Epilepsy - Diagnosis, Classification, Aetiology

Question 1

What are the criteria for epilepsy?

Answer 1

At least two unprovoked (or reflex) seizures occurring more than 24 hours apart
OR
One unprovoked seizure and a probability of further seizures of 60+% in the next ten years
OR
A diagnosis of an epilepsy syndrome

Question 2

What proportion of people have a seizure at some point in life?

Answer 2

1 in 40

Question 3

What is the most common feature of epilepsy seen on MRI?

Answer 3

Hippocampal sclerosis

Question 4

What types is epilepsy classified into?

Answer 4

Focal, generalised, combined, unknown

Question 5

What aetiologies of epilepsy are there?

Answer 5

Structural
Genetic
Infectious (eg herpes)
Metabolic (eg hyponatraemia from polydipsia)
Immune (e.g autoimmune encephalitis)
Unknown

Question 6

How does a generalised seizure typically progress?

Answer 6

Unresponsiveness
Tonic phase
Clonic phase

Question 7

What might the sign of 4 tell you about location of a seizure?

Answer 7

The origin of the seizure is contralateral to the extended arm (ie a straight right arm indicates a left hemisphere seizure)

Question 8

(Lhatoo and Luders 2006) what percentage of generalised seizures show a sign of 4?

Answer 8

33%

Question 9

(Lhatoo and Luders 2006) what percentage of generalised seizures are tonic?

Answer 9

50%
25% symmetric tonic
25% asymmetric tonic

Question 10

(Lhatoo and Luders 2006) what percentage of generalised seizures are asymmetric clonic?

Answer 10

17%

Question 11

What are typical background rhythms for EEG?

Answer 11

8-10 Hz

Question 12

What might you see in EEG at the beginning of seizure

Answer 12

Slowing of rate (4-6 Hz), spikes and waves, disorganised rhythm

Question 13

What age group is more likely to have a generalised seizure?

Answer 13

Younger people.
As people age it becomes more likely that they will have focal seizures

Question 14

How do you differentiate hemispheres on EEG?

Answer 14

Colour: right = red, left = blue
Number: right = even, left = odd

Question 15

How might a clinician induce seizure?

Answer 15

Drowsiness, hyperventilating, and counting

Question 16

A sense of fear or panic might indicate a seizure in what area?

Answer 16

Mesial temporal lobe (limbic system)

Question 17

What are other causes of transient loss of consciousness?

Answer 17

Syncope (Neural, cardiac)
Orthostatic hypotension
Psychogenic non-epileptic seizures

TIA (vertebrobasilar, anterior cerebral artery)
Drop attacks

Question 18

What are situational triggers to syncope?

Answer 18

Sustained upright position
Warm environment (causing peripheral vasodilation)
Physiological stress (crowded, humid places)
Acute pain
Post prandium
Coughing
Dehydration
Anxiety/emotion

Question 19

If someone remembers hitting the ground in a faint, what does the at indicate?

Answer 19

Pseudosyncope (they didn’t black out)

Question 20

What are symptoms of syncope that might make someone think it’s epilepsy?

Answer 20

Tonic posturing
Gaze deviation
Multifocal myoclonus
Urinary incontinence (25%)

Question 21

How long does loss of consciousness typically last in syncope?

Answer 21

<20 seconds

Question 22

Why would it be useful to have an ECG along with EEG?

Answer 22

Seizure may cause cardiac syncope (or vice versa)

Question 23

What might cause cardiogenic syncope?

Answer 23

Sinus bradycardia
Sinus arrest
Bradycardia-tachycardia syndrome
Atrial fibrillation
Long QT

Question 24

What are signs of cataplexy?

Answer 24

Laughter/anger
Partial atonia
No loss of consciousness
No ictal unresponsiveness
No post ictal clouding

Question 25

What might cataplexy be confused for?

Answer 25

Narcolepsy
Syncope

Question 26

What’s the incidence of dissociative seizures

Answer 26

1-5 per 100,000 per year

Question 27

What’s the prevalence of dissociative seizures

Answer 27

1 in 5-1 in 7

Question 28

Where is it likely that a hyperkinetic seizure came from?

Answer 28

Frontal lobe

Question 29

What features would differentiate frontal lobe seizures from generalised?

Answer 29

Partial awareness
Ictal speech
Little post ictal confusion
Normal ictal surface EEG

Question 30

What are features of mesial temporal lobe epileptic seizures?

Answer 30

More emotional (limbic)
Aura (epigastric rising sensation)
Head version (typically towards lesion)
Motionless stare
May still be able to speak
Ipsilateral nose wiping
Ipsilateral automatisms
Post ictal coughing (right TLE)

Question 31

What might hippocampal sclerosis look like on MRI?

Answer 31

Brighter area at hippocampi

Question 32

What are features of lateral temporal lobe epileptic seizures?

Answer 32

Aura (dysphasia)
Motionless stare
Contralateral clonic jerking
Facial clonic jerking
Imaging normal (or lateral lesions)
Secondary TC seizures more likely

Question 33

What are features of occipital lobe epileptic seizures?

Answer 33

Visual symptoms
Sometimes motor

Question 34

What might ability to recall visual symptoms tell you about the location of seizure?

Answer 34

Can recall symptoms - calcarine onset
Can’t recall - occipital-temporal onset (memory disturbed)

Question 35

What part of the occipital lobe would a more motor seizure come from?

Answer 35

Suprasylvian

Question 36

What are the main imitators of epilepsy?

Answer 36

PNES
Vasovagal syncope
Cardiac syncope
Sleep disorders

Question 37

What are the main comorbidities of epilepsy?

Answer 37

Obstructive sleep apnea
Psychiatric conditions

Question 38

How would one differentiate occipital lobe epilepsy from migraine by its features?

Answer 38

Migraines:
Flashing lights
Black and white
Fortification spectra: linear/zig-zag lines
Photophobia
Slow onset

OLE:
Multicoloured
Form visualisations
Hallucinations
Rapid onset

Question 39

What are some features of hyperkinetic frontal lobe seizures

Answer 39

Motor manifestations occur early
Bizarre bilateral automatisms
Cycling and kicking
Tonic posturing
Ballistic limb movements
Shouting and swearing
Pelvic thrusting
Turning trunk prone
Occurs in sleep in large numbers