Seizure Mimics and Epileptic Seizures

Syncope

• The European Society of Cardiology recommends that syncope typically presents with a flaccid collapse preceded by nausea, sweating, and pallor, with loss of consciousness lasting less than 30 seconds and any movements beginning after the onset of unconsciousness 1
• Autonomic symptoms such as nausea, vomiting, abdominal discomfort, cold sweating, lightheadedness, and blurred vision characteristically precede syncopal episodes, according to the European Heart Journal 2
• Cerebral hypoperfusion symptoms, including dark spots in vision, loss of color vision, sounds coming from a distance, and buzzing or ringing in ears, are associated with syncope 1
• Pallor and sweating are common in syncope but uncommon in epilepsy, as noted by the European Heart Journal 2
• Flaccid collapse is the hallmark presentation of syncope, contrasting with the stiff "keeling over" seen in tonic seizures 1
• Movements begin after the fall and after onset of loss of consciousness, with a mean 20-second delay, and are asymmetrical and asynchronous 1
• Duration of unconsciousness less than 30 seconds strongly favors syncope over seizure 1
• Eyes are typically open except in shallow, short-lasting syncope 1
• Immediate clearheadedness is typical after syncope, with confusion usually of short duration 2
• Nausea, vomiting, and pallor may persist after neurally-mediated syncope 2
• Fear, pain, instrumentation, prolonged standing, warm environments, hot baths, post-exercise, and postprandial periods are common triggers for syncope 3

Psychogenic Non-Epileptic Seizures (PNES)

• PNES typically present with prolonged episodes, eyes closed during unconsciousness, asynchronous thrashing movements, and pelvic thrusting, affecting 20-30% of patients in epilepsy centers, according to the European Heart Journal 1
• Duration of loss of consciousness greater than 5 minutes strongly suggests PNES over epileptic seizures 1
• Eyes closed during unconsciousness is highly characteristic of PNES, whereas eyes remain open in epileptic seizures 1
• Movement patterns in PNES include asynchronous, side-to-side thrashing movements, many movements that cannot be counted, and repeated waxing and waning in intensity with changes in movement nature 1
• Pelvic thrusting is characteristic of PNES, though rarely seen in frontal lobe seizures 1
• Eye fluttering is more likely in PNES than epileptic seizures 1
• Episodes of PNES affect 20-30% of patients attending epilepsy centers and over 10% of seizure emergencies 4
• Tongue biting does not differentiate PNES from epilepsy 1
• Urinary incontinence does not differentiate PNES from epileptic seizures or syncope 1
• Biomarkers such as neuron-specific enolase, prolactin, and creatine kinase are unreliable for differentiating PNES from epilepsy 4

True Epileptic Seizures

• Aura, including rising epigastric sensation, unusual unpleasant smell or taste, déjà vu/jamais vu, is a characteristic onset feature of epilepsy 1
• Ictal cry, or shout at onset, suggests epilepsy 1
• Triggers for epilepsy include flashing lights and sleep deprivation 3
• Stiff "keeling over" during the tonic phase is characteristic of epilepsy 1
• Movements begin at onset of unconsciousness or before the fall, and are symmetrical and synchronous 1
• Duration of unconsciousness greater than 1 minute strongly favors epilepsy 1
• Hemilateral clonic movements are associated with epilepsy 2
• Oral automatisms, including chewing, smacking, blinking, and frothing at the mouth, are characteristic of epilepsy 1
• Lateral tongue biting is highly specific for epilepsy 1
• Eyes typically remain open during unconsciousness in epilepsy 1
• Prolonged confusion is characteristic of the post-ictal phase of epilepsy 2
• Aching muscles, headache, and sleepiness are common after epilepsy 2
• Elevation of creatinine kinase and prolactin is more frequent after epilepsy, though not reliable for differentiating PNES 2

Other Seizure Mimics

• Cataplexy is characterized by paresis or paralysis triggered by emotions, usually laughter, with patients remaining conscious and having no amnesia 2
• Drop attacks are sudden falls in middle-aged women, with patients remembering hitting the floor and having no loss of consciousness 2
• Vertebrobasilar TIA presents with paresis, ataxia, and brainstem signs 1

Distinguishing Pseudoseizures from True Epileptic Seizures

Diagnostic Approach

• Video-EEG monitoring is the gold standard for diagnosing psychogenic non-epileptic seizures (PNES), capturing typical events with continuous ECG, EEG, and blood pressure monitoring, and in PNES, normal EEG during episodes is observed, while in true epileptic seizures, epileptiform discharges are recorded, and in syncope, diffuse brainwave slowing with delta waves and flat line pattern is seen 5, 6
• The American Heart Association recommends video-EEG monitoring when clinical diagnosis remains uncertain, as it can establish a diagnosis of PNES, true epileptic seizures, or syncope 5, 6

Management Approach

• Psychiatric evaluation is indicated for patients with PNES, as they have high rates of psychiatric disorders, including depression, anxiety, somatoform symptoms, dissociative disorders, and PTSD, according to the European Society of Cardiology 7
• The European Society of Intensive Care Medicine recommends benzodiazepines as first-line treatment for true epileptic seizures or status epilepticus, followed by fosphenytoin, levetiracetam, or valproic acid, and sodium valproate, levetiracetam, phenytoin, propofol, or barbiturates for ongoing seizures 8

Duration of Seizure-Like Activity in Syncope

Temporal Characteristics of Movements in Syncope

• Myoclonic movements in syncope last less than 15 seconds in the vast majority of cases, according to the European Heart Journal guidelines 9
• Total duration of unconsciousness in syncope is typically less than 30 seconds, with movements occupying only a portion of this time, as reported by the American College of Emergency Physicians 10, 11

Movement Characteristics That Distinguish Syncope from Seizure

• Brief, mild tonic-clonic activity may commonly accompany syncope of any etiology, as noted by the American College of Emergency Physicians 10, 11

Post-Event Recovery

• Confusion or disorientation lasts no more than 20-30 seconds after syncope, which is significantly shorter than the post-ictal period of generalized seizures, according to the American College of Emergency Physicians 10, 11, 12
• Clearheadedness is usually immediate after syncope, as reported by the European Heart Journal 9

Clinical Pitfalls to Avoid

• Do not diagnose epilepsy based solely on the presence of movements during loss of consciousness, as advised by the American College of Emergency Physicians and the European Heart Journal 10, 11, 9
• If movements last longer than 30 seconds, consider epilepsy rather than syncope, according to the European Heart Journal guidelines 9
• Prolonged post-event confusion (>30 seconds) indicates epilepsy rather than syncope, as reported by the American College of Emergency Physicians and the European Heart Journal 10, 11, 9

Rare Exceptions

• In cases of deep or prolonged cerebral hypoperfusion, movements may occasionally last up to 30 seconds, but this is uncommon, as noted by the European Heart Journal 13
• Stertorous (snoring) breathing in syncope is brief, lasting only about 10 seconds in deep hypoperfusion, according to the European Heart Journal 13
• Head turning may occur in syncope with deep hypoperfusion but lasts less than 30 seconds, compared to prolonged head turning in epileptic seizures, as reported by the European Heart Journal 13

Guidelines for Evaluating Suspected Syncope with Sphincter Release (European Society of Cardiology)

Definition and Clinical Significance

• Syncope accompanied by urinary or fecal incontinence is not a specific sign that distinguishes syncope from epileptic seizures. 14

Core Diagnostic Criteria for Syncope

• A syncope episode must involve complete loss of consciousness with loss of postural tone. 15, 16
• The loss of consciousness should have a rapid onset. 15, 17
• The duration of unconsciousness is typically less than 30 seconds for true syncope. 14
• Recovery should be spontaneous, complete, and without residual deficits. 15, 16, 17

Presence and Documentation of Sphincter Release

• Urinary or fecal incontinence occurring during or immediately after the episode is a common finding but does not differentiate syncope from epilepsy. 15, 16
• This finding must be recorded in the clinical history as part of the “questions about the end of the attack.” 15, 16

Essential Clinical History Elements

• Pre‑episode posture (supine, seated, standing) should be documented. 15, 16
• Typical triggers include fear, pain, medical procedures, crowded or hot environments, and prolonged standing. 14, 18, 15
• Palpitations reported before the event suggest a possible arrhythmic cause. 15, 16
• Premonitory autonomic symptoms (nausea, vomiting, sweating, pallor) point toward a vasovagal mechanism. 14, 15, 16
• Cerebral hypoperfusion cues such as visual dark spots, loss of colour perception, or distant‑sound perception support a syncope diagnosis. 14

Features During the Event that Help Differentiate Syncope from Epilepsy

• Flaccid collapse is typical of syncope, whereas a rigid “tree‑like” fall suggests epilepsy. 14
• Movements that begin after loss of consciousness (average delay ≈ 20 seconds) favour syncope; movements that start at or before loss favour epilepsy. 14
• Duration of unconsciousness < 30 seconds strongly suggests syncope. 14
• Asymmetric or asynchronous movements are more consistent with syncope; symmetric, synchronous movements are characteristic of epilepsy. 14

Post‑Event Findings

• Immediate restoration of orientation supports syncope; prolonged post‑ictal confusion (> 30 seconds) leans toward epilepsy (citation not required as per source).
• Muscle soreness, minor injuries, or persistent pallor may follow syncope. 15, 16

Factors That Favor Syncope (Class I‑Level B evidence where reported)

• Total episode duration < 30 seconds. 14
• Flaccid collapse of the body. 14
• Delayed post‑loss movements (≈ 20 seconds after unconsciousness). 14
• Immediate recovery without confusion. 14
• Presence of pallor and sweating. 14
• Autonomic premonitory symptoms (nausea, sweating, etc.). 14

Factors That Favor Epilepsy (Class I‑Level B evidence where reported)

• Episode duration > 1 minute. 14
• Rigid, “tree‑like” fall. 14
• Movements beginning at or before loss of consciousness. 14
• Prolonged post‑event confusion (> 30 seconds). 14
• Ictal scream at onset. 14
• Lateral tongue biting (highly specific). 14
• Aura (e.g., epigastric rising sensation, unusual smells/tastes, déjà‑vu). 14

Risk Stratification After Confirming Suspected Syncope with Sphincter Release

High‑Risk Features Requiring Urgent Cardiac Evaluation

• Known structural heart disease. 18, 19
• Abnormal 12‑lead ECG. 18, 16, 19
• Syncope occurring during physical exertion or while supine. 18, 15
• Episodes preceded by palpitations or accompanied by chest pain. 18, 15
• Family history of sudden cardiac death. 15, 16

Low‑Risk Features Suggesting Reflex (Neuro‑mediated) Syncope

• Absence of structural heart disease. 18, 19
• Normal ECG. 18, 19
• Typical triggers (fear, pain, prolonged standing). 18, 15
• Long‑standing history of similar episodes. 18

Recommended Diagnostic Algorithm (European Society of Cardiology)

• Detailed clinical history. 15, 16, 19
• Orthostatic blood‑pressure measurement. 15, 16
• 12‑lead ECG. 15, 16, 19 (All components supported by ESC guideline citation 18)

Common Clinical Pitfalls to Avoid

• Do not diagnose epilepsy solely on the basis of incontinence; this sign is non‑discriminatory. (source excluded per instruction)
• Brief myoclonic movements are frequently observed in syncope and should not lead to an epilepsy diagnosis. 14
• Do not overlook episode duration: > 30 seconds warrants consideration of epilepsy; < 30 seconds strongly suggests syncope. 14
• Timing of movements matters: post‑loss movements favor syncope; pre‑loss or simultaneous movements favor epilepsy. 14
• Even with typical vasovagal features, high‑risk cardiac factors mandate cardiac evaluation. 18, 19