Seizure Mimics: 11 Conditions That Look Like Seizures But Aren't

What Are Seizure Mimics?

Seizure mimics (or pseudoseizures) are events that resemble epileptic seizures but are not caused by abnormal electrical brain activity. Accurate diagnosis is critical because treatment differs entirely. Video-EEG monitoring is the gold standard for differentiation.

Common Seizure Mimics

1. Syncope (Fainting)

Sudden drop in cerebral perfusion → brief loss of consciousness. Preceded by dizziness, nausea, tunnel vision. Rapid recovery when supine. No postictal confusion. Common triggers: standing, pain, fear, dehydration.

2. Psychogenic Non-Epileptic Seizures (PNES)

Formerly "pseudoseizures." Involuntary motor/behavioral episodes from psychological distress, not cortical discharge. Features: asynchronous movements, pelvic thrusting, side-to-side head shaking, eyes closed, variable duration, no tongue biting/incontinence. Often in patients with trauma/PTSD. Diagnosed by video-EEG showing normal ictal EEG.

3. Migraine with Aura

Visual (scintillating scotoma), sensory, or speech disturbances can mimic focal seizures. Usually gradual onset (minutes), followed by headache. "Alice in Wonderland" syndrome (metamorphopsia) rare.

4. Narcolepsy / Cataplexy

Sudden muscle weakness triggered by strong emotions (laughter, surprise). Consciousness preserved. Sleep attacks may resemble absence seizures. Diagnosed by polysomnography/MSLT.

5. Vestibular Disorders

Vertigo, drop attacks (Tumarkin's otolithic crisis) cause falling without LOC. Nystagmus, hearing loss, tinnitus accompany.

6. Cardiac Arrhythmias

Brady- or tachyarrhythmias → cerebral hypoperfusion → syncope with brief myoclonic jerks (convulsive syncope). ECG, Holter, loop recorder needed.

7. Metabolic Disturbances

• Hypoglycemia: Tremor, confusion, LOC, seizures. Diabetics on insulin/sulfonylureas.
• Hyponatremia/Hypernatremia: Encephalopathy, seizures.
• Hypercalcemia: Altered mental status, coma.
• Hepatic/uremic encephalopathy: Asterixis, confusion, seizures.

8. Drug Toxicity / Withdrawal

• Antidepressants, antipsychotics, opioids, stimulants: Can lower seizure threshold.
• Alcohol/benzodiazepine withdrawal: Delirium tremens, generalized tonic-clonic seizures (6–48 hrs post-cessation).

9. Transient Ischemic Attack (TIA)

Focal neurological deficits (weakness, aphasia, visual loss) <24 hrs. Unlike seizures, no positive symptoms (jerking), no postictal state. Urgent vascular workup needed.

10. Conversion Disorder (Functional Neurological Symptom Disorder)

Motor/sensory deficits (paralysis, blindness, seizures) inconsistent with neuroanatomy. "La belle indifférence" sometimes present. Diagnosis of exclusion.

11. Movement Disorders

Paroxysmal dyskinesias, tics, stereotypies, Sandifer syndrome (GERD-related posturing in infants).

Diagnostic Approach

1. Detailed history (witness account, triggers, pre/post-ictal features).
2. Neurological exam.
3. Routine EEG → if normal, consider ambulatory/video-EEG.
4. MRI brain (if focal features).
5. Labs: glucose, electrolytes, renal/hepatic, toxicology.
6. Cardiac workup if syncope suspected.

Misdiagnosis leads to unnecessary antiseizure drugs (side effects, cost) and delays proper therapy (CBT for PNES, cardiac ablation for arrhythmia, etc.). Referral to an epileptologist is warranted for uncertain cases.