Seizure Disorders
PSYC4080
Seizure Disorders
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Seizure Disorders
 Abnormal electrical discharge in the brain.
 Neurons firing together in synchrony: paroxysmal
depolarization shifts (PDS)
 Hyperexcitation of glutamate neurons.
 Many causes: Seizures are symptoms, not a
disease.
 Presence of sensory or cognitive dysfunction is
dependent on affected area(s)
 Prevalence: 0.6% of the population
 Incidence: 15,500 new cases per year (Epilepsy
Canada)
PSYC4080
Seizure Disorders
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Neuropathology
1. Generalized seizures – involve the entire cerebral cortex
2. Focal (partial) seizures – limited to parts of the brain

PDS associated with a spike in the EEG
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Seizure Disorders
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Neuropathology
Typical Muscle Movements:
1. Tonic: stage of extreme muscle tension related to PDS
activity
2. Clonic: contractions and relaxations of muscle, occurring in
rapid succession
•
•
Rapid onset and offset of PDS activity
EEG changes during and between seizures (ictal and interictal
periods).
3. Atonic: no muscle tension
Level of Consciousness
1. Simple: No loss
2. Complex: Loss of consciousness
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Seizure Disorders
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Neuropathology
 Hyper-excitability in neurons can accelerative cell
death
 High concentration of Ca++ leads to long-term
potentiation of synaptic responses
• Activation of genes that cause synaptic
reorganization
• Axonal growth and neo-synaptogenesis
• Lowering of seizure threshold
 Children’s brains are more resistant to these long
term effects
• Relative immaturity of biochemical cascades
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Seizure Disorders
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Childhood Seizure Disorders
1. Neonatal seizures
 Occurring up to 2 months of age
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Symptoms are acute not chronic
Full body tonic and clonic movements
Loss of consciousness
More common in premature infants
90% of patients die from these seizures.
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Seizure Disorders
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Childhood Seizure Disorders
Many different diseases cause infantile seizures:
 Birth trauma or head injury
 Disorders of metabolism
 Infections (I.e. herpes encephalitis)
 Anoxic episodes (loss of oxygen)
 Genetic factors (I.e. family histories)
 40% have no known cause (idiopathic epilepsy)
 90% have first onset before age 20.
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Seizure Disorders
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Childhood Seizure Disorders
2. Infantile spasms (West Syndrome)
 Later onset (3-6 months)
 Full body (tonic) contraction, bending over, stiff
muscles
 May have up to 100 spasms per day
 Abnormal EEG, MR are associated with this
syndrome.
 More common in males.
 Poor prognosis for mental development.
 Developmental disabilities are common: Only
16% can be educated in a normal classroom
setting
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Seizure Disorders
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Childhood Seizure Disorders
3. Febrile seizures
 Common response to elevated body temperature.
 2-5% of all children between 6 months and 5
years.
 Full body seizure, tonic and clonic movements
 More common in males.
 Good prognosis: Usually no problems later in life.
 Exception to this is if the fever was due to a brain
infection, or if there is a recurrence of seizures after a
fever
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Seizure Disorders
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Childhood Seizure Disorders
 1.9% of all children have at least one epileptic
episode.
 Most frequent onset between 6 months and 6
years of age.
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Seizure Disorders
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Adult Disorders
1.
2.
3.
4.
Most common types of seizures:
Grand mal: loss of consciousness, falling on the
ground, and tonic-clonic movements
Myoclonic seizures: clonic movements in parts of
the body, usually no loss of consciousness
Absence seizure: loss of consciousness with no
muscle movements
Complex partial seizures: loss of consciousness,
oral automatisms, preceded by auras (sensory
warning of seizure onset).
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Seizure Disorders
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Neuropathology
Seizures may be intractable and require regular
follow-ups
Those at increased risk:
1. Very young age of onset (< 2 years)
2. Frequent generalized seizures
3. Failure to achieve control readily
4. Evidence of brain damage
5. A specific cause
6. Severe EEG abnormality
7. Low IQ
8. Atonic, atypical absence seizures
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Seizure Disorders
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Neuropathology
Why are children so vulnerable?
 GABAergic synapses develop before main
glutamate receptors (NMDA, AMPA)
 In early development, GABA is excitatory-binding to GABAA receptors causes
depolarization.
• Shift to inhibitory effects occurs once
glutamate receptors have matured
Thus, the neonatal brain operates with very
little inhibition.
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Seizure Disorders
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Neuropathology
 Overt psychosocial and cognitive consequences
 Including a profound fear of having a seizure in public
 Higher incidence of adjustment, academic,
psychiatric disorders in persons with epilepsy
(Bennett, 1992).
 Lower IQ is associated with seizures, especially if
the onset is early.
 Affected by underlying causes and medications
used to treat as well.
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Seizure Disorders
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Neuropathology
 Temporal lobe, and the hippocampus in particular,
may be particularly vulnerable
 Most sensitive to effects of long term potentiation
related to memory
 Memory and learning deficits may be associated with
any type of seizure.
 Worst in complex partial seizures which are
caused by temporal lobe lesions.
 Overall attention levels can be affected by most
types of seizures.
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Seizure Disorders
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Neuropathology
High “comorbidity”
1. Depression
• Major depressive episodes are common
• May be related to anticonvulsant medications
2. Anxiety Disorders
• Almost exclusively based on realistic fear of
having a seizure in public
3. Personality and Psychotic Disorders
 Obsessive compulsive
 Personality changes
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Seizure Disorders
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Other Information
Treatment Options
 Medications
 Surgery
• Lesioning tissue if seizures are local
• Electrode stimulation
 Ketogenic diet (high fat, low carb) - for
generalized seizures
 By and large, treatment does not address
psychosocial issues directly.
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Seizure Disorders
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