Definition (Pediatr Rev 2007;28:363; Epilepsia 2010;51:676)
• Epilepsy: ≥2 seizures w/o clear underlying cause
• Focal seizures: Unilateral hemispheric origin with consistent focal motor manifestations. Seizures often propagate and lead to global excitation
• Associated syndromes:
• Benign partial epilepsy (benign rolandic): Presents 3–13 yo. Tonic or clonic mvmts, often unilateral paresthesias of lower face. Typical electrical correlate in sleep
• Temporal lobe epilepsy: Presents childhood, may remit in adol, return in adulthood. Often w/ aura, psychic sx, and automatisms. May/may not arise from temporal lobe
• Frontal lobe epilepsy: Frequently occurs in nighttime clusters. Often involves auras and bizarre automatisms (e.g., bicycle pedaling, pelvic thrusting)
• Parietal lobe epilepsy: Often involves somatosensory sx, including paresthesia and detailed visual hallucinations
• Occipital lobe: Often involves vague visual sx of flashes of light/colors
• Generalized seizures: Bilateral excitation with inconsistent localization and lateralization patterns. Motor manifestations bilateral and often synchronous
• Subtypes:
• Absence: “Staring spells.” Sudden brief LOC, +/− eye flickering. Ictal EEG shows 3 Hz spike/wave pattern. Activated by hyperventilation
• Myoclonic: Sudden muscle contractions
• Clonic: Asymmetric/irregular jerking
• Tonic: Sustained contraction w/o clonic phase. Assoc w/ diffuse cerebral damage
• Tonic–clonic: Has tonic, clonic, and postictal phases
• Atonic: “Drop seizure.” Brief lapse in muscle tone
• Associated syndromes (Epilepsia 2010;51:2175; Lancet Neurol 2009;8:82):
• Infantile spasms: Usually presents 5–12 mo, remitting by ∼3 yo. Symmetric, bilateral, brief, and sudden contractions of axial muscle groups. Assoc w/ poor neurocog outcomes and Lennox–Gastaut syndrome. Freq ranges from few to 100s of szrs daily. Typical EEG correlate of hypsarrhythmia (Irregular, disorganized, high amplitude waves and spikes)
• Lennox–Gastaut: Usually presents 2–8 yo. Characterized by mental retardation and multiple generalized seizure subtypes, particularly tonic and atonic. Typical EEG correlate is a slow spike–wave pattern with highest voltage in the frontal regions
Epidemiology (Pediatr Rev 2007;28:363)
• Prevalence of epilepsy ∼1%. About 1/3 have developmental disabilities
Etiology (Pediatr Rev 2007;28:363)
• 65–70% idiopathic/cryptogenic, i.e., no identifiable structural abnormalities
• Remainders are “symptomatic,” or with identifiable abnormality impacting brain function
• Inherited/genetic: Channelopathies, chromosomal abnormalities, mitochondrial DNA disorder, metabolic disorder, hereditary neurocutaneous disorders
• Congenital: Cortical malform & dysplasia, polymicrogyria, vascular malform, prenatal injury
• Acquired: Trauma, infection, tumors, vascular disease, hippocampal sclerosis,
neurodegenerative disorders, toxic disorders
Diagnosis (Pediatr Rev 2007;28:405; Epilepsia 2009;50:2147)
• EEG: Nml in 10–20%. Can induce szr w/ hypervent, photic stim, sleep depriv
• Brain imaging: Recommended in pts w/ focal szr. Not needed w/ generalized szr if nml neurodev, <2% w/ abnormality on scan. MRI is preferred modality
• Neuropsych eval: Better qualify learning diff assoc w/ epilepsy; target interventions
Treatment (Pediatr Rev 2007;28:405; Clin Pediatr (Phila) 2005;44:383; Pediatrics 2007;119:535)
AEDs:
• Choice of AED depends on age and szr type
• Neonatal seizures: Phenobarbital and phenytoin
• Focal seizures: 1st line – carbamazepine, phenobarbital, valproic acid, topiramate, phenytoin, lamotrigine, oxcarbazepine. 2nd line – gabapentin, levetiracetam
• Generalized tonic–clonic: 1st line – carbamazepine, valproic acid, phenytoin,
phenobarbital, topiramate. 2nd line – lamotrigine
• Absence: 1st line – ethosuximide, valproic acid, lamotrigine. 2nd line – clonazepam
• Infantile spasms: 1st line – vigabatrin, ACTH, prednisone
• Lennox–Gastaut: 1st line – valproic acid, lamotrigine, clonazepam, carbamazepine, topiramate. 2nd line – ethosuximide (drop attacks)
• Several AEDs require regular monitoring of AED blood concentration to assess for dose-related toxicity, compliance, and potential drug–drug interactions
• Several AEDs affect liver metab. Carbamazepine, phenytoin, and phenobarbital are cytochrome p450 inducers & can ↑ metabolism of other AEDs and meds (e.g., OCPs, steroids, warfarin). Valproic acid is a cytochrome p450 inhibitor
Adverse Effects of AEDs (Pediatr Rev 1997;18:39; Pediatr Rev 2007;28:405)
• Ketogenic diet: High-fat, low-carb; assoc w/ improved szr control & awareness level. Long-term adverse effects: Renal stones, growth inhib, hyperlipid, vit def, constipation
• Surgery: Must have localizable seizure focus
• Vagus nerve stimulator: Adjunctive therapy for intractable partial seizures. Electric impulse to L vagus nerve.
Seizure precautions:
• Avoid common triggers (sleep depriv, hypervent, drugs/EtOH, photic light stim)
• Teach szr 1st aid. Put pt in swimmers ¾ prone position; keep mouth clear
• Basic safety precautions (e.g., water & helmet safety) & driving restrictions (vary by state)