在急診，主訴急性單側垂瞼但無其他明顯神經學異常並不少見；身為急診醫師，從徵象中找出會致命的疾病是非常重要的。這篇研究主要是建立有效的流程診斷單側垂瞼，在其中迅速找出嚴重的疾病：包括內頸動脈剝離表現出霍納氏症候群、後交通動脈瘤壓迫導致動眼神經麻痺。這篇研究主要參考國外文獻，如何快速鑑別診斷出重症，建立簡潔明瞭流程圖。研究發現，動眼神經麻痺比霍納氏症候群垂瞼明顯，明顯瞳孔反射異常需快速安排影像檢查排除頭頸部血管疾患，眼外肌異常或複視在霍納氏症後群不常見，重症肌無力危象會出現明顯神經學異常或呼吸衰竭。因此，在急診室，我們能用有效率的檢查流程，包括：垂瞼程度、瞳孔檢查、眼外肌運動檢查，快速找出會致命的疾病，把握治療的黃金時間。

Background and Purpose: Acute unilateral ptosis in Emergency department(ED) without other focal neurologic impairment isn’t uncommon chief compliant. From internal carotid artery dissection presented with Horner’s syndrome to Posterior communicating(PCOM)aneurysm caused oculomotor nerve (CN III) palsy , our job as ED doctor is to find critical illness. Afterwards, the efficient algorithm for differential diagnosis of acute unilateral ptosis is important. Methods: We use key words” unilateral ptosis” and “diagnosis” in PubMed and total 44 full text papers in recent 5 years, which we concluded practical results and finally 25 papers as reference for this article. Results: The eyelid position of ptosis pattern is vary with CN III palsy and Horner’s syndrome. Pupillary involvement requires neuroimaging for the presence of an aneurysm that may be compressing the nerve which causing CN III palsy. Horner’s syndrome only do not appear EOM limitation or diplopia. Beware of bulbar symptoms such as shortness of breath, dysphagia, or dysarthria as these can indicate an impending myasthenic crisis(MG crisis). Conclusion: We can use fast algorithm to find emergent illness of acute unilateral ptosis. By examination of eyelid position, pupillary examination, and extraocular motility(EOM), we may find the possibility of Horner’s syndrome or CN III palsy. Timely treatment can initiation after confirmed image done.