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Seizures and Epilepsy

Seizures occur at all ages. The term "seizure" designates a clinical event that represents dysfunction of the central nervous system (CNS) and may signal a serious underlying abnormality; however, more often in children the seizures result from a transient disturbance of brain function seizures.

Epidemiology and classification of seizure types

The ages of greatest risk for nonfebrile seizures are during infancy, childhood, and adolescence. The annual incidence rate from birth to 20 years of age is 0.56 per 1000.The two primary forms of epilepsy are generalized seizures and partial seizures.

Partial seizures

Partial seizures are the most common form of epilepsy.

Simple partial seizures (SPS)

SPS are most commonly focal, asynchronous, clonic or tonic motor movements, such as forced deviation of the head and eyes.

An SPS typically is short-lived, rarely persisting longer than 10 to 20 seconds, and the child remains conscious and is able to verbalize throughout the seizure. The EEG characteristically shows unilateral spikes or sharp waves.

Complex partial seizures (CPS)

CPS initially may be similar in appearance to an SPS, but they are followed by impairment of consciousness. CPS may begin with a loss of consciousness.

Aura signals the onset of a seizure in 30% of children who have CPS, with the child.

International Classification of Epileptic Seizures

Partial Seizures

--Simple partial (consciousness retained)

–Complex partial (consciousness impaired)

– Partial seizure with secondary generalization

Generalized Seizures

--Absence seizures

--Myoclonic seizures

--Clonic seizures

--Tonic seizures

--Tonic-clonic seizures

--Atonic seizures

Unclassified Seizures

Generalized Seizures

Simple absence seizures usually have their onset at 5 to 6 years of age and are characterized by brief (5-20 sec) lapses in consciousness, speech, or motor activity. Absence seizures are not accompanied by an aura or a postictal drowsiness.

Pathophysiology of epilepsy

The etiology of most seizures in children remains unknown.

The acute onset of seizures may result from head injury, CNS infection (meningitis, encephalitis), cerebrovascular diseases (infarction, arteriovenous malformation, hemorrhage, venous thrombosis), toxins (lead), brain tumor, specific epilepsy syndromes, genetic/hereditary diseases.

Hypoxic-ischemic encephalopathy is the most common cause of seizures in the newborn.

Pyridoxine dependency may be the cause of seizures that begin shortly after birth.

Metabolic encephalopathies commonly are associated with seizures in the newborn. A urea cycle abnormality or a disorder of amino acid metabolism.

Structural abnormalities of the brain and congenital disorders of neuronal migration play an important role in the causation of epilepsy.

Diagnosis

A presumptive diagnosis of epilepsy generally is made from a history of spontaneous recurrent seizures and physical examination findings. The parent usually can give a good account of the seizure.

Management of nonfebrile seizures

Anticonvulsant medication

Anticonvulsants are initiated following absence (typical or atypical) seizures, myoclonic seizures, and infantile spasms because the risk of recurrence.

Common Anticonvulsant Drugs
Drug	Seizure Type	Oral Dose	Serum Level mcg/mL	Side Effects and Toxicities
Carbamazepine (Tegretol)	Partial epilepsy Tonic-clonic	Begin 10 mg/kg/d. Increase by 5 mg/kg/d every wk to 20-30 mg/kg/d in 2 or 3 divided doses	4-12	Dizziness, drowsiness, diplopia, liver, dysfunction, anemia, leukopenia
Clonazepam (Klonopin)	Myoclonic Absence	Begin 0.05 mg/kg/d. Increase by 0.05 mg/kg per wk. Maximum, 0.2 mg/kg/d in 2 or 3 divided doses	6.3-56.8	Drowsiness, irritability, drooling, behavioral abnormalities, depression
Ethosuximide (Zarontin)	Absence Myoclonic	Begin 10 to 20 mg/kg/d in 2 divided doses; may be increased to 50 mg/kg/d	40-160	Drowsiness, nausea, rarely blood dyscrasias
Gabapentin (Neurontin)	Partial epilepsy Tonic-clonic	Begin 300 mg/d. Increase by 300 mg/d every 3 to 5 days. Maximum 900 to 1200 mg/d in 3 equally divided doses	<2	Somnolence, dizziness. ataxia, headache, tremor, vomiting, nystagmus, fatigue.
Lamotrigine (Lamictal)	Partial epilepsy Tonic-clonic Lennox-Gastaut	Begin 2 mg/kg/d in 2 equal doses. Increase to maintenance dose of 5 to 15 mg/kg/d.	1-4	Severe skin rashes, drowsiness, headache, blurred vision.
Phenobarbital	Tonic-clonic Partial epilepsy	3 to 5 mg/kg/d in 1 or 2 divided doses	15-40	Hyperactivity, irritability, short attention span, temper tantrums, altered sleep pattern, Stevens-Johnson syndrome, depression of cognitive function.
Phenytoin (Dilantin)	Partial epilepsy Tonic-clonic	5 m 6 mg/kg/d in 2 divided doses	10-20	Hirsutism, gum hypertrophy, ataxia, skin rash, Stevens Johnson syndrome.
Primidone (Mysoline)	Tonic-clonic Partial epilepsy Myoclonic	Begin 50 mg/d in two divided doses. Gradually increase to 150 to 500 mg/d divided into 3 equal doses.	5-12	Aggressive behavior and personality changes similar to those for phenobarbital.
Sodium valproate (Depakote)	Tonic-clonic Absence Myoclonic Partial epilepsy Unclassified	Begin 10 mg/kg/d. Increase by 5 to 10 mg/kg per wk. Usual dose, 20 to 60 mg/kg/d in 2 or 3 divided doses.	50-100	Weight gain, alopecia, tremor, hepatotoxicity.
Vigabatrin (Sabril)	Partial epilepsy	Begin 30 to 40 mg/kg/d. Increase by 10 mg/kg per wk. Maximum, 80 to 100 mg/kg/d in 2 equal doses	1.4-14	Agitation, drowsiness, weight gain, dizziness, headache, ataxia.

Therapeutic monitoring and routine screening

Some children achieve seizure control with subtherapeutic serum drug levels (eg, carbamazepine); for others, the seizures do not come under control.