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hemiconvulsions and GTCS. Some children may have seizures of eye deviation from the start
without visual hallucinations and it is likely that these cases have a better prognosis74,130. Other
ocular manifestations may include unidirectional ocular clonic seizures (oculoclonic seizures)
that are rare, and eyelid fluttering or repetitive eye closures that occur in about 10% of patients,
usually at a later stage when consciousness is impaired. They signal an impending secondary
GTCS.

Ictal headache, or mainly orbital pain, is a common ictal symptom, and in a small number of
patients it may start before the first visual or other ictal occipital symptoms.

Consciousness is intact during the visual symptoms (simple focal seizures), but may be
disturbed or lost in the course of the seizure, usually before or at the time of eye deviation or
convulsions. Syncopal-like attacks are rare4.

Extra-occipital seizure progression
Elementary visual hallucinations or other ictal symptoms may progress to complex focal
seizures (14%), hemiconvulsions (43%) or GTCS (13%)122. Complex focal seizures of temporal
lobe symptomatology are extremely rare and may indicate a symptomatic cause124. Ictal
vomiting may occur with progression to the non-dominant temporal lobe131.

Post-ictal headache
Post-ictal headache, mainly diffuse, but also severe, unilateral, pulsating and indistinguishable
from migraine headache, occurs in half the patients, in 10% of whom it may be associated with
nausea and vomiting2,22,124,126. This occurs immediately, or 5–10 minutes after the end of the
visual hallucinations. The duration and severity of the headache appears to be proportional to
the duration and severity of the preceding seizure, although it may also occur after brief simple
visual seizures.

Seizure stereotype
For any one patient, in every seizure the elementary visual hallucinations have a fingerprint
with a stereotypic appearance regarding morphology, colours, location, movement and other
characteristics. Most patients also know at what stage of their ictal manifestations a secondarily
GTCS may occur.

Duration and circadian distribution
Visual seizures are usually brief, lasting from a few seconds to 1–3 minutes if they occur alone
without other occipital or extra-occipital spreading2,121,122,124-127. However, a few patients with
brief visual seizures may later develop lengthy visual seizures lasting for 10–20 minutes. Visual
seizures are predominantly diurnal and occur at any time of the day but some patients may also
have infrequent seizures in sleep or on awakening.

Frequency of seizures
If untreated, the majority of patients experience frequent brief visual seizures ranging from
several every day to one per week or month. However, propagation to other seizure
manifestations, such as focal or generalised convulsions, is much less frequent occurring once
per month, year or even rarer.

Precipitating factors and idiopathic photosensitive occipital epilepsy
This is a matter of inclusion criteria. Gastaut considers photosensitivity as part of ICOE-G121,122,
while the ILAE Task Force recognises ‘idiopathic photosensitive occipital lobe epilepsy’ as a
syndrome of reflex epilepsy with age-related onset1,132. Reflex occipital seizures induced by
television, video games, and intermittent photic stimulation (IPS) manifest with similar
semiology as the spontaneous visual seizures5,131,133-136. Deviation of the eyes, epigastric
discomfort and vomiting, headache, and generalised convulsions may follow. Prognosis is