Background We investigated the clinical outcomes of fourth cranial nerve (CN4) palsy with acute vertical diplopia in adults. Methods A total of 80 patients with acute CN4 palsy who underwent at least 3 months of follow-up were included in this study. We retrospectively investigated the aetiology, rate of recovery, and factors associated with recovery between March 2016 and January 2019. Results The average age of patients with CN4 palsy was about 60 years, and the duration of recovery was 1.5 months: 48 (60.0%) patients had a vascular aetiology and 17 (21.3%) patients had a trauma history. Brain lesions were found in four (5.0%) patients and decompensated cause accounted for four (5.0%) cases. Among the total of 80 patients, 13 (16.3%) failed to completely recover. Non-isolated CN4 palsy with other cranial nerve palsies were recorded in seven cases. The comparison between recovery and non-recovery groups showed that initial deviation angle, aetiology, fundus extorsion, and head tilt status were significantly different factors. Conclusion The recovery rate of acute CN4 palsy was about 80% and duration of recovery was 1.5 months. However, the varying rates and duration of recovery was presented according to aetiology thus we should consider the prognosis by aetiology.

中文翻译：

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成人急性垂直复视第四颅神经麻痹的临床结果和病因

背景 我们研究了成人急性垂直复视的第四颅神经 (CN4) 麻痹的临床结果。方法 80例接受至少3个月随访的急性CN4麻痹患者纳入本研究。我们回顾性调查了2016年3月至2019年1月期间的病因、康复率和康复相关因素。 结果 CN4麻痹患者的平均年龄约为60岁，康复时间为1.5个月：48（60.0%）患者有血管病因，17 名（21.3%）患者有外伤史。4 例 (5.0%) 患者发现脑损伤，失代偿原因占 4 例 (5.0%)。80 名患者中，13 名（16.3%）未能完全康复。7 例记录了非孤立性 CN4 麻痹和其他颅神经麻痹。恢复组与非恢复组的比较显示，初始偏斜角度、病因、眼底外展和头部倾斜状态是显着不同的因素。结论急性CN4麻痹的恢复率约为80%，恢复时间为1.5个月。然而，根据病因呈现不同的恢复速度和持续时间，因此我们应按病因考虑预后。