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目前对于支配眼球垂直运动的神经调控通路没有完全研究清楚。但通常认为眼球垂直凝视的皮质下中枢及其传导通路位于中脑，中脑病变及丘脑病变扩延至中脑水平均可引起垂直眼球凝视障碍。常见表现为4种综合征。 1 Parinaud’s syndrome 2 Vertical ‘half-and-a-half’ syndrome 3 Vertical ‘one-and-a-half’ syndrome 4 Vertical ‘one-and-a-one’ syndrome 1、Parinaud’s syndrome Parinaud 综合征，或者叫中脑背侧综合征、顶盖前区综合征或后联合综合征。临床表现为双眼上视麻痹（如下图）。 中脑与眼球垂直运动相关结构主要有：内侧纵束头端间质核（riMLF）、Cajal间质核（interstitial nucleus of Cajal，INC）、后连合（posterior commissure，PC）。riMLF主要参与垂直扫视，INC参与垂直凝视和维持注视，PC使双眼活动同步。其结构位置如下图所示： 上视传导路径如下图：riMLF内神经元发出垂直扫视指令，INC内神经元发出垂直追踪指令，传导纤维在后联合部位交叉，投射到双侧动眼神经核的相应部分。当后联合相关区域病变时，患者出现双侧上视麻痹。 病例1：肿瘤压迫后联合 病例2：left poseromedial thalamic infarct 病例3：left paramedian midbrain lacunar stroke 2、Vertical ‘half-and-a-half’ syndrome 临床表现为病变同侧下视麻痹伴对侧上视麻痹。
正常垂直扫视传导通路为：riMLF内神经元发出垂直扫视指令后，上视扫视纤维通过后联合交叉传导至对侧动眼神经上直肌核，支配上直肌，下视扫视纤维在同侧下行至同侧动眼神经下直肌核，支配下直肌。完成垂直扫视。如下图所示：
当出现后联合交叉前病变时，出现同侧下视麻痹合并对侧上视麻痹，如图所示：
病例1：a small stroke restricted to the thalamic-mesencephalic junction
病例2：a small thalamomesencephalic stroke
3、Vertical ‘one-and-a-half’ syndrome “垂直一个半综合征”，常表现为一眼上视麻痹，双眼下视麻痹。
当病变累及riMLF及后联合交叉时，可表现出同侧上视、下视麻痹伴有对侧上视麻痹，传导通路及病变位置如下图：
病例：left periventricular mesodiencephalic infarct
(a)axial FLAIR and (b)diffusion-weighted image showing left periventricular mesodiencephalic infarct at the bottom of the third ventricle. 4、Vertical ‘one-and-a-one’ syndrome 临床表现为双眼均不能上视或下视，影像学表现常为单侧病变，具体机制不明，有待进一步研究明确，仅将病例列举如下： 病例1：Brain magnetic resonance imaging-diffusion-weighted imaging axial view (a and b) bright signal change in the right paramedian midbrain and anteromedial thalamus (red arrow); apparent diffusion coefficient axial view (d and e) corresponding dark signal change (red arrow); magnetic resonance angiography of intracranial arteries shows thinning of right posterior cerebral artery (red arrow)(c)
病例2：Brain magnetic resonance imaging-diffusion-weighted imaging axial view (a) bright signal change in left anteromedial thalamus (red arrow); apparent diffusion coefficient axial view (b) corresponding dark signal change (red arrow)。magnetic resonance angiography of intracranial arteries shows no abnormality (c)
病例3：Brain magnetic resonance imaging-diffusion-weighted imaging axial view (a) bright signal change in the left thalamus (red arrow) and occipital cortex; magnetic resonance angiography (b) shows thinning of both osterior cerebral artery。
病例4：(a) T2 axial and (b) diffusion MRI of the midbrain. The arrows indicate the ischemic lesion at caudal (left) and rostral (right) midbrain levels.
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