By Vivien Chan

JOHN was probably having a complex partial seizure at the time of the incident, said Dr Nigel Tan, senior consultant neurologist at the National Neuroscience Institute.

"Not every seizure involves a jerking of all four limbs with the person falling to the ground," he told The New Paper.

One of the key features of temporal lobe epilepsy, which John was diagnosed with, is that the sufferer has a lot of complex partial seizures.

Dr Tan noted: "During such a seizure, the person may appear dazed, stare into space, and his hand may move.

"Some people can do simple tasks. They can open doors, and wait for the "green man" before they cross the road.

"They can even get into fights, it's not uncommon. But it would be difficult for them to do complex tasks.

"And after that, they cannot remember what they've done."

This type of seizure can last between 30 seconds and five minutes, Dr Tan added.

A person has epilepsy when he has more than one episode of epileptic seizures.

Possible causes include brain injury, brain infection, brain tumour, stroke and genetic susceptibility.

In about half the cases, a cause cannot be found.

Possible triggers of seizures include forgetting to take medication, stress, lack of sleep, menstruation and an infection like flu.

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