Thurtell Matthew J, Tomsak Robert L, Leigh R John
Department of Neurology, University Hospitals Case Medical Center, Cleveland, Ohio, USA.
Ann N Y Acad Sci. 2009 May;1164:476-8. doi: 10.1111/j.1749-6632.2008.03713.x.
The central projections of the anterior semicircular canals are thought to be conveyed from the vestibular nuclei to the oculomotor nuclei in the midbrain by three distinct brainstem pathways: the medial longitudinal fasciculus, crossing ventral tegmental tract, and brachium conjunctivum. There is controversy as to whether upbeat nystagmus could result from lesions involving each of these pathways. We report a 52-year-old man who presented with a contralesional fourth-nerve palsy and primary-position upbeat-torsional nystagmus due to a small unilateral dorsal pontomesencephalic lymphomatous deposit. It is postulated that the upbeat-torsional nystagmus was caused by involvement of the brachium conjunctivum, which lies adjacent to the fourth-nerve fascicles at the dorsal pontomesencephalic junction, but involvement of the crossing ventral tegmental tract cannot be excluded. These observations suggest that, in humans, excitatory upward-torsional eye movement signals from the anterior semicircular canals could be partly conveyed to the midbrain by the brachium conjunctivum.
人们认为，前半规管的中枢投射是通过三条不同的脑干通路从前庭核传导至中脑的动眼神经核的：内侧纵束、交叉的腹侧被盖束和结合臂。对于涉及这些通路中的每一条通路的病变是否会导致上跳性眼球震颤，目前存在争议。我们报告了一名52岁男性，他因单侧桥脑背侧中脑小的淋巴瘤沉积物而出现对侧第四神经麻痹和原在位上跳扭转性眼球震颤。据推测，上跳扭转性眼球震颤是由结合臂受累引起的，结合臂位于桥脑背侧中脑交界处与第四神经束相邻，但不能排除交叉腹侧被盖束受累。这些观察结果表明，在人类中，来自前半规管的兴奋性向上扭转眼球运动信号可能部分通过结合臂传导至中脑。
