Optimizing Seizures in Sleep: Beyond the New Guidelines SEIZURES IN SLEEP 2009.pdf · of known...

Optimizing Seizures in

Sleep:

Beyond the New

Guidelines

Rebecca J. Clark-Bash, R. EEG\EP T., CNIM, F.ASNM

President, Knowledge Plus, Inc.

Lincolnshire, Illinois

[email protected]

815.341.0791

mailto:[email protected]

Why do we do EEG?

• Seizures

• Seizures

• Seizures

• Seizures

• Seizures

• Seizures

• Seizures

• Seizures

Rebecca Clark-Bash 2


What is A Seizure?

Seizure

A sudden, involuntary time-limited alteration in behavior,

including a change in motor activity, in autonomic

function, in consciousness or in sensation,

accompanied by an abnormal electrical discharge in the

brain

Epilepsy

A condition in which an individual is predisposed to

RECURRENT seizures secondary to a central nervous

system disorder


What is A Epilepsy?

Epileptic Seizures

Associated with glial proliferation (scarring on the brain)

often not detected with imaging tools (provokes the

clinical event)

High percentage of patients have treatment success

with AEDs (anti-epileptic medication) or recent

advanced treatment paths such as Vagus Nerve

Stimulator, Ketogenic Diet and Surgery

Glial proliferation produces the signature of epilepsy

Non-epileptic Seizures

5

What is A Epilepsy?

The signature of epilepsy:

Sharp Waves and Spikes

in the EEG.

“cat”


What is Epilepsy?

Epileptic Seizures

Non-epileptic Seizures

Not associated with structural damage or insult

Not associated with EEG abnormalities linked to seizure

Do not respond to AED therapy

Previously called Psuedo-Seizures or “Psycho-

Seizures”


Term Definition

Ictal EEG

Describes the recording during the event

Interictal EEG

Describes the recording in between each event

Postictal EEG

Describes the period of time immediately following an event


EEG Abnormalities & Spikes

Similar to cardiac abnormalities in the presence of known clinical cardiac signs, the EEG has only a chance of displaying the abnormality during a clinical 20 minute test.

The statistical probability of abnormality is drastically reduced if drowsiness and light sleep are not obtained.

Activation procedures are implemented during the clinicial test to attempt to provoke the abnormality.


Seizure Classifications

Partial Seizures

Simple Partial Seizures

Complex Partial Seizures

Generalized Seizures

Status Epilepticus



Classification will define the BEST medication

(AED) for treatment

An incorrect AED may not only NOT PREVENT

the seizures but also provoke them to become

more frequent and more severe.

EEG & Clinical history define and confirm the

seizure type.


Summary of Clinical & EEG Features

of Epileptic Seizures

Seizure Usual

Duration

Loss of

Consc.

Post-Ictal

Confusion

ICTAL

EEG

Simple

Partial

5-10 sec NO NO Focal

Spikes (NL)

Complex

Partial

Variable

5-10 sec

1-2 min

YES YES Focal or

Lat. Spike

Absence 5-10 /sec

Clustering

YES NO Gen.

3 /sec S & W

Gen.

Tonic-Clonic

1-2 min YES YES Gen. High

Amp Spikes

Rebecca Clark-Bash

12

0

10

20

30

40

50

60

70

80

90

0-9 1O - 19 20-39 40-59 60+

EPILEPSYINCIDENCEcases peryr per100,000



“cat”

Seizures in Sleep: Incidence

• Sleep Epilepsies– 20-25 % have seizures exclusively or mainly at

night

• Diffuse Epilepsies– 30-40 % have seizures distributed around the

clock

• Waking Epilepsies– Remaining 35-50 % have seizures exclusively or

mainly during wakefulness



Nocturnal Seizures

are not infrequent.

Janz, 1962; Gibberd & Bateson, 1974

Seizures in Sleep: Incidence

Rebecca Clark-Bash16

Do different seizures have a tendency to start

during sleep?

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

Frontal Temporal Posterior

Awake

Asleep

P<0.0001

*

*

Herman et al,

Neurology 2001;

56:1453-9.

% b

egin

ning

in s

leep


Do some seizures generalize more often during

sleep?

0

10

20

30

40

50

60

70

80

frontal temporal occipital

Awake

Asleep

P<0.0001*

*

*

Herman et al, Neurology 2001;56:1453-9.

% g

ener

aliz

ing


In what stage of sleep do seizures happen?

Herman et al, Neurology 2001;56:1453-9.

0

10

20

30

40

50

60

70

stage 1 stage 2 SWS REM

%seizures

%sleep

Sleep Disorders & Seizures

• Seizures may resemble in clinical profile:

– Urinary incontinence causing confusion with

enuresis nocturna

– Psychomotor automatisms of complex partial

seizures with sleep walking

– Emotional symptoms with sleep terrors or dream

anxiety attacks

– Rage epilepsy with sleep terrors or other REM

sleep disorders


Method of Acquisition

• How many channels are necessary?

• What are the optimal filter and sensitivity settings to record abnormalities?

• What is the best paper speed (screen display) to record abnormalites?

• Should activation procedures be implemented in polysomnographic recordings when seizures are suspected?



Ambulatory EEG:Diagnostic Yield

Bridgers &

Ebersole

(1985)

Morris

(1985)

Patients N = 206 N = 191

Seizures 11

(5.3%)

13

(6.8%)

Epileptiform

Abnormalities

25

(12.1 %)

48

(25.1%)

Total EEG

Findings

36

(17.4%)

61

(31.9%)

Rebecca Clark-Bash22

Diagnostic Yield (Morris)

Total Study

PopulationNumber %

Patients in Study 344 100 %

Total Epileptiform

Abnormalities130 38.1 %

“Normal”

Pushbutton Events125 36.3 %

Total Clinical Useful

Recordings256 74.4 %


What Technology Changed:

Number of channels:

Ebersole: 8 Channels

Morris: 16 Channels-Full Head Coverage

Filter Settings

Ebersole: Bandpass 1-35 Hz

Morris: Bandpass: 1-70 Hz



How many channels are necessary?

16


Method of AcquisitionWhat are the optimal filter and sensitivity settings

to record abnormalities?

Low Filter: 1 Hz

High Filter: 70 – 100 Hz

Sensitivity: 7 µV/mm



What is the best paper speed (screen display) to record abnormalites?

YOUR EYES define



Should activation procedures be implemented in Polysomnographic recordings when seizures are suspected?

Photic Stimulation

Disco Ball

Night Driving

Rewind Video Tape or Japenese Cartoons

Hyperventilation

Developmental delay or Daydreaming

Sleep

YES!!!!!

Epileptiform Activity in Routine EEG &

Polysomnography:

A Comparative Analysis

Generalized Epileptiform Spike & Wave Discharge

Traditional Default EEG Settings:

Paper Speed: 30 mm/sec

Sens: 7 µV/mm HF: 70 Hz LF: 1 HzPatient is Awake with Eyes Open. Bipolar Double Banana Montage, No clinical signs of seizure or behavior change.

Reformatted to Sleep Settings

• Now how might this look different in the

format recommended by the new AASM

Sleep Scoring Guidelines?

• The Guidelines recommend the following

settings:

– Sensitivity: 7 µV/mm (or 10 µV/mm)

– HFF: 35 Hz

– LFF: .1 Hz

– Paper Speed: 10 mm/sec

• AASM Guidelines Montage

– The Guidelines recommend referencing to

contralateral mastoid.

– This patient was recorded with A1 & A2

placed on the ears, so this is one deviation

from the recommendations.

• F3 – A2

• F4 – A1

• C3 – A2

• C4 – A1

• O1 – A1

• O2 – A2


• Let’s change one parameter at time to

assess the impact of each individual setting

on this discharge

• The first change will be a reduction in the

High Filter to 35 Hz.

• Spikes are defined as having a duration of

20 – 70 msec.

• This means the frequency of Spikes would

be 14 Hz – 50 Hz (Time\Duration =

Frequency)

• A High Filter setting of 35 Hz will attenuate

some spikes in the higher frequency.



Deviation From Traditional Default EEG Settings:



Let’s Look At These Side By Side:

Not That Different, Right?HFF: 70 Hz HFF: 35 Hz

• The next change will be to reduce the Paper

Speed to 10 mm/sec from the EEG setting of 30

mm/sec.

• In the EEG format ten seconds per page are

displayed.

• In the Polysomnography format thirty seconds

per page are displayed.


Reformatting to Sleep Settings

• Where are the spikes???

• I was reviewing this and began to doubt I had clipped the same point in time.

• To verify we were comparing apples to apples, let’s use the eye movements to validate this is the same place in the record.

• In addition, I’ve blown up the Sleep Record to line up the second divisions.

• No question we are looking at the same time in the record.

• Also, notice the change in alpha activity over the O1 & O2 Head Regions.

Paper Speed: 30

mm/sec

Paper Speed: 10

mm/sec

• The source of this data loss exists in two

possible sources

– Sampling Rate

– Screen Resolution

• The Sampling Rate of this recording

• The Screen Resolution of the system this

was reviewed on was

Reformatting to Sleep Settings

• Now let’s go back to the default EEG Settings

and change ONLY THE MONTAGE to the

AASNM Scoring Montage.

• Paper Speed will be 30 mm/sec as it is in

Clinical EEG.





Sens: 7 µV/mm HF: 70 Hz LF: 1 Hz

AASM Montage (A1\A2 Used Instead of M1\M2)Patient is Awake with Eyes Open. Bipolar Double Banana Montage, No clinical signs of seizure or behavior change.

Nothing Noteworthy Here




Sens: 7 µV/mm HF: 70 Hz LF: 1 Hz

AASM Montage (A1\A2 Used Instead of M1\M2)Patient is Awake with Eyes Open. Bipolar Double Banana Montage, No clinical signs of seizure or behavior change.


Conclusions

Patients with nocturnal events with normal or

equivocal routine day EEG should have either

Sleep EEG with extended polysomnographic

monitoring, or

Sleep study with extended EEG monitoring

SLEEP? STUDY?

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