The Abducens Nerve in Neurology

G. Milanes-Rodríguez; LdeF Iba?ez-Valdés; H. Foyaca-Sibat; M. Perez-Fernandez

摘要

Because abducens palsy is a very common problem in our daily practice we decide to review the anatomical variations of abducens nerves that could explain clinical variations under the similar etiologies. Therefore, we report our findings on fixed brain specimens looking for anatomical variations of abducens nerves at the Department of Anatomy from Walter Sisulu University in Mthatha, South Africa. Introduction The abducens nerve contains only somatic efferent fibers that supply the lateral rectus muscle. Several sources have attributed the vulnerability of the abducens nerve to its long intracranial course. Because of the bilateral projections of the nucleus abducens, nuclear palsy of cranial nerve VI usually implies some difficulty in adducting the contralateral eye. Pure cranial nerve VI palsy, therefore, does not suggest nuclear palsy. Neither does it suggest fascicular lesions because the latter rarely involve cranial nerve VI alone but also cranial nerve VII (ipsilateral facial palsy) and/or the mesencephalic root of cranial nerve V (ipsilateral facial hypoesthesia ).These associated disorders are known as Foville's and Millard-Gubler syndromes. They are mostly due to demyelinating disease in young persons, arterial disease in elderly peoples. However, other anatomic factors likely contribute to the apparent vulnerability of the abducens nerve to mass lesions and trauma.From its brainstem exit to its entry into the cavernous sinus, the sixth cranial nerve has a long course in the prepontine cistern where it cab be damaged by expansions of nasopharyngeal carcinoma, meningitis, and tumors of the clivus ((chordomas or meningiomas). The nerve crosses over the tip of the petrous bone where lesions from infection of the middle ear may cause cranial nerve VI and VII palsies with facial pain as a result of involvement of the trigeminal ganglion (Gradenigo's syndrome).Several diseases present with isolated sixth nerve palsy in adults but in the cavernous sinus, cranial VI may be involved with cranial nerve III and IV and the ophthalmic branch of cranial nerve V by aneurysm of the carotid siphon, tumors such as meningioma, pituitary apoplexy, or infections, but for some unknown reasons, this nerve is especially vulnerable reason why we will try to identify abnormalities that could explain this situation. An isolated cranial nerve VI palsy may result from cavernous sinus lesions. Cranial nerve VI paralysis is a rare complication of spinal tap and diabetes mellitus and inflammatory systemic disease such as giant-cell arteritis are possible causes.The causes of actual sixth nerve palsy include aneurysms of the vertebral artery (VA), tumor, head trauma when the examination must look for deafness, otorrhagia of blood or cerebrospinal fluid, and mastoid ecchymosis. Other cause include: diabetes mellitus, arteriosclerosis, multiple sclerosis, meningitis, increased intracranial pressure (one of the most common false localizing signs of increased intracranial pressure, and lumbar puncture.[1,2], isolated abducens nerve palsy related to dolichoectatic vertebral artery (DVA) compression has been reported [3]. There is a report about a patient with lifelong, bilateral horizontal gaze palsies and the anatomical findings of bilateral absence of the abducens nerve as it affected the brainstem, the course of the cranial nerves to the extraocular muscles, and muscle innervations are described and the possible relationship of these findings to Duane's syndrome and Moebius syndrome is discussed.[4] Material and method One of us (GMR) made all dissections on selected fixed brain specimens at the laboratory of anatomy from Walter Sisulu University. Selection criteria were based on the good preservation of the brain and good quality material for dissection. The main aid was to identify abnormalities of gross anatomy of the abducens nerve or on its pathways. Results and comments The abducens nerve was consistently approximately one-third the length of th

机译：由于外展神经麻痹在我们的日常实践中是一个非常普遍的问题，因此我们决定对外展神经的解剖学变异进行回顾，以解释在类似病因下的临床变异。因此，我们在南非Mthatha的Walter Sisulu大学解剖系报告了固定大脑标本上的发现，以寻找外展神经的解剖变异。简介外展神经仅包含供应外侧直肌的躯体传出纤维。有几个来源将外展神经的脆弱性归因于其较长的颅内过程。由于外展核的双侧投影，颅神经VI的神经麻痹通常意味着在对侧眼的内收方面有些困难。因此，单纯的颅神经VI麻痹并不意味着核性麻痹。它也没有提示束状病变，因为后者很少单独涉及颅神经VI，而仅涉及颅神经VII（同侧面部麻痹）和/或颅神经V的中脑根（同侧面部感觉异常），这些相关的疾病称为Foville's和Millard -古柏勒综合征。它们主要是由于年轻人的脱髓鞘疾病，老年人的动脉疾病。然而，其他解剖学因素可能会导致外展神经明显易受团块损伤和创伤的影响。从脑干出口到进入海绵窦，第六颅神经在脑桥的前脑池长了一段漫长的路程。由于鼻咽癌，脑膜炎和锁骨瘤（脊索瘤或脑膜瘤）的扩张，神经越过了骨质疏松的尖端，中耳感染所致的病变可能导致颅神经VI和VII麻痹，并伴有面痛。成人累及第六神经性麻痹但在海绵窦存在多种疾病，但颅六区可能与颅神经III和IV以及颅神经V的眼科受动脉瘤累及颈动脉虹吸，脑膜瘤，垂体中风或感染等肿瘤，但由于某些未知原因，这种神经特别容易受到感染e将尝试找出可以解释这种情况的异常情况。海绵窦病变可能导致孤立的颅神经VI麻痹。颅神经VI麻痹是脊柱水龙头和糖尿病的罕见并发症，可能是引起巨细胞动脉炎等炎性全身疾病的原因。实际的第六神经麻痹的原因包括椎动脉瘤（VA），肿瘤，颅脑外伤检查必须寻找耳聋，血液或脑脊液耳漏以及乳突瘀斑。其他原因包括：糖尿病，动脉硬化，多发性硬化，脑膜炎，颅内压增高（颅内压增高和腰椎穿刺是最常见的假定位迹象之一。[1,2]，与多发性脊柱椎动脉相关的孤立性外展神经麻痹（DVA）压迫的报道[3]。有报道称患者终生出现双侧水平视线麻痹，并且双侧外展神经缺失的解剖学发现，因为它影响了脑干，颅神经向神经干的进程。描述了眼外肌和神经支配，并讨论了这些发现与Duane综合征和Moebius综合征的可能关系。[4]材料和方法我们其中一位（GMR）在解剖实验室对选定的固定脑标本进行了解剖沃尔特·西苏鲁大学（Walter Sisulu University）：选择标准基于对大脑的良好保护和用于解剖的优质材料。主要帮助是识别外展神经或其通路的总体解剖异常。结果与评论外展神经持续约占长度的三分之一

The Abducens Nerve in Neurology

摘要

著录项

相似文献

相关主题

期刊订阅