Neuroscience
Epilepsy
Overview
Common Causes
Risk Factors
Prevention
Symptoms
Diagnosis
Treatments
Overview Epilepsy is a brain
disorder marked by repeated seizures. The seizures can be
of any type. Seizures are episodes of disturbed brain function
that may cause changes in attention and behavior, loss of
consciousness, and dangerous, uncontrolled motion of the limbs.
The root cause of the seizures is electrical excitation in
the brain.
In some cases, seizures are related to a temporary condition,
such as exposure to drugs, drug withdrawal, or abnormal levels
of sodium or glucose in the blood. In those cases, repeated
seizures can often be prevented by addressing the underlying
problem.
In other cases, injury to the brain, such as from a stroke
or head injury, can cause brain tissue to be abnormally excitable.
In some people, an inherited abnormality affects nerve cells
in the brain, which can lead to seizures. And it is sometimes
found that the cause of seizures cannot be readily identified.
Common causes of seizures
- Idiopathic (no identifiable cause)
- Usually begin between ages 5 to 20
- Can occur at any age
- No other neurologic abnormalities present
- In many cases, a family history of epilepsy or seizures
- Developmental or genetic conditions present at birth,
or injuries near birth; in this case, the seizures usually
begin in infancy or early childhood
- Metabolic abnormalities
- May affect people of any age
- Diabetes mellitus complications
- Electrolyte imbalances
- Kidney failure, uremia (toxic accumulation of wastes)
- Nutritional deficiencies
- Phenylketonuria (PKU) – a rare cause of seizures
in infants
- Other metabolic diseases, such as inborn error of metabolism
- Use of cocaine, amphetamines, alcohol or certain other
drugs
- Withdrawal from alcohol
- Withdrawal from drugs, particularly barbiturates and
benzodiazepines
- Brain injury
- May affect any age, highest incidence in young adults
- Most likely to occur if the brain membranes are damaged
- Seizures usually begin within 2 years after the injury
- Early seizures (within 2 weeks of injury) – do
not necessarily indicate that chronic seizures (epilepsy)
will develop
- Tumors and brain lesions that occupy space (such as hematomas)
- May affect any age, more common after age 30
- Partial (focal) seizures most common initially
- May progress to generalized tonic-clonic seizures
- Disorders affecting the blood vessels (such as stroke
and TIA)
- Most common cause of seizures after age 60
- Degenerative disorders (senile dementia Alzheimer type,
or similar organic brain syndromes)
- Mostly affect older people
- Infections
- May affect people of all ages
- May be a reversible cause of seizures
- Brain infections like meningitis and encephalitis can
produce seizures
- Brain abscess
- Acute severe infections of any part of the body
- Chronic infections (such as tuberculosis)
- Complications of AIDS or other immune disorders
Risk factors
Risk factors include a family history of epilepsy, head injury,
or other condition that causes damage to the brain.
The following factors may present a risk for worsening of
seizures in a person with a previously well-controlled seizure
disorder:
- Pregnancy
- Lack of sleep
- Skipping doses of epilepsy medications
- Use of alcohol or other recreational drugs
- Certain prescribed medications
- Illness
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Prevention
Generally, there is no known way to prevent epilepsy. However,
proper management of diet and sleep, and the avoidance of
drugs and alcohol, may decrease the likelihood of precipitating
a seizure in people with epilepsy.
It is also recommended that people wear protective helmets
during risky activities as a means of reducing the risk of
head injury – this can help lessen the chance of developing
epilepsy.
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Symptoms
Symptoms of epilepsy vary greatly. In some people, it can
lead to nothing more than simple staring spells, while in
others it can be as severe as a loss of consciousness and
violent convulsions. For many patients, the seizure looks
the same, or nearly the same, each time it occurs. Some patients,
though, have many different types of seizures that cause different
symptoms each time.
The type of seizure a person experiences depends on a variety
of factors, such as the part of the brain affected, the cause,
and individual response. For some people, seizures are preceded
by a strange sensation such as a tingling, smells, or emotional
changes.
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Diagnostic steps
The diagnosis of epilepsy and seizure disorders requires
a history of recurrent seizures of any type. A physical examination
(including a detailed neuromuscular examination) may be normal,
or it may show abnormal brain function related to specific
areas of the brain.
An electroencephalograph (EEG), which monitors the electrical
activity in the brain, may confirm the presence of various
types of seizures. It may also indicate the location of the
lesion causing the seizure. EEGs can often be normal in between
seizures, so it may be necessary to do prolonged EEG monitoring.
Some blood tests are used to rule out other temporary and
reversible causes of seizures. Tests for the cause and location
of the problem may include procedures such as:
- A head CT, MRI scan, or PET scan
- A lumbar puncture (spinal tap)
- Blood chemical analysis
Sometimes, disorders may cause symptoms that resemble seizures.
These include transient ischemic attacks, rage or panic attacks,
and other disorders that cause loss of consciousness.
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Treatment
If an underlying cause for recurrent seizures (such as infection)
has been identified, the cause should be treated, and this
may stop the occurrence of further seizures. This may include
surgical removal of tumors, abscesses (infection), or abnormal
areas of congenital abnormal brain tissue which are emitting
electrical activity.
Drug treatments may reduce the number of seizures and eliminate
the need for surgery. Response is individual, and the medication
used and dosage may have to be adjusted repeatedly. The type
of medicine used depends on the seizure type, as some seizure
types respond well to one medication and may respond poorly
to others.
Learn more about the Epilepsy
Program at Saint Mary’s
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