Jules Stein Eye Institute, University of California, Los Angeles, USA.
Am J Ophthalmol. 2011 Dec;152(6):1067-1073.e2. doi: 10.1016/j.ajo.2011.05.031. Epub 2011 Sep 8.
To seek evidence of neurovascular compression of motor cranial nerves (CNs) in otherwise idiopathic neuropathic strabismus using high-resolution magnetic resonance imaging (MRI).
Prospective, observational case series.
High-resolution, surface coil orbital MRI was performed in 10 strabismic patients with idiopathic oculomotor (CN III) or abducens (CN VI) palsy. Relationships between CNs and intracranial arteries were demonstrated by 0.8-mm thick, 162-μm resolution, heavily T2-weighted MRI in fast imaging using steady-state acquisition sequences. Images were analyzed digitally to evaluate cross-sectional areas of extraocular muscles.
In one patient with CN III palsy, an ectatic posterior communicating artery markedly flattened and thinned the ipsilateral subarachnoid CN III. Cross-sections of the affected medial, superior, and inferior rectus muscles 10 mm posterior to the globe-optic nerve junction were 17.2 ± 2.5 mm(2), 15.5 ± 1.3 mm(2), and 9.9 ± 0.8 mm(2), significantly smaller than the values of 23.6 ± 1.9 mm(2), 30.4 ± 4.1 mm(2), and 28.8 ± 4.6 mm(2), respectively, of the unaffected side (P < .001). In 2 patients with otherwise unexplained CN VI palsy, ectatic basilar arteries contacted CN VI. Mean cross-sections of affected lateral rectus muscles were 24.0 ± 2.3 mm(2) and 29.8 ± 3.1 mm(2), significantly smaller than the values of 33.5 ± 4.1 mm(2) and 36.9 ± 1.6 mm(2), respectively, in unaffected contralateral eyes (P < .05).
Nonaneurysmal motor CN compression should be considered as a cause of CN III and CN VI paresis with neurogenic muscle atrophy when MRI demonstrates vascular distortion of the involved CN. Demonstration of a benign vascular cause can terminate continuing diagnostic investigations and can expedite rational management of the strabismus.
利用高分辨率磁共振成像（MRI）寻找其他特发性神经源性斜视中运动颅神经（CN）的神经血管压迫证据。
前瞻性、观察性病例系列研究。
对 10 例特发性动眼神经（CN III）或展神经（CN VI）麻痹的斜视患者进行高分辨率、表面线圈眶内 MRI。使用稳态采集序列的快速成像，通过 0.8 毫米厚、162 微米分辨率的重度 T2 加权 MRI 显示 CN 与颅内动脉的关系。通过数字分析评估眼外肌的横截面积。
在 1 例 CN III 麻痹患者中，扩张的后交通动脉明显压平并变薄了同侧蛛网膜下腔的 CN III。眼球神经-视神经结合部后 10mm 处受累内直肌、上直肌和下直肌的横截面积分别为 17.2±2.5mm²、15.5±1.3mm²和 9.9±0.8mm²，明显小于对侧未受累眼的 23.6±1.9mm²、30.4±4.1mm²和 28.8±4.6mm²（P<0.001）。在 2 例其他原因不明的 CN VI 麻痹患者中，基底动脉扩张与 CN VI 接触。受累外直肌的平均横截面积分别为 24.0±2.3mm²和 29.8±3.1mm²，明显小于对侧未受累眼的 33.5±4.1mm²和 36.9±1.6mm²（P<0.05）。
当 MRI 显示受累 CN 的血管扭曲时，应考虑非动脉瘤性运动 CN 压迫是导致 CN III 和 CN VI 麻痹伴神经性肌肉萎缩的原因。良性血管原因的证实可以终止持续的诊断性检查，并可以加速斜视的合理治疗。
