| Scintillating scotoma | |
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| Classification and external resources | |
A depiction of a scintillating scotoma that was almost spiral-shaped, with the scintillations having a Widmanstätten pattern, and with distortion of shapes but otherwise melting into the background similarly to the physiological blind spot. |
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| ICD-10 | H53.1 |
| ICD-9 | 368.12 |
| eMedicine | neuro/480 |
| MeSH | D012607 |
Scintillating scotoma is the most common visual aura preceding migraine and was first described by 19th century physician Hubert Airy (1838–1903). It is often confused with ocular migraine which originates in the eyeball or socket.
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It may occur as an isolated symptom without headache in acephalgic migraine. Although many variations occur, scintillating scotoma usually begins as a spot of flickering light near or in the center of the visual fields, which prevents vision within the scotoma. The scotoma area flickers, but is not dark. The scotoma then expands into one or more shimmering arcs of white or colored flashing lights. An arc of light may gradually enlarge, become more obvious, and may take the form of a definite zigzag pattern, sometimes called a fortification spectrum, because of its resemblance to the fortifications of a castle or fort seen from above.[1] Patterns within the arc have also been known to share striking similarity with Widmanstätten patterns. The scotoma may be bilateral or unilateral and vision beyond the borders of the expanding scotoma(s) remains normal.
The visual anomaly results from abnormal functioning of portions of the occipital cortex, at the back of the brain, not in the eyes nor any component thereof, such as the retinas.[2] This is a different disease from retinal migraine, which is monocular (only one eye).[3]
It may be difficult to read and dangerous to drive a vehicle while the scotoma is present. Normal central vision may return several minutes before the scotoma disappears from peripheral vision.
Sufferers can keep a diary of dates on which the episodes occur to show to their physician, plus a small sketch of the anomaly, which may vary between episodes.
There is no generally accepted cause of scintillating scotomas, but monosodium glutamate (MSG) is frequently reported as a dietary trigger.[4]
According to the National Library of Medicine's Medical Encyclopedia, migraine attacks may be triggered by:
Symptoms typically appear gradually over 5 to 20 minutes and generally last fewer than 60 minutes, leading to the headache in classic migraine with aura, or resolving without consequence in acephalgic migraine.[1] Many migraine sufferers evolve from scintillating scotoma as a prodrome to migraine, to scintillating scotoma without migraine. The scotoma typically spontaneously resolves within the stated time frame, leaving few or no subsequent symptoms, though some report fatigue, nausea and dizziness as sequelae.[6]
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