Transcript Video EEG monitoring

Comprehensive Video
EEG monitoring
JWM Neurology
Kate Kobza, MD
August 2006
Why do we need it?
Limitations of routine EEG:
 Limited
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sampling
An EEG is a sampling of brain activity
occurring at the time of the recording
Seizures and spells are paroxysmal and may
be missed on a short study
 No
video to correlate patient
behavior with suspicious EEG
changes
Limitations of routine EEG:
 Yield
of a single routine scalp EEG is 50%
 Certain artifacts and normal variants can
be confused with epileptiform discharges
 Some EEG abnormalities do not have a
close correlation with clinical
seizures
Limitations of routine EEG:

Pathophysiologically – epileptic seizures are
characterized by an excessive, disorderly,
neuronal discharge

An EEG study may disclose epileptiform
abnormalities which have a high correlation with
occurrence of epileptic seizures

The only way to definitively prove
epilepsy is to record a seizure
What does a video EEG
study consist of?
Methodology
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EEG electrodes are attached to
the scalp with glue
ECG electrodes are placed
Patient is moved to a room with
video monitoring
Patient and family are given an
alarm to push with any spell
Trained nurses and staff
respond to alarms to observe
patient and treat if necessary
Methodology
 Miscellaneous
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options:
Antiepileptic medications may be discontinued
or decreased
Known inducers of events may be performed
• Sleep deprivation
• Suggestion (important in nonepileptic events)

Extra electrodes may be added
• Sphenoidal
• Foramen ovale
Methodology
 Multi-channel
long term EEG recording
with split screen video recording
 Digital storage of EEG and video data that
can be reviewed later
 Performed under close
monitoring of trained
technologists and nurses
 Study is reviewed by a
trained neurologist or
epileptologist
Outpatient settings
 Represents
a partially controlled
environment
 Useful for:
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Minor or non-convulsive seizures
Diagnostic purposes only
 Benefits:

Less costly
 Drawbacks:
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Invasive electrodes not possible
No medication withdrawal possible
Inpatient settings

Completely controlled environment
 Useful for:
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Benefits:
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Major or convulsive seizures
Medication withdrawal possible
Other tests: Blood sugars, SPECT possible
Inducers can be used, if present
Invasive electrode monitoring possible
Intracranial EEG possible
Drawbacks:

Expensive
Who orders a study?
What patients might be
candidates?
 Primarily
neurologists order
video EEG studies
 Video
EEG can be
ordered on infants,
children, and
adults
Indications for video
EEG monitoring
Common indications:
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Follow up of borderline or nonconclusive routine
EEGs
Diagnosis of recurrent spells
Classification of seizure type
Quantification of interictal epileptiform activity
Preoperative evaluation of surgical candidates
Evaluation of patient in coma as treatments for
status epilepticus
Follow-up borderline EEG
 Allows
for prolonged
collection of digital
EEG
 Areas of uncertainty
(i.e. artifact vs.
abnormality) can be
correlated with video
material for
clarification
Aids in diagnosis of spells:
 Causes
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other than epileptic seizures:
Syncope
Sleep apnea
Periodic movements of sleep
Non-epileptic seizures
Breath-holding spells
Migraine
Other uses:
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Characterization or
any repetitive or
stereotyped behavior
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autonomic changes in
infants
repetitive behaviors in
the ICU setting
unexplained
nocturnal events
Characterization of seizures

Accurate diagnosis
and classification of
seizures is essential
for proper
therapeutic
intervention
 Medication choices
are driven by
seizure classification
Classification of seizure types
 Generalized
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Absence
Generalized tonic, clonic, or atonic
Myoclonic
 Partial
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onset
Simple or complex
Secondary generalization
 Non
epileptic
Examples of seizure types
 Complex
partial
 Generalized tonic-clonic
 Nonepileptic
Complex partial
Generalized tonic-clonic
Nonepileptic
Diagnosis of non-epileptic events:
Pseudoseizures
Studies1 have shown that 22% of patients with
medically intractable seizures studied by video
EEG monitoring had nonepileptic events
 Approximately 1/3 of patients studied at video
monitoring centers have nonepileptic events
 The majority of patients with nonepileptic events
have been inappropriately treated with
antiepileptic medications for years
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1
Matson et al.
Nonepileptic events
 Video
EEG monitoring provides evidence
to support medication choices
• Allows safe discontinuation of antiepileptic drugs
 Information
can be used when discussing
a diagnosis of pseudoseizure with patients
• Many patients are relieved by diagnosis
• Many others are doubtful as they have been told
for many years that they have epilepsy
 This
is used to as a treatment modality
Nonepileptic events
 Majority
of patients with nonepileptic
events also experience epileptic seizures
 Video EEG can quantitate frequency of
each type
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Aids in education of family members about
clinical differences
• Avoid abuse of resources
• Limit health provider calls
• Avoid abuse (overuse) of antiepileptic drugs
Quantification of interictal
epileptiform activity
 Quantify
the number of seizures per day
 Helpful for:

Absence seizures
• Helpful in decision to stop medications
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Nonconvulsive seizures
Document efficacy of suppressive
medications
Things we don’t like to hear as a passenger.
Localization of epileptogenic focus
 Useful
in patients with
intractable epilepsy as
part of a presurgical
evaluation
 Focus
of study is to
correlate EEG findings
with lesion on MRI
Preoperative evaluation of surgical
candidates
 Usually
for intractable
temporal or extra-temporal
epilepsy
 Can be performed with
sphenoidal or foramen
ovale electrodes
 Subdural grid placements
can be used in conjunction
with a neurosurgeon
Evaluation of patient in coma as
treatments for status epilepticus
Status epilepticus
 Patients
often demonstate continued
subclinical seizure discharges after the
clinical behaviors have cease
 EEG monitoring is necessary in all
patients in drug induced coma as a
treatment for status epilepticus
• Need to document burst suppression pattern
induced by meds
Long term EEG monitoring:
Other uses
 Intraoperatively:
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Functional stimulation
during resections
Intraoperative surface
EEG monitoring
• carotid endarterectomy
Other monitoring modalities:
 Digital
ambulatory
monitoring
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Patient wears a digital
EEG recorder home
Records 24 hours of
digital EEG
Patient records
symptoms in a diary
In Summary:
Video EEG monitoring
 Captured
50-96% of epileptic and
nonepileptic events (Legatt AD and
Ebersole JS, 1998).
 Established a diagnosis in 88-95%
(Legatt AD and Ebersole JS, 1998).
 Improved outcome in 30-74% of patients
(Legatt AD and Ebersole JS, 1998).
St. Vincent Hospital
EEG – outpatient or inpatient
 Ambulatory EEG – 24 hour outpatient study
 Video EEG monitoring
 Routine
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3 adult rooms (hardwired)
1 portable unit (adult or pediatric)
1 ICU monitoring room
A neurologist