(often referred to as a seizure disorder) is a
neurological condition characterized by recurrent
seizures. The condition is named from the Greek
epilepsis ("to take a firm grip on"). It is commonly
controlled with medication, although
surgical methods are used as well.
The diagnosis of epilepsy
requires the presence of recurrent, unprovoked seizures;
accordingly, it is usually made based on the medical
history. EEG, brain MRI, SPECT, PET, and
magnetoencephalography may be useful to discover an etiology
for the epilepsy, discover the affected brain region, or
classify the epileptic syndrome, but these studies are not
useful in making the initial diagnosis.
Long-term video-EEG monitoring for epilepsy is the gold
standard for diagnosis, but it is not routinely employed
owing to its high cost and inconvenience. It is, however,
sometimes used to distinguish psychogenic non-epileptic
seizures from epilepsy.
Convulsive or other seizure-like activity, non-epileptic in
origin, can be observed in many other medical conditions,
- psychogenic non-epileptic
seizures (often wrongly called "pseudoseizures")
breath-holding spells of childhood
hypoglycemia and associated neuroglycopenia
paroxysmal kinesiogenic dyskinesia
infantile gratification / masturbation (onanism)
are often called upon to distinguish among the above
diagnoses and epilepsy.
Epilepsies are classified
- By their first cause (or
- By the observable
manifestations of the seizures, known as "semiology."
- By the location in the
brain where the seizures originate.
- As a part of discrete,
- By the event that
triggers the seizures, as in
primary reading epilepsy.
All the causes (or
etiologies) of epilepsy are not known, but many predisposing
factors have been identified, including brain damage
resulting from malformations of brain development, head
trauma, neurosurgical operations, other penetrating wounds
of the brain, brain tumor, high fever, bacterial or viral
encephalitis, stroke, intoxication, or acute or inborn
disturbances of metabolism. Hereditary or genetic factors
also play a role.
Seizures may occur in any person under certain
circumstances, including acute illness and drug overdoses,
but these provoked seizures are not part of the definition
of epilepsy. Epilepsy connotes that an individual has
unprovoked seizures which recur over time. In about 50% of
all cases, there is no cause for epilepsy that is currently
detectable even with state of the art investigations. In
about 50% of cases, evidence of a brain injury, scar or
malformation is found, to which the epilepsy is attributed.
In many, but not all cases, abnormal electrical activity can
be detected in the brain with an electroencephalogram (EEG),
either during or in between seizures.
The most common ages of incidence are under the age of 18
and over the age of 65. It has been estimated that about 1%
of the population meets the diagnostic criteria for epilepsy
at any given time, but some theorize that the prevalence may
be much higher in fact.
A significant and measurable decline in cognitive function
is known to be associated with epilepsy, although it has not
been entirely clear to what extent this is due to the
epilepsy itself or to the drugs used to treat it.
Phenobarbital, in particular, has been shown to decrease IQ
and classroom performance when used to treat epilepsy in
children; the effects persist after the phenobarbital is
stopped. Some newer anti-epileptic drugs are considered by
some to have less severe cognitive effects than older drugs.
On an individual level, a person's reaction to epileptic
seizures and/or anti-epileptic drugs may be idiosyncratic,
so it is difficult to predict how a particular person might
Mutations in several genes have been linked to some types of
epilepsy. Several genes that code for protein subunits of
voltage-gated and ligand-gated ion channels have been
associated with forms of generalized epilepsy and infantile
seizure syndromes. Several ligand-gated ion channels have
been linked to some types of frontal and generalized
epilepsies. Epilepsy-related mutations in some non-ion
channel genes have also been identified.
One interesting finding in animals is that repeated
low-level electrical stimulation to some brain sites can
lead to permanent increases in seizure susceptibility: in
other words, a permanent decrease in seizure "threshold."
This phenomenon, known as kindling (by analogy with the use
of burning twigs to start a larger fire) was discovered by
Dr. Graham Goddard in 1967. Chemical stimulation can also
induce seizures; repeated exposures to some pesticides have
been shown to induce seizures in both humans and animals.
One mechanism proposed for this is called excitotoxicity.
The roles of kindling and excitotoxicity, if any, in human
epilepsy are currently hotly debated.
Some people with epilepsy
have certain triggers or provocants that will reliably
produce a seizure. If the provocant can reasonably be
considered to be part of normal daily life, and yet it
causes a seizure, the seizures are considered 'unprovoked'
for the purpose of diagnosing the person with epilepsy.
Examples of these 'normal provocants' include reading, hot
water on the head,
hyperventilation and flashing or flickering lights. This
last provocant is a special type of
reflex epilepsy called
Types of seizure
Epileptic seizures are
classified both by their patterns of activity in the brain
and their effects on behaviour.
In terms of their pattern of
activity, seizures may be described as either partial
(focal) or generalised. Partial seizures only involve
a localised part of the brain, whereas generalised seizures
involve the entire cortex. The term 'secondary
generalisation' may be used to describe a partial seizure
that later spreads to the whole of the cortex and becomes
Partial seizures may be
further subdivided into both simple and complex seizures.
This refers to the effect of such a seizure on
consciousness; simple seizures cause no interruption to
consciousness (although they may cause sensory distortions
or other sensations), whereas complex seizures interrupt
consciousness to varying degrees. This does not necessarily
mean that the person experiencing this sort of seizure will
fall unconscious (like fainting). For example, a complex
partial seizure may involve the unconscious repetition of
simple actions, gestures or verbal utterances, or simply a
blank stare and apparent unawareness of the occurrence of
the seizure, followed by no memory of the seizure. Other
patients may report a feeling of tunnel vision or
dissociation, which represents a diminishment of awareness
without full loss of consciousness. Still other patients can
perform complicated actions, such as travel or shopping,
while in the midst of a complex partial seizure.
The effects of partial seizures can be quite dependent on
the area of the brain in which they are active. For example,
a partial seizure in areas involved in perception may cause
a particular sensory experience (for example, the perception
of a scent, music or flashes of light) whereas, when centred
in the motor cortex, a partial seizure might cause movement
in particular groups of muscles. This type of seizure may
also produce particular thoughts or internal visual images
or even experiences which may be distinct but not easily
described. Seizures centred on the temporal lobes are known
to produce mystical or ecstatic experiences in some people.
These may result in a misdiagnosis of psychosis or even
schizophrenia, if other symptoms of seizure are disregarded
and other tests are not performed. Unfortunately for those
with epilepsy, anti-psychotic medications prescribed without
anti-convulsants in this case can actually lower the seizure
threshold further and worsen the symptoms.
When the effects of a partial seizure appear as a 'warning
sign' before a more serious seizure, they are known as an
aura: it is frequently the case that a partial seizure will
spread to other parts of the brain and eventually become
generalized, resulting in a tonic-clonic convulsion. The
subjective experience of an aura, like other partial
seizures, will tend to reflect the function of the affected
part of the brain.
Generalised seizures can be sub-classified into a number of
categories, depending on their behavioural effects:
seizures (sometimes referred to as petit mal seizures)
involve an interruption to consciousness where the person
experiencing the seizure seems to become vacant and
unresponsive for a short period of time (usually up to 30
seconds). Slight muscle twitching may occur.
Tonic-clonic seizures (sometimes referred to as grand mal
seizures), involve an initial contraction of the muscles
(tonic phase) which may involve tongue biting, urinary
incontinence and the absence of breathing. This is followed
by rhythmic muscle contractions (clonic phase). This type of
seizure is usually what is referred to when the term
'epileptic fit' is used colloquially.
Myoclonic seizures involve sporadic muscle contraction and
can result in jerky movements of muscles or muscle groups.
Atonic seizures involve the loss of muscle tone, causing the
person to fall to the ground. These are sometimes called
'drop attacks' but should be distinguished from similar
looking attacks that may occur in narcolepsy or cataplexy.
Status epilepticus refers to continuous seizure activity
with no recovery between successive tonic-clonic seizures.
This is a life-threatening condition and emergency medical
assistance should be called immediately if this is
suspected. A tonic-clonic seizure lasting longer than 5
minutes (or two minutes longer than a given person's usual
seizures) is usually considered grounds for calling the
Epilepsia partialis continua is a rare type of focal motor
seizure (hands and face) which recurs every few seconds or
minutes for extended periods (days or years). It is usually
due to strokes in adults and focal cortical inflammatory
processes in children (Rasmussen's encephalitis), possibly
caused by chronic viral infections or autoimmune processes.
There are many different
epilepsy syndromes, each presenting with its own unique
combination of seizure type, typical age of onset, EEG
findings, treatment, and prognosis. Below are some common
Infantile spasms (West
syndrome) is associated with brain development
abnormalities, tuberous sclerosis, and perinatal insults to
the brain. It affects infants (as implied by its name),
which by definition is between 30 days to 1 year of life. It
carries a poor prognosis such that only 5-10% of children
with infantile spasms will develop normal to near-normal
function, while more than two-thirds will have severe
deficits. The typical seizures are characterized by sudden
flexor and extensor spasms of head, trunk, and extremities.
The key EEG finding in these patients is a hypsarrythmia, or
a high-voltage slow wave with multifocal spikes. The first
line treatment for these patients is adrenocorticotropic
hormone (ACTH or corticotropin) since traditional
antiepileptic drugs generally cannot adequately control
seizure activity. Vigabatrin is also used in many countries,
and is particularly effective when tuberous sclerosis is the
cause of seizures.
Childhood absence epilepsy affects children between the ages
of 4 and 12 years of age. These patients have recurrent
absence seizures that can occur hundreds of times a day. On
EEG, one finds the stereotyped generalized 3 Hz spike and
wave discharges. A subset of these patients will also
develop generalized tonic-clonic seizures. This condition
carries a fairly good prognosis in that these children do
not usually show cognitive decline or neurological deficits.
First line treatment for pure absence seizures is
ethosuximide. If patients do not respond or have mixed
seizures along with their absence seizures, then valproic
acid can be used.
Benign focal epilepsy of childhood (Benign Rolandic
epilepsy) begins in children between the ages of 4 and 13
years. Apart from their seizure disorder, these patients are
otherwise normal. Seizures occur at night and sleep promotes
secondary generalization. As such, parents only report
generalized seizures because focal manifestations are often
subtle and go unnoticed. Between seizures, patients have a
stereotyped EEG pattern that includes di- or triphasic sharp
waves over the central-midtemporal (Rolandic) regions.
Prognosis is uniformly good with seizures disappearing by
adolescence. Carbamazepine is the first line treatment,
though phenytoin and phenobarbital have also been used with
Juvenile myoclonic epilepsy (JME) begins in patients aged 8
to 20 years. These patients have normal IQ and are otherwise
neurologically intact. There is usually a family history of
similar seizures. The seizures are morning myoclonic jerks
often with generalized tonic-clonic seizures that occur just
after waking. EEG readings reveal generalized spikes with
4-6 Hz spike wave discharges and multiple spike discharges.
Interestingly, thse patients are often first diagnosed when
they have their first generalized tonic-clonic seizure later
in life when they experience sleep deprivation (e.g.,
freshman year in college after staying up late to study for
exams). Valproic acid is the first line treatment. This
condition is lifelong, thus patients must be taught
appropriate sleep hygiene to prevent generalized tonic-clonic
Temporal lobe epilepsy is the most common epilepsy of
adults. In most cases, the epileptogenic region is found in
the mesial temporal structures (e.g., the hippocampus,
amygdala, and parahippocampal gyrus). Seizures begin in late
childhood and adolescence. There is an association with
febrile seizures in childhood, and some studies have shown
herpes simplex virus (HSV) DNA in these regions, suggesting
that perhaps this epilepsy has an infectious etiology. Most
of these patients have complex partial seizures often
preceded by an aura.
is usually treated with medication prescribed by a
physician; primary caregivers, neurologists, and
neurosurgeons all frequently care for people with epilepsy.
In some cases the implantation of a stimulator of the vagus
nerve, or a special diet can be helpful. Neurosurgical
operations for epilepsy can be palliative, reducing the
frequency or severity of seizures; or, in some patients, an
operation can be curative.
Responding to a seizure
cases, the proper emergency response to a generalized tonic-clonic
epileptic seizure is simply to prevent the patient from
self-injury by moving him or her away from sharp edges,
placing something soft beneath the head, and carefully
rolling the person onto his or her side to avoid
asphyxiation. Should the person regurgitate, the material
should be allowed to drip out the side of the patient's
mouth by itself. If the seizure lasts longer than 5 minutes,
Emergency Medical Services should be contacted. Prolonged
seizures may develop into status epilepticus, a dangerous
condition requiring hospitalization and emergency treatment.
Objects should never be placed in a person's mouth during a
seizure as this could result in injury to the person's mouth
or obstruction of the airway. Despite common folklore, it is
not possible for a person to swallow their own tongue during
After a seizure, it is typical for a person to be confused,
disoriented, and possibly agitated or sleepy. It is
important to stay with the person until this passes; people
should not eat or drink until they have returned to their
normal level of awareness, and they should not be allowed to
wander about unsupervised. Many patients will sleep deeply
for a few hours after a seizure; this is not dangerous. In
about 50% of people with epilepsy, headaches may occur after
a seizure. These headaches share many features with
migraines, and respond to the same medications.
Some medications can be
taken daily in order to prevent seizures altogether or
reduce the frequency of their occurrence. These are termed
"anticonvulsant" or "antiepileptic" drugs (sometimes AEDs).
All such drugs have side effects which are idiosyncratic and
others which are dose-dependent; it is not possible to
predict who will suffer from side effects or at what dose
the side effects will appear.
Some people with epilepsy
will experience a complete remission when treated with an
anticonvulsant medication. If this does not occur, the dose
of medication may be increased, or another medication may be
added to the first. The general strategy is to increase the
medication dose until either the seizures are controlled, or
until dose-limiting side effects appear; at which point the
medication dose is reduced to the highest amount that did
not produce undesirable side effects.
Serum levels of AEDs can be
checked to determine medication
compliance and to assess the effects of drug-drug
interactions; serum levels are generally not useful to
predict anticonvulsant efficacy in an individual patient,
though in some cases (such as a seizure flurry) it can be
useful to know if the level is very high or very low.
If a person's epilepsy
cannot be brought under control after adequate trials of two
different drugs, that person's epilepsy is generally said to
be 'medically refractory.'
drugs may prevent seizures or reduce seizure frequency:
these include carbamazepine (common brand name Tegretol),
clobazam (Frisium), clonazepam (Klonopin), ethosuximide (Zarontin),
felbamate (Felbatol), fosphenytoin (Cerebyx), flurazepam (Dalmane),
gabapentin (Neurontin), lamotrigine (Lamictal),
levetiracetam (Keppra), oxcarbazepine (Trileptal),
mephenytoin (Mesantoin), phenobarbital (Luminal), phenytoin
(Dilantin), pregabalin (Lyrica), primidone (Mysoline),
sodium valproate (Epilim), tiagabine (Gabitril), topiramate
(Topamax), valproate semisodium (Depakote), valproic acid (Depakene,
Convulex), and vigabatrin (Sabril).
Other drugs are commonly used to abort an active seizure or
interrupt a seizure flurry; these include diazepam (Valium)
and lorazepam (Ativan). Drugs used only in the treatment of
refractory status epilepticus include paraldehyde (Paral)
and pentobarbital (Nembutal).
Bromides were the first of the effective anticonvulsant pure
compounds, but are no longer used due to their toxicities
and low efficacy.
Surgical treatment can be an
option for epilepsy when an underlying brain abnormality,
such as a benign tumor or an area of scar tissue (e.g.
hippocampal sclerosis) can be identified. The abnormality
must be removable by a neurosurgeon.
Surgery is usually only offered to patients when their
epilepsy has not been controlled by adequate attempts with
multiple medications. Before surgery is offered, the medical
team performs many tests to assess whether removal of brain
tissue will result in unacceptable problems with memory,
vision, language or movement, which are controlled by
different parts of the brain. Resective surgery, as opposed
to palliative, successfully eliminates or significantly
reduces seizures in about 80% of the patients who undergo
it. Many patients decide not to undergo surgery owing to
fear or the uncertainty of having a brain operation.
The most common form of resective surgical treatment for
epilepsy is to remove a portion of either the right or left
temporal lobe, depending on where the seizures are
occurring. A study of 48 patients who underwent this
operation, anterior temporal lobectomy, between 1965 and
1974 determined the long-term success of the procedure. Of
the 48 patients, 21 had had no seizures that caused loss of
consciousness since the operation. Three others had been
free of seizures for at least 19 years. The rest had either
never been completely free of seizures or had died between
the time of the surgery and commencement of the study.
Palliative surgery for epilepsy is intended to reduce the
frequency or severity of seizures. Examples are callosotomy
or commissurotomy to prevent seizures from generalizing
(spreading to involve the entire brain), which results in a
loss of consciousness. This procedure can therefore prevent
injury due to the person falling to the ground after losing
consciousness. It is performed only when the seizures cannot
be controlled by other means. Resective surgery can be
considered palliative if it is undertaken with the
expectation that it will reduce but not eliminate seizures.
Hemispherectomy is a drastic operation in which most or all
of one half of the cerebral cortex is removed. It is
reserved for the most catastrophic epilepsies, such as those
due to Rasmussen syndrome. If the surgery is performed on
very young patients (2-5 years old), the remaining
hemisphere may acquire some rudimentary motor control of the
ipsilateral body; in older patients, paralysis results on
the side of the body opposite to the part of the brain that
was removed. Because of these and other side effects it is
usually reserved for patients who have exhausted other
Ketogenic diets may
occasionally be effective in controlling some types of
epilepsy; although the mechanism behind the effect is not
fully understood, shifting of pH towards a metabolic
acidosis and alteration of brain metabolism may be involved.
Ketogenic diets are high in fat and extremely low in
carbohydrates, with intake of fluids often limited. This
treatment, originated as early as the 1920s at Johns Hopkins
Medical Center, was largely abandoned with the discovery of
modern anti-epileptic drugs, but recently has returned to
the anti-epileptic treatment arsenal. Ketogenic diets are
sometimes prescribed in severe cases where drugs have proven
There are several downsides to what initially seems a benign
therapy, however. The ketogenic diet is not good for the
heart or kidneys and medical problems resulting from the
diet have been reported. In addition, the diet is extremely
unpalatable and few patients are able to tolerate it for any
length of time. Since a single potato chip is adequate to
break the ketosis, staying on the diet requires either great
willpower or perfect control of a person's dietary intake.
People fed via gastrostomy or young children who receive all
their food in the presence of a caregiver are better
Vagus nerve stimulation is a recently developed form of
seizure control which uses an implanted electrical device,
similar in size, shape and implant location to a heart
pacemaker, which connects to the vagus nerve in the neck.
Once in place the device can be set to emit electronic
pulses, stimulating the vagus nerve at pre-set intervals and
milliamp levels. Treatment studies have shown that
approximately 50% of people treated in this fashion will
show significant seizure reduction.
Some people with epilepsy receive a special dog which has
the rare talent of sensing the onset of a seizure and is
trained to alert the human so they can reach a safe location
before their seizure puts them in danger. Other epilepsy
care dogs do not sense seizures, but serve as companions and
guardians during the loss of consciousness accompanying a
The Institutes for The Achievement of Human Potential
promulgate a home program consisting of a healthy diet,
clean air, and respiratory training. This alternative
approach is regarded as unscientific by most medical
History and stigma
In the past, epilepsy was
associated with religious experiences and even demonic
possession. Apocryphally, epilepsy has been called the
"Sacred Disease" because people thought that epileptic
seizures were a form of attack by demons, or that the
visions experienced by persons with epilepsy were sent by
the gods. However, in many cultures, persons with epilepsy
have been stigmatized, shunned, or even imprisoned; in the
Salpêtrière, the birthplace of modern neurology, Jean-Martin
Charcot found people with epilepsy side-by-side with the
mentally retarded, chronic syphilitics, and the criminally
insane. In Tanzania to this day, onlookers will not touch a
person having an epileptic fit, owing to fear of demons,
even if the seizure causes the person to fall into the
cooking fire (the flickering light from fire may have
provoked the seizure in the first place.) In ancient Rome,
epilepsy was known as the Morbus Comitialis ('disease of the
assembly hall') and was seen as a curse from the gods.
Stigma continues to this day, in both the public and private
spheres, but polls suggest it is generally decreasing with
time, at least in the developed world; Hippocrates remarked
that epilepsy would be considered divine only until it was
have caused many fatal car accidents and plane crashes. Most
people diagnosed with epilepsy are forbidden by their local
laws from operating vehicles. However, there are usually
exceptions for those who can prove that they have stabilized
their condition. Those few whose seizures do not cause
impairment of consciousness, or whose seizures only arise
from sleep, may be exempt from such restrictions, depending
on local laws. There is an ongoing debate in bioethics over
who should bear the burden of ensuring that an epilepsy
patient does not drive a car or fly an airplane.
In the U.S., people with epilepsy can drive if their
seizures are controlled with treatment and they meet the
licensing requirements in their state. How long (they) have
to be free of seizures varies in different states, but it's
most likely to be between three months and a year. The
majority of the 50 states place the burden on patients to
report their condition to appropriate licensing authorities
so that their privileges can be revoked where appropriate. A
minority of states (including California) place the burden
of reporting on the patient's physician. After reporting is
carried out, it is usually the driver's licensing agency
that decides to revoke or restrict a driver's license.
Empirical studies have demonstrated that these laws may
deter epilepsy patients from seeking treatment from a
physician for their condition because they fear the loss of
their driving privileges.
In the UK, it is the responsibility of the patient to inform
the Driver and Vehicle Licensing Agency (DVLA) if they have
epilepsy. The DVLA rules are quite complex, but in summary ,
those continuing to have seizures or who are within 6 months
of medication change may have their license revoked. A
doctor who becomes aware that a patient with uncontrolled
epilepsy is continuing to drive has, after reminding the
patient of their responsibility, a duty to break
confidentiality and inform the DVLA. The doctor should
advise the patient of the disclosure and the reasons why
their failure to notify the agency obliged the doctor to