You turn on the light to signal your staff that you'd like someone to come
bring the patient into the procedure room with the slit-lamp to more fully examine the
patient's retina. While you're waiting and chatting with the couple, Mr. Moore exclaims
that "it's happening again". The nurse comes in to bring Mr. Moore to the
procedure room and place him in it while you answer a quick call. A few minutes later, you
see the following via the slit lamp:
Based on your history and physical, you're now pretty sure it either a Central or Branch
Retinal Artery Occlusion. The history of an acute, monocular,
painless, transient vision loss is consistent with this diagnosis. Further, you
heard a neck bruit which might well indicate a plaque causing carotid stenosis and
occasionally showering emboli to the eyes and/or brain (which could account for transient
possible TIA/right arm palsy) -- although you heard the bruit on the right side and the vision problem is on the left.
Conversely, Giant-Cell Arteritis is unlikely since there was no temporal tenderness or jaw
claudication. Also, there is no trauma and the retinal exam is not consistent with Retinal
Detachment - which can reveal an elevated retina and/or retinal folds (see Table 1).
Finally, Vitreous Hemorrhage is less likely since the pt gave no history of trauma or
floaters and has no predisposing condition for neovascularization such as diabetes.
Question 5: At this point, what should you do?
Answer to Question 5
In this rare case, a textbook maneuver actually works and, much to the Moores' relief (and
yours), his vision is restored- for now.
If more time had elapsed without intervention, you might have seen the following:
After vascular stasis, you can see "boxcarring" (rows
of corpuscles separated). Later still, the retinal inner layer becomes opalescent,
especially around the fovea, resulting in a "cherry-red-spot"
But, remember, this problem still needs to be addressed immediately. You call your buddy
from medical school who is now an opthalmologist to see if he can fit Mr. Moore into his
schedule today. Your buddy sees him, concurs with your assessment and immediately refers
him to another friend who is now a vascular surgeon. She orders a carotid doppler before
seeing the patient.
Question 6: What results would be consistent with your
physical exam (right neck bruit), but a vision loss on the left?
Answer to Question 6
The surgeon sits down with the Moores to explain the pro's and con's of surgery. She
starts with explaining the anatomy and pathology. Then she explains that a recent study
showed a yearly 6% chance of a stroke in pts who had been symptomatic (TIAs, amaurosis
fugax, or mild strokes) (1) and clearly there is a risk of further vision loss.
(1): Mansour MA, et al, J Vasc Surg, 1995 Feb; 21(2): 346-56.
Question 7: Where is the most common area for a carotid
plaque?
Answer to Question 7
Question 8: Of course, there is a risk in the surgery, too.
What complication has the highest risk? What is the mortality of a carotid
endarterectomy?
Answer to Question 8
If the risk of the surgery is less than the risk of stroke, many pts will opt for the
surgery. But physicians must also remember that even if the risk/benefit ratio seems to
point in one direction, pts may still take the other option because of value judgements.
Further, life expectancy plays a part in this decision for some pts.
Mr. Moore's previous CAD history also plays a part in the risk/benefit analysis. He
undergoes pre-op testing which reveals adequate cardiac function and no other
contraindicating conditions. He agrees to the surgery and, as a pre-op test, the surgeon
orders an arteriogram. It looks like this:
They begin the surgery, first disecting everything out:
Meticulous dissection is essential to avoid dislodging emboli from the carotid plaque as
well as protecting cranial nerves such as the hypoglossal and vagus. Cerebral blood flow
is also a concern during the operation. Some surgeons shunt blood from the common carotid
to the distal internal carotid while others use operative monitoring via EEG - and some do
both. In Mr. Moore's case the surgeon chooses to monitor via EEG, deeming shunting
unnecessary. The plaque they removed was pretty impressive:
Then they use the graft that was dissected out (often from the saphenous vein) to enlarge
the vessel around that area.
The surgery goes well and there are no complications. Mr. Moore goes home and is prescribed aspirin daily.
 |
He recouperates by the time it's opening day for the Phillies' and enjoys watching
them beat the Dodgers 4-2. |
 |
End of Case 1
Start Case 2
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