1. History
- Onset and duration: Sudden onset of bilateral tonic stiffening followed by rhythmic clonic jerking, typically lasting 1–3 minutes with eyes open, apnea, and cyanosis [1]
- Timing: GTC seizures in idiopathic generalized epilepsy usually occur within 1 hour of waking; ask about time of day and sleep/wake state [1]
- Preceding symptoms (aura): Uncommon in primary GTC; if present (e.g., déjà vu, epigastric rising, focal symptoms), consider focal-to-bilateral tonic-clonic seizure [1]
- Triggers: Sleep deprivation, alcohol use/withdrawal, illicit drugs (cocaine, methamphetamine), medication non-compliance, strobe lights, stress, metabolic derangements [1-2]
- Postictal state: Drowsiness, confusion, muscle aches, headache — typically lasts minutes to hours; rapid recovery suggests syncope or psychogenic nonepileptic seizure (PNES) [1]
- Important negatives: Ask about prior unrecognized absences, myoclonic jerks, photosensitivity, staring spells, and childhood febrile seizures [1][3]
- Witness account: Essential — phone the witness; ask about head/eye deviation, color change, movements, duration, and recovery [1][3]
2. Alarm Features
- Seizure >5 minutes → treat as status epilepticus [3-4]
- Multiple seizures without return to neurologic baseline [4]
- Failure to regain consciousness within 30–60 minutes (consider nonconvulsive status epilepticus) [2]
- New focal neurologic deficits postictally (Todd's paralysis vs. stroke)
- Fever, nuchal rigidity, or immunocompromise → CNS infection [5-6]
- Anticoagulant use or recent head trauma → intracranial hemorrhage [7]
- First seizure in a patient >40 years → higher concern for structural lesion (tumor, stroke) [7]
- Pregnancy → eclampsia
- Signs of elevated ICP (papilledema, vomiting, altered mental status) [1]
3. Medications
Acute seizure termination (status epilepticus protocol)
- First-line: Benzodiazepines — IM midazolam 10 mg, IV lorazepam 4 mg (may repeat once), or IV diazepam 10 mg [5][8]
- Second-line (benzodiazepine-refractory): Levetiracetam, fosphenytoin, or valproate — all equally effective per the ESETT trial (~47% response rate) [9-10]
- Third-line (refractory SE): Continuous infusion of propofol, midazolam, or pentobarbital with ICU admission [3][5]
Chronic antiseizure medications (ASMs) for GTC
- Levetiracetam (Keppra): 250 mg → 1000–2000 mg/day; preferred in women of childbearing potential; watch for irritability/mood changes [1][11]
- Valproate: 500–1500 mg/day; most efficacious for idiopathic generalized epilepsy but contraindicated in women of childbearing potential (teratogenicity up to 10% major malformations, neurodevelopmental delay in up to 40%) [1][11]
- Lamotrigine: Effective for GTC but may worsen myoclonus/absences; requires slow titration (4–6 weeks) [1][11]
Medications that lower seizure threshold (avoid or use with caution): Tramadol, bupropion, fluoroquinolones, meperidine, theophylline, cocaine, methamphetamine [1][4]
Medications that may worsen idiopathic generalized epilepsy: Carbamazepine, oxcarbazepine, phenytoin, gabapentin, pregabalin [11]
4. Diet
- Alcohol: Major trigger — both acute intoxication and withdrawal lower seizure threshold; counsel strict limitation or avoidance [1-2]
- Caffeine: Excessive intake may lower seizure threshold in susceptible individuals
- Ketogenic diet: Established adjunctive therapy for drug-resistant epilepsy, particularly in pediatric populations; less commonly used in adults with GTC
- Hydration: Avoid severe dehydration or overhydration (hyponatremia can provoke seizures)
5. Review of Systems
- Neuro: Headache, vision changes, focal weakness, speech difficulty, memory lapses, prior staring spells, myoclonic jerks
- Cardiac: Palpitations, syncope, chest pain (rule out cardiac syncope mimicking seizure) [1]
- Infectious: Fever, neck stiffness, rash (meningitis/encephalitis)
- Psych: Depression, anxiety, panic attacks, self-harm history (PNES risk) [3]
- OB/GYN: Pregnancy status (eclampsia, teratogenicity of ASMs)
- Substance use: Alcohol, cocaine, methamphetamine, synthetic cannabinoids, prescription drug misuse
6. Collateral History and Family History
- Witness account is the single most important diagnostic element — phone the eyewitness if not present [1][3]
- Ask witnesses about: eye position, color change, movements (tonic vs. clonic vs. thrashing), duration, responsiveness, and recovery pattern
- Family history of epilepsy: Suggests genetic generalized epilepsy; autosomal dominant frontal lobe epilepsy has specific familial patterns [1][12]
- Family history of sudden cardiac death or long QT syndrome (cardiac syncope mimic) [1]
- Social context: Living situation (safety at home), occupation (heights, machinery, driving), childcare responsibilities
7. Risk Factors
- Prior brain insult: Stroke, TBI, CNS infection, neurosurgery (~2-fold increased recurrence risk) [13]
- EEG with epileptiform abnormalities: Strongly predicts recurrence [12-13]
- Abnormal brain imaging (structural lesion) [13]
- Nocturnal seizure [12-13]
- Sleep deprivation [1-2]
- Alcohol/substance use [1-2]
- Age: Bimodal distribution — highest incidence in young adults (<25) and elderly (>65) [1][14]
- Family history of epilepsy [12]
- Metabolic derangements: Hyponatremia, hypoglycemia, uremia, hepatic failure [15]
8. Differential Diagnosis
The following table summarizes key differentiating features:
Cannot-miss diagnoses: Meningitis/encephalitis, intracranial hemorrhage, brain tumor, eclampsia, hyponatremia, hypoglycemia, cardiac arrhythmia (long QT, Brugada) [1][5-6]
9. Past Medical History
- Prior seizures (including childhood febrile seizures, absences, myoclonic jerks)
- History of TBI, stroke, CNS infection, brain tumor, neurosurgery
- Developmental delay or intellectual disability
- Psychiatric history (depression, anxiety — relevant for ASM selection and PNES risk)
- Cardiac history (arrhythmias, structural heart disease)
- Current ASM use and compliance
- Mitochondrial disease (POLG1 mutations — valproate contraindicated) [1]
10. Physical Exam
- Vitals: Temperature (infection), blood pressure (hypertensive emergency/eclampsia), heart rate, oxygen saturation
- Neuro: Full neurologic exam once postictal state resolves — focal deficits suggest structural lesion; Todd's paralysis (transient postictal focal weakness) resolves within hours [6]
- Head/mouth: Lateral tongue bite is highly specific for GTC seizure (vs. tip-of-tongue bite in syncope/PNES); facial injury, posterior shoulder dislocation [1]
- Skin: Angiofibromas/hypomelanotic macules (tuberous sclerosis), self-harm scars (PNES), needle marks [1]
- Cardiovascular: Murmurs (aortic stenosis, HCM), orthostatic vitals [1]
- Fundoscopy: Papilledema (elevated ICP) [1]
11. Lab Studies
- Point-of-care glucose — immediate, to rule out hypoglycemia [5][16]
- BMP (sodium, calcium, magnesium, glucose, BUN/Cr) — identify metabolic provoking factors [5-6]
- CBC — infection screening [6]
- Pregnancy test in women of childbearing potential [5]
- Toxicology screen — if substance use suspected [2][5]
- Antiseizure medication levels — if on chronic ASMs (compliance assessment) [4]
- Additional if indicated: Lactate, CK, troponin, blood gas, LFTs, prolactin (if drawn within 10–20 min, sensitivity 53%, specificity 93% for epileptic seizure vs. PNES) [5-6]
- LP: If fever, meningismus, immunocompromise, or altered mental status persists after imaging [5-6]
12. Imaging
- CT head without contrast: First-line in the ED for first seizure with high-risk features (age >40, focal deficits, head trauma, anticoagulation, immunocompromise, malignancy, persistent altered mental status) [6-7]
- MRI brain with epilepsy protocol: Gold standard for identifying structural epileptogenic lesions (hippocampal sclerosis, cortical dysplasia, tumors, vascular malformations); should be obtained for all patients with a first unprovoked seizure, ideally outpatient [6][17]
- Up to 30% of patients with a first seizure have abnormalities on brain imaging [6]
- Imaging unnecessary: Known epilepsy patient with typical breakthrough seizure, returned to baseline, and clear provoking factor (e.g., medication non-compliance, sleep deprivation) — use clinical judgment
13. Special Tests
- EEG: Should be obtained ideally within 24 hours of a first unprovoked seizure to maximize yield; epileptiform discharges found in ~50% of first-seizure patients; sleep-deprived EEG increases sensitivity [2][6]
- Emergent EEG: Indicated when patient does not return to baseline within 30–60 minutes (rule out nonconvulsive status epilepticus) [2]
- Video-EEG monitoring: Gold standard for distinguishing epileptic seizures from PNES [6][17]
- Serum prolactin: Elevated 10–20 min post-seizure supports epileptic seizure over PNES (specificity 93%), but limited by timing constraints [5-6]
14. ECG
- 12-lead ECG is indicated in all patients with a first seizure or unexplained blackout [1]
- Rule out:
- Long QT syndrome (QTc prolongation → torsades de pointes mimicking seizure)
- Brugada syndrome (ST elevation in V1–V3)
- Prior MI with risk of ventricular tachycardia
- Hypertrophic cardiomyopathy
- Wolff-Parkinson-White (delta wave)
- Post-seizure ECG may show transient sinus tachycardia, ST changes, or QTc prolongation — these are usually benign and self-limited
15. Assessment
A GTC seizure presents as sudden bilateral tonic stiffening followed by clonic jerking, lasting 1–3 minutes, with loss of consciousness, apnea, cyanosis, and a prolonged postictal phase. [1] The clinical priority is distinguishing provoked vs. unprovoked seizures (~40% have an identifiable provoking factor), identifying dangerous mimics (cardiac syncope, PNES), and risk-stratifying for recurrence. [6]
Severity stratification
- Status epilepticus: Seizure >5 min or recurrent seizures without return to baseline — neurologic emergency [3-4]
- High-risk first seizure: Age >40, focal deficits, abnormal imaging, epileptiform EEG, nocturnal seizure, prior brain insult [7][13]
- Lower-risk first seizure: Age <40, normal exam, no comorbidities, clear provoking factor, return to baseline [7]
Recurrence risk after a first unprovoked seizure: 21–45% within 2 years; risk nearly doubles with epileptiform EEG or structural lesion. [13]
16. Treatment Plan
Acute management (actively seizing)
- Protect airway, position laterally, supplemental O₂, suction
- Check glucose immediately; give thiamine 100 mg IV before dextrose if nutritional deficiency suspected [16]
- If seizure >5 min: Benzodiazepine — IM midazolam 10 mg (preferred if no IV) or IV lorazepam 4 mg; may repeat once [5][8]
- If benzodiazepine-refractory: Levetiracetam 60 mg/kg (max 4500 mg), fosphenytoin 20 mg PE/kg, or valproate 40 mg/kg IV — all equivalent per ESETT [9]
- If refractory SE: Continuous infusion anesthetics (propofol, midazolam, pentobarbital) with intubation and ICU admission [3][5]
Post-seizure management
- Identify and treat provoking factors (electrolytes, infection, toxins, medication non-compliance)
- ASMs are not routinely recommended after a single unprovoked seizure unless high recurrence risk (epileptiform EEG, structural lesion, nocturnal seizure) [1][13]
- If starting ASM: Levetiracetam is preferred first-line for most patients, especially women of childbearing potential; add folate supplementation [1][11]
- Valproate is most efficacious for idiopathic generalized epilepsy with generalized spike-wave discharges but avoid in women of childbearing potential [11][18]
The following algorithm from JAMA provides a systematic approach to evaluating new-onset seizures:
17. Disposition
Admit if
- Status epilepticus or recurrent seizures
- Failure to return to neurologic baseline
- New focal neurologic deficits
- Acute structural lesion on imaging (hemorrhage, mass, stroke)
- Suspected CNS infection
- Significant metabolic derangement requiring correction
- Inability to obtain timely outpatient workup (EEG, MRI) [6]
Discharge if
- Single seizure with return to full neurologic baseline
- No acute provoking factor requiring inpatient treatment
- Stable vital signs and normal or non-acute imaging
- Reliable follow-up arranged (neurology within 1–2 weeks, outpatient EEG within 24–48 hours, MRI) [2][6]
Consult neurology
- First unprovoked seizure (outpatient referral)
- Status epilepticus (emergent)
- Diagnostic uncertainty (PNES vs. epilepsy)
- Refractory seizures despite ASM therapy
18. Follow Up / Return Precautions
Follow-up timing
- Neurology follow-up within 1–2 weeks of first seizure [1]
- EEG ideally within 24 hours, or as soon as possible outpatient [6]
- MRI with epilepsy protocol if not obtained in ED [6]
- If ASM started, follow-up in 2 months to assess response, adherence, and adverse effects [1]
Return precautions — instruct patient to return immediately for:
- Another seizure
- Seizure lasting >5 minutes (call 911)
- Persistent confusion, weakness, or inability to speak
- Fever, severe headache, or neck stiffness
- Worsening or new neurologic symptoms
Patient counseling
- Driving: Most states require 6 months seizure-free for noncommercial driving after an unprovoked seizure; 3 months after an acute symptomatic seizure; document counseling [2]
- Safety: Avoid unobserved swimming, tub baths (shower instead), working at heights, heavy machinery; drowning risk is 15–19× higher in persons with epilepsy [2]
- SUDEP: Sudden unexpected death in epilepsy occurs at 20× the rate of the general population; risk is highest with frequent GTC seizures; medication adherence is the most important modifiable risk factor [2]
- Lifestyle: Prioritize regular sleep, limit alcohol, avoid illicit drugs, manage stress [1-2]
- Medication adherence: Non-compliance is a leading cause of breakthrough seizures and ED presentations [4]
References
1. Initial Management of Seizure in Adults. — Smith PEM. The New England Journal of Medicine. 2021.
2. New-Onset Seizure in Adults and Adolescents: A Review. — Gavvala JR, Schuele SU. The Journal of the American Medical Association. 2016.
3. Adult Epilepsy. — Asadi-Pooya AA, Brigo F, Lattanzi S, Blumcke I. Lancet. 2023.
4. Clinical Policy: Critical Issues in the Management of Adult Patients Presenting to the Emergency Department With Seizures: Approved by the ACEP Board of Directors, April 17, 2024. — Smith MD, Sampson CS, Wall SP, et al. Annals of Emergency Medicine. 2024.
5. Diagnosis and Management of Status Epilepticus: Improving the Status Quo. — Gettings JV, Mohammad Alizadeh Chafjiri F, Patel AA, et al. The Lancet. Neurology. 2025.
6. Evaluation After a First Seizure in Adults. — Rowland K, Lambert CE. American Family Physician. 2022.
7. First‐Episode Seizure. — Jesse M. Pines, Christopher R. Carpenter Evidence‐Based Emergency Care. 2023.
8. Evidence-Based Guideline: Treatment of Convulsive Status Epilepticus in Children and Adults: Report of the Guideline Committee of the American Epilepsy Society. — Glauser T, Shinnar S, Gloss D, et al. Epilepsy Currents. 2016.
9. Efficacy of Levetiracetam, Fosphenytoin, and Valproate for Established Status Epilepticus by Age Group (ESETT): A Double-Blind, Responsive-Adaptive, Randomised Controlled Trial. — Chamberlain JM, Kapur J, Shinnar S, et al. Lancet. 2020.
10. Strategies to Innovate Emergency Care of Status Epilepticus. — Kapur J. Neurotherapeutics : The Journal of the American Society for Experimental NeuroTherapeutics. 2025.
11. Antiseizure Medications for Adults With Epilepsy: A Review. — Kanner AM, Bicchi MM. The Journal of the American Medical Association. 2022.
12. Prognostic Factors Predicting an Unprovoked Seizure Recurrence in Children and Adults Following a First Unprovoked Seizure. — Adan G, Neligan A, Nevitt SJ, et al. The Cochrane Database of Systematic Reviews. 2025.
13. Evidence-Based Guideline: Management of an Unprovoked First Seizure in Adults: Report of the Guideline Development Subcommittee of the American Academy of Neurology and the American Epilepsy Society. — Krumholz A, Wiebe S, Gronseth GS, et al. Neurology. 2015.
14. Epilepsy in Older People. — Sen A, Jette N, Husain M, Sander JW. Lancet. 2020.
15. Initial Management of Epilepsy. — French JA, Pedley TA. The New England Journal of Medicine. 2008.
16. Status Epilepticus in Adults. — Betjemann JP, Lowenstein DH. The Lancet. Neurology. 2015.
17. Improving Epilepsy Diagnosis Across the Lifespan: Approaches and Innovations. — Pellinen J, Foster EC, Wilmshurst JM, Zuberi SM, French J. The Lancet. Neurology. 2024.
18. Risk of Recurrence in Patients With an Unprovoked Tonic-Clonic Seizure and Generalized Epileptiform Discharges on EEG. — Jomaa N, Nasreddine W, Hmeimess G, et al. Epilepsia. 2023.