Epilepsy & EEG Flashcards

1
Q

What are the two major excitatory neurotransmitters and what neurons typically form excitatory synapses?

A

Neurotransmitters:

  • Glutamate (main)
  • Aspartate

Principal neurons (Na+ and Ca2+ influx)

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2
Q

What are the two major inhibitory neurotransmitters and what neurons typically form inhibitory synapses?

A

Neurotransmitters:

  • GABA (main)
  • Glycine

Interneurons (Cl- influx, K- efflux)

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3
Q

Repetitive activation of action potentials produces what type of firing in neurons?

A

Burst firing

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4
Q

Burst firing especially occurs in what part of the brain?

A

Hippocampus

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5
Q

What does excessive glutamate result in?

A

Seizures

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6
Q

Activation of what type of receptors plays an important role in the spread of epileptic activity?

A

NMDA receptors

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7
Q

Describe “recurrent excitatory pathways” and their significance to seizures.

A
  • Recurrent excitatory pathway occurs in the hippocampus and neocortex via pyramidal collaterals.
  • This provides activation that is normally governed by widespread inhibitory circuits.
  • Promotes spread of the seizure discharge.
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8
Q

What part of the brain anatomy promotes epileptogenesis?

A

Hippocampus

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9
Q

What hippocampal “disease” is common in temporal lobe epilepsy?

A

Hippocampal sclerosis (see in long-standing epilepsy)

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10
Q

How does hippocampal sclerosis affect epilepsy?

A
  • Synaptic reorganization and increased axonal collateralization provide increased excitatory input between neurons. (the more seizures you have, the easier it is to have another one because connections are strengthened)
  • This promotes synchronous epileptic firing and seizure propagation.
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11
Q

High frequency repetitive firing results in accumulation of what?

A

Ca2+ near the presynaptic terminal

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12
Q

How does high frequency repetitive firing (and accumulation of Ca2+ at the presynaptic terminal) result in synaptic enhancement?

A
  • Facilitation: Increased glutamate release
  • Potentiation: Enhanced synaptic activity
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13
Q

How does repetitive neuronal firing affect synaptic inhibition?

A

Repetitive neuronal firing DEPRESSES inhibitory (GABA) synaptic activity

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14
Q

Describe how electrical coupling of neurons affects epilepsy.

A

In areas with densely packed neurons (hippocampus), neurons may be connected directly via gap junctions, or ephaptic transmission due to close apposition of membranes, allowing direct propagation of seizure discharge.

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15
Q

What are the 5 major cellular mechanisms of epilepsy? (KNOW THIS)

A
  • Modification or alteration of ion channels
  • Synaptic reorganization and modificatoin
  • Modulation of gene expression
  • 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
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16
Q

Define epilepsy.

A

Recurrent seizures produced by abnormal repetitive neuronal firing in the brain.

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17
Q

What is the most common cause of single seizures (especially in pediatrics)?

A

Febrile seizures

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18
Q

What are the two major categories of seizure?

A

Focal (partial)

Primary generalized

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19
Q

Describe the eptileptiform discharges of EEG in epilepsy.

A

Indicate susceptibility to seizures

May be generalized or focal.

  • Generalized: Spike wave
  • Focal: Spikes or sharp waves
20
Q

Why is it important to correctly classify seizures?

A

To choose the correct antiepileptic drug.

21
Q

What is Lennox-Gastaut Syndrome?

A

Type of epilepsy with the following characteristics:

  • Onset early in childhood, difficult to treat
  • Many causes, mostly cryptogenic (unknown cause)
  • Multiple Seizure Types
    • Atypical absence
    • Generalized convulsive
    • Atonic (results in frequent injury or falls)
    • Myoclonic
    • Partial
  • Results in negative underdevelopmental impact (mental retardation)
  • Slow spike and wave (2Hz)
22
Q

What is an atonic seizure?

A
  • Seizure with no warning (abrupt onset)
  • Injuries are common
  • Difficult to treat
  • May respond to Vagal Nerve Stimulator (VNS) - Maintains vagal tone to prevent seizures
  • Corpus callosotomy may prevent falls
23
Q

What type of epilepsy remits by 15-16 years of age or earlier?

A

Benign focal epilepsy of childhood

24
Q

How do patients having an absence seizures present?

A
  • Brief stares and states of unresponsivenesss
  • May experience associated eye flutters (eyelid myoclonia)
  • Sudden onset with arrest of activity
  • No aura or postictal confusion
  • Generalized 3Hz spike and wave
  • Does not cause brain damage
25
Q

What are the characteristics of primary generalized convulsive seizures?

A
  • No warning (abrupt onset)
  • May result in tonic, clonic, tonic-clonic, or clonic-tonic-clonic activity.
  • May experience bowel and bladder incontinence
  • Postictal unresponsiveness or confusion
  • Generalized spikes and waves on the patient’s EEG
26
Q

What is the classic clinical feature of myoclonic seizure?

A
  • 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
27
Q

Vagal nerve stimulation and corpus callosotomy may be viable treatments in ____________ seizures.

A

Atonic

28
Q

__________ is the general “premonition” that a seizure is about to occur. This feeling is usually caused by a brief partial seizure.

A

Aura

29
Q

What type of seizure is characterized by an acute arrest of activity?

A

Absence

30
Q

When focal seizures spread to involve the entire brain, it is referred to as __________________.

A

Secondary generalization

31
Q

What is a focal seizure?

A

Seizures conceptualized as originating at some point within networks limited to one hemisphere

  • Can maintain consciousness
32
Q

What is a generalized seizure?

A

Seizures conceptualized as originating at some point within and rapidly engaging bilaterally distributed networks

33
Q

What are common types of epilepsy seen in the neonatal period?

A
  • Benign familial neonatal epilepsy (BFNE)
  • Early myoclonic encephalopathy (EME)
  • Ohtahara syndrome
34
Q

What is a common type of epilepsy seen in the infancy period?

A

West Syndrome (KNOW THIS)

35
Q

What are common types of epilepsy seen in the childhood period?

A
  • Panayiotopoulos Syndrome
  • Benign epilepsy with centrotemporal spikes (BECTS)
  • Lennox-Gastaut Syndrome
  • Childhood absence epilepsy (CAE)
36
Q

What are common types of epilepsy seen in the adolescence-adult period?

A
  • Juvenile absence epilepsy (JAE)
  • Juvenile myoclonic epilepsy (JME)
37
Q

What type of epilepsy is associated with laughing fits?

A

Gelastic seizures with hypothalamic hamartoma

38
Q

What is West Syndrome? What usually is the cause of it?

A
  • Flexion or extension spasms (looks like startle reflex) AKA Infantile Spasms
  • Usually occur in clusters
  • Peak onset is 5-6 months
  • Commonly from injury (i.e. Shaken Baby Syndrome) but there are many potential causes
  • Not responsive to phenobarbital
  • Hypsarrhythmia EEG pattern
39
Q

What is the EEG pattern for West Syndrome (Infantile Spasms)?

A

Hypsarrhythmia (high amplitude and irregular waves and spikes in a background of chaotic and disorganized activity)

  • Seen when infant is NOT seizing
40
Q

What is the EEG pattern for Lennox-Gastaut Syndrome?

A

Slow spike and wave (2Hz)

41
Q

What is characteristic of a frontal lobe seizure? What is another name for it?

A
  • Seizure is the EXACT SAME every time
  • Aura is common
  • Focal onset
  • May secondarily generalize

Focal Seizure without Impairment of Consciousness (Simple Partial)

42
Q

What is characteristic of a focal temporal lobe seizure? What is another name for it?

A
  • Aura is common
  • Alteration of consciousness
  • Automatisms (vocalization is common, they get restless)
  • Postictal confusion
  • May secondarily generalize

Focal Seizure with Impariment of Consciousness (Complex Partial)

43
Q

Nocturnal seizures are common with what type of epilepsy?

A
  • Benign Epilepsies of Childhood
    • Benign Epilepsy with Centrotemporal Spikes (BECTS)
    • Panayiotopoulos Syndrome (Benign Epilepsy with Occipital Spikes)
  • Usually goes away by 15 - 16 years of age
  • Seizures are usually infrequent
44
Q

What is the inheritance pattern for Juvenile Myoclonic Epilepsy (JME)?

A

Autosomal dominant

45
Q

What are some examples of epilepsy surgeries?

A
  • Temporal lobectomy (75-90% seizure free)
  • Extratemporal lesional resection (50-75% seizure free)
  • Extratemporal non-lesional resection (<50% seizure free)
  • Functional hemispherectomy
  • Corpus callostomy (especially for atonic and brief tonic seizures)