Man with diplopia on head tilt

Abstract

A 47-year-old male with a past medical history of hypertension, diabetes , and coronary artery disease presented with diplopia for 4 days at the urging of his optometrist (Figures 1 and 2). 2 DIAGNOSIS 2.1 Cranial nerve IV palsy Extraocular movements are controlled by six muscles and three nerves. The lateral rectus is the primary abductor and is innervated by cra-nial nerve (CN) VI (the abducens nerve). A sixth nerve palsy produces diplopia on attempted lateral gaze of the affected eye. The medial, superior, and inferior recti and the inferior oblique muscles are all innervated by CN III (the oculomotor nerve); additionally, the levator palpebrae muscle and the sphincter pupillae are innervated via the parasympathetic fibers of CN III. A third nerve palsy produces ptosis, a downward-out position of the affected eye in neutral gaze, and limited ability to adduct the affected eye. 1 The superior oblique muscle is innervated by CN IV (the trochlear nerve). Fourth nerve palsies are the most difficult to detect, and when isolated and in the absence of trauma, are almost always ischemic or congenital in etiology. 2 Additional etiologies like herpes zoster, migraine, giant cell arteritis, cavernous sinus thrombosis, and space-occupying lesions should also be considered when signs and/or symptoms warrant (although these are exceedingly rare and unlikely to be isolated). 3,4 This palsy often goes unnoticed because other extraocu-lar muscles compensate. The superior oblique is primarily a depressor of the eye, but it serves an important and unique role by intorting the eye (rotating down and inward) on ipsilateral head tilt. Without this This is an open access article under the terms of the Creative Commons Attribution-NonCommercial-NoDerivs License, which permits use and distribution in any medium, provided the original work is properly cited, the use is non-commercial and no modifications or adaptations are made. c