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  • Updated 03.10.2020
  • Released 02.12.2004
  • Expires For CME 03.10.2023

Visual-sensitive epilepsies


This article includes discussion of visual-sensitive epilepsies, visual- triggered epilepsies, visual-evoked epilepsies, and visual reflex epilepsies. The foregoing terms may include synonyms, similar disorders, variations in usage, and abbreviations.


Visual-sensitive seizures elicited mainly by video games, television, and flickering lights in discotheques are the commonest reflex seizures, and most physicians can expect to encounter them. Children and teenagers are more vulnerable. However, in modern life with the increasing numbers of video game players and spread of visual electronic media, the demographics of visual-induced seizures have expanded to nearly any age, and they sometimes get to epidemic proportions. In this updated article, the author reviews these seizures and their triggers and explains the basics of photosensitive epilepsy, pattern-sensitive epilepsy, fixation-off sensitivity, and seizures triggered by television screens and video games. He details developments in their clinical manifestations, differential diagnosis, pathophysiology, and genetics as well as means of their detection and their management. He emphasizes populations at risk, factors of misdiagnosis, treatment strategies, avoidance of various triggers, and certain antiepileptic drugs that may aggravate the seizures.

Key points

• Visual-sensitive seizures are provoked by photic, pattern, and other visual stimuli, alone or in combination.

• They are the commonest type of reflex seizures and are mainly triggered by video games, television, and flickering lights of discotheques.

• Though more common in teenagers, the demographics of visual-induced seizures have changed with the intrusion of video games and certain television programs in modern life.

• Clinically, generalized seizures (absences, myoclonic jerks, generalized tonic-clonic seizures) are more common than focal seizures, which are usually visual.

• Patients may have pure visual-sensitive epilepsy (triggered by visual stimuli only), but often these patients may also have spontaneous seizures.

• Certain epileptic syndromes (eg, juvenile myoclonic epilepsy, Dravet syndrome, Unverricht-Lundborg disease) commonly manifest with photosensitive seizures.

• The role of EEG is fundamental in identification of the offending stimuli with significant clinical and pathophysiological implications.

• Avoidance, prevention, or modification of the provocative triggers is the key point of management, and this may be sufficient for patients with pure visual-sensitive seizures.

• Appropriate antiepileptic medication is needed for those with continuing reflex and spontaneous seizures.

Historical note and terminology

Seizures triggered by visual stimuli were known in classical antiquity (168; 110; 81; 55; 08; 66; 84).

The first reference to photosensitive epilepsy is attributed to Apuleius Lucius (150 AD), a Roman philosopher in his “Apologia and Florida.” However, Apuleius does not refer to flickering lights:

Nay, even supposing I had thought it a great achievement to cast an epileptic into a fit, why should I use charms when, as I am told by writers on natural history, the burning of the stone named gagates is an equally sure and easy proof of the disease? For its scent is commonly used as a test of the soundness or infirmity of slaves even in the slave-market. Again, the spinning of a potter's wheel will easily infect a man suffering from this disease with its own giddiness. For the sight of its rotations weakens his already feeble mind, and the potter is far more effective than the magician for casting epileptics into convulsions (Apuleius Lucius, 150 AD).

Note that “gagate” is an old name for the stone “jet” or “black amber,” a carbon fossil that is compact and very light. Jet was known in ancient Egypt, where it was used for making mirrors; in Greece and Rome they used it for cutting amulets, bracelets, and rings. Also, the potter’s wheel in that time was solid, not spoked, which would be needed to produce intermittent light (110).

The oldest clear reference to photosensitive epilepsy is by Soranus Of Ephesus (2nd century AD) a Greek gynecologist, obstetrician, and pediatrician, who in Acute and Chronic Diseases, which contains an excellent chapter on nervous disorders, wrote:

The use of flame, or very bright light obtained from flame, has an agitating effect. In fact when a case of epilepsy is in its quiescent stage, the ultimate use of light with its sharp penetrating action may cause the recurrence of an attack. (Soranus Of Ephesus, 2nd century AD).

Clementi was the first to describe experimental, light-induced epilepsy in studies of photic stimulation in dogs after strychnine application to the visual cortex (29). The effective triggering stimuli had to be repetitive. The following quote is from an English translation of Clementi’s report (66):

Under such experimental conditions, (continuous strychninisation of dog occipital cortex for 20’-30’), photic stimulation triggered an epileptic attack that began after a few minutes with nystagmus, mydriasis, and tonic eye deviation toward the side contralateral to the strychninised hemisphere, and continued with clonic movements involving first the periocular muscles and then the entire body. . . . Noteworthy extension of the strychninised occipital cortical area appears to be a necessary condition for onset of reflex epilepsy if strychninisation is limited to a single hemisphere. If, on the other hand, strychnine is applied over both hemispheres, strychninisation of a highly limited area may be sufficient (29).

The first clinical evidence of photosensitive epilepsy by Gowers and later by Holmes refers to occipital seizures induced by light (64; 76).

In very rare instances the influence of light seems to excite a fit. I have met with two examples of this. One was a girl of seventeen whose first attack occurred on going into bright sunshine for the first time, after an attack of typhoid fever. The immediate warning of an attack was giddiness and rotation to the left. At any time an attack could be produced by going out suddenly into bright sunshine. If there was no sunshine an attack did not occur.

The other case was that of a man, the warning of whose fits was the appearance before the eyes of “bright blue lights, like stars--always the same.” The warning, and a fit, could be brought on at any time by looking at a bright light, even a bright fire. The relation is, in this case, intelligible, since the discharge apparently commenced in the visual centre (64).

Holmes attributed this “reflex epilepsy” to an enhanced excitability of the visual cortex:

Some men subject to epileptiform attacks commencing with visual phenomena owing to gunshot wounds of the occipital region, have told me that bright lights, cinema exhibitions and other strong retinal stimuli tend to bring on attacks (76).

Radovici and associates in 1932 reported the first case of eyelid myoclonia (often erroneously cited as self-induced epilepsy) with experimental provocation of seizures documented with cine film (144).

AA...age de 20 ans, presente des troubles moteurs sous forme de mouvements involontaires de la tete et des yeux sous l' influence des rayons solaires (Radovici et al 1932).

Goodkind in 1936 also detailed various methods used to experimentally induce “myoclonic and epileptic attacks precipitated by bright light” in a photosensitive woman:

The patient was placed on a bed in a darkened room in such a position that when the black window shade was raised, her face only was directed towards the early afternoon sunlight, which came through an ordinary wire window screen. On such exposure of the eyes to the sun, she responded within a few seconds with marked, diffuse, and apparently uncontrollable clonic jactitatory movements. The movements ceased the moment a blindfold was applied or the black window shade was lowered. She reacted definitely also when either eye was uncovered separately. . . . The patient was also exposed to ultra violet radiation from a quartz mercury vapour lamp and to bright pocket flash light, to little or no effect. A small beam from a carbon arc lamp produced several rapid myoclonic jerks (63).

With the advent of EEG by Berger in 1929, a new era started for the study of photosensitive epilepsies. Adrian and Matthews in 1934 were the first to introduce intermittent photic stimulation in the use of EEG (01). The subject was looking at an opal glass bowl that was illuminated from behind by a lamp, in front of which a disc with cut-out sectors was rotated.

Strauss in 1940 was the first scientist to record epileptic seizures induced experimentally by photic stimulation (156). His patient, a woman aged 33 years, had suffered right hemiparalysis and right Jacksonian fits from childhood. The epileptic attacks could be provoked by various sensory stimuli (tactile, auditory, visual etc.). He recommended that these stimuli should be noted not only by purely clinical observation but also, if possible, by EEG studies on the patient.

Flashing light into the right eye was associated with changes in the electroencephalogram. Three-per-second waves at high potential appeared, associated with twitching around the right corner of the mouth. The slow waves did not appear when the same stimulus was applied after cocainization of the right eye. The potentials, without a doubt, were true brain potentials because they could not be reproduced by having the patient imitate the twitching activity. Moreover, their appearance in the record from the left side makes it improbable that they represent muscle potentials from the muscles on the right side of the face (156).

The real interest and detailed study of epilepsy by means of intermittent photic stimulation (IPS) activation was established by Walter and his associates in Bristol, England who started using a high intensity lamp of strobotron light to produce IPS (176; 177; 175). They found that IPS at a “magic frequency,” mostly 12 to 18 Hz, could induce subjective and objective symptoms, which correlated with specific EEG patterns. The most dramatic EEG abnormalities occurred in patients, mostly children, with a history of seizures but also to a lesser extent in subjects with only a family history of epilepsy. Clinically, these could be associated with bilateral or asymmetrical myoclonic jerks and “petit mal” attacks, rarely in combination.

Cobb also recorded IPS-induced absence seizures with EEG in 3 patients with seizures provoked by sunlight flickering through trees (30). Familial sensitivity to intermittent photic stimulation was first described in 1949 (44).

Henri Gastaut and his associates in Marseilles, France have made numerous and vital contributions of what we know about photosensitive epilepsies (58; 57; 56; 177; 59).

Grey Walter provided me with a stroboscope so that, on my return to Marseille we could concentrate on the study of the effects of ILS [intermittent light stimulation] in epileptics. The team was composed of:

Joseph Roger, who selected the epileptic patients in the Neurology department, ran [sic] by his father; Anne Beaumanoir, who, together with my wife, recorded the EEG of these patients on our only 4-stylus Grass recorder; myself, who tuned the frequency of the stroboscope flashes until I found the “magical” one; Mireille Taury who, inside a Faraday cage with the patient, wielded the lamp of the stroboscope in front of the eyes of the “victim” who was terrorised by the coming seizures; and Robert Naquet who was then too young to be a full member of the team, but who volunteered to take the place of the patient as a supposedly normal control, before he was to exchange this position with the monkeys who would bring him fame (55).

However, there was a problem. EEGs from the majority of patients with photosensitivity showed generalized discharges, and the view that photosensitivity was a generalized “centrencephalic” epilepsy dominated the relevant literature (58; 56; 13; 14). Photically induced EEG abnormalities confined or starting from the occipital regions, occipital foci driven or activated by IPS, and visual seizures with or without secondarily generalization attracted less attention though there were reports with ictal EEG recording of onsets of photically induced seizures consisting of rapid spikes and fast rhythms starting in or limited to 1 or both occipital regions (134; 106; 35; 49). Clinically, seizures started with elementary or complex visual hallucinations, hemianopia, or blindness and were often followed by tonic deviation of the head and eyes with secondarily generalized tonic-clonic seizures. Bizarre and prolonged 16-minute seizures of complex visual hallucinations with nausea, belching, confusion, and additional “psychoneurotic-like” symptoms induced by IPS were recorded in a middle-aged woman who had infrequent spontaneous and photic seizures and “so-called migraine for 20 years.” Extensive neuroradiological investigations were normal, and the patient was well at a 13-year follow-up (49).

Panayiotopoulos was the first to document that photosensitive epilepsy originates from the occipital regions and, thus, is not a generalized epilepsy (110).

Occipital spikes in photosensitive patients with generalized PPR
(Left) Patterned intermittent photic stimulation (2 mm × 2 mm graticule superimposed on the grass of the stroboscope) evoked occipital spikes, which are time-locked to flash at 6 flashes/second of a patient with spontaneous and ph...

Nomenclature and classification. Photosensitive epilepsy was classified among the generalized epilepsies by the ILAE Commission (31). This is for the following reasons:

• Photoparoxysmal responses (PPR) were considered to be primarily generalized (56; 59; 10; 73) although the initial occipital onset of the generalized EEG discharge was well reported (128; 110; 110).

• A quarter of patients with spontaneous seizures and EEG photosensitivity belong to a variety of epileptic syndromes of idiopathic generalized epilepsy.

According to the ILAE Task Force (Engel 2001; Engel 2006):

(1) Visual precipitating stimuli are:

(a) flickering light--color to be specified when possible
(b) pattern
(c) other visual stimuli.

(2) Related epileptic syndromes are:

(a) photosensitive occipital lobe epilepsy
(b) other visual sensitive epilepsies.

The new ILAE “practical clinical definition of epilepsy” considers “the condition of recurrent reflex seizures, for instance in response to photic stimuli, represents provoked seizures that are defined as epilepsy. Even though the seizures are provoked, the tendency to respond repeatedly to such stimuli with seizures meets the conceptual definition of epilepsy, in that reflex epilepsies are associated with an enduring abnormal predisposition to have such seizures” (50).

According to the 2010 ILAE proposal (12) and the ILAE epilepsy diagnosis manual (Commission on Classification and Terminology of the International League Against Epilepsy 2014), reflex epilepsies are classified as electroclinical syndromes “with less specific age relationship.” However, despite their prevalence and significance, there is no consideration of visual-sensitive seizures of any type in the recent position papers of the ILAE Commission for Classification and Terminology (51; 151).

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