Nuzzi Raffaele, Dallorto Laura, Rolle Teresa
Eye Clinic, Department of Surgical Sciences, University of Torino, Turin, Italy.
Front Neurosci. 2018 May 29;12:363. doi: 10.3389/fnins.2018.00363. eCollection 2018.
Glaucoma is a leading cause of irreversible blindness worldwide. The increasing interest in the involvement of the cortical visual pathway in glaucomatous patients is due to the implications in recent therapies, such as neuroprotection and neuroregeneration. In this review, we outline the current understanding of brain structural, functional, and metabolic changes detected with the modern techniques of neuroimaging in glaucomatous subjects. We screened MEDLINE, EMBASE, CINAHL, CENTRAL, LILACS, Trip Database, and NICE for original contributions published until 31 October 2017. Studies with at least six patients affected by any type of glaucoma were considered. We included studies using the following neuroimaging techniques: functional Magnetic Resonance Imaging (fMRI), resting-state fMRI (rs-fMRI), magnetic resonance spectroscopy (MRS), voxel- based Morphometry (VBM), surface-based Morphometry (SBM), diffusion tensor MRI (DTI). Over a total of 1,901 studies, 56 case series with a total of 2,381 patients were included. Evidence of neurodegenerative process in glaucomatous patients was found both within and beyond the visual system. Structural alterations in visual cortex (mainly reduced cortex thickness and volume) have been demonstrated with SBM and VBM; these changes were not limited to primary visual cortex but also involved association visual areas. Other brain regions, associated with visual function, demonstrated a certain grade of increased or decreased gray matter volume. Functional and metabolic abnormalities resulted within primary visual cortex in all studies with fMRI and MRS. Studies with rs-fMRI found disrupted connectivity between the primary and higher visual cortex and between visual cortex and associative visual areas in the task-free state of glaucomatous patients. This review contributes to the better understanding of brain abnormalities in glaucoma. It may stimulate further speculation about brain plasticity at a later age and therapeutic strategies, such as the prevention of cortical degeneration in patients with glaucoma. Structural, functional, and metabolic neuroimaging methods provided evidence of changes throughout the visual pathway in glaucomatous patients. Other brain areas, not directly involved in the processing of visual information, also showed alterations.
青光眼是全球不可逆性失明的主要原因。人们对青光眼患者皮质视觉通路受累的兴趣日益增加，这是由于其对近期治疗方法（如神经保护和神经再生）具有重要意义。在本综述中，我们概述了目前对青光眼患者使用现代神经影像学技术检测到的脑结构、功能和代谢变化的理解。我们在MEDLINE、EMBASE、CINAHL、CENTRAL、LILACS、Trip数据库和NICE中筛选了截至2017年10月31日发表的原创性研究。纳入了至少有6例受任何类型青光眼影响患者的研究。我们纳入了使用以下神经影像学技术的研究：功能磁共振成像（fMRI）、静息态fMRI（rs-fMRI）、磁共振波谱（MRS）、基于体素的形态学测量（VBM）、基于表面的形态学测量（SBM）、扩散张量MRI（DTI）。在总共1901项研究中，纳入了56个病例系列，共计2381例患者。在青光眼患者的视觉系统内外均发现了神经退行性变过程的证据。通过SBM和VBM已证实视觉皮层存在结构改变（主要是皮层厚度和体积减小）；这些变化不仅限于初级视觉皮层，还涉及联合视觉区域。与视觉功能相关的其他脑区显示出一定程度的灰质体积增加或减少。在所有使用fMRI和MRS的研究中，初级视觉皮层内均出现了功能和代谢异常。rs-fMRI研究发现，在青光眼患者的无任务状态下，初级视觉皮层与高级视觉皮层之间以及视觉皮层与联合视觉区域之间的连接中断。本综述有助于更好地理解青光眼患者的脑异常情况。它可能会激发对晚年脑可塑性以及治疗策略（如预防青光眼患者的皮质变性）的进一步思考。结构、功能和代谢神经影像学方法为青光眼患者整个视觉通路的变化提供了证据。其他未直接参与视觉信息处理的脑区也显示出改变。
