Saeki N, Murai N, Sunami K
Department of Neurological Surgery, Chiba University School of Medicine, Japan.
No To Shinkei. 1992 Apr;44(4):383-7.
This is a report of 3 cases presented with oculomotor nerve palsy caused by small midbrain infarct. The aim of this report is to clarify the functional topography of intranuclear and intrafascicular portion of the oculomotor nerve with MRI. Three cases are 2 males and 1 female, ranging 51 to 68 years in age. Except for the long tract signs at the acute stage, cardinal sings were all eye-related, incomplete in 1 case and pupil sparing-type in 2 cases. In MRI, the size of the lesion extended 5 to 12 mm. In the incomplete palsy case, the infarction extended from the level immediately below the 3rd ventricle into the whole length of midbrain, whereas in the pupil-sparing types, more limited lesion excluding the upper part of the midbrain was noted. Anatomically the longitudinal size of the nucleus is 10mm and nerves functionally related to pupil reaction, eye motion and eyelid elevation are arranged in rosrocaudal order. Therefore, it is speculated that in midbrain, intrafascicular location of nerve fibers associated with pupil reaction is rostral and oculomotor nerve palsy of pupil sparing type is caused by the lesion excluding the rostral midbrain. MRI findings of the present 3 cases are compatible with this speculation. The lowest border of red nucleus is at the level of superior colliculus, whereas oculomotor nucleus has its lowest margin at the inferior colliculus. Therefore, red nucleus becomes an informative landmark to visualized the level of oculomotor nerve injury, since the red nucleus is clearly demonstrated in high intensity in T2 weighted image.
这是一篇关于3例因中脑小梗死导致动眼神经麻痹病例的报告。本报告的目的是通过磁共振成像（MRI）阐明动眼神经核内和神经束内部分的功能解剖结构。3例患者中，男性2例，女性1例，年龄在51至68岁之间。除急性期的长束征外，主要体征均与眼部有关，1例为不完全性，2例为瞳孔保留型。在MRI上，病变大小为5至12毫米。在不完全性麻痹病例中，梗死从第三脑室正下方水平延伸至中脑全长，而在瞳孔保留型病例中，可见病变更局限，未累及中脑上部。从解剖学上讲，动眼神经核的纵向大小为10毫米，与瞳孔反应、眼球运动和眼睑上抬功能相关的神经按前后顺序排列。因此，推测在中脑，与瞳孔反应相关的神经纤维在神经束内的位置靠前，瞳孔保留型动眼神经麻痹是由不累及中脑前部的病变引起的。本3例患者的MRI表现与这一推测相符。红核的最低边界位于上丘水平，而动眼神经核的最低边缘位于下丘水平。因此，红核成为一个有用的标志，可用于观察动眼神经损伤的水平，因为在T2加权图像上红核能清晰地显示为高信号。
