What is Epilepsy
Epilepsy is a neurological disorder characterised by seizures, or "electrical storms" in the brain. In different patients these may range from dramatic convulsive seizures, to "absence" seizures that take the form of brief lapses in awarenes
Causes
A seizure is best thought of as an uncontrolled, abnormal burst of electrical
and chemical activity that spreads rapidly between nerve cells (millions upon
millions of them) in the brain. A seizure may start in one region of the brain
(the "focus") and spread to other parts. The first symptoms of a seizure,
referred to as the "aura" (often a strange sensation or smell) reflect the
function of that part of the brain first affected by the epileptic activity. A
seizure that initially causes only twitching of one hand and then goes on to
convulsions with loss of consciousness, for example, reflects seizure activity
that starts in the front part of one hemisphere and then spreads to involve
widespread areas on both sides of the brain.Seizures are a feature of a variety of states of ill-health, and have many differing causes. Seizures may be the only manifestation of disease, may be caused by a specific brain disorder, or are seen as part of a more generalised bodily illness.
Primary epilepsy refers to seizures, often seen in children and teenagers, where the brain is abnormally prone to seizure activity, probably due to an inherited tendency. Secondary seizures, on the other hand, are typically due to spread from a seizure focus (a scar). Finally, isolated seizures may be related to an underlying transient medical condition, and will stop as soon as the underlying condition is effectively treated; examples would include organ failure (liver or kidney failure), infections such as meningitis, head injury, brain surgery, drug and alcohol abuse.
In all forms of epilepsy, stress, sleep deprivation, a change in diet or medication, alcohol, certain specific activities, and menstruation and pregnancy in women may precipitate individual seizures.
Epileptic seizures are generally brief (usually seconds to minutes), often dramatic episodes that usually alter awareness, and may cause complete loss of consciousness. In such a circumstance, the person experiencing the seizure will have an incomplete recollection, or none at all of the event itself, and onlookers will need to provide a description of what happened to health personnel. The initial symptoms (e.g. sudden loss of consciousness, involuntary twitching of a limb or a strange feeling or sensation) are often the most helpful in categorising a particular seizure.
Furthermore, because awareness can be lost very
rapidly, and in some cases without warning, those prone to seizures need to be
very circumspect about certain activities. Seizing while driving, swimming,
bathing alone or using machinery, for example, has the potential for harm to
self or others. Most seizures are self-limited, and not life-threatening in
themselves. Occasionally, seizures do not stop, a situation known as status
epilepticus. This is a medical emergency, has a high mortality, and requires
immediate medical attention. Other possible complications of epilepsy are
discussed below.
There are several different types of seizure. Classification is important because different seizures have differing underlying causes, and often respond to specific medications:
Partial(focal) seizures involve epileptic activity in a restricted region of the brain and do not cause loss of consciousness, until they spread to other regions of the brain.
A partial seizure that develops into a generalised seizure is referred to as a secondarily generalised seizure, at which point convulsions and loss of consciousness occur.
The most frequent type of partial seizure is the
so-called complex-partial seizure. This is often called a temporal lobe
seizure, since the temporal lobe is the commonest site for these seizures to
arise. However, complex partial seizures can arise from any part of the brain.
Patients typically experience a strange feeling or odd smell (the aura) followed
soon afterwards by an alteration of consciousness. This causes mental clouding
and a "spaced out" manner. In general, patients will not respond to commands and
may manifest unusual behaviors such as picking at their clothing, smacking their
lips or wandering in a purposeless manner. Unconsciousness, convulsions and
collapse do not occur.
A less common type of partial seizure is the
simple partial seizure. Here, seizure activity is restricted to a region
of the brain that controls movement or receives sensation, producing restricted
jerking of a limb (simple motor seizure), or an abnormal feeling. Occasionally,
persistent weakness of the limbs may follow such a seizure. The person remains
conscious and aware of his or her surroundings, and is able to communicate with
others.
Generalised seizures are those that cause loss of consciousness, and imply widespread involvement of both hemispheres of the brain. However, the term is confusing: "generalised" refers to the fact that there is a widely distributed change on EEG. Many generalised seizures do not cause loss of consciousness.
Generalised tonic-clonic seizures,
previously termed "grand mal" seizures, are the most dramatic and frightening
kind of seizure. Sudden collapse with loss of consciousness is followed by
muscle spasm ("tonic") and violent jerking ("clonic") of the limbs that builds
to a climax and then subsides and stops on its own after several minutes. The
involuntary contraction of muscles can cause tongue biting, temporary arrest of
breathing, and incontinence. Injury may occur in falling to the ground and as a
result of the violent movements of the limbs. Exhaustion, muscle aches and
headache are common for several hours after the seizure has settled, in the
so-called "post-ictal" period.
Absence seizures ("petit mal") also
involve loss of consciousness, and as such are also generalised seizures, but
are quite distinct from tonic-clonic convulsions. Seen most frequently in
children, absences involve very brief periods (seconds) of "blanking out" that
may occur many times a day, and are often put down to daydreaming. These staring
spells briefly interrupt whatever the child is doing and may be associated with
fidgeting or picking at clothes (automatisms). The child and his or her family
may be quite unaware of anything unusual, and absence seizures frequently only
come to light when schoolwork suffers.
Other varieties of generalised seizure may involve sudden loss of muscle tone with collapse or large-scale jerks of the whole body, but these are rare.
Obtaining a clear description of the seizure
either from the patient themselves, or more often from reliable eyewitnesses, is
the initial and most important step in diagnosing an epileptic seizure. The
physician needs to recognise features that suggest a seizure and distinguish it
from other kinds of brief neurological events. These include TIAs (transient
ischaemic attacks – "mini-strokes"), fainting spells, behavioral problems and a
range of involuntary movements. Seizures are characterised by the presence of an
aura, rhythmical jerking, alteration or loss of consciousness, and a post-ictal
period of recovery. A careful history may also provide clues to finding a cause
for seizures, such as a head injury or alcohol or drug addiction.
Usually patients have no signs of epilepsy or ill-health between seizures, and a physical examination may be quite normal. In some patients, signs of neurological disease may point towards a cause for the seizures.
An electroencephalogram (EEG) is a recording of
the brain's electrical activity as measured by electrodes placed on the outside
of the scalp. A recording made during the normal interval between seizures in an
epileptic often reveals a seizure "signature" – spiky waves on the smooth,
regular background pattern of normal brain waves – and can provide important
information about the type and location of the seizure. A normal EEG does not
rule out the diagnosis of epilepsy, however. During a seizure, abnormal activity
tends to be clearly evident on the EEG recording. Certain patients may be
admitted to an epilepsy unit for long-term monitoring. Here, a video recording
of the patient asleep and awake and an EEG tracing are obtained over many hours,
and the two can be compared side by side.
Other investigations, including various blood tests, and CT or MRI scans of the brain help to determine a cause, and are often obtained as part of the workup of a first seizure.
Treatment
Many seizures are the direct result of an underlying brain or bodily disorder. In such a case, treatment of the underlying condition will often be sufficient to prevent seizures from recurring, and the seizures themselves will need no specific management. In general, seizures that have only occurred once are not treated unless they recur. Once seizures are recurrent, specific anti-epileptic medication will generally be needed. Some epileptics will only have seizures in certain settings, or find that their seizures are reliably provoked by specific triggers. Alcohol use and sleep deprivation are frequently responsible.
There has recently been an explosion of new drugs
for treating epilepsy. These new-generation medications may be better tolerated
and are all considerably more expensive than the older medications, which remain
the mainstay of treatment. Examples of widely-used established medications are
Carbamazepine, Phenytoin, Phenobarbital, Valproic acid and Ethosuximide.
Examples of newer medications are Levetiracetam, Lamotrigine, Topiratmate and
Gabapentin. All anti-epileptic drugs have side effects, and currently, no
particular drug is clearly more effective than another. Choosing the best agent
is a complex task best done by a neurologist with a special interest in
epilepsy. The choice will rest on the type of seizure, as well as the efficacy
of the medication and how well it is tolerated by the individual patient. Most
patients are rendered seizure-free with the use of a single medication, or, if
necessary, medications in various combinations.
Follow-up should occur at least annually.
Monitoring drug levels in the blood is important for continued control of
seizures and reduction of side-effects, but is often unnecessary with newer
agents. Illness, pregnancy, sleep deprivation, skipping medication doses and
using drugs, alcohol or certain medications may cause seizures in someone with
previously well-controlled epilepsy. People with epilepsy should wear
Medic-Alert bracelets, and family members should be instructed in how to assist
during a seizure.
The last decade has seen the development of
effective surgery for seizures of certain kinds. In general, surgery is reserved
for patients with a seizure focus that can be precisely identified, and who have
failed drug therapy. Workup for surgery is complex, but when successful, surgery
may render patients seizure-free without having to use medications. Other
modalities of treatment, such as the vagal nerve stimulator, are also used in
specific cases, although results with vagal nerve stimulators are
disappointing.
- Protect the person from injury. Clear the area of furniture or other objects that may cause injury. Cradle the head with a pillow if it is on a hard surface, but don't restrain the person's movements.
- Turn the person onto one side with the head down. This allows drainage of saliva and prevents inhalation of vomit.
- The vast majority of seizures will end spontaneously after a minute or two, and no specific treatment is necessary. When seizures continue, or consciousness is not regained between seizures, status epilepticus is diagnosed and requires urgent management that may be started by the emergency medical service, but is best performed in a hospital.
Although epilepsy tends to be a lifelong condition, effective management is available for most, allowing a seizure-free, productive life. Most occupations and recreational activities are open to people with controlled epilepsy, and most countries allow driving after a seizure-free period of 6-12 months (on or off medication).
Complications of seizures can occur in many
forms. Although seizures themselves tend to be self-limiting, the consequences
of abruptly losing contact with the environment can be dangerous. These include:
accidents while driving, bathing, swimming or using machinery; injuries
sustained from falling or trauma to flailing limbs; and aspiration of vomit,
leading to choking or aspiration pneumonia.
Status epilepticus refers to seizures that do not
stop, or are so close together that consciousness is not regained. In this
serious circumstance, respiratory and metabolic failure occurs, and mortality is
high, even with intensive care treatment.
Even when seizures do not directly threaten life
or limb, the condition can be damaging. If absence seizures are not recognized
in children, these brief interruptions of attention throughout the day can lead
to learning disability. Older children and adults may find the prospect of
seizures so socially embarrassing or frightening that they withdraw from the
world. Explanation of the condition, the broader education of the public, and
contact with other people affected by seizures can do much to alleviate
this.
Lastly, all anti-epileptic drugs have
side-effects, and in an individual patient this often governs the choice of
agent. Most of these side-effects are reversible and simply represent individual
intolerance to a particular medication or excessively high dose. Rarely,
side-effects can be unpredictable and serious. Pregnant women need especially
careful choice of medication, and younger women who may fall pregnant need
effective contraceptive advice. All women who are considering falling pregnant
should take supplements of folic acid.
If seizures occur as the result of an underlying disease of the brain (e.g. a tumour) or the body (e.g. kidney failure), treatment of these primary conditions can prevent seizures from occurring, and anti-epileptic medication may become unnecessary. In other circumstances, drug treatment or surgery for epilepsy can prevent seizures from recurring. Occasionally, drug therapy is prescribed prophylactically – as is the case after brain surgery, where a short course of anti-epileptic medication is often prescribed routinely to all patients, even those with no history of seizures.
In established epilepsy, avoiding changes in routine, disturbed sleep, drugs and alcohol, and (in a minority of patients) certain situations or activities known to promote seizures, are other practical forms of prevention.
People suffering from seizures are still stigmatised and suffer from discrimination which is bad.
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