Physicians and staff at the Institute of Neurology and Neurosurgery
are making strides in advancing the medical community’s
understanding of complex neurological conditions. Their ongoing
research and clinical expertise are improving and increasing
the number of treatments available for epilepsy and other
seizure disorders.
Eric B. Geller, M.D., Director, Adult Comprehensive Epilepsy
Center, Saint Barnabas Institute of Neurology and Neurosurgery
Epilepsy, a condition of recurrent seizures, occurs commonly
in people with developmental disabilities. Epilepsy is not
a disease, but rather a manifestation of an underlying brain
problem. There are numerous causes of epilepsy, from inherited
genetic defects to acquired brain injury from stroke or trauma.
The proper approach to managing epilepsy involves identifying
the seizure types and epilepsy syndrome or cause of epilepsy,
in order to determine the therapy most likely to work. This
article will outline the current diagnostic approach to epilepsy,
and describe available therapeutic approaches.
The first step is to decide if the seizures are from a partial
(focal) epilepsy, coming from a small region of brain, or
a generalized epilepsy, in which the entire brain is involved
from the beginning of the seizure. Partial and generalized
epilepsies differ in causes and treatments, so making this
distinction is important. Because seizures rarely occur in
front of the doctor, a careful description from the patient,
family members, or caretakers is extremely important. The
presence of a clear warning for the seizure, movements on
one side of the body or head turning to one side are indicators
of focal seizure onset. The diagnosis is unfortunately not
always clear from the history, particularly in individuals
with developmental disabilities. This group may have difficulty
communicating any warning that they may feel. In addition,
they are more likely to have multiple seizure types, making
diagnosis more difficult.
The electroencephalogram (EEG), which measures brain electrical
activity, is a critical test in assessing epilepsy. Although
recording a seizure on EEG can make a definitive diagnosis,
seizures are unlikely to happen during a routine outpatient
test. The brain produces specific electrical abnormalities,
called spikes or sharp waves, which occur in between seizures.
These EEG abnormalities can help us to determine whether
the seizures begin in a focal or generalized fashion, and
in some cases may allow classification into a specific type
of epilepsy. When a routine outpatient test does not show
epileptic abnormalities, other methods may be helpful, such
as performing a prolonged (multi-hour) sleep-deprived EEG,
or 24-hour ambulatory EEG, in which a portable recorder allows
the patient to be recorded at home.
When the diagnosis of seizure type remains in doubt, or
the seizures do not respond well to medication, inpatient
video-EEG testing may be performed. Video-EEG involves a
hospital stay of several days, during which antiepileptic
medication may be reduced or eliminated. The goal is to allow
seizures to occur in a protected environment, so that a more
precise diagnosis can be made. EEG is recorded 24 hours a
day, and the patient is videotaped to capture the behavioral
changes and body movements that occur during seizures for
later analysis. The results of video-EEG testing may show
that the original diagnosis of epilepsy type was wrong, and
allow a change to more effective medications, or that the
patient may be a candidate for alternative therapies such
as brain surgery. In many cases, it turns out that the behavior
in question was not an epileptic seizure at all, even in
people who also have true epileptic seizures. Such non-epileptic
events can be caused by numerous medical or psychological
conditions, and are usually treatable once recognized.
The other key test in epilepsy diagnosis is imaging of the
brain, which is usually best done with magnetic resonance
imaging (MRI). MRI is now capable of detecting even very
small abnormalities of the brain, such as scar tissue or
areas of abnormal brain development. Other safe, noninvasive
imaging tests include positron emission tomography (PET),
single photon emission computerized tomography (SPECT), and
magnetic resonance spectroscopy. These tests allow imaging
of different types of brain function rather than just structure,
and are often used in evaluation patients for possible epilepsy
surgery as well as research into the causes of epilepsy.
Once the diagnosis of epilepsy type is made, treatment can
be initiated or modified appropriately. Any treatable causes
of epilepsy, such as an enzyme deficiency, should certainly
be treated, but this is usually unlikely to stop seizures
completely. The mainstay of treatment is antiepileptic medication.
There has been dramatic progress in medical therapy in recent
years. Since 1993, there have been eight new antiepileptic
medications released, and three new forms of older medications
that allow easier dosing. There are also several new medications
awaiting approval by the Food and Drug Administration. This
increase in treatment options allows much more flexibility
in designing a medication regimen to meet the individual’s
needs, often with fewer side effects. Although the new drugs
were initially tested as treatment for complex partial seizures,
several of them are proving quite effective for generalized
epilepsy as well. These new medications are proving particularly
useful for individuals with developmental disabilities, who
often have multiple seizure types and require multiple medications.
Some people have seizures that are resistant to medication,
despite high doses which cause side effects. In these cases,
alternative therapies should be sought. Epilepsy surgery
(brain surgery to treat seizures) has been performed for
many decades, but is becoming increasingly helpful with the
use of careful preoperative testing now available. In appropriately
selected cases, the chance of seizure-free outcomes may be
70% or higher. The most common type of epilepsy surgery is
the focal resection, in which a small portion of brain is
removed. This is most commonly done to remove a tumor, scar,
or other well-localized abnormality which is causing epilepsy. Functional
hemispherectomy is a procedure in which a large portion
on one side of the brain (hemisphere) is removed, and the
remainder is disconnected from the rest of the brain. This
procedure is performed only when there is already severe
damage to one hemisphere and the other side is relatively
normal, such as in stroke, Sturge-Weber disease, or Rasmussen’s
syndrome. Callosotomy is a procedure in which the
corpus callosum (the band connecting the two sides of the
brain) is partially severed, to prevent seizure spread. Unlike
the other procedures, callosotomy is unlikely to cure seizures,
but may help reduce severe drop attacks which can cause injury.
Epilepsy surgery can be performed effectively and safely
in adults, children, and even infants. Such surgery is best
performed in specialized centers which have advanced diagnostic
testing and experienced personnel available.
The ketogenic diet is gaining increasing popularity
as a treatment for epilepsy, especially in children. This
is a very abnormal diet which essentially produces a state
of controlled starvation, in which the body produces high
levels of ketones. For reasons which remain unclear, ketones
inhibit seizure activity. The diet can be very effective,
with approximately two-thirds of patients improving seizure
control. Working with the ketogenic diet requires a great
deal of effort and dedication on the part of parents and
caretakers, as it is quite strict. Experienced nutritionists
can provide a great deal of assistance in food choices and
managing the diet.
Vagus nerve stimulation (VNS) is a new treatment for medically-resistant
epilepsy in people who are not candidates for brain surgery.
VNS involves a short surgery to implant a pacemaker-like
device under the skin, with a wire wrapped around the vagus
nerve, a large nerve in the neck. The VNS system gives intermittent
electrical shocks to the vagus nerve, which then conducts
the stimulation to the brain. Although the mechanism of action
remains unclear, VNS has been shown to reduce seizure frequency
significantly. Like antiepileptic medications, VNS was originally
tested in complex partial seizures, but there is an increasing
number of reports of efficacy in generalized epilepsy, particularly
in patients with mental retardation and multiple seizure
types.
The following cases illustrate the above points, with particular
reference to patients with developmental disabilities:
-
A young woman with Rett’s syndrome (a progressive
childhood disease with loss of speech and motor function)
presented with generalized tonic-clonic seizures occurring
weekly, despite high levels of three medications. After
starting one of the new antiepileptic drugs, seizures
were completely controlled for over one year.
-
A young man had complex partial seizures that had become
increasingly frequent in recent years, and were resistant
to numerous medication trials. He appeared autistic,
and had never developed speech or verbal comprehension.
An abnormality on skull x-ray had been detected in childhood,
but he had never had further testing. Video-EEG demonstrated
all seizures to come from the left temporal lobe region.
An MRI scan showed a large, benign tumor in the same
region, which had likely been there since birth. The
tumor was located near Wernicke’s speech area,
explaining the lack of language development. Surgical
removal of the tumor led to full control of seizures
using a single medication, with no side effects.
-
A young man with mental retardation underwent epilepsy
surgery (focal resection) to treat medically-resistant
epilepsy. Unfortunately, seizures continued after surgery.
A vagus nerve stimulator was implanted, and stimulation
adjusted over several months. During this period, seizure
frequency was reduced by 50%, and he became much more
alert and verbal.
-
A young woman had Lennox-Gastaut syndrome, a condition
with mental retardation and multiple seizure types. The
antiepileptic medication she used was fairly effective
in controlling seizures, but caused unpleasant side effects
including tremor, weight gain and hair loss. The use
of one of the new antiepileptic medications allowed reduction
of the dose of her first medication, and improvement
in her side effects.
-
A young man had mild mental retardation and partial
epilepsy of unknown cause. He had repeated episodes of
status epilepticus, despite being on high levels of two
antiepileptic medications. During his most recent, very
severe episode of status epilepticus, it was recognized
that his chronically high blood ammonia level represented
a genetic enzyme deficiency that is often exacerbated
by one of his medications. The status epilepticus, which
lasted four days, finally stopped when this medication
was removed and he was given a special low-protein diet
to treat the enzyme deficiency.
Epilepsy is one of the most treatable chronic medical diseases.
The goals of “no seizures, no side effects, no disability” may
not be met in everybody, but they remain worthy targets.
With currently available treatment options, many people can
benefit from reduced seizure frequency and/or reduced side
effects, resulting in improved quality of life. Comprehensive
epilepsy centers provide adult and pediatric neurologists,
neurosurgeons, and other specialists who can provide help
to people with medically - resistant epilepsy, to improve
both seizure control and quality of life. Research continues
into the causes and treatments of different forms of epilepsy.
For those individuals who cannot be helped with current techniques,
re-evaluation every few years is worthwhile as newer methods
may prove more effective.
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