Case 6

HPI: 56 y/o male presents to the ED c/o HA & diplopia x 2 weeks. The HA is described as strong, dull & constant above his right eye. He denies any trauma or eye pain, and reports that his vision’s improved when his right eye is closed. He denies visual floaters, haloes, flashes or discharge.

ROS: as above, denies F/C, N/V/D, dizziness, vertigo, weakness or weight loss

PMH: HTN

Soc: denies alcohol, tobacco or drug use

Meds: atenolol

All: NKDA

PE: Vs T 98.3, P 72, R 20, BP 153/92

Gen: non toxic appearing child

HEENT: no palp cords; eyes as demonstrated below; with right pupil slightly larger than left but equally reactive; no fluoresceine uptake, foreign body, hyphema or hypopion noted; fundi, conjuctiva & anterior chambers both benign

Neck: supple, no bruit

CV: RRR, no murmur

Resp: CTAB, no W/C

Abd: soft, NT/ND

Skin: well hydrated, no rash

Neuro: no other neuro deficit

“Look straight ahead.”

“Look to your left.”

Diagnostic Data: Head & Orbital CTs were normal, ESR 20, accucheck 208

What’s your diagnosis & how should you further work-up this patient?

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Answer: Isolated CN 3 Palsy

Discussion: Diplopia is divided into monocular or binocular. Monocular diplopia results from defects of the ocular media, such as cataract, scarring or lens dislocation. Binocular diplopia resolves when either eye is covered. The differential diagnoses for binocular diplopia include anatomic (tumor, blow-out fracture), vascular (cavernous sinus thrombosis, temporal arteritis, migraine), endocrine (thyroid ophthalmopathy), infectious (diphtheria, botulism), and neurologic (myasthenia gravis, CNs palsy) abnormalities. Conversion disorder should be considered if no abnormality is found by Ophthalmology follow-up, especially with monocular diplopia.

This patient exam demonstrated CN 3 palsy with evidence of ptosis & loss of medial gaze on the affected side. Remember the “chemical formula” ((SO4)LR6)3, a mnemonic for the extraocular muscles innervation – superior oblique by CN 4, lateral rectus by CN 6, and all the rest by CN 3. In CN 3 palsy, check the papillary response. If the pupil is spared, consider a cavernous sinus syndrome or a microvascular problem such as diabetes. Temporal arteritis was also considered because of the patient’s history. Ophthalmology consultation was obtained, and follow-up revealed that the patient had isolated CN 3 palsy from previously undiagnosed diabetes mellitus for which treatment was initiated.