Kritzinger Justin, Micieli Jonathan A
Temerty Faculty of Medicine, University of Toronto, Toronto, ON, Canada.
Department of Ophthalmology and Vision Sciences, University of Toronto, Toronto, ON, Canada.
Case Rep Ophthalmol. 2023 Mar 3;14(1):87-92. doi: 10.1159/000529669. eCollection 2023 Jan-Dec.
Third nerve palsy (3NP) commonly results from a microvascular ischemic insult. Typically, computed tomography or magnetic resonance angiography is performed to rule out a posterior communicating artery aneurysm. If this is normal and the pupil is spared, patients are often observed with the expectation of spontaneous improvement within 3 months. Oculomotor nerve enhancement on MRI with contrast in the context of microvascular 3NP is not well recognized. Here, we report third nerve enhancement in a case of a 67-year-old woman with diabetes and other vascular risk factors who presented with left eye ptosis and a limitation of extraocular eye movements consistent with 3NP. She underwent an extensive inflammatory workup that was negative and the diagnosis of a microvascular 3NP was made. A spontaneous recovery was achieved within 3 months, and she did not receive any treatment. She remained clinically well, although increased T2 signal in the oculomotor nerve persisted after 10 months. While the exact mechanism remains unknown, it is likely that microvascular ischemic insults lead to intrinsic changes of the third nerve that may result in enhancement and persistent T2 signal. Additional workup for inflammatory causes of 3NP may not be required when enhancement of the oculomotor nerve is seen in the right clinical context. Further study is required to understand why enhancement is a rarely reported finding in patients with microvascular ischemic 3NP.
动眼神经麻痹（3NP）通常由微血管缺血性损伤引起。通常会进行计算机断层扫描或磁共振血管造影以排除后交通动脉瘤。如果结果正常且瞳孔未受累，通常会对患者进行观察，期望在3个月内自发改善。在微血管性3NP的情况下，磁共振成像（MRI）增强扫描时动眼神经强化的情况尚未得到充分认识。在此，我们报告一例67岁患有糖尿病和其他血管危险因素的女性患者，其表现为左眼上睑下垂和眼外肌运动受限，符合3NP。她接受了全面的炎症检查，结果均为阴性，诊断为微血管性3NP。患者在3个月内自发恢复，未接受任何治疗。尽管10个月后动眼神经的T2信号仍持续增强，但她的临床状况良好。虽然确切机制尚不清楚，但微血管缺血性损伤可能导致动眼神经的内在变化，从而可能导致强化和T2信号持续存在。在正确的临床背景下，当发现动眼神经强化时，可能无需对3NP的炎症原因进行进一步检查。需要进一步研究以了解为何在微血管缺血性3NP患者中强化是一种罕见的表现。
