati College of Medicine, Cincinnati, OH, USA.
Department of Brain and Spinal Surgery, Naval Medical Center Portsmouth, Portsmouth, VA, USA.
Neurocrit Care. 2022 Jun;37(Suppl 1):60-66. doi: 10.1007/s12028-021-01376-0. Epub 2021 Nov 18.
How widely spreading depolarizations (SDs) propagate through the gyrencephalic brain, including sulci and deeper cortical areas, remains an important clinical question. Here, we investigated SDs that occur spontaneously after subarachnoid placement of autologous blood clots in sulci of the juvenile swine brain.
To investigate the three-dimensional spread of waves, animals underwent continuous diffusion-weighted magnetic resonance imaging (DW-MRI) for up to 6 h following clot placement. SD is the mechanism of the cytotoxic edema of developing infarction that is diagnosed by DW-MRI, and DW-MRI also captures transient diffusion restriction caused by SD in less injured or healthy brains. Here, images (b = 0, 375, and 750) were acquired across five coronal slices with 1.25 × 1.25-mm in-plane resolution and 5-mm slice thickness, and the protocol was repeated every 6.83-9.15 s. Spatial drift correction, temporal smoothing, and signal intensity normalization were applied to generate videos of diffusion signal intensity changes for each coronal slice.
Review of video data from five animals revealed ten discrete events consisting of focal diffusion restriction that propagated through cerebral cortex. All events originated in the cortex surrounding the sulcal clot, either in the gyrus (n = 4) or in the sulcal depth (n = 6). In six cases, two to three independent waves spread simultaneously in medial, lateral, and antero-posterior directions. Waves traveled within sulcal walls, traversed the depths of sulci to re-emerge on the adjacent gyrus, and, in three cases, spread fully around the dorsolateral convexity. One event spread deep to olfactory regions along midline cortex, and no events were observed contralateral to the subarachnoid clot.
Together, these results suggest that SDs in the injured gyrencephalic brain originate near the injury focus and can spread extensively through the cortex to wide and deep uninjured regions. These findings have implications for transient neurologic deficits in the neurocritically ill patient and relevance to patient monitoring and therapeutics.
自发性蛛网膜下腔出血后，大脑回间沟和深部脑皮质等部位广泛出现的去极化波（SD）如何传播，这是一个重要的临床问题。本研究旨在探讨自体血凝血块放置在幼年猪脑回间沟后自发出现的 SD。
为了研究波的三维传播，动物在放置血块后进行了长达 6 小时的连续弥散加权磁共振成像（DW-MRI）。SD 是形成发展性梗塞细胞毒性水肿的机制，DW-MRI 也可以捕获在损伤较小或健康的大脑中由 SD 引起的短暂弥散受限。DW-MRI 中，b 值为 0、375 和 750 时，在 5 个冠状切片上采集图像，分辨率为 1.25×1.25mm，层厚为 5mm，每隔 6.83-9.15s 重复一次该序列。对图像进行空间漂移校正、时间平滑和信号强度归一化，生成每个冠状切片扩散信号强度变化的视频。
对 5 只动物的视频数据进行回顾，发现 10 个离散事件，这些事件表现为局灶性弥散受限，在大脑皮质中传播。所有事件均起源于围绕脑回间沟的皮质，位于脑回（n=4）或脑回间沟深部（n=6）。在 6 个病例中，2 到 3 个独立的波同时在内侧、外侧和前-后方向上传播。波在脑回间沟壁内传播，穿过脑回的深度，在相邻脑回重新出现，在 3 个病例中，波完全传播到大脑外侧凸。1 个事件沿中线皮质向嗅区深部传播，在蛛网膜下腔血凝血块的对侧未观察到事件。
综上所述，这些结果表明，损伤性脑回间沟大脑中的 SD 起源于损伤焦点附近，并可广泛传播至皮质，扩散到广泛而深的未损伤区域。这些发现对神经危重症患者短暂性神经功能缺损具有重要意义，也与患者监测和治疗相关。
