Meienberg O, Müri R
Baillieres Clin Neurol. 1992 Aug;1(2):417-34.
Lesions of the brain stem can either affect the nuclei or the fascicles of the third, fourth or sixth cranial nerves and thus produce ocular motor disorders. Lesions of the oculomotor nuclear complex differ from lesions of the third nerve, since the motoneurones in the nucleus are specifically grouped. Similarly, a lesion of the sixth nerve nucleus results in a conjugate gaze palsy and not in an abducens palsy, because of 'interneurones' being intermingled with the abducens motoneurons. Isolated lesions of a nerve fascicle, which is the part of the cranial nerve running through the brain stem, usually cannot be distinguished clinically from lesions of the nerve outside the brain stem unless other brain stem signs are present. In the case of an isolated ocular motor nerve palsy, modern imaging techniques, particularly magnetic resonance imaging, may help to localize the lesion to the brain stem. Most often, however, brain stem lesions also involve structures surrounding the ocular motor nuclei or fascicles, sometimes leading to characteristic eponymic syndromes. In congenital eye movement disorders the pathoanatomical situation is more complex. Since the lesion takes place during intrauterine or early postnatal development, corrective misdirection of neurones occurs in addition to aplasia or hypoplasia of parts of the cranial nerves. Correspondingly, abnormal movements accompanying an attempted eye movement can be observed in some characteristic syndromes.
脑干病变可影响第三、第四或第六对脑神经的核团或神经束，从而导致眼球运动障碍。动眼神经核复合体的病变与第三神经的病变不同，因为核内的运动神经元是特定分组的。同样，第六神经核的病变会导致同向凝视麻痹，而不是外展神经麻痹，这是因为“中间神经元”与外展运动神经元混合在一起。穿过脑干的脑神经部分即神经束的孤立性病变，通常在临床上无法与脑干外神经的病变区分开来，除非有其他脑干体征。在孤立性眼球运动神经麻痹的情况下，现代成像技术，尤其是磁共振成像，可能有助于将病变定位到脑干。然而，脑干病变最常还累及眼球运动核或神经束周围的结构，有时会导致具有特征性的以人名命名的综合征。在先天性眼球运动障碍中，病理解剖情况更为复杂。由于病变发生在子宫内或出生后早期发育阶段，除了脑神经部分发育不全或发育不良外，还会出现神经元的矫正性错误定向。相应地，在一些特征性综合征中可以观察到试图眼球运动时伴随的异常运动。
