The Journal of Emergency Medicine, Vol. 35, No. 3, pp. 239–246, 2008 Copyright © 2008 Elsevier Inc. Printed in the USA. All rights reserved 0736-4679/08 $–see front matter doi:10.1016/j.jemermed.2007.04.020 Original Contributions EVALUATION OF THIRD NERVE PALSY IN THE EMERGENCY DEPARTMENT Michael M. Woodruff, MD and Jonathan A. Edlow, MD Department of Emergency Medicine, Beth Israel Deaconess Medical Center, Boston, Massachusetts Reprint Address: Michael M. Woodruff, MD, Department of Emergency Medicine, Beth Israel Deaconess Medical Center, One Deaconess Rd., Boston, MA 02215 e Abstract—Third nerve palsy is an uncommon condition CASE PRESENTATION that carries significant risk of serious disease due to both the variability of its presentation and its association with A 59-year-old man with a history of migraines presented intracranial aneurysms. In this article, we review the exist- to the Emergency Department (ED) complaining of ap- ing literature on the pathophysiology, diagnosis, and man- proximately 5 weeks of progressive double vision and a agement of third nerve palsy presenting to the Emergency Department. © 2008 Elsevier Inc. mild headache that began gradually 2–3 days prior. On the day of presentation, the patient had noted left facial e Keywords—third nerve palsy; emergency medicine; cra- and eye pain that was described as “sharper” in nature, nial neuropathy; dilatated pupil and unusual. The patient had vomited once before ar- rival. In the ED, the patient appeared comfortable and had normal vital signs. There was ptosis of the left INTRODUCTION eyelid, with a sluggishly reactive pupil and partial inabil- ity to adduct the left eye. In its resting position, the left Of all the cranial nerve palsies, isolated dysfunction of eye was deviated laterally and inferiorly. On further the third nerve (CN III) is a particularly thorny issue examination, there was no chemosis or proptosis of the for the emergency physician. Although rare, it is a affected eye, and visual acuity was normal. The con- condition that demands thorough and appropriate eval- tralateral eye was completely normal. Cranial nerves II uation due to its frequent association with intracranial and IV–XII were normal. Strength, sensation, reflexes, aneurysms (1,2). Furthermore, the clinical presenta- and cerebellar function were normal. tion of third nerve dysfunction is remarkably varied— The neurology team was consulted, and they agreed the nerve supplies seven different muscles, and almost that this was a case of isolated partial CN III palsy. A any combination of these can be affected to varying magnetic resonance imaging (MRI) scan of the brain was degrees. Over the past 50 years, a good deal of work normal, and magnetic resonance angiography (MRA) has been done to define the anatomic and pathologic showed no evidence of an aneurysm causing the CN III features of third nerve palsies to enable clinicians to dysfunction. The emergency physician and the neurolo- determine when an aneurysm might be the cause of the gist agreed that the patient had a high pre-test probability palsy. In this article we review the existing literature of an aneurysm causing this type of CN III palsy; there- on CN III palsy and offer a straightforward approach fore, the neurosurgeon was consulted, and a traditional to the problem that is useful to the practicing emer- catheter angiogram was performed. A 5-mm saccular gency physician. aneurysm was discovered originating from the posterior RECEIVED: 18 October 2005; FINAL SUBMISSION RECEIVED: 27 June 2006; ACCEPTED: 12 November 2006 239 240 M. M. Woodruff and J. A. Edlow communicating artery. After lengthy discussions, the pa- To examine the pupil, a light is shined directly into tient opted for endovascular coiling of the aneurysm, the eye, and note is made of the degree of constriction of because the risk of rupture of symptomatic aneurysms is the iris muscle. Bright ambient light may interfere with likely to be higher than that of asymptomatic aneurysms. this examination by constricting the pupil too much, so ideally the room lights should be dimmed. The process is repeated in the opposite eye, and the two responses are compared. The consensual reflex (constriction of the QUESTION 1: IS THIS A THIRD NERVE contralateral pupil with illumination of the ipsilateral PALSY? pupil) is also noted. If CN III is affected, the ipsilateral pupil will react sluggishly to both direct and consen- The presentation of third nerve palsy is extremely varied, sual light. If the pupil involvement is “complete,” the so the clinician must think of this possibility with com- pupil will not react at all. plaints relating to the eye. A CN III dysfunction can To examine the levator palpebrae muscle, note is present with diplopia, ptosis, eye pain, headache, pupil- made of the portion of the iris that is covered by the lary dilatation, monocular blurry vision, or any combi- upper lid, and compared with the opposite side. Ptosis nation thereof (3). Unfortunately, the differential diag- can be exaggerated by having the patient look up. If nosis for these complaints is broad and includes ptosis is present, the patient should be tested for lid myasthenia gravis, botulism, orbital infections, orbital fatigue: the ptosis may worsen when the patient refrains trauma, lens pathology, retinal pathology, migraine, and from blinking for a time or attempts to maintain upgaze. dysfunction of cranial nerves III, IV, and VI. Ptosis from myasthenia gravis is often asymmetric, fat- A careful history will quickly narrow the differential. igable, and improves with short periods of rest (4). Other For example, it must be established whether the diplopia conditions causing ptosis include Horner’s syndrome, is monocular (does not resolve with closing one eye) or botulism (or injection of botulinum toxin), palpebral binocular (resolves on closing one eye), because the trauma, and cluster headache; ptosis also may be con- differential diagnosis for monocular diplopia is generally genital (5). “Pseudoptosis” is caused by enopthalmos limited to refractive or ocular problems. The physician (e.g., from an orbital blowout fracture), which makes the must search for any associated symptoms, such as facial lid seem to be relatively lower on the side with the or extremity weakness, fevers, or changes in speech, gait, sunken globe. or coordination that might suggest the presence of intra- Examination of the extraocular muscles should begin cranial infection, hemorrhage, ischemia, or mass. If any with inspection of the resting position of the pupils when historical or clinical features suggest spontaneous sub- the gaze is directed straight ahead. Subtle differences in arachnoid hemorrhage (e.g., sudden onset of severe the orientation of the pupils can be detected by noting the headache, meningismus, photophobia) a non-contrast position of the reflection of the examiner’s light in the head computed tomography (CT) scan should be per- pupil and comparing it to the opposite pupil. The patient formed; if CT is non-diagnostic, lumbar puncture should is then asked to perform ductions, or movement of the be performed. Although opthalmoplegic migraine can eyes through all the cardinal directions. Any or all of the cause CN III palsy, the diagnosis of migraine headache motor divisions of CN III may be affected, and palsy in a patient without a history of such should not be made may be complete or partial; if there is complete palsy of without neurologic workup. the oculomotor functions of CN III, the patient will be To confirm the diagnosis of CN III palsy, the physi- unable to elevate or adduct the corresponding eye and the cian must perform a detailed physical examination of the eye will assume the classic “down and out” resting eye. CN III has a number of motor functions (Table 1). position (Figure 1). This is due to the remaining input of Table 1. Individual Functions of CN III Muscle Action How to Test Pupillary Constrictor Miosis (pupillary constriction) Shine light in each eye, compare response Ciliary muscles Accommodation (thickening of the lens) Watch pupillary response as light is brought close to patient’s nose Levator palpebrae superioris Opening of eyelid Examine resting position of lid relative to pupil Superior rectus Supero-lateral gaze Test lateral/supero-lateral gaze Inferior rectus Infero-lateral gaze Test lateral/infero-lateral gaze Inferior oblique Supero-medial gaze Test medial/supero-medial gaze Medial rectus Adduction Test medial gaze Third Nerve Palsy in the ED 241 to direct illumination, but will constrict normally when the contralateral eye is illuminated. Next, test the extraocular movements. Normal ex- traocular movements make a third nerve palsy very un- likely. If extraocular movements are affected, the third nerve palsy should be further investigated, as described later in this article. With normal eye movements, the next step is to exclude a pharmacologic cause. A careful Figure 1. Complete CN III palsy. The affected eye assumes a “down and out” resting position due to unopposed input history directed at any inadvertent exposures to mydri- from CN VI and CN IV. The pupil is dilatated and ptosis is atics is essential. Some authors recommend instilling present. topical 1% pilocarpine into the affected eye; in the case of pharmacologic blockade by parasympatholytics (sco- polamine, atropine), the pupil will not constrict; in the the abducens nerve (CN VI—abduction of the eye) and case of third nerve palsy, the pupil will constrict briskly. the trochlear nerve (CN IV—abduction and depression In the case of mydriasis caused by sympathomimetics, of the eye). the pupil will also constrict, but these patients also In addition to examination of the cranial nerves, the should have blanched conjunctivae and a retracted upper physical examination for diplopia or eye pain should eyelid (10). include inspection for chemosis or conjunctival injection, Next, perform a careful slit-lamp examination.