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Epilepsy

Epilepsy. Gregory B. Sharp, M.D. Chief of Pediatric Neurology University of Arkansas For Medical Sciences Medical Director, Neuroscience Center of Excellence. Objectives – To Review:. Basic mechanisms of epilepsy Classification of seizures Seizure types Epilepsy syndromes

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Epilepsy

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  1. Epilepsy Gregory B. Sharp, M.D. Chief of Pediatric Neurology University of Arkansas For Medical Sciences Medical Director, Neuroscience Center of Excellence

  2. Objectives – To Review: • Basic mechanisms of epilepsy • Classification of seizures • Seizure types • Epilepsy syndromes • Non-epileptic seizures

  3. Synaptic Transmission • Neuron to neuron communication is mediated by neurotransmitters (NTs) and resultant EPSPs and IPSPs • Excitatory NTs • Glutamate • Aspartate • Inhibitory • GABA • Glycine

  4. Burst Firing • Some neurons have the ability to fire very rapidly in bursts • Prolonged after-depolarization produced decreased inactivation of Na+ and Ca2+ conductance occurs within the dendritic tree • Allows repetitive activation of action potentials producing burst firing • This especially occurs in the hippocampus

  5. Glutamate Receptors • At least 3 primary classes with multiple subtypes • NMDA • AMPA • Kainate • Activation of NMDA receptors plays an important role in the spread of epileptic activity

  6. Recurrent Excitatory Pathways • Recurrent excitatory pathways occur in the hippocampus and neocortex via pyramidal collateralls • This provides activation that is normally governed by widespread inhibitory circuits • Promotes spread of the seizure discharge

  7. Hippocampal Sclerosis • Hippocampal anatomy promotes epileptogenesis • Hippocampal sclerosis is common in temporal lobe epilepsy • Significant synaptic reorganization and increased axonal collateralization provide increased excitatory input between neurons • Promotes synchronous epileptic firing and seizure propagation

  8. Frequency Related Synaptic Enhancement • High frequency repetitive firing results in increase accumulation of Ca near the presynaptic terminal produces • Facillitation – increased glutamate release • Potentiation – enhanced synaptic activity

  9. Synaptic Inhibition: GABA • GABAA receptors: mediate brief opening of Cl- channels • GABAB receptors: prolong activation of K+ channels • Repetitive firing depresses inhibitory synaptic activity

  10. Electrical Coupling of Neurons • In areas with densely packed neurons (hippocampus), neurons may be connected directly via gap junctions or communicate via ephatic transmission due to close apposition of membranes allowing direct propagation of the seizure discharge

  11. Cellular Mechanisms of Epilepsy • Burst firing • Recurrent excitatory connections • Synaptic enhancement and potentiation produced by rapid firing • Depression of inhibitory synapses by high frequency firing • Nonsynaptic spread of electrical activity

  12. Epilepsy • Recurrent seizures produced by abnormal repetitive neuronal firing in the brain • Occurs in 1-2% of the population

  13. “Epsilepsee” in Arkansaw BigSeizure “Grandma Seizure” vs. “Petit Mal Seizure” Little Seizure “Mini-Mall”

  14. Seizure Classification Partial (Focal) Primary Generalized Simple Complex Absence Myoclonic Atonic Convulsive Tonic Clonic Tonic-clonic Clonic-tonic-clonic May secondarily generalize

  15. Partial Onset Seizure – Left Temporal Generalized Onset Seizure

  16. General Guidelines for Therapy: Epilepsy Pearls • Correct classification of seizures leads to correct AED selection • Treat when the benefit of therapy outweighs the risk

  17. Natalie • 3-week-old infant with no apparent perinatal complications • Hypotonia • Slow feeder, poor suck • Several spells per day of staring with slight jerking movements

  18. Neonatal Seizure

  19. Cerebrovascular IVH Hypoxic ischemic injury Cerebral infarction Genetic/Metabolic Chromosomal abnormalities Inherited Benign familial Amino acid disorder Organic acidemia Urea cycle defect Non-ketotic hyperglycinemia Mitochondrial disorder Neurocutaneous disorder Others Acute Metabolic Problems Hypoglycemia Hypocalcemia Hypo/hypernatremia Infectious Bacterial meningitis TORCH Viral encephalitis Cerebral Anomalies Hydrocephalus Migrational abnormalites Agenesis of corpus calosum Holoprosencephaly Lissencephaly Others Others Causes of Neonatal Seizures

  20. Samuel • 7-month-old infant with cerebral injury from “shaken baby” syndrome • Now with episodes described as “startle reflexes” commonly occurring in clusters • Not responsive to maintenance phenobarbital

  21. Infantile Spasms

  22. Infantile Spasms • Flexion or extension spasms • Tend to occur in clusters • Cryptogenic vs. symptomatic • Many potential causes • Onset: Birth to 2 years • Peak onset: 5-6 months • 80% develop mental retardation • 60-70% have lifelong epilepsy • Hypsarrhythmia pattern on EEG

  23. Charlie • 9-year-old boy with long-standing history of intractable epilepsy with tonic-clonic, tonic, myoclonic, atypical absence and atonic seizures • Moderate mental retardation • Frequent injuries from falls

  24. Head Drops: Lennox Gastaut

  25. Lennox-Gastaut Syndrome • Onset in early childhood • Many underlying etiologies, often cryptogenic • Multiple seizure types including • Atypical absence, generalized convulsive, atonic, myoclonic, partial • Negative neurodevelopmental impact • Mental retardation • Slow spike and wave (2 hertz)

  26. Atonic • No warning, abrupt onset • Injuries common • Very difficult to treat • May respond well to VNS • Corpus callosotomy may prevent falls

  27. Atonic

  28. Terry • 2-year-old boy with 3-week history of recurrent episodes of sudden fear or panic • Initial frequency of 2-3 per day, now increased to 1 per hour or more • Maintenance of consciousness • LMD felt these were not seizures

  29. Simple Partial Seizure

  30. Gabrielle • 12 y/o Hispanic girl with 1-year history of frequent spells with several daily • Diagnosed with “pseudoseizures” • Maintenance of consciousness • Events are stereotypical with extension of the right arm and turning to the left, followed by agitated movements and vocalization with an abrupt recovery

  31. Frontal Lobe Seizure

  32. Simple Partial • Focal onset • Aura is common • No alteration of consciousness • May secondarily generalize

  33. William • 12-year-old boy with intractable seizures with episodes of confusion and disorientation • Ash leaf spots noted on Wood’s lamp exam • Intractable seizures despite numerous AED’s

  34. MRI: Tuberous Sclerosis Subependymal nodules Hamartoma

  35. Complex Partial Seizure

  36. Complex Partial • Aura is common • Represents the ictal onset • Stereotypical, but may be difficult to describe • Alteration of consciousness • Automatisms • Postictal confusion • May secondarily generalize

  37. Chelsea • 9-year-old girl with 2 seizures during the last 4 months • First episode occurred during sleep consisting of a brief generalized convulsion • Second seizure occurred during wakefulness and involved the right face and arm with subsequent secondary generalization

  38. Benign Focal Epilepsy of Childhood • Rolandic (centrotemporal) or occipital spikes • Benign Rolandic Epilepsy of Childhood • Benign Occipital Epilepsy of Childhood • Nocturnal seizures are common • Seizures are usually infrequent • Remits by 15-16 years of age or earlier

  39. Tina • 13 y/o girl with frequent staring episodes described as a blank stare with unresponsiveness, noted daily at school • Decreasing school performance • *Key question: Is there an acute arrest of activity?

  40. Absence

  41. Absence • Brief stare with unresponsiveness • May have associated eye flutter or simple automatisms • Sudden onset with arrest of activity • No aura or postictal confusion • Generalized 3 per second spike and wave • 80% will experience resolution with age • 20% will have convulsive seizures.

  42. Absence Followed by Clonic-Tonic-Clonic

  43. Primary Generalized Convulsive • No warning; abrupt onset • Tonic, clonic, tonic-clonic or clonic-tonic-clonic activity • Bowel and bladder incontinence common • Postictal unresponsiveness or confusion • Generalized spike and wave

  44. Bubba • 13-year-old boy who had a single generalized convulsion 3 weeks ago • No previous history of seizures • *Key question: Do you ever have small jerks of your arms, especially early in the morning? • Answer: “Oh yeah, I’ve been doing that for a couple of years”

  45. Myoclonic Seizure

  46. Myoclonic • Sudden single jerks of the arms and head • Single or in clusters • No alteration in consciousness • May progress to clonic-tonic-clonic seizure • Generalized multispike wave

  47. Juvenile Myoclonic Epilepsy(JME) • Myoclonic seizures with onsetin late childhood or adolescence • May develop generalized convulsive or absence seizures • Autosomal dominant inheritance • Chromosome 6

  48. Monica • 14 year old girl with 1 week history of new onset convulsive seizures • Hospitalized and loaded with phenytoin with worsening seizures • Normal EEG

  49. Is it Real or is it Memorex? Pseudoseizure

  50. Non-Epileptic Seizures in Children (ACH study) • NES - 65 children (video EEG) • 7-17 years (mean 13) • 42 girls, 23 boys • 1/4 Coexisting history of epilepsy • 3/4 had an identifiable psychosocial stressor

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