Northeast Regional
Epilepsy Group
Christos Lambrakis M.D.
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September 20th, 2014
How is PNES Diagnosed
with Video-EEG
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PNES
• Non-epileptic seizures are episodes that
resemble epileptic seizures clinically but are
not derived from electrical disturbances.
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Psychogenic Non-epileptic
Seizures
• Resemble epileptic seizures but lack EEG
correlate.
• Very common (~25% of patients referred to
Video-EEG monitoring for evaluation of
intractable epilepsy).
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Psychogenic Non-epileptic
Seizures
• Psychiatric manifestation
– Somatoform/Conversion Disorder (most common)
• Unconscious production of physical symptoms due to
psychological factors
– Factitious Disorder
• Consciously determined symptoms driven by a powerful
unconsciously determined need.
– Malingering
• Willful production of symptoms for a specific external
incentive.
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Psychogenic Non-epileptic
Seizures
• Often difficult to distinguish clinically from
epileptic seizures.
• Clues:
– Resistance to AEDs
– Emotional Triggers (stress)
– Bilateral clonic movements without loss of
consciousness
– Absence of post-event confusion/lethargy.
• Video-EEG is very helpful in diagnosis.
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Electroencephalogram (EEG)
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Electroencephalogram
EEG
• Represents a record of the small shifting
brain electrical potentials from the surface
of the brain recorded over the scalp.
• As seizures are caused by a disturbance of
electrical activity, the EEG is uniquely
suited to further our understanding of a
patients seizures.
Goals of Video-EEG
Monitoring
• Is it really an epileptic seizure?
(Epilepsy vs. non-epileptic events)
• What type of seizure is it? (Characterize
epilepsy type)
• Where does the seizure originate from?
Is it focal? (i.e. does it come from one
specific region?)
Electrodes
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Inpatient Video-EEG
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Outpatient Ambulatory VideoEEG
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Routine EEG
• Short duration (<1 hour)
• Low sensitivity. Events are seldom recorded.
• Presence of inter-ictal baseline epileptogenic
abnormalities does not confirm or exclude
either diagnosis.
– Patient with inter-ictal epileptogenic
abnormalities can still have PNES.
– Patient with normal inter-ictal EEG can still
have epilepsy.
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Video-EEG Monitoring
• Long term inpatient monitoring allows for
recording of seizure events.
• Clinical and electroencephalographic
features can be reviewed aiding in seizure
characterization and localization.
• Baseline EEG may be helpful in
determining risk of future seizures.
Video-EEG Monitoring
• Gold standard for differentiating PNES
from ES.
• Recommended for patients with recurrent
episodes despite multiple medication trials.
• Goal is to record typical event and
document lack of EEG correlate.
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Video-EEG Monitoring
• Video component can be helpful in
documenting movements or behaviors
typically incompatible with ES.
• Important in verifying that event recorded is
representative of events which prompted
medical attention.
– ** ~20% of patients with PNES also have ES.
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Psychogenic Non-epileptic
Seizures
• Many clinical patterns:
– Migratory motor activity (most common)
– Generalized motor activity
– Unilateral (less common)
– Alteration of awareness (Common)
** Can be difficult to distinguish from frontal
lobe seizures.
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Non-epileptic Seizures
• EEG during PNES can be difficult to
interpret.
• Movements during an PNES event cause
rhythmic artifacts on EEG that look very
similar to epileptic seizure activity.
• Some epileptic seizures (partial) can be
electrically silent on EEG and can be
misdiagnosed as PNES.
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EEG (Seizure)
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Non-epileptic Seizures
• Analysis of the clinical semiology of the
episodes thru video can be helpful in
differentiation between PNES and ES.
– ** Definitive diagnosis should not rest solely
on clinical observation. Certain types of
epileptic seizures (frontal and temporal) can
look very similar to a PNES event.
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Psychogenic Non-epileptic
Seizures
• Characteristics of PNES
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Variable responsiveness or preserved awareness.
Out of phase movements of extremities.
Discontinuous motor activity
Pelvic thrusting.
Side to side head movements.
Eye closure/eye flutter
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Psychogenic Non-epileptic
Seizures
• Characteristics of PNES
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–
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Varied character of events
Suggestibility
Emotional triggers
Prompt recovery (Absence of post-ictal state)
Poor response to anti-epileptic medications
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Video-EEG Monitoring
Limitations
• Event may not occur (consider home
ambulatory Video-EEG).
• Missed PNES diagnosis (EEG over
interpreted as ES due to rhythmic artifact).
• Incorrect PNES diagnosis (Partial ES may
not display electrical abnormalities).
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Psychogenic Non-epileptic
Seizures
• ~20 % of patients with PNES will also have
coexistent epileptic seizures.
• Latency between manifestation of PNES
and diagnosis is ~ 7years.
• Prompt diagnosis is crucial to avoid
iatrogenic morbidity (Exposure to
unnecessary medication ~80%, Intubation
~50%).
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