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When Is Aura More Than a Migraine?

When Is Aura More Than a Migraine?

Sudden-onset scintillating scotoma may indicate other medical problems.

Paul M. Karpecki, O.D.

A 70-year-old male recently presented with an onset of a scintillating scotoma. He had no history of migraine headaches, nor had he experienced an episode of a migraine prodrome or aura until now.

Is this significant, or is it simply a case of late onset migraine prodrome? He did not experience any headache after the prodrome but has had three separate episodes of a scintillating scotoma pattern in the last month.

We’ll look at the clinical studies related to this condition for all ages and determine whether we must consider the “zigzag pattern” as more than just a simple insignificant migraine prodrome.

The Migraine Prodrome
About 20% of women and 10% of men suffer from migraine headaches sometime in their lives, and about half to two-thirds of them will have had a migraine attack within the previous year.1 Generally, there are two types:

About one-third to one-half of migraine patients experience an aura. Courtesy: Paul C. Ajamian, O.D.
• Classic migraine, in which the patient experiences an aura such as a scintillating scotoma, prior to a headache.

• Common migraine, in which there is no prodrome, or aura, before the headache.2

About one-third to one-half of all migraine patients experience an aura, or prodrome. A visual pattern such as a scintillating scotoma is by far the most common prodrome, although the prodrome may also be somatosensory, such as an enhanced scent ability.

Another study found that patients with migraines complained more often of an after-image than did non-migraine patients.3 There was no difference between classic or common migraine patients. What does this mean for your exam? If the patient complains of a persistent after-image after you’ve completed ophthalmoscopy, you might then question the patient about a history of migraine headaches.

Individuals who suffer from classic migraines report a diversity of migraine auras. In a study in Germany, the most common form of visual hallucination reported is known as the fortification illusion, which appears as a typical zigzag pattern. The researchers reproduced this pattern using orientation maps of the primary visual cortex, and found that the discontinuous repetitive nature of the zigzag pattern can reflect the specific layout of the visual cortical orientation maps.4

Challenging Diagnosis
A diagnosis of migraine is often straightforward, especially when a patient presents with an aura followed by a fairly intense headache. However, the diagnosis may be especially challenging when the aura appears without the headache (called an acephalic migraine).

An additional diagnostic challenge: When the aura occurs for the first time in individuals above age 50, when there is a persistent visual field loss, or when there are simultaneous neurological findings such as pupil abnormalities or nerve palsies.2

Several studies suggest that  a possible link exists between migraines (or at least the prodrome) and glaucoma; seizures, as in patients with epilepsy; and compression from space-occupying lesions.5-7 (For more on glaucoma, see “Glaucoma and Aura: A Coincidence?”).

Research has also indicated that ischemia and inflammation (as in temporal arteritis) can cause a visual disturbance mimicking a migraine prodrome in as many as 75% of all patients.8

Glaucoma and Aura: A Coinicidence?

Is there a link between glaucoma and migraines? A study reported earlier this year suggests so. Researchers looked at glaucomatous visual field defects in 77 patients who had a history of either a common migraine or a classic migraine (with aura).11 They found that 62% of the patients had glaucomatous visual field defects, primarily a nasal step defect. IOP was within normal limits on all patients.

Some additional findings: The glaucomatous group was significantly older, with a significantly higher age of onset for migraine. Risk of having glaucomatous-like defects was higher in the patients who had migraine attacks once a month or less frequently. The researchers also noticed a tendency of pain and visual field defects to develop ipsilaterally was noticed.

The authors concluded that a relationship exists between the pathophysiology of migraine, visual field defects and glaucomatous optic neuropathy. They also recommend visual field screening for normal tension glaucoma in patients with migraine.—P.M.K.
In one study that looked at late-onset scintillating scotoma, two patients experienced the typical visual aura pattern of a migraine, but this was caused by platelet microthrombi in the vessels of the visual cortex. Both patients were past age 50, and both had a history of abnormal platelet aggregation. Given that increased platelet aggregation is associated with cerebral vascular accidents, patients age 50 and older who have their first onset of a scintillating scotoma should have appropriate hematological tests to prevent a potential stroke.9
 
In another study, three cases of scintillating scotoma in older patients were associated with internal carotid artery dissection.10 All three patients presented with visual symptoms that resembled the migraine aura, but some of the scotomas lasted as long as 40 minutes.

A scintillating scotoma may be a manifestation of an internal carotid artery dissection, or a space occupying lesion. This is especially so when the scotoma is associated with other neurological symptoms, including cranial nerve palsies, nystagmus, pupil irregularities, diplopia, persistent visual field defects, severe headaches, a change in gait or extraocular nerve palsies.2

Scintillating scotoma is often an aura that occurs prior to a classic migraine headache. Even so, whenever patients report this phenomenon, especially if the onset occurs later in life, we must consider other possible causes.

1. Kaufman DM, Solomon S. Migraine visual auras. A medical update for psychiatrists. Gen Hosp Psychiatry 1992 May; 14 (3):162-70.
2. Gutteridge IF, Cole BL. Perspectives on migraine: prevalence and visual symptoms Clin Exp Optom 2001 Mar;84(2):56-70.
3. de Silva RN. A diagnostic sign in migraine? J R Soc Med. 2001 Jun;94(6):286-7.
4. Dahlem MD, Engelmann R, Lowel S, Muller SC Does the migraine aura reflect cortical organization? Eur J Neurosci 2000 Feb;12(2):767-70.
5. Panayiotopoulos CP. Elementary visual hallucinations, blindness, and headache in idiopathic occipital epilepsy: differentiation from migraine. J Neurol Neurosurg Psychiatry 1999 Apr;66(4):536-40.
6. Donnet A, Bartolomei F. Migraine with visual aura and photosensitive epileptic seizures. Epilepsia. 1997 Sep;38(9): 1032-4.
7. Hupp SL, Kline LB, Corbett JJ. Visual disturbances of migraine. Surv Ophthalmol 1989 Jan-Feb;33(4):221-36.
8. Caselli RJ, Hunder GG. Neurologic complications of giant cell (temporal) arteritis. Semin Neurol 1994 Dec;14(4):349-53.
9. Raymond LA, Kranias G, Glueck H, Miller MA. Significance of scintillating scotoma of late onset. Surv Ophthalmol 1980 Sep-Oct;25(2):107-13.
10. Ramadan NM, Tietjen GE, Levine SR, Welch KM. Scintillating scotoma associated with internal carotid artery dissection: report of three cases. Neurology 1991 Jul;41(7):1084-7.
11. Comoglu S, Yarangulmeli A, Koz OG, et al. Glaucomatous visual field defects in patients with migraine. J Neurol 2003 Feb;250(2):201-6.

Vol. No: 140:07Issue: 7/15/03

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