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  • Updated 06.11.2022
  • Released 04.23.1999
  • Expires For CME 06.11.2025

Photosensitive occipital lobe epilepsy

Introduction

Overview

Photosensitive occipital lobe epilepsy is an 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 may occur without a previous history of spontaneous seizures while playing video games or watching television. Developmental delay and learning difficulty may be seen in some patients. 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. Critical neuronal mass activation in the occipital cortex, propagation of the abnormal discharges along the cortico-cortical or cortico-subcortical pathways, and the influence of specific epilepsy genes predisposing to this phenotype were also found to be important contributors.

Key points

• Photosensitive occipital lobe epilepsy is typical of, although not exclusive to, adolescence.

• Misdiagnosis with migraine is frequent.

• Differentials include Lafora body disease, symptomatic occipital epilepsy with photosensitivity, and genetic generalized epilepsies with photosensitivity.

• Seizure control is related more to avoidance of precipitants than to treatment.

• Overall prognosis is generally good.

Historical note and terminology

Reflex epilepsies are characterized by specific modes of seizure precipitation and have been incorporated in the new definition of epilepsy (14; 20; 24). 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 (27). Numerous studies have since clarified many characteristics of visually induced seizures (50; 06; 40; 38; 88). Visually-induced seizures are frequently seen as one element of genetic generalized epilepsies along with other seizure types (14; 20; 31; 38; 88) 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 (29; 88). 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 (77; 65; 30; 29). The clinical and EEG characteristics of a focal onset were not always specifically detailed, especially in the early reports (16; 35; 49; 23; 18; 03; 45; 11; 47; 65; 22; 30; 28; 75; 89), where generalized features received much emphasis. Photosensitive occipital lobe epilepsy has been recognized by the ILAE task force on classification and terminology in the group of self-limited focal epilepsies according to the 2017 ILAE classification (20; 69). According to the 2022 position paper by the ILAE task force on nosology and definitions of childhood onset epilepsy syndromes, idiopathic photosensitive occipital lobe epilepsy or IPOLE was renamed as POLE (Photosensitive Occipital Lobe Epilepsy), which is characterized by photic-induced, focal seizures involving the occipital lobe in individuals with normal development, neurologic examination, and intellect, in which the patient experiences a visual aura with involuntary head version and with intact awareness (71).

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