Epilepsy

---Epilepsy means "seizure". Epileptics suffer repeated fits or other seizures when electrical storms rage though the brain. No fewer than two million Americans live with this neurological handicap - more than suffer any other except stroke.

---Epilepsy takes many forms, now internationally grouped in two main types: generalised attacked and those termed focal, partial or localised. Some start in one part of the brain and invade others. Generalised convulsive attacks (alias grand mal or tonic-clonic attacks) account for over half of all fits. Many start with an aura: an unpleasant sensation or a strange smell, taste, sound or vision produced by part the brain where the trouble begins. As trouble spreads through the brain, more parts stop working properly, so more of the body goes out of control. The victim falls down unconscious. For moments, his body lies stiff, often with outstretched limbs. Then these make short, jerky movements. The person may bite his tongue, foam in his mouth, and urinate. The attack subsides as the brain’s overexcited neurons grow exhausted. Unconsciousness gives way to sleep, or confused consciousness. When normal consciousness returns, perhaps hours later, the individual cannot recall what happened.

---Temporal lobe epilepsy (with attacked that arise in the brain’s temporal lobes) is the next commonest form. Victims experience memory upsets and vivid hallucinations of things smelled, tasted, heard or seen. Some saints’ vision may have occurred in this way. Rather than falling down, patients may briefly become automatons, perhaps even undressing in some public place.

---Lesser kinds of epilepsy include petit mal ("little sickness") where the person momentarily "freezes;" and drop attacks, where the victims falls with no warning, and gets up at once. The extent and nature of an epileptic attack hold clues to the area of areas of brain affected. The cause may be more difficult to find. But brain scans and other diagnostic aids now help doctors differentiate between an inherited tendency to fits and those due to brain tumours, head injuries, brain infections and other causes. Incidentally, some "fits" turns out to be no more than hysteria, fainting, or breath-holding.

---Treatment depends upon the type of epilepsy. Sometimes removing an affected bit of the brain cures the trouble. But most patients find that taking anticonvulsant drugs prevents attacks. In fact, these drugs now enable more than four-fifths of all epileptics to lead normal lives.

Firing Neurons

Neurons in the brain are continuously firing in often recognisable patterns.

Some neurons in the cerebral cortex produce regular, widely spaced impulses.

Other neurons fire much more irregularly, producing a few closed space impulses at irregular intervals.

Epileptic neurons typically produce groups of extremely closely spaced impulses in fairly regular bursts.

Noise-induced Epilepsy

---A particular sound may induce an epileptic fits in a susceptible person. In one person, the sound of bells started off strong rhythms in previously inactive neurons in the temporal cortex. After 22 seconds, the rhythms have spread out to most parts of the brain under investigation and a fit resulted.

Light-induced Epilepsy

---A flashing light, even the flicker of a television picture, can produce an epileptic fit. A rapidly flashing light shone into a person’s eyes for a short period stimulated a massive discharge of electrical activity in the brain. Neurons from all areas of the cortex fired together at a low frequency - the typical pattern of epilepsy.

Compressed Spectral Array

---This is an advanced computerised method for pictorially representing the electrical activity occurring simultaneously in different parts of the brain.

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