How do you diagnose and manage pseudoseizures (psychogenic non-epileptic seizures) versus epileptic seizures?

Distinguishing Pseudoseizures from True Epileptic Seizures

A detailed history focusing on specific clinical features usually suffices to distinguish psychogenic non-epileptic seizures (PNES) from true epileptic seizures, with video-EEG monitoring serving as the gold standard when clinical diagnosis remains uncertain. 1

Key Clinical Features for Recognition

Timing and Duration of Events

Duration of unconsciousness is the single most discriminating feature:

• PNES: Episodes lasting >5 minutes strongly suggest PNES, sometimes extending 10-30 minutes 2, 3
• True epileptic seizures: Unconsciousness typically lasts <30 seconds to 90 seconds total 2, 3
• Syncope (another mimic): Loss of consciousness <30 seconds 2

Movement Characteristics

The relationship between movements and loss of consciousness is critical:

In PNES:

• Movements begin after apparent loss of consciousness 2, 3
• Asynchronous, side-to-side thrashing movements that cannot be counted 2
• Repeated waxing and waning in intensity with changes in movement nature 2
• Pelvic thrusting (highly characteristic, though rarely seen in frontal lobe seizures) 2

In true epileptic seizures:

• Movements begin at the exact moment of loss of consciousness or before the fall 2, 3
• Symmetrical and synchronous movements 2
• Stiff "keeling over" during tonic phase 2
• Hemilateral clonic movements 2

Eye Position During Unconsciousness

This is one of the most reliable distinguishing features:

• PNES: Eyes closed during unconsciousness (highly characteristic) 2
• True epileptic seizures: Eyes remain open 2
• Syncope: Eyes typically open except in shallow, short-lasting episodes 2

Pre-Event Features

Before PNES:

• No specific aura pattern 2
• Often triggered by emotional stress 4

Before true epileptic seizures:

• Rising epigastric sensation, unusual unpleasant smell or taste, déjà vu/jamais vu 2
• Ictal cry or shout at onset 2
• Triggers include flashing lights and sleep deprivation 2

Before syncope (another important mimic):

• Nausea, sweating, pallor, lightheadedness, blurred vision 2
• Triggered by fear, pain, prolonged standing, warm environments 2

Post-Event Features

After PNES:

• Variable recovery pattern 2
• High rates of psychiatric comorbidities (depression, anxiety, PTSD, history of childhood trauma) 4

After true epileptic seizures:

• Prolonged confusion (post-ictal phase) 2
• Aching muscles, headache, sleepiness 2
• Elevation of creatinine kinase and prolactin (though not reliable for differentiation) 2

After syncope:

• Immediate clearheadedness 2
• Nausea, vomiting, and pallor may persist 2

Features That Do NOT Differentiate

Common pitfalls to avoid:

• Tongue biting does not differentiate PNES from epilepsy (though lateral tongue biting is highly specific for epilepsy) 2
• Urinary incontinence occurs in both PNES and epileptic seizures 2
• Biomarkers (neuron-specific enolase, prolactin, creatine kinase) are unreliable 2, 4

Diagnostic Approach

Initial Clinical Assessment

When uncertain about the diagnosis, it is better to postpone diagnosis than to falsely diagnose epilepsy, given the significant treatment and psychosocial implications. 5

Focus your history on:

1. Exact timing of movement onset relative to loss of consciousness 2, 3
2. Duration of the episode 2, 3
3. Eye position during unconsciousness 2
4. Nature of movements (synchronous vs. asynchronous) 2
5. Pre-event symptoms (aura vs. autonomic symptoms) 2
6. Post-event recovery pattern 2

Diagnostic Testing Algorithm

When clinical diagnosis remains uncertain:

1. Video-EEG monitoring is the gold standard for PNES diagnosis 3, 4, 6, 7

   • Captures typical events with continuous ECG, EEG, and blood pressure monitoring 3
   • In PNES: Normal EEG during episodes 1
   • In true epileptic seizures: Epileptiform discharges recorded 1
   • In syncope: Diffuse brainwave slowing with delta waves and flat line pattern 1

2. Tilt-table testing with simultaneous EEG and hemodynamic monitoring can be useful when syncope vs. seizure differentiation is unclear 1, 3

   • Can establish psychogenic pseudosyncope diagnosis: apparent unconsciousness with normal hemodynamics 3

3. Routine EEG is NOT recommended in the absence of specific neurological features suggestive of seizure 1

Critical warning: About 20-30% of patients with refractory "seizures" at epilepsy centers have been misdiagnosed, often due to overinterpretation of EEGs (misreading phase reversals as abnormalities). 6, 8

Important Diagnostic Pitfalls

Be aware of conditions that can mimic PNES:

• Frontal lobe seizures may present with similar characteristics to PNES 4
• NMDA receptor autoimmune encephalitis can present with posturing and rhythmic movements without epileptiform findings on EEG 9
• 10-30% of patients referred to epilepsy centers have PNES, and many have received wrong diagnosis of epilepsy 4, 8
• Comorbidity between epilepsy and PNES ("dual diagnosis") occurs and is a serious challenge 8

Management Approach

Initial Management Steps

1. Clearly communicate the PNES diagnosis to the patient 4

   • This is essential but challenging, as the mean latency between manifestations and diagnosis is 7 years 4

2. Discontinue or avoid antiepileptic drugs (AEDs) 4, 7

   • Patients with PNES do not respond to anticonvulsants 7
   • May display paradoxical reactions to treatment 7
   • May develop abnormal neurological signs from anticonvulsant toxicity 7
   • One out of four to five patients admitted with "refractory epilepsy" actually has PNES 8

3. Psychiatric evaluation is indicated 1

   • PNES patients have high rates of psychiatric disorders: depression, anxiety, somatoform symptoms, dissociative disorders, PTSD 4
   • Strong correlations exist between childhood trauma, history of abuse, PTSD, and PNES 4

Ongoing Management

Neurologist involvement remains essential even after diagnosis 4

• Continue follow-up to monitor for development of true epileptic seizures (prevalence of epilepsy in PNES patients is higher than general population) 4
• Coordinate with psychiatry for treatment of comorbidities 4

Realistic expectations:

• Even after correct diagnosis, a high proportion of PNES patients continue to have seizures and serious disability 4
• Nearly half who become seizure-free remain unproductive 4
• Many continue to have symptoms of psychopathology including somatoform, depressive, and anxiety disorders 4

Treatment of Acute Events

If true epileptic seizures or status epilepticus:

• Benzodiazepines as first-line treatment 1, 3
• Followed by fosphenytoin, levetiracetam, or valproic acid 1, 3
• Sodium valproate, levetiracetam, phenytoin, propofol, or barbiturates for ongoing seizures 1
• Myoclonus is particularly difficult to treat; phenytoin is often ineffective 1
• Propofol is effective for post-anoxic myoclonus 1