1.2.4 Retinal migraine ICHD 3 Beta
Repeated attacks of monocular visual disturbance, including scintillations, scotomata or blindness, associated with migraine headache.
A. At least two attacks fulfilling criteria B and C
B. Aura consisting of fully reversible monocular positive and/or negative visual phenomena (e.g., scintillations, scotomata or blindness) confirmed during an attack by either or both of the following:
1. clinical visual field examination
2. the patient’s drawing (made after clear instruction) of a monocular field defect
C. At least two of the following three characteristics
1. the aura spreads gradually over ≥5 min
2. aura symptoms last 5-60 min
3. the aura is accompanied, or followed within 60 min, by headache
D. Not better accounted for by another ICHD-3 diagnosis, and other causes of amaurosis fugax have been excluded.
Some patients who complain of monocular visual disturbance in fact have hemianopia. Some cases without headache have been reported, but migraine as the underlying aetiology cannot be ascertained.
1.2.4 Retinal migraine is an extremely rare cause of transient monocular visual loss. Cases of permanent monocular visual loss associated with migraine have been described. Appropriate investigations are required to exclude other causes of transient monocular blindness.
This is a migraine visual aura occurring just in one eye, or in what may be referred to as a “monocular” distribution rather than the usual bilateral, homonomous pattern. According to the theory of Leao, a spreading wave of electrical depolarization moving across one side of the occipital brain is what causes the migraine with aura patient to see the scintillating, zig-zag pattern in both halves of the visual fields. In a homonomous pattern the carefully observant and carefully instructed patient may notice the visual aura in, for example, the right halves of both eyes. This would comprise the right eye temporal field, and the left eye nasal field. The visual aura should be followed by a typical migraine without aura headache.
Visual radiations from eye to occipital brain [i]
Every neurologist knows that patients best note the images in the dominant field (in the example given above the dominant field would be the right eye) and only on close questioning may the patient be able to admit seeing the spectral image in the non-dominant field (in the example given the non-dominant field would be the image in the right part of the left eye.) Sometimes the patient may be asked if they saw the image with both eyes closed and this memory may help them declare the occurrence of the non-dominant field. Examiners who see patients during the attacks commonly have the patient do the alternate-eye-covering test to differentiate a homonomous from a monocular pattern although Spierings[ii] has stated that he never found this test to be helpful. If a properly educated patient can draw what they saw and the image is just in one eye and followed by a migraine headache, then this is what is termed retinal migraine.
Images in just one eye bring up the prospect of other medical problems causing the symptoms than migraine, such as amaurosis fugax from embolic carotid disease or optic neuropathy. Careful clinical examination and testing should sort out other diagnoses. The differential diagnosis includes: vasculitis, hypercoagulable states, illicit drug use, and rheumatologic disorders. Workup includes exclusion of a possible embolic source and diagnostic testing with EKG, echocardiogram, carotid duplex scanning, CAT scan or MRI brain scan, and angiography.[iii]
Literature Review of retinal migraine
Carroll[iv] introduced the term “Retinal Migraine” writing in Headache in 1970. He described 15 patients with transient and persistent monocular visual loss but no associated headaches. Criticism has been leveled at Carroll because ICHD II criteria, which were first published in 1988, were not applied to his cases and many of the patients had no headache. Note that ICHD II calls this entity “Retinal Migraine” and not “eye migraine, ocular migraine, or ophthalmic migraine” which are other terms commonly used for this syndrome.
Grosberg, et al,[v] writing in 2006 in Cephalalgia on “Retinal migraine reappraised,” reported that most of their patients were women in the second or third decade of life who had a history of migraine with aura. Grosberg, et al, reported 6 new cases and reviewed 40 from the literature. This is different from ICDH 3 Beta criteria regarding retinal migraine, which states that most patients have migraine without aura. The authors stated “in the typical attack monocular visual features consist of partial or complete vision loss lasting < 1 hour, ipsilateral to the headache.” Permanent monocular visual loss occurred in half of the reported cases although ICDH-II criteria require reversible visual loss. Grosberg, et al, stated:
Based on this observation, the authors recommend migraine prophylactic treatment in an attempt to prevent permanent visual loss, even if attacks are infrequent. We also proposed a revision to the ICDH-II diagnostic criteria for retinal migraine.
Hill, et al,[vi] wrote an article entitled “Most Cases Labeled as “Retinal Migraine” Are Not Migraine,” in the Journal of Neuro-Ophthalmology in 2007. These authors pointed out that monocular vision loss has often been labeled “retinal migraine” yet many of the previously reported cases do not meet the diagnostic criteria of ICDH-II which defines “retinal migraine” as an attack of reversible monocular visual disturbance with migraine headache and a normal neuro-ophthalmic exam between attacks. In their paper these authors reported:
We performed a literature search of articles mentioning "retinal migraine," "anterior visual pathway migraine," "monocular migraine," "ocular migraine," "retinal vasospasm," "transient monocular visual loss," and "retinal spreading depression" using Medline and older textbooks. We applied the IHS criteria for retinal migraine to all cases so labeled. To be included as definite retinal migraine, patients were required to have had at least two episodes of transient monocular visual loss associated with, or followed by, a headache with migrainous features.
They found only 5 patients who met ICDH-II criteria for definite retinal migraine. No patient with permanent visual loss met the IHDH-II criteria for retinal migraine. Hill, et al, concluded that:
Definite retinal migraine, as defined by the IHS criteria, is an exceedingly rare cause of transient monocular visual loss. There are no convincing reports of permanent monocular visual loss associated with migraine. Most cases of transient monocular visual loss diagnosed as retinal migraine would more properly be diagnosed as "presumed retinal vasospasm."
Evans and Grosberg[vii] writing in Headache in 2008 on “Expert Opinion: Retinal Migraine: Migraine Associated With Monocular Visual Symptoms,” presented a case and discussed pathophysiology, work up, and treatment. Their case summary follows:
This 25-year-old man reports a 12-year history of similar headaches occurring about one or 2 times monthly. He develops a left or right temple throbbing which is mild at first and later becomes a 10/10 associated with nausea, vomiting, light and noise sensitivity. About 30 minutes after the onset of all of the headaches, he develops sudden total darkness where he cannot see in the eye contralateral to the headache lasting about 4 hours. The headache is severe for about 5 hours and then mild for 24 to 36 hours. Aspirin or acetaminophen is of mild help. He tries to go to bed. He had never seen a physician for the headaches before. Past medical history was negative. There was no family history of migraine. Neurological examination was normal.
Evans and Grosberg stated:
The most likely cause of recurrent stereotypical episodes of transient monocular visual loss in association with headaches is retinal migraine. Secondary causes of transient monocular visual loss are less likely to be found in cases that have been recurring for a long period of time.
Evans and Grosberg felt that the true occurrence of retinal migraine was unknown but that it was a rare entity. The type of visual disturbance noted may be positive and/or negative visual disturbances within one eye associated with migraine headache. They noted that:
Typical descriptions of positive visual phenomena include flashing rays of light, zigzag lightning patterns or perceptions of bright colored streaks, halos or diagonal lines. The negative visual losses include blurring, blank areas, black dots or spots in the field of vision.
Regarding pathophysiology, Evans and Grosberg said:
The underlying pathophysiology of retinal migraine remains largely unknown. In some cases, vasospasm of the retinal or ciliary circulation may have caused retinal or optic nerve ischemia; this may explain the amaurosis and rare funduscopic findings during acute attacks of retinal migraine. An alternative theory is spreading depression of retinal neurons, a phenomenon that has been demonstrated in the chick retina. Similarly, it is possible that those rare cases with prolonged monocular defects associated with migraine headache could have a mechanism similar to that seen in the cerebral cortex of migraineurs who have persistent aura without infarction.
Evans and Grosberg stressed that prolonged and permanent monocular visual loss was more common in retinal migraine than in cases of prolonged aura or migrainous infarction in patients with conventional migraine. Thus, retinal migraine carries a worse prognosis, a situation provoking consideration of pharmacological treatment. Currently they did not feel there was enough clinical information to support specific comments on treatment although they felt that triptans or ergotamine should be avoided because of their vasoconstrictive properties. Patients should be counseled to avoid oral contraceptives. Preventive therapies such as calcium-channel blockers, tricyclic antidepressants, beta-blockers, and neuromodulators have only anecdotal data to support their use. Daily prophylactic aspirin would be reasonable advice.
[i] Rucker CW. The Interpretation of Visual Fields. American Academy of Ophthalmology and Otolaryngology. 15 Second Street SW, Rochester, Minnesota 55901. Third Edition. 1957.
[ii] Spierings ELH. Monocular Symptoms in Retinal Migraine, comment. Journal Watch Neurology. 2007;9(5):38.
[iii] Evans RW, Grosberg, BM. Expert Opinion: Retinal Migraine: Migraine Associated With Monocular Visual Symptoms. Headache. 2008;48:142-145.
[iv] Carroll D. Retinal Migraine. Headache. 1970;10(1):9-13.
[v] BM Grosberg, S Solomon, DI Friedman, RB Lipton (2006) Retinal migraine reappraised. Cephalalgia. 2006;26(11):1275–1286.
[vi] Hill DL, Daroff RB, Ducros A, Newman NJ, Biousse V. Most Cases Labeled as "Retinal Migraine" Are Not Migraine. Journal of Neuro-Ophthalmology. 2007;27(1):3-8.
[vii] Evans RW, Grosberg BM. Expert Opinion: Retinal Migraine: Migraine Associated With Monocular Visual Symptoms. Headache. 2008;48:142-145.