Television epilepsy and pattern sensitivity

Properly functioning domestic television sets may induce seizures in epileptic patients (TV epilepsy). We investigated the effects of different types of visual stimuli on paroxysmal electroencephalographic (EEG) activity in 32 patients known to be sensitive to intermittent photic stimulation (stroboscopic light). We monitored sensitivity to patterns of horizontal and vertical lines, both stationary and vibrated (pattern sensitivity), and to normal broadcasts on a domestic, black and white (405- or 625-line) TV receiver (TV sensitivity). Twenty-three of the 32 patients were sensitive to pattern. Twenty-two were sensitive to vibrated patterns, and 11 to static patterns (P less than 0-01), All patients sensitive to pattern were also sensitive to TV; The association between sensitivity to pattern and to TV was significant. Clinical history of TV epilepsy (16 out of 32 patients) and laboratory evidence of pattern or TV sensitivity were not significantly associated. The high incidence of pattern sensitivity among flicker-sensitive patients and its association with TV sensitivity suggests that linear patterns produced by the raster of a black and white set as it scans, or "line-jitter" produced by the raster in areas of low TV-signal strength may contribute to the epileptogenic effect of TV.

Stripes, complex cells and seizures. An attempt to determine the locus and nature of the trigger mechanism in pattern-sensitive epilepsy

The study concerns an epileptic patient whose absence attacks were contingent on the viewing of striped patterns. A series of experiments demonstrated first that seizures were not due to the intermittent stimulation of retinal cells produced as physiological nystagmus vibrated the image of the pattern, and secondly that seizures were triggered at the cortical level, probably by the firing of complex cells. Spectacles which occluded pattern vision in one eye were highly effective in reducing seizure incidence.