Summers can be serene on West Lake Menokee, but not for Lou Macari.* As the proprietor of Macari’s Beach Cottages, he spends much of his time fielding complaints about the resort’s Eisenhower-era amenities. Last summer was especially difficult, with visitors kicking up a stink about the plumbing, and by mid-July he was suffering severe headaches, which he attributed to stress. He tried to shrug off the pain, but after three weeks of worsening headaches—and a septic tank that was frequently backed up—he decided to ask for help. First, he asked his brother-in-law to lend a hand at the resort; next, he asked for a ride to the ER.
From ER to Otolaryngologist
The attending physician noted that Mr. Macari, a white 50-year-old, was experiencing right-sided retro-orbital headaches that hadn’t been responding to NSAIDs. Mr. Macari said that he had no previous history of headaches and no visual complaints at that time. His past medical history was significant only for anxiety and hyper-
cholesterolemia, for which he was taking zolpidem and atorvastatin. Although his father had died from a cerebral aneurysm that had hemorrhaged, Mr. Macari’s family history was otherwise unremarkable, as was his social history.
Magnetic resonance angiography and a computed tomography scan were performed as part of the initial evaluation. This revealed bilateral frontal sinus opacities that were consistent with acute sinusitis, but there were no other significant findings. He was started on oral antibiotics and referred to otolaryngology for follow-up in three weeks.
Back at the resort, Mr. Macari found life less of a handful now that his brother-in-law was helping out. But he was perturbed that his headaches persisted despite the reduced stress and a variety of antibiotic regimens.
After three weeks, he presented to otolaryngology for the follow-up. While his symptoms still included persistent right-sided retro-orbital headaches, the otolaryngolosist noted that Mr. Macari also had new onset of binocular oblique diplopia over the previous 24 hours, and mild ophthalmoplegia on exam. He was referred to our neuro-ophthalmology clinic and we scheduled him for later that same day. It was the Friday of Labor Day weekend.
We Get a Look
When we met Mr. Macari and his wife, they wondered whether his headaches were due to the daily stress of running the resort. Indeed, they joked that we take as long as we liked to examine him—they were happy to “take it easy” while the brother-in-law held down the fort.
His wife also told us that she had noticed a droop in his right eyelid in the past week. Mr. Macari had no other complaints.
On exam he was afebrile. His visual acuity was 20/25, pinholing to 20/20 in the right eye and 20/16 in the left. His confrontation visual field, slit-lamp and fundus exams were all normal. His pupils, however, were 5.5 mm in the right eye and 4.5 mm in the left when in dim light, constricting to 3.5 mm and 2 mm respectively when in bright light. His extraocular motility showed mild limitation, revealing –1.0 supraduction, –1.5 adduction and –1.0 infraduction in the right eye.
There was no evidence of a relative afferent pupillary defect.
|What's Your Diagnosis? |
|(Left) Mr. Macari underwent an angiogram. (Right) After reviewing the angiogram, we ordered an MRI. |
The Differential Diagnosis
Given his mild underaction of elevation, depression and adduction in the setting of ptosis, and his anisocoria—with the right eye bigger than the left, and the difference greatest in bright light—we diagnosed a right-sided, pupil-involving, isolated, incomplete, oculomotor nerve palsy.
The differential diagnosis for this condition includes extrinsic compression, intrinsic pathology and, rarely, ischemia.
Examples of extrinsic compression include vascular sources (e.g., aneurysm of the posterior communicating artery), pituitary apoplexy with lateral expansion, or neoplastic processes (e.g., meningioma, gliomas and carcinoma).
Intrinsic pathology may include schwannomas of the third nerve, malignant gliomas of the third nerve, lymphomatous infiltration or granulomatous inflammations (e.g., sarcoidosis).
However, given the acute onset of his diplopia and life-threatening nature of cerebral aneurysm, together with his positive family history, a vascular source of his symptoms—such as an aneurysm of the right posterior communicating artery or of the distal internal carotid artery—was of highest suspicion and needed to be ruled out.
An Urgent Evaluation
Typically an MRI with magnetic resonance angiography (or computerized tomographic angiography) would be indicated as initial studies in a patient with this presentation. But with the three-day holiday weekend fast approaching, we decided to perform an angiogram, the gold-standard for ruling out aneurysm, while members of the support staff were available.
Results were negative for aneurysm, but we did discover an incidental right-sided, posteriorly draining, arteriovenous fistula located near the clivus. (See arrow in the left image above showing early filling of a venous structure during the arterial phase of the aneurysm.)
With aneurysm ruled out, an MRI was ordered to evaluate for any mass lesions that could account for his isolated third-nerve palsy.
Results were negative for any compressive lesions, with the only significant findings once again being his frontal sinus disease consistent with frontal sinusitis.
However, on closer examination, one coronal section of T1 post-contrast MRI appeared to show enhancement of the right third nerve in the same region as the posteriorly draining arteriovenous fistula. (See the right image above)
We Review the Literature
A Medline search crossing arteriovenous fistula and oculomotor nerve palsy yielded several references.
These studies describe approximately 30 cases of isolated incomplete third- nerve palsies with pupil involvement resulting from posteriorly draining arteriovenous shunts. The accounts of the patient presentations were similar to Mr. Macari’s, with several weeks of unilateral retro-orbital pain followed by partial or complete third-nerve palsies with pupil involvement. Although aneurysms of the posterior communicating artery or distal internal carotid artery were initially suspected, subsequent neuroimaging was typically negative for compression or aneurysm. In the cases described, an arteriovenous fistula draining posteriorly into the inferior petrosal sinus was found incidentally on angiogram.
It is emphasized that, unlike anteriorly draining arteriovenous shunts (which present with pulsating exophthalmos, bruit and conjunctival chemosis resulting from superior ophthalmic vein congestion), posteriorly draining shunts often present with only isolated nerve palsies (most commonly the third- and the sixth-cranial nerve) and have been termed “white-eyed shunts.”
The exact mechanism of the third- nerve palsy is unknown, although some suggest that nerve compression from expansion of expanded venous sinus as the cause. Others hypothesize that ischemic neuropathy secondary to venous congestion/arterial steal is more plausible.
Regardless of mechanism, the studies describing the relationship between arteriovenous fistula and pupil-involved incomplete third-nerve palsy indicate that the arteriovenous fistulas can be successfully treated with embolization techniques of the involved vein.
Further, the studies suggest that embolization may not always be necessary, as the fistulas can sometimes resolve spontaneously, with a concomitant resolution of third-nerve palsy. In many cases these spontaneous resolutions occurred immediately after the angiogram, for reasons unknown. Thus, a conservative approach has been advised in cases that are not severe.
Mr. Macari appeared to be among those individuals with spontaneous resolution of fistula post-angiogram.
Immediately following his angiogram, he subjectively felt that his headaches were less severe and his double vision was improving.
He was followed closely in the hospital for the next several days, each day showing steady improvement in his ptosis, diplopia and anisocoria. He was discharged after six days.
Three weeks after his initial presentation to the neuro-ophthalmology clinic, Mr. Macari’s ptosis and anisocoria had completely resolved without recurrence. His diplopia and retro-orbital pain had also completely resolved and he remained headache-free. He was given no restrictions on physical activities and encouraged to return to his normal life, with the caveat that arteriovenous fistulas occasionally can recanalize, and he should be alert to any recurrence of the symptoms that had prompted him to seek medical attention.
After thanking us for our help, Mr. Macari invited us and our staff to a complimentary weekend at his resort. Although some of the amenities needed repairs, he insisted that the worst of the problems were now fixed. He urged us to take his offer seriously, and then asked us how we had paid our way through college. We would be especially welcome, he joked, if we had spent our summers working as plumbers.
* The name of the patient, the resort and the lake are all fictitious.
Dr. Lynch recently completed his medical degree at the Carver College of Medicine. Dr. Kardon is professor of ophthalmology and director of the neuro-ophthalmology service there.
|Medline Results |
Our search results included:
Acierno, M. D. et al. Arch Ophthalmol 1995;113:1045–1049.
Hawke, S. H. B. et al. Arch Neurol 1989;46:1252–1255.
Kurata, A. et al. Am J Neuroradiol 1993;14:1097–1101.
Lee, A. G. Neuro-Ophthalmology 1996;16:183–187.
Miyachi, S. et al. Surg Neurol 1993;39:105–109.
Nukui, H. et al. Surg Neurol 1984;21:543–552.
Perez Sempere, A. et al. Eur Neur 1991;31:186–187.
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