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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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Gregory B. Sharp, M.D.

Chief of Pediatric Neurology

University of Arkansas For Medical Sciences

Medical Director, Neuroscience Center of Excellence

objectives to review
Objectives – To Review:
  • Basic mechanisms of epilepsy
  • Classification of seizures
  • Seizure types
  • Epilepsy syndromes
  • Non-epileptic seizures
synaptic transmission
Synaptic Transmission
  • Neuron to neuron communication is mediated by neurotransmitters (NTs) and resultant EPSPs and IPSPs
  • Excitatory NTs
    • Glutamate
    • Aspartate
  • Inhibitory
    • GABA
    • Glycine
burst firing
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
glutamate receptors
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
recurrent excitatory pathways
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
hippocampal sclerosis
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
frequency related synaptic enhancement
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
synaptic inhibition gaba
Synaptic Inhibition: GABA
  • GABAA receptors: mediate brief opening of Cl- channels
  • GABAB receptors: prolong activation of K+ channels
  • Repetitive firing depresses inhibitory synaptic activity
electrical coupling of neurons
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
cellular mechanisms of epilepsy
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
  • Recurrent seizures produced by abnormal repetitive neuronal firing in the brain
  • Occurs in 1-2% of the population
epsilepsee in arkansaw
“Epsilepsee” in Arkansaw


“Grandma Seizure” vs.

“Petit Mal Seizure”

Little Seizure


seizure classification
Seizure Classification

Partial (Focal)

Primary Generalized











May secondarily generalize

partial onset seizure left temporal
Partial Onset Seizure – Left Temporal

Generalized Onset Seizure

general guidelines for therapy epilepsy pearls
General Guidelines for Therapy: Epilepsy Pearls
  • Correct classification of seizures leads to correct AED selection
  • Treat when the benefit of therapy outweighs the risk
  • 3-week-old infant with no apparent perinatal complications
  • Hypotonia
  • Slow feeder, poor suck
  • Several spells per day of staring with slight jerking movements
causes of neonatal seizures


Hypoxic ischemic injury

Cerebral infarction


Chromosomal abnormalities


Benign familial

Amino acid disorder

Organic acidemia

Urea cycle defect

Non-ketotic hyperglycinemia

Mitochondrial disorder

Neurocutaneous disorder


Acute Metabolic Problems





Bacterial meningitis


Viral encephalitis

Cerebral Anomalies


Migrational abnormalites

Agenesis of corpus calosum





Causes of Neonatal Seizures
  • 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
infantile spasms1
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
  • 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
lennox gastaut syndrome
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)
  • No warning, abrupt onset
  • Injuries common
  • Very difficult to treat
  • May respond well to VNS
  • Corpus callosotomy may prevent falls
  • 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
  • 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
simple partial
Simple Partial
  • Focal onset
  • Aura is common
  • No alteration of consciousness
  • May secondarily generalize
  • 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
mri tuberous sclerosis
MRI: Tuberous Sclerosis

Subependymal nodules


complex partial
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
  • 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
benign focal epilepsy of childhood
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
  • 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?
  • 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.
primary generalized convulsive
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
  • 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”
  • 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
juvenile myoclonic epilepsy jme
Juvenile Myoclonic Epilepsy(JME)
  • Myoclonic seizures with onsetin late childhood or adolescence
  • May develop generalized convulsive or absence seizures
  • Autosomal dominant inheritance
    • Chromosome 6
  • 14 year old girl with 1 week history of new onset convulsive seizures
  • Hospitalized and loaded with phenytoin with worsening seizures
  • Normal EEG
non epileptic seizures in children ach study
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
nes in children psychosocial stressors
NES in Children:Psychosocial Stressors
  • * #1 Sexual or physical abuse
  • Others:
    • Death of a family member
    • Forced separation from family members
    • Physical disability or illness of a parent
    • Significant family conflict
    • Major illness
    • Financial stressors
    • Moving
    • Relational difficulties
alternative therapy for epilepsy
Alternative Therapy for Epilepsy
  • Ketogenic diet
  • Vagus nerve stimulator
  • Epilepsy surgery
ketogenic diet
Ketogenic Diet
  • First described by Wilder, Mayo Clinic Bulletin, 1921
  • Mark 9:29 “This kind can come forth by nothing, but by prayer and fasting.”
  • Typically reserved for children with severe, debilitating and intractable seizures
  • 4:1 (Fat: Protein + Carbohydrates)
    • 75-90% of caloric intake as fat
  • Urinary ketosis 80- 160 millimolar
ketogenic diet efficacy
Ketogenic Diet: Efficacy
  • 150 children prospectively evaluated
  • Age range: 4 months - 16 years
  • Average of 410 seizures per month
  • Results after 1 year:
    • 55% remained on the diet
    • 1/2 had > 50% reduction in seizures
    • 1/4 had > 90% decrease in seizures

Freeman, Vining, et.al. Pediatrics, December, 1998

vagus nerve stimulator rule of thirds
Vagus Nerve Stimulator:Rule of Thirds
  • 1/3 have prominent improvement
  • 1/3 have moderate improvement
  • 1/3 have little or no improvement
  • Benefits
    • fewer seizures, less severe seizures, shorter recovery period, decreased medications and side effects, less fear and anxiety, more control
epilepsy surgery criteria for consideration
Epilepsy Surgery:Criteria for Consideration
  • Seizures must be medically intractable
  • Seizures must be debilitating
  • There should be no chance for spontaneous resolution
epilepsy surgery
Epilepsy Surgery
  • Temporal lobectomy
    • 75-90% seizure free
  • Extratemporal lesional resection
    • 50-75% seizure free
  • Extratemporal non-lesional resection
    • < 50% seizure free
  • Functional hemispherectomy
    • considered in extreme circumstances
  • Corpus callosotomy
    • good for atonic and brief tonic seizures