ANTICONVULSANTS
Epilepsy is defined as a disorder of recurrent seizures
due to a chronic (persisting over a long period)
underlying cause. Epilepsy comes from the Greek
word epilepsia, which means to seize.
A seizure is a sudden attack or convulsion (a violent
involuntary contraction of voluntary muscles) due to
involuntary electrical activity in the brain. Patients
who experience isolated seizures due to a correctable
cause (drug toxicity, alcohol abuse or metabolic
abnormalities) do not necessarily have epilepsy.
Epilepsy is classified as either symptomatic or
idiopathic. Symptomatic implies that a probable
cause has been identified and permits a specific
course of therapy. Idiopathic means that no obvious
cause can be found.
Epilepsy begins before the age of 18 in more than
75% of patients. It is estimated that 1 of every 11
people in the U.S. will experience a seizure at some
time during life. Identification of the cause of
seizures is important in the determination of
management.
Finding a cause for the sudden abnormal discharge of
cerebral neurons is not possible in all cases. Some
possible causes are:
Primary or acquired neurologic disorders:
1. Fever (body temp. above 100.4 F) in
childhood.
2. Genetic disorders
3. Idiopathic (unknown origin)
4. Head trauma (injury)
5. Brain tumor
6. CNS infection
Systemic or metabolic disorders:
1. Anoxia (lack of oxygen to the tissues)
2. Drug overdose
3. Hypocalcemia (abnormally low calcium
concentration)
4. Hypoglycemia (low blood sugar level)
5. Hepatic failure (pertaining to the liver)
6. Renal failure (pertaining to the kidney)
7. Alcohol abuse
8. Eclampsia (late pregnancy characterized by
convulsions)
Pathophysiology (the study of how normal
physiological processes are altered by disease)
Seizures are caused by a disturbance in the normal
balance of excitatory (stimulating or irritating) and
inhibitory (restraining) influences in the brain.
Most anti-epileptic drugs suppress seizures by
altering neurotransmitter activity within the CNS.
Classification of seizures
Seizures are classified as being either generalized or
partial, based on their clinical features.
Generalized Seizure: those that begin in both
hemispheres of the brain.
Partial Seizure: begin in an area of the brain that is
limited to one hemisphere and have some underlying
focal (one specific area) brain lesion (injury or
wound). The injury may have been perinatal (shortly
before or after birth), trauma, stroke or brain tumor.
GENERALIZED SEIZURES
1. Tonic-Clonic Seizures: (traditionally called
grand mal) are preceded by an “aura”. This
seizure begins with tonic (rigid) flexion of the
extremities followed by extension. This phase
lasts approximately 15-20 seconds. This is
quickly followed by the clonic (jerking) phase,
during which there are spasms of the trunk and
extremities and often biting of the tongue. The
clonic phase may last 20-30 seconds. Urinary
and fecal incontinence may occur. The patient
may sleep or awaken confused and disoriented.
Gradually over 15-30 minutes the patient will
return to consciousness. The patient may have
no recall of the event.
2. Absence Seizures: (traditionally called petit
mal) this seizure occurs with an interruption of
consciousness followed by a fixed stare. During
the seizure there is no loss of postural tone. The
seizure lasts several seconds and ends as
quickly as it began. These seizures may occur
hundreds of times a day and would be perceived
by family or teachers as daydreaming.
PARTIAL SEIZURES
1. Simple Partial Seizures: these seizures are
characterized either by motor spasms (jerking of
one limb) or sensory symptoms (a foul odor or
visual distortion). Feelings of fear or déjà vu
may accompany simple partial seizures. In all
cases, patients can respond to their environment
throughout the attack.
2. Complex Partial Seizures: an “aura” will
precede the seizure. Consciousness will be
impaired for approximately 2 minutes. During
this time patients may exhibit lip smacking,
buttoning or unbuttoning of clothing or
wandering behavior. The patient may lose
contact with their surroundings.
Disorders That May Mimic Epilepsy
1. GERD (gastroesophageal reflux)
2. Breath-holding spells
3. Migraine (vascular headache usually
accompanied by irritability, nausea, vomiting
and photophobia)
4. Sleep disorders
5. Movement disorders (shuddering attacks,
involuntary movements, twitching or spasm of a
muscle or group of muscles, tics and habit
spasms usually involving the face or shoulders).
6. Psychological disorders (panic attacks,
hyperventilation attacks, rage attacks or
pseudoseizures. Seizures that resemble epilepsy
but are not epileptic in nature).
Psychosocial Issues
In addition to medical issues that accompany the
diagnosis of epilepsy, patients often experience
anxiety and fear knowing they have a disorder
that affects the brain and loses control over their
body and consciousness.
Patients also fear a loss of independence due to
the need for daily medication. People with epilepsy
may be subject to driving restrictions and may
need to document their condition on insurance
and employment applications.
Alterations of usual activities may be required due
to the timing and characteristics of the seizures.
Activities such as unattended swimming, working
at heights and operating dangerous machinery may
be restricted.
Conditions that are identified by patients, as
seizure precursors are stress, exercise, alcohol or
caffeine consumption, altered sleep schedules
and missed meals.
TREATMENT
The goals of treatment are to completely control
seizures and to minimize drug-related adverse
effects. The drug chosen should be based on
seizure type, the age and sex of the patient,
concurrent medical conditions and potential
adverse effects. However, even with appropriate
drug treatment, some patients continue to suffer.
BRAND
GENERIC
FORM
Various
phenobarbital
tabs,sol,inj
Dilantin
phenytoin
tabs,caps,susp,inj
Tegretol
carbamazepine tabs,susp
Klonopin
clonazepam
tabs,inj
Valium
diazepam
tabs,inj
Withdrawal From Antiepileptic Drug Therapy
Studies have shown that among patients with
epilepsy who are followed for more than 10 years,
more than half attain a 2-5 year remission from
seizures during drug therapy. Patients who remain
free of seizures for 2 years or more may be
considered candidates for drug withdrawal.
The benefit of drug withdrawal is a return by the
patient to a lifestyle not hampered by the need for
chronic medication. Relapse rates after drug
withdrawal in patients who have been free of
seizures for 2 years or more are approximately
30% for children and 40% for adults. The risk of
seizure recurrence is highest during the first year
after drug withdrawal.
Depending on the patient and the drug, withdrawal
is gradual over a period of 1 to 3 months.
A common cause for recurrence of seizures is noncompliance by the patient. Reasons for noncompliance include: high drug cost, adverse
effects of drug therapy, fears regarding effects
of medication and lifestyle issues.
Adverse Effects
1.
2.
3.
4.
5.
6.
Dizziness
Hypersalivation
Sedation
Ataxia (loss of muscular coordination)
Slurred speech
Depression
The total cost of epilepsy to the U.S. in direct
(medication and treatment) and indirect (loss of
productivity) costs is approximately $12.5 billion
per year.