Table of Contents
Seizures can be classified into partial or generalized and simple or complex.
Partial (focal) seizures occur as a result of abnormal electrical activity in one hemisphere in the brain, which will affect one side of the body or even an extremity. Partial seizures can be simple, not involving loss of consciousness, or complex, which affects the conscious level.
Generalized seizures affect both brain hemispheres and can affect the whole body associated with loss of consciousness. It is important to differentiate between seizures and epilepsy, which is recurrent seizures due to a known or unknown factors. Two or more seizure episodes without return to baseline activity and mental status or continuous five minutes of seizures is known as status epilepticus.
The repetitive abnormal muscular contractions associated with seizure activity or status epilepticus are harmful to the physiologic body environment in many ways. During muscular contraction, hyperthermia and hyperglycemia followed by depletion of glucose stores will develop.
Rhabdomyolysis and lactic acidosis with renal failure also are common complications of status epilepticus. Apnea with hypoxia can also be a complication, which will result in hypertension to maintain cerebral oxygenation. Multi-organ failure can be the end result due to hypercarpia and hypoxemia.
Etiology of Seizures
Thorough evaluation of seizure patients is mandatory to identify the etiologic factor. The incidence of the first seizure attack is common before 2 and after 65 years age with male predominance.
|Central causes||Systemic causes|
|Brain tumors||Metabolic abnormalities|
|Brain infections||Toxic and drug exposure|
|Brain edema||Clozapine, cocaine and alcohol withdrawal|
Types of Seizures
The electrical discharge involves a small focus or single hemisphere of the brain and the seizure involves one side of the body or single extremity. Usually there is an aura proceeding partial seizures.
Partial seizures can be simple with no loss of mental status or complex partial with loss of consciousness. Simple partial seizures can be motor, sensory and autonomic. Patients may report automatisms, which are repetitive involuntary movements e.g. lip smacking and chewing.
The electrical activity involves the whole brain and affects both body sides or multiple extremities. Generalized seizures can be classified into:
Generalized tonic-clonic or grand mal seizures where patients lose consciousness followed by generalized body stiffness called the tonic phase. After that the patient starts generalized convulsions or jerking, which is called the clonic phase. Each of the tonic and clonic phases lasts from 30 to 60 seconds, then the patients goes into deep sleep called the postictal phase. The patients lose control over the bladder leading to incontinence. Various injuries are common during the grand mal seizures; therefore it is important to secure the airway and prevent tongue biting during the attack.
Myoclonic seizures, which does not include loss of consciousness but the patient experiences brief jerk movement of a group of muscles that is described as shock like jerks.
Clonic seizures, which are repetitive jerking movements that cannot be stopped by physical restraining. The contractions are rhythmic and involves both body sides.
Tonic seizures, where muscle tone is suddenly increased leading to stiffening of the body usually involves both sides without loss of consciousness.
Atonic seizures, where loss of muscle tone leads to falls. These are also called drop attacks or akinetic seizures.
Absence seizures were formerly called petit mal seizures and consist of momentary loss of consciousness without motor jerking. It is most common in children where it affects school activities. The patients are not aware of the seizure disorder but other report that they stare blankly several times a day.
Febrile seizures are the most common during childhood between 6 months and 5 years. The seizures occur during febrile illness due to viral or bacterial infection or after vaccination-induced fever. Positive family history is common among affected children. It can be simple with tonic-clonic convulsions or twitches that last for less than 15 minutes and no paralysis or paresis after the episode and it can be complex, which lasts more than 15 minutes with residual weakness of the affected extremities.
Evaluation of febrile seizures in children
Exclusion of other causes of childhood febrile seizures including meningitis is crucial for management. Febrile seizures are common in the first 24 hours of fever and common in children with frequent fever episodes or with positive family history of febrile seizures.
Management of febrile seizures
ABCs with securing the airway, breathing and circulation are the first step. The convulsing patient should be placed on the lateral decubitus with administration of intravenous diazepam for rapid control of seizures. Parents can use diazepam gel into the rectum before arriving to the emergency department in case of prolonged seizures.
Acetaminophen is used to treat fever episodes. Patients with febrile seizures can have recurrent attacks of febrile seizures which commonly disappear with advanced age. There is no residual brain impairment or epilepsy risk.
Evaluation of the First Seizure
The first step after stabilization in evaluating a patient with the first seizure episode is to identify any reason behind this attack and the possibility of recurrence of this episode. The recurrent unprovoked seizures are considered epilepsy but provoked seizures due to acute brain lesion or systemic metabolic abnormality is not considered epilepsy.
Brain causes of epilepsy in adults include brain trauma, brain tumor, stroke, infection or malformation. Brain anoxia due to drowning, cardiac arrest can also present with seizures.
Systemic causes include:
- Toxic and drug abuse e.g. alcohol withdrawal is a common cause of seizures which occur in the first day after the last drink.
- Hyperthyroidism is a common cause of convulsions and can exacerbate an existing seizure disorder.
- Hyponatremia with brain edema may lead to tonic clonic fits.
- Hyperglycemic seizures occur in diabetic patients and manifest as focal fits.
- Hypoglycemic seizures due to insulin injection, insulinoma or hypoglycemic drugs. The patient will present with diaphoresis, tachycardia and confusion due to autonomic stimulation.
- Hypocalcemia and hypomagnesemia may manifest as tetany and convulsions specially after parathyroid resection.
- Renal failure can lead to convulsions in uremic patients with loss of consciousness and metabolic disorders even with hemodialysis.
Thorough history is mandatory for identification of any etiologic factor including family history, past medical history, medication history and social history. Positive family history of epilepsy is a risk factor for epilepsy. Past medical history of febrile seizures, metastatic malignancy, systemic lupus erythematosus, sickle cell disease, CNS infection or previous surgery should be evaluated.
Causes of non-febrile seizures in children can be genetic, CNS infections, brain structural abnormality and metabolic disorders.
Laboratory work up
- Basal metabolic profile including sodium, potassium, calcium, magnesium, blood urea nitrogen and creatinine, glucose
- Thyroid hormone levels
- Drug toxicology screen
- Renal function tests
- Liver function tests
- EEG (electroenchephalography) can be used for screening but not specific in excluding seizure disorder. It can detect specific types of seizures and predict recurrence.
- CT & MRI can detect brain tumors, infarctions, abscess and vascular malformations.
- ECG can evaluate arrhythmia as an etiology for brain anoxia or syncopal episodes.
- Lumbar puncture and CSF analysis to evaluate for brain infections, CNS lymphoma and subarachnoid hemorrhage.
Management of the first seizure episode
Prolonged attack of more than 2 minutes requires immediate abortion with antiepileptic medications to avoid serious consequences. Intravenous administration of benzodiazepines is effective in aborting the attack. Prophylaxis with antiepileptic drugs may be needed with recurrent episodes while correction of the underlying pathology is ongoing.
Epilepsy and Pregnancy
Epilepsy during pregnancy can be associated with various critical conditions that may compromise both the mother and the fetus including miscarriage, fetal malformations, preterm labor, stillbirth and promotion of seizure threshold.
The risk of developing congenital malformation in the fetus is double that of the population but remains as low as 6%. The risk is greater with more than one medications and high doses. Congenital malformations include cleft lip and palate, neural tube defects, lower IQ, cardiac and genital defects.
Risk of epilepsy increases during pregnancy in women with previous history including eclampsia, stress, lack of sleep, inadequate medication levels, hormonal changes and salt and water retention.
Management of epilepsy in pregnant women
- Genetic counseling as early as possible
- Check the level of antiepileptic drugs monthly with attempts to lower the dose or withdraw the medication if necessary after 2 years of seizure free period
- Folic acid supplementation is mandatory to prevent neural tube defects and congenital anomalies.
- Vitamin K should be given to pregnant women and newborn babies to prevent bleeding from antiepileptic drugs.
- During pregnancy, maternal and amniotic fluid alpha fetoprotein level can be used to assess fetal anomalies.
- At the time of labor consider prophylaxis with intravenous diazepam or phenytoin. If there are signs of fetal distress, immediate delivery is indicated.
- Antiepileptic drugs are not a contraindication to normal vaginal delivery or breastfeeding.
- No switch or discontinuation of the antiepileptic medication during pregnancy is indicated as long as optimum symptoms control is achieved.
The goal is to achieve long term seizure free survival with least complications.
Absence seizures are best treated by ethosuximide. Valproic acid has similar efficacy but more side effects. Valproic acid and lamotrigine are indicated if absence seizures are associated with tonic-clonic or myoclonic seizures. Ethosuximide is a t type calcium channel blocker with a long half-life of about 40 hours. Common side effects are mainly GI disturbance.
Generalized tonic-clonic, tonic and myoclonic seizures are best treated with valproic acid, lamotrigine and levetiracetam. Valproic acid acts via blockade of sodium and calcium channel. It is considered a broad spectrum antiepileptic medication that can be used for all kinds of seizure disorders. Side effects include pancreatitis, weight gain, fetal defects, hair loss, GI upset, osteoporosis and abnormal blood count.
lamotrigine is a similar broad spectrum anticonvulsant which acts by inhibiting glutamate release in the brain. Side effects include rash, fatigue and cognitive impairment. Levetiracetam is also a broad spectrum drug with better side effect profile. It has no cognitive impairment effects but can induce fatigue, mood changes and insomnia.
Other antiepileptic medications
- Phenobarbital is a barbiturate type drug that works via increasing GAPA inhibition. Side effects include addiction, memory impairment, congenital anomalies and mood changes.
- Phenytoin is the most widely used. It acts by inhibiting sodium channels. Side effects include Stevens-Johnson syndrome, hair growth, rash, cognitive impairment and osteoporosis.
- Carbamazepine acts via sodium channels against partial seizures. Side effects include agranulocytosis, Stevens-Johnson syndrome, weight gain and blurring of vision.
- Gabapentin works through GAPA transport in the brain. Side effects include fatigue and weight gain.