C h a p t e r 3 7
Disorders of Brain Function
947
legs and arms extended. If the person is standing, they
may fall to the ground.
Clonic Seizures.
Clonic seizures, which are similar to
those seen during the clonic phase of a tonic-clonic sei-
zure, are characterized by repetitive rhythmic muscular
contractions that are bilateral and symmetric, and are
accompanied by hyperventilation.
Atonic Seizures.
In atonic seizures, there is a sudden,
split-second loss of muscle tone leading to slackening of
the jaw, drooping of the limbs, and falling to the ground.
These seizures also are known as “drop attacks.”
Diagnosis andTreatment
The diagnosis of seizure disorders is based on a thor-
ough history and neurologic examination, including
a full description of the seizure.
7,56,60,61
The physical
examination and laboratory studies help exclude any
metabolic disorder (e.g., hyponatremia) that could pre-
cipitate seizures. Magnetic resonance imaging scans are
used to identify structural defects such as temporal lobe
sclerosis or underlying congenital malformations caus-
ing the seizure. One of the most useful diagnostic tests is
the EEG, which is used to record changes in the brain’s
electrical activity. It is used to support the clinical diag-
nosis of epilepsy, to provide a guide for prognosis, and
to assist in classifying the seizure disorder.
The first rules of treatment are to protect the per-
son from injury during a seizure, preserve brain func-
tion by aborting or preventing seizure activity, and treat
any underlying disease. People with epilepsy should be
advised to avoid situations that could be dangerous or
life-threatening if seizures occur. The management of
seizure disorders focuses on treatment of the underly-
ing conditions that cause or contribute to the seizures,
avoidance of precipitating factors, suppression of recur-
rent seizures by prophylactic therapy with antiepileptic
medications, surgery or neurostimulation, and address-
ing psychological and social issues.
7,56,60
Antiepileptic DrugTherapy
Antiepileptic drug therapy is the mainstay of treatment
for most persons with epilepsy. It is individualized for
each patient based on the different types and causes of
seizures as well as medication efficacy and side effects.
Antiepileptic drugs act mainly by suppressing repeti-
tive firing of isolated neurons that act as epileptogenic
foci for seizure activity or by inhibiting the transmis-
sion of electrical impulses involved in seizure activity.
62
Because of their selective mechanisms of action, different
drugs are used to treat the different types of seizures. For
example, ethosuximide, which suppresses the brain wave
activity associated with lapses of consciousness, is used
in the treatment of absence seizures, but is not effective
for tonic-clonic seizures that progress from focal seizures.
More than 20 drugs are available for the treatment
of epilepsy.
64
This group includes 12 new antiepileptic
drugs that have been approved for use in the United
States in the past several decades.
63
The goal of pharma-
cologic treatment is to bring the seizures under control
with the least possible disruption in lifestyle and mini-
mum of side effects from the medication. Whenever
possible, a single drug should be used. Monotherapy
eliminates drug interactions and additive side effects.
Determining the proper dose of the anticonvulsant
drug is often a long and tedious process, which can be
very frustrating for the person with epilepsy.
64
Blood
tests are often used to determine that the blood con-
centration is within the therapeutic range. Consistency
in taking the medication is essential. Antiepileptic drug
use never should be discontinued abruptly. Special
consideration is needed when a person taking an anti-
epileptic medication becomes ill and must take addi-
tional medications. Some drugs act synergistically, and
others interfere with the actions of other medications.
This situation needs to be carefully monitored to avoid
overmedication or interference with successful seizure
control.
Women of child-bearing age require special consider-
ation concerning fertility, contraception, and pregnancy.
Many of the drugs interact with oral contraceptives;
some affect hormone function or decrease fertility. All
such women should be advised to take folic acid sup-
plementation. For women with epilepsy who become
pregnant, antiseizure drugs increase the risk for con-
genital abnormalities and other perinatal complications.
Carbamazepine, phenytoin, phenobarbital, primidone,
and valproic acid can interfere with vitamin D metabo-
lism and predispose to osteoporosis.
Surgical and NeurostimulationTherapy
Surgical treatment may be an option for persons with
epilepsy who are refractory to drug treatment.
7,60
With
the use of modern neuroimaging and surgical tech-
niques, a single epileptogenic lesion can often be identi-
fied and removed without leaving a neurologic deficit.
The most common surgery consists of removal of the
amygdala and an anterior part of the hippocampus and
entorhinal cortex, as well as a small part of the tempo-
ral pole, leaving the lateral temporal neocortex intact.
Another surgical procedure involves partial removal of
the corpus callosum to prevent spread of a unilateral
seizure to a generalized seizure.
Neurostimulation, with the development of a variety
of different devices and targets of stimulation, is a rap-
idly evolving field in the treatment of epilepsy.
65
Methods
of external (noninvasive) trigeminal stimulation have
been developed and are currently being evaluated. These
methods seem promising not only as therapy, but also as
a useful predictor of success with other forms of stimu-
lation therapy. A subcutaneous implantable device is
also being evaluated.
Generalized Convulsive Status
Epilepticus
Seizures that do not stop spontaneously or occur in suc-
cession without recovery are called
status epilepticus.
