Peking University Aerospace School of Clinical Medicine, Beijing 100049, PR China.
Peking University Aerospace School of Clinical Medicine, Beijing 100049, PR China.
Neuroimage Clin. 2020;26:102216. doi: 10.1016/j.nicl.2020.102216. Epub 2020 Feb 18.
Persistent postural-perceptual dizziness (PPPD) is a functional vestibular disorder characterized by persistent dizziness, unsteadiness, and non-spinning vertigo. It is the most common cause of chronic vestibular syndrome, but its pathogenesis is currently unclear. Recent studies have indicated that sensory integration may be altered in PPPD patients.
Using independent component analysis (ICA) combined with seed-based functional connectivity analysis, we aimed to analyze changes in brain network functional connectivity (FC) in PPPD patients during the resting state and to explore the underlying pathogenesis of PPPD, particularly the abnormal integration of multiple sensations.
Study subjects included 12 PPPD patients and 12 healthy controls and were recruited from January to August 2018. Detailed medical data were collected from all participants. Vestibular function, neurological and medical examinations were conducted to exclude other diseases associated with chronic dizziness. Functional MRI was performed on all subjects. ICA and seed-based functional connectivity analysis were performed to examine changes in intra- and inter-network FC in PPPD patients.
In total, 13 independent components were identified using ICA. Compared with healthy controls, PPPD patients showed decreased intra-network FC in the right precuneus within the posterior default mode network. Moreover, seed-based functional connectivity analysis showed decreased intra-network FC between the right precuneus and the bilateral precuneus and left premotor cortex, and enhanced FC between the right precuneus and bilateral corpus callosum. With respect to the inter-network, FC in PPPD patients was increased between the occipital pole visual network and auditory, sensorimotor networks, as well as the lateral visual and auditory networks. Additional analyses showed that FC changes were negatively correlated with dizziness handicap inventory functional scores.
In PPPD patients, dysfunction in the precuneus may cause abnormalities in external environment monitoring and in posture and movement regulation. Compensatory strategies may then be adopted to maintain balance. At the local level, information exchange between the two cerebral hemispheres is enhanced via the corpus callosum. At the whole brain level, through enhancement of functional activities of the visual network, the integration of multiple sensations and the regulation of posture and movement are primarily driven by visual information.
持续性姿势感知性头晕（PPPD）是一种以持续性头晕、不稳和非旋转性眩晕为特征的功能性前庭障碍。它是慢性前庭综合征最常见的原因，但目前其发病机制尚不清楚。最近的研究表明，PPP 患者的感觉整合可能会发生改变。
本研究采用独立成分分析（ICA）结合基于种子的功能连接分析，旨在分析 PPPD 患者在静息状态下脑网络功能连接（FC）的变化，并探讨 PPPD 的潜在发病机制，特别是多种感觉的异常整合。
研究对象包括 12 例 PPPD 患者和 12 例健康对照者，均于 2018 年 1 月至 8 月招募。所有参与者均收集详细的医学数据。进行前庭功能、神经和医学检查，以排除与慢性头晕相关的其他疾病。对所有受试者进行功能磁共振成像检查。采用 ICA 和基于种子的功能连接分析，观察 PPPD 患者的内、网络间 FC 的变化。
共识别出 13 个独立成分。与健康对照组相比，PPP 患者在后默认模式网络的右侧顶下小叶内表现出内网络 FC 降低。此外，基于种子的功能连接分析显示，右侧顶下小叶与双侧顶下小叶和左侧运动前皮质之间的内网络 FC 降低，而右侧顶下小叶与双侧胼胝体之间的 FC 增强。对于网络间，PPP 患者的枕极视觉网络与听觉、感觉运动网络以及外侧视觉和听觉网络之间的 FC 增加。进一步分析表明，FC 的变化与头晕残障量表功能评分呈负相关。
在 PPPD 患者中，顶下小叶功能障碍可能导致对外界环境监测和姿势与运动调节异常。然后可能会采取代偿策略来维持平衡。在局部水平，通过胼胝体增强两个大脑半球之间的信息交换。在全脑水平，通过增强视觉网络的功能活动，主要通过视觉信息来驱动多种感觉的整合和姿势与运动的调节。
