September 20th, 2014 How is PNES Diagnosed with Video-EEG
PNES • Non-epileptic seizures are episodes that resemble epileptic seizures clinically but are not derived from electrical disturbances.
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).
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. *
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.
ElectroencephalogramEEG • 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?)
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.
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.
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.
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.
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.
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.
Psychogenic Non-epileptic Seizures • Characteristics of PNES • 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
Psychogenic Non-epileptic Seizures • Characteristics of PNES • Varied character of events • Suggestibility • Emotional triggers • Prompt recovery (Absence of post-ictal state) • Poor response to anti-epileptic medications
Video-EEG MonitoringLimitations • 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).
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%).