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Neuropsychiatric disorders > EEG interpretation > Flashcards

EEG interpretation Flashcards

1. Normal wake and sleep EEG 2. Interictal and ictal EEG in Epilepsies 3. Video-EEG – telemetry modalities 4. Video-EEG in the diagnosis NES 5. The use of EEGs in disorders of consciousness

1
Q

abbrv.

IED

A

Interictal epileptiform discharges

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2
Q

define

Ictal

A

This is the time from the first symptom to the end of the seizure

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3
Q

Define IED

*Epileptiform cerebral discharges

*Ictus (greek) the seizure
*Interical [in between seizures]

A

This is the distinction between interictal and ictal.

IEDs are paroxysmal. They are clearly distinguishable from background activity on EEG.

There must be an abrupt change in polarity occurring during several milliseconds.

Duration must be less than 200 milliseconds.

There must be a physiologic field i.e., specific brain region.

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4
Q

Spikes

A

Duration is less than 70 milliseconds

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5
Q

Sharp waves

A

Duration is between 70 to 200 milliseconds

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6
Q

Ictal activity in focal epilepsy

A

Is observed as changes in dynamic rhythm, amplitude and frequency propagation (spread seen as spread over multiple channels on EEG)

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7
Q

define

EEG sensitivity

A

This is the true positive rate. The proportion of patients (with epilepsy) who have epileptiform activity on EEG

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8
Q

define

EEG specificity

A

This is the true negative rate. The proportion of healthy subjects who do not have epileptiform activity on EEG

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9
Q

What is the sensitivity (true positive) of present IED on EEG in patients with epilepsy?

A

40%

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10
Q

What is the false positive rate of present IED on EEG in healthy subjects?

A

0.5 to 4%

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11
Q

What is the specificity (true negative) of absent IED on EEG in healthy subjects?

A

more than 96%

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12
Q

What is the false negative rate of absent IED on EEG in epilepsy patients?

A

60%. This means that 60% of patients with epilepsy will have a NORMAL EEG

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13
Q

What effect does repeat EEGs/ sleep EEG have on the sensitivity and specificity of EEG?

A

Sensitivity is increased to 80 to 90%.

Specificity is unchanged.

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14
Q

What is semiology?

A

The clinical signs that can be looked for to confirm/ support a diagnosis of epilepsy plus ictal assessment

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15
Q

What components contribute to semiology

A
  • personal account
  • witness account
  • medical observation
  • semiology (video recording)
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16
Q

What are the clinical signs used to diagnose epilepsy?

A

Evolution
Lateralisation
Localisation

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17
Q

define

Interictal

A

This is the time between seizures

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18
Q

Postictal

A

This is the period immediately following the seizure before returning to baseline

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19
Q

What are the ictal/ postictal signs of refractory epilepsy?

A

Dystonic posturing
Unilateral automatisms
Postictal dysphasia
Ictal speech
Forced head version

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20
Q

Where is the epileptogenic zone for dystonic posturing in refractory epilepsy?

A

Contralateral. Dystonic posturing occurs on the opposite side of the body to the lesion.

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21
Q

Where is the epileptogenic zone for unilateral automatisms in refractory epilepsy?

A

Ipsilateral. Unilateral automatisms occur on the same side of the body as the lesion.

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22
Q

Postictal dysphasia is characteristic of a lesion where?

A

The dominant (left) hemisphere

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23
Q

Ictal speech is characteristic of a lesion where?

A

The non-dominant (right) hemisphere

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24
Q

Where is the epileptogenic zone for forced head version in refractory epilepsy?

A

Contralateral to the lesion

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25
Postictal nose wiping, preserved consciousness with automatism and vomiting are signs of which type of epilepsy?
Temporal lobe epilepsy
26
Clonic movements are a sign of which type of epilepsy?
Frontal lobe epilepsy
27
more semiology flashcards
etc.
28
Which two features are key in differentiating epileptic from functional seizures?
Awareness and responsiveness
29
What are the key features of an EEG during wakefullness?
Awake Can follow commands Not encephalopathic Not drowsy No focal abnormality
30
What are the features of Alpha rhythm in awake EEG?
Alpha rhythms are the dominant rhythm in 86%. Alpha waves are between 8-13 Hz. Maximum amplitudes are seen over the occipital area. Alpha waves are BLOCKED when eyes are OPEN. Amplitudes are below 50 microvolts.
31
What are the features of Beta rhythm in awake EEG?
Beta waves are between 13-35 Hz. Rhythms are seen over the fronto-central region. Amplitudes are below 30 microvolts.
32
Theta rhythm
33
Delta rhythm
34
Cerebral transients representing either normal physiological phenomena or variants are clinically significant. True or False?
False. They are not clinically significant
35
Name 5 common non cerebral transients seen on EEG
Muscle (EMG) ECG Blink artefacts Eye movements Sweat artefacts Movement artefacts Respirations artefacts Electrode artefacts
36
What are K-complexes?
Arousal responses to external or internal stimuli.
37
What are the features of K-complexes?
They are bi- or polyphasic. Fast component followed by a high voltage slow wave. Maximal amplitudes is seen over CZ electrode.
38
How many stages are there on normal sleep EEG?
6
39
What are the stages of normal sleep EEG?
1. Awake 2. Very light sleep (stage 1) 3. Light sleep (stage 2) 4. Deeper sleep (stage 3) 5. Deep sleep (stage 4) 6. REM
40
What are the features of a normal EEG
1. A well developed alpha rhythm 2. Maximal amplitudes in the occipital and parietal region 3. Attenuation of rhythm on eye opening
41
Name two abnormalities seen on EEG that support diagnosis
Spikes and sharp waves
42
Patients with epilepsy can have a normal EEG. True or False
True
43
Healthy subjects can have an abnormal EEG. TRUE OR FALSE
TRUE
44
Which two features are always suggestive of a cerebral lesion?
A single focus of abnormally fast or slow activity. Gross asymmetries of normal or abnormal activity between hemispheres.
45
Learning objectives
- normal wake and sleep EEG - interictal and ictal EEG in epilepsies\ - video EEG (VEEG) *telemetry modalities* - video EEG in the diagnosis of nonepileptic seizures - the use of EEG in disorders of consciousness
46
What are some examples of epilepsy syndromes?
- TLE (temporal lobe epilepsy) - FLE (frontal lobe epilepsy) - BECT (benign epilepsy with contemporal spikes) - CAE (childhood absence epilepsy) - JME (juvenile myoclonic epilepsy)
47
#True or False Interictal EEG proves the presence of epilepsy
False ##Interictal EEG **does not** prove the presence of epilepsy
48
# True or False Some transients on EEG are normal depending on age/ state
True
49
50
VEEG modalities
- routine and sleep EEG - ambulatory - polysomnographies - electro-corticogram (EcoG) - inpatient video-telemetry and home video telemetry - algorhythm of videotelemetry assessment (semiology)
51
Self-sustaining generalised photo-paroxysmal response
seizure activity continues after the photic stimulation continues
52
# PS and PSE What are the classifications of photosensitivity syndromes
1. pure photosensitive epilepsy 2. epilepsy with photosensitivity 3. photosensitivity without epilepsy
53
What does the presence of alpha waves plus unresponsiveness tell us?
The person is experiencing a dissaciative seizure (NES) | Alpha waves are seen during wakefullness
54
# *disorders of conciousness* What is conciousness?
Awareness (*memory*) and responsiveness
55
What are some disorders of conciousness?
- coma (++) - sleep (+++) - wakefullness - minimal conciousness (-/+) - dementias (+) - vegetative state (+/-) - seizures (+++) - parasomnias (++) - general anesthesia (++) - locked in syndrome (++) - *vertical eye movements online pontine* - NES (+++) | *power of EEG
56
# true or false In the most epileptic seizures eyes are open
True
57
# What is the syndrome eye blinking unresponsive patient responsive alpha normal ECG
Nonepileptic seizure/ dissociative seizure
58
# What is the syndrome alpha activity (reactive EEG) to being called asked to close eyes and alpha remains but alpha when eyes are open (paradoxical)
drowsy
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64
# what is the syndrome alpha less than 8 Hz
encephalopathic
64
normal eeg reactive eye opening (alpha blocks) flattening to being called (reactivity) less reactivity less sleep architecture slow alpha
encephalopathy | differentials could be drugs or drowsiness
64
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rhythmical activity e.g. SIRPID
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Neuropsychiatric disorders (30 decks)

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