Occipital epilepsy · Grey Matter

Occipital epilepsy is epilepsy whose seizures start in the occipital lobe, and because that lobe builds vision, its seizures are seen before they are felt: lights, colours and shapes, or a patch of blindness, that the person knows are not really there.

Occipital epilepsy. Occipital epilepsy is epilepsy whose seizures start in the occipital lobe, and because that lobe builds vision, its seizures are seen before they are felt: lights, colours and shapes, or a patch of blindness, that the person knows are not really there.

A seizure in the visual cortex makes that cortex do what it always does, only without input from the eyes. The typical result is an elementary visual hallucination: small coloured circles or spots, often in the visual field opposite the seizing hemisphere, appearing within seconds and lasting seconds to a few minutes. Some seizures show as loss of vision instead, and some are followed by deviation of the eyes or blinking. If the discharge spreads forward into the temporal or parietal lobes, the seizure takes on their signs, and it can become a tonic-clonic seizure.

It is often confused with migraine aura, and the timing separates them best. Occipital seizures are brief and colourful, usually circular, and can recur many times a day; a migraine aura builds over at least five minutes, lasts five to sixty, and is more often a black-and-white zigzag edge with a blind patch behind it.

There are childhood and structural forms. Self-limited forms appear in children (one dominated by visual seizures, another, Panayiotopoulos syndrome, by vomiting and other autonomic signs during sleep) and usually end by adolescence; in adults the cause is more often a lesion such as a scar, a malformation or a tumour.

Some people with occipital seizures are photosensitive, so flashing lights or patterns can provoke them, which links this card to reflex epilepsy.

The visual signs give it a place in the theme. The same visual cortex can host a fading perturbation, a slow wave of spreading depression or a fast discharge, and the visual symptoms are how each of the three shows from the inside.

Questions: How can coloured lights from an occipital seizure be told apart from a migraine aura? Speed and shape separate them best. Occipital seizures are produced by a fast discharge, so their lights appear within seconds, last seconds to a couple of minutes, are usually coloured and round, and can recur many times a day. A migraine aura is produced by spreading depression, which crosses the cortex at a few millimetres per minute, so by the international criteria it spreads over at least five minutes and lasts five to sixty, typically as a flickering black-and-white zigzag edge with a blind patch inside. The distinction is clinical, and overlapping cases are sorted out with an EEG and a neurologist. What does a seizure in the visual cortex look like from the inside? A seizure in the visual cortex makes that cortex produce what it normally produces, only without input from the eyes, so it is seen as light. The typical form is small, brightly coloured circles or spots, often in the half of the visual field opposite the seizing hemisphere, appearing within seconds and lasting seconds to a few minutes. Some seizures cause a patch of blindness instead, and if the discharge spreads forward, the seizure takes on the signs of the areas it reaches.