Unilateral oculomotor nerve palsy secondary to internal carotid artery aneurysm without pupil involvement: a case report.

Acquired oculomotor palsies (OMP) can result from numerous factors. The most common causes are presumed microvascular, trauma, compressive neoplasm, postneurosurgery and compression from aneurysm.1,2 ONP caused by internal carotid artery (ICA) aneurysm is a common clinical manifestation suggesting impending rupture or re-rupture of the aneurysm.3 Classically, OMP is associated with a complete or incomplete involvement of the levator palpebrae superioris (causing ptosis) and a "down and out" appearance of the ipsilateral eye. This particular eye duction reflects the actions of depression (by the superior oblique muscle innervated by the fourth cranial nerve) and abduction (by the lateral rectus muscle innervated by the sixth cranial nerve of the globe.4 The pupil involvement is seen in the vast majority of patients with compressive third nerve palsies.2 This case report will present a patient with unilateral acquired oculomotor nerve palsy secondary to an incidental left-sided cavernous ICA aneurysm without pupil involvement.[1] Modi P, Arsiwalla T. Cranial Nerve III Palsy. [Updated 2022 Jul 4]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2022 Jan-.; [2] Fang C, Leavitt JA, Hodge DO, Holmes JM, Mohney BG, Chen JJ. Incidence and Etiologies of Acquired Third Nerve Palsy Using a Population-Based Method. JAMA Ophthalmol. 2017 Jan 1;135(1):23-28. doi: 10.1001/jamaophthalmol.2016.4456. PMID: 27893002; PMCID: PMC5462106.; [3] Mino M, Yoshida M, Morita T, Tominaga T. Outcomes of Oculomotor Nerve Palsy Caused by Internal Carotid Artery Aneurysm: Comparison between Microsurgical Clipping and Endovascular Coiling. Neurol Med Chir (Tokyo). 2015;55(12):885-90. doi: 10.2176/nmc.oa.2014-0434. Epub 2015 Sep 11. PMID: 26369721; PMCID: PMC4686451.; [4] Costello, Fiona. Third Nerve Palsy (Oculomotor Nerve Palsy). Medscape article review. https://emedicine.medscape.com/article/1198462-overview; [5] Trobe JD. Third nerve palsy and the pupil. Footnotes to the rule. Arch Ophthalmol. 1988;106(5):601-2. pmid:3358724.; [6] Lin, Hsin-Le MD; Hu, Tzu-Te MD∗. Isolated third nerve palsy with pupillary involvement resulting from carotid-cavernous sinus fistula: A case report. Medicine: February 2019 - Volume 98 - Issue 6 - p e14472 doi: 10.1097/MD.0000000000014472; [7] Goldstein JE, Cogan DG. Diabetic ophthalmoplegia with special reference to the pupil. Arch Ophthalmol. 1960;64:592-600. pmid:13706649.; [8] Galtrey CM, Schon F, Nitkunan A. Microvascular Non-Arteritic Ocular Motor Nerve Palsies-What We Know and How Should We Treat? Neuroophthalmology. 2014 Nov 21;39(1):1-11. doi: 10.3109/01658107.2014.963252. PMID: 27928323; PMCID: PMC5123092.; [9] Kissel JT, Burde RM, Klingele TG, Zeiger HE. Pupil-sparing oculomotor palsies with internal carotid-posterior communicating artery aneurysms. Ann Neurol. 1983;13(2):149-54. pmid:6830174.; [10] Rucker CW: Paralysis of the third, fourth, and sixth cranial nerves. Am J Ophthalmol46:787-794, 1958; [11] Cogan D, Mount HTJ: Intracranial aneurysms causing ophthalmoplegia. Arch Ophrhalmol 70:757-771, 196; [12] Dailey EJ, Holloway J, Murto R, Schlezinger N: Evaluation of ocular signs and symptoms in cerebral aneurysm. Arch Ophthalmol 71:463-474, 1964; [13] Fard MA, Montgomery E, Miller NR. Complete, Pupil-Sparing Third Nerve Palsy in a Patient With a Malignant Peripheral Nerve Sheath Tumor. Arch Ophthalmol. 2011;129(6):805-820. doi:10.1001/archophthalmol.2011.122; [14] Motoyama Y, Nonaka J, Hironaka Y, Park YS, Nakase H. Pupil-sparing oculomotor nerve palsy caused by upward compression of a large posterior communicating artery aneurysm. Case report. Neurol Med Chir (Tokyo). 2012;52(4):202-5. doi: 10.2176/nmc.52.202. PMID: 22522330