Ch26+27 Seizures and Special Seizures

Question 1

What’s the definition of a seizure

Answer 1

an abnormal paroxysmal neuronal discharge that results in abnormal sensation, motor function, behaviour, or consciousness.

Question 2

What’s a primary generalized seizure

Answer 2

Bilaterally symmetric and synchronous, involving both cerebral hemispheres as the onset, consciousness lost from the start. Approx 40% of all seizures.

Question 3

What’s a partial/focal seizure

Answer 3

Implies one hemisphere involved a onset, about 57% of all seizures.

Question 4

What’s a complex partial/focal seizure

Answer 4

Focal onset followed by either delayed impairment of consciousness, immediate impairment of consciousness, secondary generalisation

Question 5

How does the 2017 International Leagues Against Epilepsy Classify Seizures?

Answer 5

Question 6

Give three features that are typical of mesial temporal lobe epilepsy?

Answer 6

Aura (epigastric, emotional, olfactory, gustatory)

Complex partial oftern begin with arrest and stare

Postictal disorientation, recent-memory deficit and amnesia of ictus

Question 7

Describe the feauture of juvenile myoclonic epilepsy

Answer 7

Myoclonic jersk

GTCS

Absence

Polyspike discharges on EEG

Question 8

What’s West Syndrome?

Answer 8

Seizure disorder that begins in the first year of life

Recurrent gross flexion and occational extenstion of trunk and limbs

Seizures diminish with age

[responds to ACTH or corticosteroids]

EEG - hypsarrythmia

Question 9

What’s Lennox-gastaut syndrome? And what is the surgical option?

Answer 9

Atonic seizures of childhood ‘ drop attacks’

Corpus Callosotomy

Question 10

What factors lower the seizure threshold?

Answer 10

Sleep deprivation

Hyperventilation

Photic stimulation

Systemic infection

Metabolic derangement

Question 11

Name two AEDs that interfere with platelet function?

Answer 11

Valproic acid

Phenytoin

Question 12

What’s the dose of phenytoin for status? (BNF)

Answer 12

20mg/kg loading

Then 100mg TDS

Question 13

What are the signs of phenytoin toxicity?

Answer 13

Nystagmus, diplopia, ataxia, asterixis, slurred speech, confusion, CNS depression

Question 14

For a woman of childbearing age requiring an AED what is tradtional first choice?

Answer 14

carbamazepine

Question 15

What birth defect is valproate associated with?

Answer 15

NTD (1-2%)

Question 16

What’s the incidence of early (<7 days) post traumatic seizures in severe head injury? (severe e.g. LOC>24 hours, amnesia<24 hours, focal deficit, confusion, haematoma)

vs mild./moderate

Answer 16

30% severe

1% n mild to moderate

Question 17

What’s the cindence of late post traamatic seizures (>7 days) in patients with significant head trauma (LOC>2 mins, GCS<8, epidural haematoma etc) within 2 years of HI?

Answer 17

10-13%

Question 18

What the incidence of post traumatic seizures in penetrating head injuries (followed to 15 years)?

Answer 18

50%

Question 19

Describe the evidence for the use of phenytoin for prophylaxis of post-traumatic seizures?

Answer 19

Temkin (1990) NEJM - Phenytoin reduces the risk of early but not late post traumatic seizures

Question 20

Describe some features suggestive of pseudo/non-epileptic seizures

Answer 20

Arching of the back

Asynchnous movement

Stop and go (seizures usually build gradually)

Forced eye closure

Provoked with atypical stimuli

Bilateral shaking with preserved awareness (exception SMA seizures)

Weeping (whining)

Multiple or variable seizures types

Question 21

What’s the most common type of seizure? What’s the prevalence?

Answer 21

Febrile convulsion. 2.7% prevalence in developmentally and other wise neurologically normal children

Question 22

Define status epilepticus

Answer 22

Sz>5mins

Or persistent seizure activity with no neurological recovery in between (Not greenberg!)

Question 23

What percentage of seizures that persists over 5 mins will continue over 1 hour?

Answer 23

61%

Question 24

How do you manage status epilepticus?

Answer 24

ABCs

Benzodiazepine (e.g. lorazepam 4mg IV, midazolam 10mg IM, diazepam (can be rectal)

Load with phenytoin

Alternatives to phenytoin - valproate, phenobarbital, levetiracetam

If seizures continue >30 mins and are refractory - intubate and propofol or midazolam infusion

Question 25

In an unknown patient presenting with status and hypoglycaemia what drug must you give before bolusing glucose?

Answer 25

Thiamine (giving glucose first in thiamine deficiency can precipitate Wernicke’s encephalopathy)

Question 26

What’s the incidence of birth defects to mother’s with a known seizure disorder?

Answer 26

4-5% (double normal) - effect due to AED vs genetic vs environment unknown

Question 27

What’s the mechanism of action of phenytoin?

Answer 27

Voltage-dependent block of sodium channels (prevents high-frequency repetitive firing)

Question 28

What’s the mechanism of levetiracetam?

Answer 28

It inhibits Synaptic Vesicle 2A (SV2A) protein inhibitor (via calcium) reducing neurotransmitter release and acting a neuromodulator

Question 29

What’s the mechanism of benzodiazepines?

Answer 29

They increase the affinity of GABA(A) receptor for GABA

Question 30

What’s the mechanism of carbamazepine?

Answer 30

Sodium Channel Blocker

Question 31

What’s the mechanism of valproate?

Answer 31

Believed to be mixed (sodium channels and increases GABA)