Malloy Kelly A
Pennsylvania College of Optometry, Elkins Park, Pennsylvania 19027, USA.
Optometry. 2007 Feb;78(2):55-62. doi: 10.1016/j.optm.2006.08.015.
An abduction deficit can have many potential etiologies. Clinical testing can help distinguish a neurogenic from a restrictive process. For any patient with a current or past history of cancer, even in the setting of vasculopathic risk factors, a further workup is necessary to rule out a metastatic process.
A 66-year-old man reported sudden blurry vision but did not describe a definite diplopia. Clinical evaluation found left cranial nerve (CN) VI palsy. Although he did have vasculopathic risk factors, neuroimaging found prostate cancer metastasis to the mid to left clivus, extending to the left cavernous sinus region as well as a smaller metastasis to the left temporal lobe. The patient underwent radiation treatment with improvement in his clinical presentation and symptoms. His prostate cancer was subsequently treated more aggressively, and 2 years later, despite spinal metastases, he was doing relatively well.
Prostate cancer commonly metastasizes, with a high propensity to invade bone. CN VI runs along the midline-structured bony clivus, between the pons and the cavernous sinuses. Therefore, a metastatic lesion to the clivus can be responsible for unilateral or bilateral CN VI palsy. In men, a common primary site of cancer metastasis to the clivus is the prostate. Eye doctors must look closely for evidence of even subtle abduction deficits in all patients with a history of prostate cancer. Early detection can lead to improved medical treatment and extended life expectancy.
外展功能障碍可能有多种潜在病因。临床检查有助于区分神经源性与限制性病变过程。对于任何有癌症现病史或既往史的患者，即使存在血管病变风险因素，也需要进一步检查以排除转移瘤。
一名66岁男性报告突发视力模糊，但未描述明确的复视。临床评估发现左侧第六颅神经（CN）麻痹。尽管他确实存在血管病变风险因素，但神经影像学检查发现前列腺癌转移至中至左侧斜坡，延伸至左侧海绵窦区域，同时左侧颞叶也有较小转移灶。患者接受了放射治疗，临床表现和症状有所改善。随后对其前列腺癌进行了更积极的治疗，2年后，尽管出现了脊柱转移，但他的情况相对良好。
前列腺癌常发生转移，极易侵犯骨骼。第六颅神经沿中线结构的骨性斜坡走行，位于脑桥和海绵窦之间。因此，斜坡转移瘤可导致单侧或双侧第六颅神经麻痹。在男性中，前列腺是转移至斜坡的常见原发癌部位。眼科医生必须密切关注所有前列腺癌患者是否存在即使很轻微的外展功能障碍迹象。早期发现可改善医疗治疗并延长预期寿命。
