Epilepsy & EEG

Question 1

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

Answer 1

Neurotransmitters:

• Glutamate (main)
• Aspartate

Principal neurons (Na⁺ and Ca²⁺ influx)

Question 2

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

Answer 2

Neurotransmitters:

• GABA (main)
• Glycine

Interneurons (Cl^- influx, K^- efflux)

Question 3

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

Answer 3

Burst firing

Question 4

Burst firing especially occurs in what part of the brain?

Answer 4

Hippocampus

Question 5

What does excessive glutamate result in?

Answer 5

Seizures

Question 6

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

Answer 6

NMDA receptors

Question 7

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

Answer 7

• 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.

Question 8

What part of the brain anatomy promotes epileptogenesis?

Answer 8

Hippocampus

Question 9

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

Answer 9

Hippocampal sclerosis (see in long-standing epilepsy)

Question 10

How does hippocampal sclerosis affect epilepsy?

Answer 10

• 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.

Question 11

High frequency repetitive firing results in accumulation of what?

Answer 11

Ca²⁺ near the presynaptic terminal

Question 12

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

Answer 12

• Facilitation: Increased glutamate release
• Potentiation: Enhanced synaptic activity

Question 13

How does repetitive neuronal firing affect synaptic inhibition?

Answer 13

Repetitive neuronal firing DEPRESSES inhibitory (GABA) synaptic activity

Question 14

Describe how electrical coupling of neurons affects epilepsy.

Answer 14

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.

Question 15

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

Answer 15

• 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

Question 16

Define epilepsy.

Answer 16

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

Question 17

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

Answer 17

Febrile seizures

Question 18

What are the two major categories of seizure?

Answer 18

Focal (partial)

Primary generalized

Question 19

Describe the eptileptiform discharges of EEG in epilepsy.

Answer 19

Indicate susceptibility to seizures

May be generalized or focal.

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

Question 20

Why is it important to correctly classify seizures?

Answer 20

To choose the correct antiepileptic drug.

Question 21

What is Lennox-Gastaut Syndrome?

Answer 21

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)

Question 22

What is an atonic seizure?

Answer 22

• 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

Question 23

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

Answer 23

Benign focal epilepsy of childhood

Question 24

How do patients having an absence seizures present?

Answer 24

• 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

Question 25

What are the characteristics of **primary generalized convulsive** seizures?

Answer 25

* 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

Question 26

What is the classic clinical feature of **myoclonic** seizure?

Answer 26

* **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**

Question 27

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

Answer 27

Atonic

Question 28

\_\_\_\_\_\_\_\_\_\_ is the general "premonition" that a **seizure is about to occur**. This feeling is usually caused by a brief partial seizure.

Answer 28

Aura

Question 29

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

Answer 29

Absence

Question 30

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

Answer 30

Secondary generalization

Question 31

What is a **focal** seizure?

Answer 31

Seizures conceptualized as originating at some point within networks **limited to one** **hemisphere** * Can maintain consciousness

Question 32

What is a **generalized** seizure?

Answer 32

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

Question 33

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

Answer 33

* Benign familial neonatal epilepsy (BFNE) * Early myoclonic encephalopathy (EME) * Ohtahara syndrome

Question 34

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

Answer 34

**West Syndrome** (KNOW THIS)

Question 35

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

Answer 35

* Panayiotopoulos Syndrome * Benign epilepsy with centrotemporal spikes (BECTS) * Lennox-Gastaut Syndrome * Childhood absence epilepsy (CAE)

Question 36

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

Answer 36

* Juvenile absence epilepsy (JAE) * Juvenile myoclonic epilepsy (JME)

Question 37

What type of epilepsy is associated with **laughing** fits?

Answer 37

**Gelastic seizures** with **hypothalamic hamartoma**

Question 38

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

Answer 38

* **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

Question 39

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

Answer 39

**Hypsarrhythmia** (high amplitude and irregular waves and spikes in a background of **chaotic** and **disorganized** activity) * **Seen when infant is NOT seizing**

Question 40

What is the EEG pattern for **Lennox-Gastaut** Syndrome?

Answer 40

**Slow spike and wave (2Hz)**

Question 41

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

Answer 41

* Seizure is the **EXACT SAME** every time * Aura is common * Focal onset * May secondarily generalize Focal Seizure **without** Impairment of Consciousness (Simple Partial)

Question 42

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

Answer 42

* **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)

Question 43

**Nocturnal seizures** are common with what type of epilepsy?

Answer 43

* **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

Question 44

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

Answer 44

Autosomal dominant

Question 45

What are some examples of epilepsy surgeries?

Answer 45

* 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)