July 25 Highlight and Commentary

Nonepileptic visual sensitivity: A rare or underdiagnosed manifestation?

Seri et al. report a 9-year-old boy with syncope triggered by visual stimuli. He had five episodes while playing video games or watching television, characterized by initial dizziness and paleness, followed by sudden loss of consciousness. During intermittent photic stimulation at 4 to 10 flashes/second the patient’s EKG showed a progressive bradycardia, which was time-locked to the onset of visual stimuli.

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Visually induced syncope: A nonepileptic manifestation of visual sensitivity?

Commentary by John B.P. Stephenson, BM, DM, FRCP

Vasovagal syncope induced by visual stimuli, unrelated to the perceptual or emotional properties of such visual stimuli, seems rare, and this carefully studied patient is of great interest, with wide implications. Television syncope with an emotional trigger is probably not at all uncommon, the stimuli involving “blood and gore”; such as “watching an illusionist on the television putting a knife through someone’s arm” (Case 15.13 in ¹). By contrast, neurally mediated syncope triggered by intermittent photic stimulation has to my knowledge been reported only once previously, and that was 40 years ago.²

The 9-year-old boy in the present report might very easily have been diagnosed with photosensitive epilepsy. Indeed, though he did not have epilepsy, he may well have had epileptic seizures induced by his photic-triggered syncope—so-called anoxic-epileptic seizures³—because by clinical history he had at times “clonic movements of the upper limbs, lasting approximately 2 minutes.” That is too long for the movements—spasms, jerks, and others—of nonepileptic convulsive syncope. Interestingly, the patient reported earlier² also had anoxic-epileptic seizures, with rhythmic jerking after prolonged cardiac asystole, as figure 2 in their article makes clear.

The object of this discussion is not to advertise the existence of anoxic-epileptic seizures—although they are not rare³—but perhaps their occurrence after intermittent photic stimulation may give us some clue as to why anoxic-epileptic seizures occur in the more usual situations when visual stimuli are not involved.

Of more general importance to all in adult or child neurology is the fact that still in 2006 the authors need to conclude their case report by stating “We suggest that EKG data are always acquired during EEG procedures in patients investigated for possible photosensitivity.” Surely EKG data should be acquired during every EEG examination, whatever the indication.

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