Scintillating scotoma
Encyclopedia
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.
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 fortification
s of a castle or fort seen from above. 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. This is a different disease from retinal migraine
, which is monocular (only one eye).
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.
(MSG) is frequently reported as a dietary trigger.
According to the National Library of Medicine's Medical Encyclopedia, migraine attacks may be triggered by:
with aura, or resolving without consequence in acephalgic migraine
. 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.
Aura (symptom)
An aura is a perceptual disturbance experienced by some migraine sufferers before a migraine headache, and the telltale sensation experienced by some people with epilepsy before a seizure. It often manifests as the perception of a strange light, an unpleasant smell or confusing thoughts or...
preceding migraine
Migraine
Migraine is a chronic neurological disorder characterized by moderate to severe headaches, and nausea...
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.
Presentation
Acephalgic migraine
Acephalgic migraine is a neurological syndrome...
. Although many variations occur, scintillating scotoma
Scotoma
A scotoma is an area of partial alteration in one's field of vision consisting of a partially diminished or entirely degenerated visual acuity which is surrounded by a field of normal - or relatively well-preserved - vision.Every normal mammalian eye has a scotoma in its field of vision, usually...
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
Zigzag
A zigzag is a pattern made up of small corners at variable angles, though constant within the zigzag, tracing a path between two parallel lines; it can be described as both jagged and fairly regular....
pattern, sometimes called a fortification spectrum, because of its resemblance to the fortification
Star fort
A star fort, or trace italienne, is a fortification in the style that evolved during the age of gunpowder, when cannon came to dominate the battlefield, and was first seen in the mid-15th century in Italy....
s of a castle or fort seen from above. 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. This is a different disease from retinal migraine
Retinal migraine
Retinal migraine is a retinal disease often accompanied by migraine headache and typically affects only one eye...
, which is monocular (only one eye).
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
Peripheral vision
Peripheral vision is a part of vision that occurs outside the very center of gaze. There is a broad set of non-central points in the field of view that is included in the notion of 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.
Causes
There is no generally accepted cause of scintillating scotomas, but monosodium glutamateMonosodium glutamate
Monosodium glutamate, also known as sodium glutamate or MSG, is the sodium salt of glutamic acid, one of the most abundant naturally occurring non-essential amino acids....
(MSG) is frequently reported as a dietary trigger.
According to the National Library of Medicine's Medical Encyclopedia, migraine attacks may be triggered by:
- allergic reactions
- bright lights
- loud noises
- certain odors
- perfumes
- physical or emotional stress
- changes in sleep patterns
- smoking or exposure to smoke
- skipping meals
- alcohol
- caffeine
- menstrual cycle fluctuations
- birth control pills
- tension headaches
- foods containing tyramine (red wine, aged cheese, smoked fish, chicken livers, figs, and some beans)
- monosodium glutamate (MSG)
- nitrates (like bacon, hot dogs, and salami)
- other foods such as chocolate, nuts, peanut butter, avocado, banana, citrus, onions, dairy products, and fermented or pickled foods
Prognosis
Symptoms typically appear gradually over 5 to 20 minutes and generally last fewer than 60 minutes, leading to the headache in classic migraineMigraine
Migraine is a chronic neurological disorder characterized by moderate to severe headaches, and nausea...
with aura, or resolving without consequence in acephalgic migraine
Acephalgic migraine
Acephalgic migraine is a neurological syndrome...
. 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.
External links
- AgingEye Times
- Imigraine.Net - includes images of scintillating scotomata
- Youtube Video Depiction of Scintillating Scotoma
- Visual Migraine Simulation Video Depiction of Scintillating Scotoma