Seizures

Authors: Flaherty, Alice W.; Rost, Natalia S.

Title: Massachusetts General Hospital Handbook of Neurology, The, 2nd Edition

Copyright 2007 Lippincott Williams & Wilkins

> Table of Contents > Child Neurology > Seizures

Seizures

A. See also

Adult Seizures, p. 108.

B. Status epilepticus

A medical emergency. see p. 108.

C. H&P

Ask about birth history, maternal illnesses, precipitating factors, fever, skin color changes, movements, family history. Try to get parents to videotape an episode. Thorough skin and physical exam.

D. Tests

• EEG: Baseline rhythms change dramatically with age. Many pts with epilepsy have normal EEGs. Sleep EEGs help; if necessary, give chloral hydrate 50 mg/kg PO, max. 1,000 mg. Consider continuous video-EEG monitoring.

• Tests: Glucose, electrolytes, Ca, Mg, UA. In newborns and infants, consider ammonia, lactate, pH, metabolic screens.

• Head scans: Intracranial ultrasound in newborns to rule out hemorrhage. CT in acute workups. MRI for structural detail.

P.148

E. Neonatal seizures

• Sx during seizures: Seizures in newborns are poorly organized and multifocal. Look for eye deviations, repetitive movements, tonic stiffening, apnea.

  • Premature infants: Apnea and bradycardia may be the only sign.

  • Intubated, chemically paralyzed infants: Sudden blood pressure changes may be the only sign.

• DDx: Benign jitteriness, benign sleep myoclonus, nonconvulsive apnea, normal movement, opisthotonos (back arching from meningitis or brain injury), hyperekplexia (genetically exaggerated startle reflex causes transient stiffness).

• Causes of neonatal seizures: The time frames are approximate.

  • First 72 h of life: Hypoxic-ischemic encephalopathy, cerebral hemorrhage, bacterial meningitis, TORCH infection, cerebral dysgenesis, drug withdrawal, hyperammonemia, hypoglycemia, hypocalcemia, effect of local anesthetic, pyridoxine dependency. Rarely from inborn errors of metabolism.

  • After 72 h: Cerebral hemorrhage, infection, hypocalcemia, inborn errors of metabolism, herpes simplex encephalitis, stroke, cerebral dysgenesis, kernicterus, benign familial neonatal seizures. Rarely from hypoxic injury.

• Rx of neonatal seizures: Correct electrolyte abnormalities. If no hypoglycemia (<30mg/ml), give:

  • Phenobarbital Load 15 mg/kg IV; may repeat to a total load of 40 mg/kg. Monitor SBP and breathing. Maintenance is 3-5 mg/kg qd IV or PO.

  • DPH: A second-line agent. Poorly absorbed PO in infants. Load 10 mg/kg IV 2. Monitor cardiac rhythm. Maintenance 5 mg/kg qd.

  • Pyridoxine? Severe, refractory seizures in infancy may be pyridoxine dependent. Test with pyridoxine 100 mg IV 2; EEG usually improves within minutes. Can become apneic during test. Rx pyridoxine 10-30 mg/kg/d.

F. Infantile seizures

(1 mo-2 yr):

• DDx: Apnea, migraine (can present as paroxysmal vertigo), paroxysmal dystonia, benign myoclonus, cyanotic syncope (usually triggered by anger or fear), pallid syncope (usually triggered by sudden pain). Both types of syncope can be associated with tonic/clonic movements.

• Simple febrile seizures: Seizure lasts <15 min, single occurrences in 24 h, febrile illness, nonfocal seizure and exam.

  • Relation to nonfebrile seizures: Febrile seizures are seen in 4% of children; only 2% of those will have epilepsy. Features that suggest epilepsy: neurodevelopmental abnormality, focal seizure, family history.

  • Tests and rx: Unnecessary unless the seizure is focal, prolonged, or leaves residual deficits. Prophylactic acetaminophen and prn rectal diazepam may help.

• Nonfebrile seizures: Causes are similar in infants and children; *see next section. The following are types of seizures that present between 1 mo and 2 yr.

  P.149

  
  

  • Infantile spasms: AKA West's syndrome.

    • H&P: Onset is always before 1 yr. See brief myoclonic extensor or flexor spasms (salaam movements), sometimes mistaken for colic. Symptomatic spasms are those with known cause; cryptogenic spasms are idiopathic.

    • EEG: Usually shows interictal hypsarrhythmia (chaotic, very high voltage slow waves and spikes) or ictal burst-suppression pattern. If high suspicion and normal interictal EEG, do long-term monitoring.

    • Rx: ACTH, especially in cryptogenic cases (in which the ACTH toxicity is justified because the prognosis is slightly better). In symptomatic cases, where prognosis is poor, consider clonazepam.

  • Myoclonic epilepsy: May be benign or severe.

    • H&P: Brief seizures, no LOC, vary from head nodding to sudden leg flexion and fall (with arms flung up and out). In severe myoclonic epilepsy, there is developmental delay and progressive ataxia and hyperreflexia.

    • EEG: 3-Hz spike-wave in benign myoclonic epilepsy; >3-Hz polyspike-wave in severe myoclonic epilepsy.

    • Rx: Valproic acid 15 mg/kg qd divided bid. Watch closely for hepatotoxicity. Avoid carbamazepine, lamotrigine.

  • Biotinidase deficiency.

G. Childhood seizures

• DDx: Migraine, syncope, hyperventilation, narcolepsy-cataplexy, night terrors, startle dz (hyperekplexia), pseudoseizures, daydreaming.

• Generalized tonic-clonic seizures: The most common type.

  • H&P: see p. 109.

  • Causes: Traumatic hypoxic or ischemic brain injury, CNS infection, cerebral dysgenesis, metabolic abnormality, drug or toxin effect, drug withdrawal.

  • Rx: No need to start ACDs after a single seizure in an otherwise normal child. Phenobarbital (5 mg/kg qd), DPH (5 mg/kg qd; poorly absorbed in infants), and carbamazepine (load slowly to 15 mg/kg qd) are equally effective for recurrent seizures.

• Simple partial seizures:

  • H&P: Focal movement or dysfunction, often with subsequent secondary generalization.

  • Causes: Benign centrotemporal or occipital epilepsy is the most common cause; see below. Any focal lesion, most often a neuronal migration disorder, mass, neurocysticercosis.

  • Benign centrotemporal (rolandic) epilepsy: Genetic.

    • H&P: Onset usually age 5-10; stop before age 14. Seizure usually occurs during sleep and wakes the child with mouth paresthesias and twitching for 1-2 min. Usually no LOC. Seizures sometimes spread to the arm or generalize.

    • EEG: Interictal uni- or bilateral centrotemporal spikes, enhanced in sleep.

    • Rx: Usually unnecessary.

  • Benign occipital epilepsy: Probably genetic.

    P.150

    
    

    • H&P: Onset usually age 4-8; stop before age 12. Seizure usually has visual changes, often followed by migraine-like headache or nausea. Often induced by sleep-wake transition, photic stimulation, or video games.

    • EEG: Interictal 2-Hz uni- or bilateral occipital spike-wave, inhibited by eye opening.

    • Rx: Standard ACDs are usually successful.

• Complex partial seizures: see p. 110.

• Myoclonic seizures: see p. 149.

• Absence seizures:

  • H&P: Onset 3-12 yr. Attacks last 5-10 sec, up to 100 qd. The child stares vacantly, sometimes with rhythmic eyelid movement; some have automatisms. No aura or postictal confusion. Absence status can cause confusion. 50% of pts. with absence will also have at least one generalized seizure.

  • Cause: Autosomal dominant gene, age-dependent penetrance.

  • EEG: Bilateral synchronous 3-Hz spike-wave during the seizure. Can be triggered by hyperventilation.

  • Rx: Ethosuximide, initial dose 20 mg/kg qd divided tid. Or valproate.

• Landau-Kleffner syndrome:

  • H&P: Onset age 2-11 yr. Usually starts with selective word deafness or seizures (partial or generalized), followed by autistic personality changes.

  • Cause: Unknown, except in rare cases of temporal lobe tumor. Hard to tell from autism, which may also have abnormal EEG.

  • EEG: Multifocal parietal and temporal spikes. Sometimes associated with electrical status epilepticus of sleep (ESES), with seizures during >80% of sleep.

  • Rx: ACDs help the seizures but not aphasia. Early steroids may cause remission of aphasia and seizures. Some use high-dose oral diazepam for ESES.

• Lennox-Gastaut syndrome:

  • H&P: Seizures (atypical absence, atonic, and myoclonic) and mental retardation. Onset usually at age 1 5 yr. May follow infantile spasms.

  • Causes: Usually from neurocutaneous disorder, peri- or postnatal brain injury.

  • EEG: Slow (1-2.5 Hz) spike-wave complexes.

  • Rx: Valproate, benzodiazepines, felbamate.