BioMedical Engineering Imaging Institute, Icahn School of Medicine at Mount Sinai, New York, NY, United States of America.
Nash Family Department of Neuroscience, Icahn School of Medicine at Mount Sinai, New York, NY, United States of America.
PLoS One. 2021 Mar 26;16(3):e0247678. doi: 10.1371/journal.pone.0247678. eCollection 2021.
Cognitive dysfunction after surgery under general anesthesia is a well-recognized clinical phenomenon in the elderly. Physiological effects of various anesthetic agents have been studied at length. Very little is known about potential effects of anesthesia on brain structure. In this study we used Diffusion Tensor Imaging to compare the white matter microstructure of healthy control subjects under sevoflurane anesthesia with their awake state. Fractional Anisotropy, a white mater integrity index, transiently decreases throughout the brain during sevoflurane anesthesia and then returns back to baseline. Other DTI metrics such as mean diffusivity, axial diffusivity and radial diffusivity were increased under sevoflurane anesthesia. Although DTI metrics are age dependent, the transient changes due to sevoflurane were independent of age and sex. Volumetric analysis shows various white matter volumes decreased whereas some gray matter volumes increased during sevoflurane anesthesia. These results suggest that sevoflurane anesthesia has a significant, but transient, effect on white matter microstructure. In spite of the transient effects of sevoflurane anesthesia there were no measurable effects on brain white matter as determined by the DTI metrics at 2 days and 7 days following anesthesia. The role of white matter in the loss of consciousness under anesthesia will need to be studied and MRI studies with subjects under anesthesia will need to take these results into account.
全麻术后认知功能障碍是老年人中一种公认的临床现象。各种麻醉剂的生理效应已经被广泛研究。然而，麻醉对大脑结构的潜在影响却知之甚少。在这项研究中，我们使用弥散张量成像（DTI）比较了健康对照者在七氟醚麻醉下和清醒状态下的白质微观结构。各向异性分数（FA），一个白质完整性指数，在七氟醚麻醉期间会在整个大脑中短暂下降，然后恢复到基线水平。其他 DTI 指标，如平均弥散度、轴向弥散度和径向弥散度，在七氟醚麻醉下增加。虽然 DTI 指标与年龄有关，但七氟醚引起的短暂变化与年龄和性别无关。容积分析显示，在七氟醚麻醉期间，各种白质体积减少，而一些灰质体积增加。这些结果表明，七氟醚麻醉对白质微观结构有显著但短暂的影响。尽管七氟醚麻醉有短暂的影响，但在麻醉后 2 天和 7 天，通过 DTI 指标测量，并未发现对脑白质有可测量的影响。在麻醉下失去意识的过程中，白质的作用仍需要研究，并且在进行 MRI 研究时需要考虑这些结果。
