Seizures: A Complete Overview

A seizure is a sudden, abnormal burst of electrical activity in the brain — and they are far more varied and common than most people realize. Not all seizures involve convulsions. Some cause a person to simply stare blankly for seconds. Others produce unusual sensations, involuntary movements, or altered awareness.

Key Statistics

• 3.4 million Americans have active epilepsy
• 1 in 26 people develop epilepsy during their lifetime
• 150,000 new U.S. epilepsy cases are diagnosed each year
• 30–40% of epilepsy cases have genetic causes

What Is a Seizure? A seizure occurs when neurons in the brain fire abnormally and excessively, disrupting the normal electrical patterns that govern thought, sensation, movement, and consciousness. It is important to distinguish between a seizure (a single event) and epilepsy (a chronic brain condition characterized by recurrent, unprovoked seizures). A single seizure does not mean a person has epilepsy.

During a seizure, a group of neurons begin firing in an abnormal, synchronized, high-frequency pattern. This electrical storm spreads through brain networks, recruiting more neurons and producing the seizure's observable effects. The brain region where the seizure originates determines what symptoms appear.

Types of Seizures — 2025 ILAE Classification The International League Against Epilepsy (ILAE) released an updated seizure classification in 2025, reducing recognized seizure types from 63 to 21. The core framework organizes seizures by where they begin:

Focal Seizures (begin in one area of the brain):

• Focal Preserved Consciousness (FPC): Formerly "simple partial." Person remains fully aware. May experience unusual sensations, emotions, or motor symptoms.
• Focal Impaired Consciousness (FIC): Formerly "complex partial." Consciousness is impaired — person may stare, appear confused, make automatic movements.
• Focal to Bilateral Tonic-Clonic (FBTC): Begins as a focal seizure, then spreads to both hemispheres.
• Aura: A subjective warning — an FPC that signals what's coming. May include unusual smells, déjà vu, or visual disturbances.

Generalized Seizures (involve both hemispheres from the start):

• Tonic-Clonic (Grand Mal): Classic seizure with stiffening then rhythmic jerking. Typically 1–3 minutes.
• Absence (Petit Mal): Brief staring spells of 5–30 seconds. Common in children; may be mistaken for daydreaming.
• Myoclonic: Sudden, brief muscle jerks — often in the morning shortly after waking.
• Atonic (Drop Attacks): Sudden loss of muscle tone causing the person to collapse. High injury risk.
• Tonic: Sudden stiffening of muscles causing a person to fall if standing.
• Clonic: Rhythmic jerking movements without the preceding tonic phase.

First Aid: What to Do During a Seizure

DO:

• Stay calm and stay with the person
• Time the seizure — duration matters
• Clear the area of hard or sharp objects
• Gently turn the person onto their side (recovery position)
• Cushion their head with something soft
• Loosen anything tight around the neck
• Stay until they are fully conscious and oriented

DO NOT:

• Do NOT hold the person down or restrain them
• Do NOT put anything in their mouth
• Do NOT give food or water until fully alert
• Do NOT leave them alone until fully recovered

Call 911 if: The seizure lasts more than 5 minutes · The person doesn't regain consciousness · A second seizure begins shortly after · The person is injured, pregnant, or diabetic · This is their first known seizure · The seizure occurs in water.

Causes & Risk Factors

• Genetic factors: 30–40% of epilepsy cases have genetic causes
• Structural brain changes: Stroke, traumatic brain injury, brain tumor, cortical malformations
• Infections: Meningitis, encephalitis, autoimmune encephalitis
• Provoked/Acute causes: Febrile seizures, hypoglycemia, drug or alcohol withdrawal
• Perinatal injury: Birth complications leading to hypoxic-ischemic encephalopathy
• Unknown/Cryptogenic: A definitive cause is not identified in approximately 60% of cases

Status Epilepticus: A Neurological Emergency A seizure lasting more than 5 minutes — or recurrent seizures without full recovery between them — is defined as status epilepticus (SE). It is a medical emergency. Every minute of untreated SE worsens the prognosis. First-line treatment: IV lorazepam or rectal/nasal diazepam in the community.

Diagnosis Accurate diagnosis is essential — different seizure types require different treatments. The diagnostic workup typically includes: MRI brain, EEG (electroencephalography), blood tests (glucose, electrolytes, metabolic panel), and in selected cases, lumbar puncture, genetic testing, or autoimmune antibody panels. Video-EEG monitoring is the gold standard for difficult-to-classify cases.

Treatment: Anti-Seizure Medications (ASMs) Over 30 ASMs are available — choice depends on seizure type, epilepsy syndrome, age, sex, and comorbidities:

• Levetiracetam (Keppra): Most widely prescribed. Broad spectrum. No drug-drug interactions.
• Lamotrigine (Lamictal): Excellent tolerability. Preferred in women of childbearing age.
• Valproate (Depakote): Most effective for generalized epilepsies. Significant teratogenicity risk.
• Oxcarbazepine/Carbamazepine: Effective for focal/temporal lobe epilepsy.
• Ethosuximide (Zarontin): First-line for childhood absence epilepsy.
• Cenobamate: Newer agent showing up to 55% seizure-free rate in drug-resistant focal epilepsy trials.

When Medications Aren't Enough Approximately 30% of people with epilepsy have drug-resistant epilepsy (DRE). Non-pharmacological options include:

• Epilepsy Surgery: Over 60–80% of selected patients become seizure-free after temporal lobectomy.
• Vagus Nerve Stimulation (VNS): Reduces seizures by ≥50% in about half of patients.
• Responsive Neurostimulation (RNS): A closed-loop brain stimulator that detects and aborts seizures.
• Ketogenic Diet: Particularly effective in children — seizure-free in ~10–15%, >50% reduction in ~50%.

SUDEP: Sudden Unexpected Death in Epilepsy SUDEP is the leading cause of epilepsy-related death — claiming an estimated 1 in 1,000 adults with epilepsy per year, and up to 1 in 150 with severe, drug-resistant epilepsy. Risk factors include: frequent generalized tonic-clonic seizures, nocturnal seizures, sleeping alone, and subtherapeutic medication levels. Reducing tonic-clonic seizures is the most important way to reduce SUDEP risk.

Resources

• Emergency: Call 911 for any seizure lasting more than 5 minutes
• Epilepsy Foundation Helpline: 1-800-332-1000 | epilepsy.com

This content is for informational purposes only and does not constitute medical advice. A seizure lasting more than 5 minutes is a medical emergency — call 911.