L17 Seizures and Epilepsy

Question 1

What is a seizure (clinically)? What is the major problem?

Answer 1

Hypersynchronous neuronal discharge, a transient occurrence of signs and symptoms due abnormal excessive synchronous neuronal activity in the brain (usually less than 2 minutes duration)
The major problem is an imbalance between excitation and inhibition

Question 2

What is the definition of a seizure based on an electrographic?

Answer 2

A clear ictal event comprising of a sudden repetitive, evolving, stereotyped waveform with a definite start, middle and end.

Question 3

What is involved in a generalized seizure? What is one type of generalized seizure?

Answer 3

Both hemispheres have excessive neuronal activity at the same time and same region (primarily)
One type is an absence seizure (stop and stare, or twitch/stiff)

Question 4

What is a focal seizure?

Answer 4

Seizure that occurs in one hemisphere, in one region.
The lesion is not necessarily where it will propagate to, and the area it propagates to dictates the symptoms you see
When a focal seizure propagates to both sides of the brain it is called a secondary generalized seizure

Question 5

What are the three definitions of epilepsy?

Answer 5

1. Two or more unprovoked or reflex seizures that are greater than 24 hrs apart (not due to substance or injury)
2. A single unprovoked seizure or reflex seizure and a greater than 60% risk of having another seizure over the next 10 yrs
3. An epilepsy syndrome
   These give a predisposition to seizures

Question 6

What age range do genetic factors usually affect?

Answer 6

Common in kids

Question 7

What are the most common causes of epilepsy in adults and kids?

Answer 7

Children and adults show similar proportions of structural, metabolic, immune, and unknown causes
Unknown causes are greatest, about 40%
Children show more genetic causes and adults show more infection causes

Question 8

What are 5 differences in seizures in children vs adults?

Answer 8

Different mechanisms of epileptogenesis
Different propagation of seizures (usually not generalized in neonates due to decreased myelination)
Unique EEG patterns
Different responses to medication
Different clinical manifestations

Question 9

What are some things (diagnoses) that can cause seizures, or things that seizures can cause?

Answer 9

Congenital heart disease
Sleep apnea

Question 10

What is ictal apnea? What can cause it?

Answer 10

Pathophysiology unknown, likely originating in limbic system
Genetic syndromes
Mesial temporal lesions

Question 11

What are the three key points from the case of a child with ictal apnea?

Answer 11

Apnea can be ictal, especially in young children
Video EEG necessary for diagnosis, and this video EEG can identify subtle non-automatic manifestations

Question 12

In the case of the child with night time spitting, what lead docs to think it was a behavioural cause? What confirmed it was seizures?

Answer 12

Behavioural: only at night, stereotypical and short, multiple times a night and every night, no recollection
Decided to do an EEG ideally to capture an episode
Diagnosed with focal seizures and ictal hypersalivation, which is an autonomic manifestation during a seizure

Question 13

What is involved in an autonomic manifestation during a seizure?

Answer 13

Maturation related susceptibility of central autonomic network
Lower threshold for epileptogenic activation

Question 14

What is the role of GABA and Glutamate in a seizure?

Answer 14

Glutamate: main excitatory NT in the brain, promotes seizures
GABA: main inhibitory NT in the brain, stops seizures
When there is more glutamate than GABA in the brain you may get a seizure

Question 15

Why does the neonate brain have such a low threshold to seize?

Answer 15

GABA-A receptors are excitatory rather than inhibitory
Developmental imbalance between excitatory and inhibitory mechanisms
High density of NMDA receptors (excitatory) in the hippocampus and neocortex
Delayed maturation of GABA-B, adenosine and 5HT receptors

Question 16

In the young girl with frequent nighttime arousals, what was used to make a diagnosis of seizures?

Answer 16

Used regular EEG but it was normal, used a video EEG to diagnose with seizures and sleep-related hypermotor epilepsy (previously known as nocturnal frontal lobe epilepsy)

Question 17

Why is it hard to differentiate between nocturnal seizures and parasomnia?

Answer 17

Ictal and interictal EEGs can be normal or non-specifically abnormal
Etiology: genetic and structural (frontal cortical dysplasia type 2b)

Question 18

What are three characteristics of frontal sleep related hypermotor epilepsy?

Answer 18

During nREM sleep
Brief, highly stereotypical, occurrence in sleep, overlap with parasomnias

Question 19

What are some differences between parasomnias and nocturnal seizures?

Answer 19

Parasomnias: pre-school age, childhood, first 1/3 of the night, N3 sleep, 5-30 mins, SINGLE EVENT per night, EEG normal, normal daytime behaviour, respond to benzos at bedtime

Nocturnal seizures: anytime from infancy to adolescents, randomly throughout night, N1/N2 stages of sleep, brief (less than 5 mins), MULTIPLE EVENTS per night, EEG normal or abnormal, irritable/tired/ can have daytime seizures, respond to sodium channel blockers

Question 20

What is the most important part of evaluating someone for possible seizures?

Answer 20

THOROUGH HISTORY AND EVENT DESCRIPTION

Question 21

What are three takeaways about video EEG and regular EEG?

Answer 21

Video EEG is a valuable tool in the assessment of children with suspected seizures
EEG can support the diagnosis of epilepsy, and may help in determining the type of epilepsy and guide management
Child with unexplained stereotypical episodes (and seizures are suspected), should have an EEG, ideally both awake and sleeping

Question 22

What are consequences of overtreatment or undertreatment of seizures?

Answer 22

Overtreatment: neurotoxicity, prolonged NICU stay
Undertreatment: “kindling” of additional seizures, worsen brain injury
Clinical diagnosis of seizures is UNRELIABLE, and seizures are defined by EEG

Question 23

What are clonic seizures?

Answer 23

Rhythmic jerks, focal or multifocal

Question 24

What are some similarities and differences between conventional EEG and aEEG.

Answer 24

Both allow continuous bedside assessment of brain function.
Conventional EEG requires an experienced technologist and reader but aEEG is simpler and easy to apply and interpret
Conventional EEG has good spatial coverage, and aEEG has limited spatial coverage

Question 25

What are some advantages of EEG/aEEG?

Answer 25

Bedside, continuous, real time monitoring, non-invasive, assessment of cerebral function and maturation, assessment of neurological injury, seizure detection, prognosis

Question 26

What are the goals of seizure management?

Answer 26

Early and accurate seizure diagnosis
Improvement of long term outcome
Suppress EEG-proven seizures

Question 27

What are two ways to treat seizures?

Answer 27

Etiology specific therapy, commonly used
Anti seizure medication: evidence for efficacy and safety is weak, high rate of incomplete response to initial medication, early treatment might be key to improved seizure control

Question 28

What is status epilepticus?

Answer 28

The most common medical neurological emergency in children
A single prolonged seizure lasting for more than 5 mins or recurrent seizures without regaining consciousness in between events, and lasting for 5 mins
Historically a 30 min time frame was used

Question 29

What is the mechanism in status epilepticus?

Answer 29

Failure of the mechanisms that limit spread and recurrence of isolated seizures.
Ineffective inhibition (GABA decreases) and excessive excitation (glutamate increase)

Question 30

Why was the time frame changed from 30 minutes to 5 mins?

Answer 30

5 minutes is the timeframe for treatment decisions, especially for generalized tonic-clonic seizures
Seizures lasting longer than 5 mins are unlikely to stop spontaneously
The longer the seizure continues, the more difficult it is to stop them with anti-seizure medications
Prolonged seizures may cause permanent neurological injury

Question 31

What is the etiology of status epilepticus?

Answer 31

Can occur in the setting of an underlying epilepsy, first manifestation of a seizure disorder
Infections, hypoxia-ischemia, cerebrovascular event, drugs, TBI, electrolyte disturbance, metabolic disease

Question 32

What is refractory status epilepticus?

Answer 32

Continuous seizures or recurrent seizures without return of consciousness
Despite:
1st line therapy at adequate dose (lorazepam) AND
2nd line therapy at adequate dose (Phenytoin, Phenobarbital, Levetiracetam)
Requiring admission to PICU and high dose anesthetic infusion