This article includes discussion of idiopathic photosensitive occipital lobe epilepsy, idiopathic occipital lobe epilepsy, idiopathic photosensitive epilepsy, IPOE, IPOLE, and photosensitive occipital lobe epilepsy. The foregoing terms may include synonyms, similar disorders, variations in usage, and abbreviations.
Idiopathic photosensitive occipital lobe epilepsy is an idiopathic epilepsy syndrome with visually induced seizures that usually begins around puberty. Ictal manifestations are described as bright, colorful, or multicolored rings or spots in the periphery of the visual field. Some patients report ictal blindness or severe blurring of vision. Visual phenomena are often followed by a versive phase, with head and eye deviation, and when the seizures progress, the most frequent ictal sequence is epigastric discomfort, unresponsiveness, and vomiting. Single or repeated seizures when playing video games or in front of the television might appear without a previous history of spontaneous seizures. Visually triggered seizures are associated with the inability of the visual cortex to process afferent inputs of high luminance and contrast through the normal mechanisms of cortical gain control. In this article, the authors explain the clinical, electrophysiological, and etiological characteristics of this epilepsy syndrome.
• Idiopathic photosensitive occipital lobe epilepsy is typical of, although not exclusive to, adolescence.
• Misdiagnosis with migraine is frequent.
• Seizure control is related more to avoidance of precipitants than to treatment.
Historical note and terminology
Reflex epilepsies are characterized by specific modes of seizure precipitation (Commission on Classification and Terminology of the International League Against Epilepsy 1989; Engel 2001). The most frequent forms of reflex epilepsies are the photosensitive epilepsies, in which seizures are provoked by environmental light stimulation. Gastaut and colleagues provided the first evidence of the electroclinical correlates of intermittent photic stimulation in photosensitive patients stimulated with a flash lamp (Gastaut et al 1948). Numerous studies have since clarified many characteristics of visually induced seizures (Newmark and Penry 1979; Binnie and Jeavons 1992; Kasteleijn-Nolst Trenite et al 2001). Visually-induced seizures are frequently seen as one element of idiopathic generalized epilepsies also featuring other seizure types (Commission on Classification and Terminology of the International League Against Epilepsy 1989; Engel 2001; Guerrini and Genton 2004) or as the only type of seizures in 'pure' photosensitive epilepsies. Most often they appear to be generalized, but in up to 17% of photosensitive patients, they may originate from the occipital lobe (Guerrini et al 1998). Although photic-induced occipital seizures are associated with a brain lesion in some patients, the more typical pattern of recurrent photosensitive occipital seizures is usually observed in the context of idiopathic epilepsy, with onset around puberty (Tassinari et al 1989; Ricci and Vigevano 1993; Guerrini et al 1995; Guerrini et al 1998). The clinical and EEG characteristics indicating an idiopathic localization-related epilepsy were not always specifically detailed, especially in the early reports (Davidson and Watson 1956; Herrlin 1960; Naquet et al 1960; Fischer-Williams et al 1964; De Marco and Ghersini 1985; Aso et al 1988; Maeda et al 1990; Brinciotti et al 1992; Michelucci and Tassinari 1993; Ricci and Vigevano 1993; Ferrie et al 1994; Guerrini et al 1995; Guerrini et al 1997; Takahashi and Tsukahara 1998; Yalcin et al 2000), where generalized features received much emphasis.
Likewise observed in primary reading epilepsy (Commission on Classification and Terminology of the International League Against Epilepsy 1989), idiopathic photosensitive occipital lobe epilepsy can be defined as an idiopathic localization-related (local, focal, partial) epilepsy with age-related onset and specific mode of precipitation. The syndrome has been recognized by the ILAE task force on classification and terminology (Engel 2001).
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