epilepsy
Meaning of epilepsy: Not one disease but a shared endpoint with dozens of causes, from a birth injury to a scar, a gene or a tumor.
Definition of epilepsy
Epilepsy is a brain disorder in which a person has a lasting tendency to unprovoked seizures, bursts of abnormal electrical activity that disrupt movement, sensation, awareness or behavior. The diagnosis rests on that ongoing tendency rather than on any single event, so a seizure brought on by a passing insult such as low blood sugar does not by itself mean epilepsy.
What is happening in the brain?
Brain cells communicate with small electrical signals, and the network normally holds excitation and restraint in balance. In a seizure a group of cells fires together in a synchronized burst that overwhelms the restraint and recruits neighboring cells into the same rhythm. What the person experiences depends entirely on which region is recruited and how far the activity spreads. A discharge confined to the strip of brain controlling one hand twitches that hand alone, while the same discharge spreading across both halves causes loss of consciousness with stiffening and jerking. Epilepsy means a brain has a settled tendency to generate those bursts, whether from a scar, a malformation, a stroke, a tumor, a past infection, an inherited change in the channels that carry nerve signals, or from no cause that can be identified.
What kinds of seizures occur?
| Type | What it looks like |
|---|---|
| Focal aware | Twitching, an odd smell or a rising feeling in the stomach, with awareness kept |
| Focal with impaired awareness | Staring, lip smacking or aimless fumbling, with no memory of the episode |
| Generalized tonic-clonic | Stiffening then rhythmic jerking of the whole body, with loss of consciousness |
| Absence | Brief blank spells, mostly in children, often mistaken for daydreaming |
| Myoclonic | Single sudden jerks of a limb or of the whole body |
| Atonic | Abrupt loss of muscle tone causing a sudden fall |
How is it recognized and managed?
The account of what happened, ideally from someone who watched, carries more weight than any single test, because the shape of an episode is what separates a seizure from a faint, a panic attack or a disturbance of sleep. An EEG records electrical activity from the scalp and can show a supportive pattern, but a normal recording between episodes does not rule the diagnosis out, since the abnormal activity is intermittent. Imaging looks for a structural cause. Medication controls seizures in most people, and where they persist despite well chosen drugs the epilepsy is described as refractory, after which surgery, nerve stimulation or dietary treatment come into consideration. A seizure that does not stop, or a run of seizures with no recovery of awareness between them, is called status epilepticus, and it is a time-critical emergency because sustained abnormal activity injures brain tissue.
Also known as
Used in a sentence
Epilepsy was diagnosed after a second unprovoked seizure and a supportive EEG.
Good to know
A normal recording between episodes does not exclude epilepsy, because the abnormal activity is intermittent, so the described account of the events carries more diagnostic weight than any single test.
Word origin
Where “epilepsy” comes from
Epilepsy comes from the Greek epilepsia, a seizing upon, built from epi meaning upon and lambanein meaning to take hold.