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Overview
Epilepsy is a chronic neurological
condition characterized by recurrent seizures that
are caused by abnormal cerebral nerve cell
activity. Epilepsy is classified as idiopathic or
symptomatic. Idiopathic epilepsy has no
known cause, and the person has no other signs of
neurological disease or mental deficiency.
Symptomatic epilepsy results from a known
condition, such as stroke, head injury, poisoning,
Lennox-Gastaut syndrome, and cerebral palsy.
Incidence and Prevalence
More than 2 million people in the United States
and over 50 million worldwide suffer from
epilepsy. In the United States, more than 300,000
people with epilepsy are under the age of 14, and
more than 500,000 are over the age of 65.
Seizure
A nerve cell transmits signals to and from the
brain in two ways by (1) altering the
concentrations of salts (sodium, potassium,
calcium) within the cell and (2) releasing
chemicals called neurotransmitters (gamma
aminobutyric acid). The change in salt
concentration conducts the impulse from one end of
the nerve cell to the other. At the end, a
neurotransmitter is released, which carries the
impulse to the next nerve cell. Neurotransmitters
either slow down or stop cell-to-cell
communication (called inhibitory
neurotransmitters) or stimulate this process
(called excitatory neurotransmitters). Normally,
nerve transmission in the brain occurs in an
orderly way, allowing a smooth flow of electrical
activity. Improper concentration of salts within
the cell and overactivity of either type of
neurotransmitter can disrupt orderly nerve cell
transmission and trigger seizure activity.
Certain areas of the brain are more
likely than others to be involved in seizure
activity. The motor cortex, which is responsible
for body movement, and the temporal lobes,
including the hippocampus, which is involved in
memory, are particularly sensitive to biochemical
changes (e.g., decreased oxygen level, metabolic
imbalances, infection) that provoke abnormal brain
cell activity.
Seizure Phases
A seizure often has three distinct phases: aura,
ictus, and postictal state. The first phase
involves alterations in smell, taste, visual
perception, hearing, and emotional state. This is
known as an aura, which is actually a small
partial seizure that is often followed by a larger
event. The seizure is known as ictus. There
are two major types of seizure: partial and
generalized. What happens to the person during the
seizure depends on where in the brain the
disruption of neural activity occurs. Following a
seizure, the person enters into the postictal
state. Drowsiness and confusion are commonly
experienced during this phase. The postictal state
is the period in which the brain recovers from the
insult it has experienced.
Types
The International Classification of
Epileptic Seizure identifies seizure types by the
site of origin in the brain. The two main
categories of seizures include partial seizures
and generalized seizures. A partial seizure can
evolve to a generalized seizure. There are several
subtypes of each. Only the most common are
described here.
Partial Seizures
The site of origin is a localized or discreet area
in one hemisphere of the brain. The two most
common types of partial seizure are simple partial
and complex partial.
Simple Partial
These produce symptoms associated with the area of
abnormal neural activity in the brain: motor
signs, sensory symptoms, autonomic signs and
symptoms (involuntary activity controlled by
autonomic nervous system), and psychic symptoms
(altered states of consciousness). There is no
impairment of consciousness in simple partial
seizures.
Complex Partial
Impairment of consciousness, characteristic of
complex partial seizures (CPS), results in the
inability to respond to or carry out simple
commands or to execute willed movement, and a lack
of awareness of one’s surroundings and events.
Automatisms may occur. An automatism is a more or
less coordinated, involuntary motor activity. A
simple complex seizure may begin as a simple
partial seizure.
Generalized Seizures
At the onset, seizure activity occurs
simultaneously in large areas of the brain, often
in both hemispheres. Seizures can be convulsive or
nonconvulsive. The two most common types are
tonic-clonic and absence.
Tonic-clonic (grand mal)
There
is loss of consciousness during the seizure. The
tonic phase, consisting of increased muscle tone
(rigidity), is followed by the clonic phase, which
involves jerking of the extremities. Automomic
symptoms may also be present.
Absence (petit mal)
This
type occurs most often in children, usually
beginning between the ages of 5 and 12 years and
often stopping spontaneously in the teens. The
loss of consciousness is so brief that the child
usually does not even change position. Most
absence seizures last 10 seconds or less. There is
no postictal state, but the person usually lacks
awareness of what occurs during the seizure.
Myoclonic
These seizures are so brief that they may go
unnoticed. They involve sudden muscle contractions
that occur much more rapidly than clonic activity
and are often confused with tics. Myoclonic
seizures occur at all ages and are associated with
epileptic syndromes such as West syndrome and
Lennox-Gastaut syndrome.
Syndrome- and Situation-Related
Epilepsy
Infants and Children
Epilepsy is one of several symptoms that occur in
West syndrome and Lennox-Gastaut syndrome. West
syndrome, also called infantile spasm, is a rare
disorder of infancy and early childhood. It is
characterized by epilepsy, hydrocephalus,
congenital anomalies, and mental retardation.
Lennox-Gastaut syndrome
usually develops between the ages of 1 and 8 years
old and is characterized by atonic, absence, and
myoclonic seizures. Many of these children are
developmentally delayed and have behavioral
problems.
Adults
Several medical conditions may precipitate
epilepsy in adults, notably withdrawal from
chronic alcohol and drug abuse, eclampsia, and
stroke.
Causes and Risk Factors
Many abnormalities of the nervous
system can result in seizure activity. Seizures
can also occur in the normal nervous system when
its metabolic balance is disturbed. The etiology
(cause) of epilepsy may be idiopathic (not clearly
known) or related to a particular disease state.
About 35% of all cases of epilepsy have no clearly
definable cause.
Genetic Factors
Some persons may have a genetic predisposition to
the development of seizures. There is also an
increased incidence of epilepsy in relatives of
those with a seizure disorder.
Head Injury
Seizures may develop at or around the time of
injury or years after (usually not more than 2
years later).
Stroke
Seizures can occur at the time of a stroke or many
years later. They may occur with strokes that
result in lack of blood flow to the brain or with
those that involve bleeding (hemorrhage) into or
around the brain.
Metabolic Disturbances
Disorders that change levels of various metabolic
substances in the body sometimes result in
seizures.
-
Electrolyte imbalance (altered
levels of sodium, calcium, or magnesium)
-
Hypoglycemia (low blood sugar) or
hyperglycemia (elevated blood sugar)
-
Renal failure (kidney disease)
with uremia (increased urea in the blood) or
changes that occur around the time of kidney
dialysis
-
Hepatic failure (severe liver
disease) and elevation of associated toxins
-
Hypoxia (lowered oxygen level in
the brain)
Toxins
Overdose of and abrupt withdrawal from some
prescription drugs can result in seizure activity.
Substances that may induce seizures include the
following:
-
tricyclic antidepressants (Elavil®,
Limbitrol®, Tofranil®)
-
lithium (Eskalith®)
-
antipsychotic medications (e.g.,
chlorpromazine, haloperidol, clozapine)
-
aminophylline (bronchodilator;
Phyllocontin®, Truphylline®)
-
high doses of penicillin
Chronic illicit drug use also may
cause seizures, particularly cocaine, heroine,
amphetamines, and PCP. Alcohol withdrawal can
produce seizures, which usually occur 12-24 hours
after the last drink but can occur up to 48 hours
or more after binge drinking. Poisoning from
carbon monoxide, lead, and other heavy metals also
may cause seizures.
Infections
Infections of the nervous system may result in
seizure activity. These include meningitis
(infections of the coverings, called the meninges,
of the brain and of the spinal fluid),
encephalitis (infection of the brain), and HIV
(human immunodeficiency virus) and related
infections.
Tumors
Malignant (cancerous) and benign brain tumors may
be associated with seizures. The location of the
lesion influences the risk.
Degenerative Disorders
Several neurodegenerative disorders produce
seizure activity, including the following:
-
Alzheimer’s disease
-
Creutzfeld-Jakob disease
-
Neurofibromatosis
-
Phenylketonuria (PKU)
-
Tuberous sclerosis
-
Sturge-Weber syndrome
-
Tay-Sachs disease
Cerebral Palsy
Epilepsy is often a symptom of cerebral palsy,
which results from lack of oxygen, infection, or
trauma during birth or infancy.
Febrile Seizures
Febrile seizures occur in small children and are
caused by high fever. From birth up to the age of
5, about 2% to 4% of children in the United States
experience a febrile seizure. Approximately
one-third of these children may experience another
febrile seizure, but only a few develop epilepsy.
Triggers
Triggers do not cause seizures but provoke the
onset of a seizure or cause a seizure in a patient
whose epilepsy is under control. Alcohol
consumption, hormonal changes of the menstrual
cycle, sleep deprivation, flickering or flashing
light, and stress can trigger a seizure in a
susceptible person.
Treatment
Antiepileptic drugs (AEDs) can
prevent seizure activity by altering
neurotransmitter activity in nerve cells, but
cannot correct the underlying condition.
Approximately 70% of patients successfully control
seizures with medication. Nearly 50% of those
require two drugs to be seizure free. Because
medications interact, the drug regimen must be
carefully designed to maximize the effectiveness
and to avoid serious complications and side
effects.
Treatment with a single drug (monotherapy)
is the goal. Seizure management is complicated
when patients are given more than one drug. The
patient may experience drug interactions,
increased side effects, and other adverse
reactions.
Compliance
is essential. To control seizures, a constant
level of medication must be maintained in the
body. Antiepileptic drugs should not be
discontinued abruptly because of the risk for
triggering life-threatening status epilepticus.
Although, antiepileptic drugs have
teratogenetic potential (may cause abnormal
embryo development), most women with epilepsy
require treatment to prevent seizures during
pregnancy. To control seizures and minimize risk
to the fetus, women should educate themselves
about medication and pregnancy prior to
conception.
Surgery
Surgery is an option for a small
number of patients whose epilepsy cannot be
controlled with medication. A good candidate for
surgery has seizures that always begin in the same
cerebral location, which can be resected (removed)
without creating deficits. Neurosurgeons generally
avoid performing surgery in areas of the brain
responsible for speech, hearing, and other
important functions.
Lobectomy (lesionectomy)
This
procedure removes a small part of the brain where
seizures originate. It is appropriate only for
partial seizures.
Multiple Subpial Transection
When seizures originate in part of the brain that
cannot be removed, the surgeon may use this
procedure, in which a series of small incisions
are made that impede the spread of nerve activity.
Corpus Callosotomy
In this procedure, the surgeon severs the nerve
fibers that connect the hemispheres of the brain
to each other. This procedure is used to treat
uncontrolled generalized tonic-clonic seizures,
complex partial seizures with drop attacks, and
other generalized seizures. Reduced seizure
activity usually continues on one side of the
brain.
Hemispherectomy
This procedure is a last resort in children with
severe brain damage on one side and seizures that
do not respond to medication. It involves removing
the entire affected side of the brain. The
remaining hemisphere develops language and motor
areas for both sides of the body. With intense
rehabilitation, many patients will lead functional
lives.
Vagus Nerve Stimulator
This small device is implanted near the collarbone
and attached to the vagus nerve, which connects
the lower part of the brain to the heart, lungs,
and gastrointestinal tract. It delivers small
bursts of electrical energy to the brain at
regular, preprogrammed intervals. In some
patients, seizure frequency is reduced. Most
patients remain on antiepileptic medication but
may be able to reduce the dosage.
Ketogenic Diet
The ketogenic diet is used in children who do not
respond to standard therapy or cannot tolerate the
side effects produced by antepileptic drugs. The
diet is a high-fat, low-carbohydrate diet that
fundamentally changes the body’s metabolism from
using glucose as a primary energy source to using
fats. Ketones are a type of lipid, or fat, that
provides energy for skeletal muscle, the heart,
kidneys, and the brain.
It is most effective in children 10
years of age and younger. Compliance, which is
essential for controlling seizures, is difficult
to maintain. The regimen often is initiated with
fasting period (12-24 hours). Every meal includes
exact amounts of fats, proteins, carbohydrates,
and beverages, and only those foods listed for the
diet can be eaten. Snacking is discouraged and
sugars are not allowed. A vitamin and mineral
supplement must be given.
The diet should be undertaken only
with close medical supervision. Children must be
monitored for growth and nutritional deficiencies.
Common complications include poor growth and poor
weight gain, hypercholestrolemia (high
cholesterol), and constipation.
Management
Yoga, acupuncture, aromatherapy, biofeedback,
behavior psychotherapy, and meditation may improve
the quality of life for patients with epilepsy.
Some of these therapies reduce stress, which
decreases seizure activity in some patients.
First Aid
A person experiencing a generalized
tonic-clonic seizure or a simple partial seizure
that has become convulsive requires first aid. The
goals of first aid are to
-
prevent injury,
-
maintain an open airway,
-
provide reassurance to the
patient and bystanders,
-
recognize an emergency condition,
and
-
know when to call for help.
Guidelines
for helping someone having a seizure:
1.
Help the person lie down as soon as possible.
2.
Look for a medical alert bracelet, pendant, or
wallet card.
3.
If a medical alert ID or other documentation
indicating that the person has epilepsy cannot be
located, call an ambulance.
4.
If the person is pregnant or diabetic, call an
ambulance.
5.
Turn the person onto one side and put a soft
object (e.g., pillow, sweater, jacket) under their
head. Lying on the side allows secretions to drain
from the mouth; prevents the inhalation of
secretions; and allows the tongue to fall forward,
keeping the airway open. Do not try to hold the
tongue.
6.
Do not put anything into the person’s mouth.
During the initial phase of a generalized tonic-clonic
seizure, the jaw muscles tighten and it is
impossible to open the mouth. Forcing an object
into the mouth can damage the jaw or teeth.
7.
Loosen ties and collars.
8.
Remove harmful objects from the immediate area.
9.
Do not restrain the person in any way. Restraining
while the person is rigid or having convulsions
may cause broken bones or bruising. Restraining
someone having a complex partial seizure may
provoke them into aggressive behavior.
10.
Remain with the person until they are completely
aware of who they are and their environment, stay
calm, and offer reassurance to the person and to
bystanders.
11.
Call an ambulance if
·
the seizure lasts longer than 5
minutes,
·
one seizure follows another without
the person regaining consciousness,
·
the person is seriously injured.
Someone having a complex partial
seizure may wander or look confused but does not
require first aid. It is helpful to calmly and
gently guide the person away from harmful objects
or situations. Do not attempt to restrain the
person.
First aid is not necessary for
someone having an absence seizure . They
experience a temporary lapse in alertness and need
monitoring to ensure their safety. |
