EPILEPSY - AN INTRODUCTION
by Epilepsy Association of Scotland
Definition
Epilepsy is a condition which affects one person in every 200, and means
that a person has a tendency to have recurring seizures. It occurs in people of
both sexes, cuts across all racial, social, and age groups, and affects people
of all levels of intelligence. The spectrum of epilepsy is very wide. It
includes:
- people whose seizures have been completely controlled and who experience no
adverse side-effects from their treatment
- people who have occasional seizures
- people who have epilepsy that is very difficult to control, whose seizures
are frequent and severe, and who sometimes have other disabling conditions.
It is most commonly diagnosed in childhood and adolescence, but can develop
in any one at any age. It can also develop in an older person as a consequence
of such factors as strokes, heart attacks, diminishing supplies of blood to the
brain, etc.
Epilepsy is generally divided into two main categories, called generalised
and partial.
Generalised epilepsy involves a disturbance in the brain's normal electrical
activity affecting the whole brain and during which there is always some loss
of consciousness. However, there are several different kinds of seizure
patterns in this generalised category, each with distinct features.
Partial epilepsy involves a disturbance in the brain's normal electrical
activity confined to a local area of the brain, which causes either simple
partial seizures or complex partial seizures. In some cases partial epilepsy
may develop into generalised epilepsy if the disturbance spreads from the
localised area to affect the whole brain.
Seizures
A seizure indicates that a disturbance is occurring in the usual electrical
activity of certain brain cells. It can vary from person to person, for
example:
- in frequency and length
- in what the person having the seizure experiences before, during, and after
the seizure
- in how long it takes the person to feel back to their normal self
Seizure symptoms also vary greatly. The seizure pattern may be very obvious
to a person who is nearby, or it may pass almost unnoticed except by a trained
observer. There are over 20 different kinds of seizure, the majority of which
are short-lived and self-righting.
The pattern a seizure takes depends on whereabouts in the brain the
disturbance originates, and where and how quickly that disturbance spreads.
Some people experience an "aura" (e.g. a strange taste, smell, noise,
or sensation) which indicates that a seizure is already taking place, and warns
that a further seizure is likely to occur.
Types of seizure
Generalised seizures
Absence seizures involve a momentary loss of consciousness which can look
like a very brief daydream. It often happen so quickly that an onlooker may
notice nothing unusual.
In tonic seizures, muscles of the body develop an exaggerated tone so that
arms, back, legs, and sometimes the whole body itself goes rigid, consciousness
is lost, and the person (if they are standing) can fall very heavily to the
ground.
Atonic seizures involve loss of muscle tone in which the body goes limp and
consciousness is lost. Again, a person who is standing can fall very heavily to
the ground.
Clonic seizures involve loss of consciousness followed by jerking of legs,
arms, and sometimes of the whole body.
Myoclonic seizures involve a brief loss of consciousness and sudden muscle
spasms which, if severe (particularly in young children) can throw the person
to the ground.
Major convulsive (tonic clonic seizures) are the most easily recognised form
of seizure, during which the person loses consciousness and falls to the
ground. They first stiffen (the tonic phase), and then start to convulse or
jerk (the clonic phase). They may make strange noises, and there may be saliva
around the mouth in the process of the seizure. They may also be incontinent.
Infantile spasms are sometimes called West's Syndrome, or salaam, seizures
because there is a brief, sudden flexion of the head, body, and limbs as if the
baby is making a "salaam". Consciousness is lost during the seizure.
Partial seizures
Simple partial seizures
Depending upon the part of the brain where the disturbance occurs, simple
partial seizures may affect movement, sensory perceptions, the autonomic system
of the body (breathing, heart beat, digestion etc), or could be a combination
of any of these (e.g. involuntary arm twitching may be accompanied by a feeling
of nausea).
Complex partial seizures
Complex partial seizures are so called because only part of the brain is
affected, and because the disturbance affects a number of different functions,
often causing a change in awareness. In such seizures, people may experience
strange and unusual feelings, lose their sense of time, and become removed from
social contacts. Observers may see the person behaving in odd, random, and
inappropriate ways (e.g. lip smacking, plucking at clothes, moving aimlessly or
compulsively around a room, and sometimes speaking strangely).
Nearly all seizures are self-righting, and the person comes round
spontaneously. Quiet, gentle reassurance is often all that may be required to
help them to recover. For more details, see "How best to help".
It is possible for a person to have one or two seizures in the course of a
lifetime (maybe as a result of a high temperature or a head injury) without
developing epilepsy, so it is most important to ensure that an accurate
diagnosis of epilepsy is made before any treatment is begun.
Basic facts
It should be remembered that:
- anyone can develop epilepsy at any stage in their life
- the spectrum of epilepsy is wide; it includes people whose seizures are
completely controlled, as well as those with intractable epilepsy whose
seizures are frequent, severe, and prolonged
- some people's seizures follow a definite pattern whereas, others are
unpredictable
- some people get a warning before a seizure
- most seizures are over quickly, and are easily managed
- epileptic symptoms vary from person to person; it is important to establish
the pattern of a person's epilepsy on an individual basis
- epilepsy is a single condition that can occur along with other disabilities
(e.g. learning difficulties)
- epilepsy is a condition which requires understanding and acceptance
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