|
What is epilepsy surgery?
Epilepsy surgery involves a brain operation
to control epileptic seizures. Different types of epilepsy require different
types of operations.
Who is a candidate for epilepsy surgery?
In general, epilepsy surgery may be
considered in people of any age, from infancy to adulthood. The best candidates
for epilepsy surgery are:
- People with epileptic seizures
that cannot be controlled satisfactorily with medication and whose lives
would be improved if seizures were controlled. The definition of
"satisfactory" control varies from person to person.
- People with a brain abnormality
that can be identified as the cause of seizures. Some abnormalities such as
brain tumors may require surgery even if seizures are well controlled with
medication.
Which types of epilepsy respond to surgery?
1. Focal
resective surgery is performed in people with partial epilepsy, in
which seizures arise from a small part of the brain. It involves removing a
small part of the brain, with the intent of sparing important neurological
functions such as movement, sensation, speech, and memory. The most common
location of surgery is in the temporal lobe (under the temple). Partial epilepsy
may be caused by a scar from birth, injury or head trauma, brain tumors,
arteriovenous vascular malformations (a tangle of blood vessels resulting in
fewer than normal connections between capillaries), infections, or abnormal
brain development.
2.
Hemispherectomy is performed in people with abnormalities of one
hemisphere (side) of the brain. Conditions such as Sturge-Weber disease,
Rasmussen’s encephalitis, hemimegalencephaly, or perinatal stroke may injure a
large area on just one side of the brain. People with these disorders typically
have severe neurologic problems, such as paralysis and loss of sensation on one
side of the body. With this procedure, a portion of the damaged brain is
removed, and the rest of the hemisphere is disconnected from the good portions
of the brain to prevent the seizures from spreading.
3.
Callosotomy involves cutting part of the corpus callosum, a large bundle of
nerve fibers that connect the two sides of the brain. The goal is to prevent
spreading of seizures from one side of the brain to the other. Callosotomy is
usually performed in people with severe generalized tonic (stiffening) or
atonic (limp) seizures that cause falling and injuries ("drop attacks").
What is the evaluation process for epilepsy
surgery?
A number of steps are necessary to identify
the location and cause of the seizures, and to determine the best treatment.
A neurologist will perform a
medical history and neurological examination.
Electroencephalogram (EEG) is a
"brain wave" test that detects abnormal areas that may cause seizures.
Magnetic resonance imaging (MRI)
gives a detailed picture of the inside of the brain. MRI may help identify
the cause and location of the seizures.
Adjustments or changes in
medication may be made before considering surgery. Sometimes, just adjusting
medications can control seizures. Usually, at least three medicines are
tried before considering epilepsy surgery. Blood tests are necessary to
adjust medication levels for best effect.
Video-EEG monitoring is conducted
during a five- to seven-day inpatient stay. EEG is performed continuously,
and medications are reduced so that seizures can be recorded. Analysis of
seizures on videotape gives further clues about the source of the seizures.
Other tests give information
about how different parts of the brain are functioning. Areas causing
seizures often do not function well. Such testing includes a positron
emission tomograpy (PET) scan, neuropsychological testing (memory, language,
and thinking), and an intracarotid amobarbital test, in which half the brain
is put to sleep for a few minutes to test the function of the other side.
Psychiatric evaluation may reveal other conditions, such as depression,
which also require treatment.
In some cases, EEG electrodes
must be put directly into or on the surface of the brain surgically to find
the source of the seizures and to map out important brain functions that
should be spared.
|
