Seizure workup

1. Stabilize and confirm it was a seizure

• Check airway, breathing, circulation and fingerstick glucose first. Treat hypoglycemia right away.
• In an ongoing seizure or status epilepticus, treatment comes before the workup.
• Get a witness account: onset (focal or generalized), duration, tongue biting, incontinence, post-ictal state, and any aura.
• Take a history for the following:
  • Provoking factors: sleep deprivation, alcohol or drug use or withdrawal, new medications (bupropion, tramadol, and others), and fever.
  • Head trauma, stroke, CNS infection, tumor, and family history.
  • Pregnancy.
• Syncope (including convulsive syncope) and psychogenic nonepileptic events are the main mimics.
• Examine for focal deficits, meningismus, head injury, and signs of drug or alcohol use. Also look at the skin for neurocutaneous stigmata.

2. Labs

• CBC with platelets and differential
• Electrolytes, calcium, magnesium, phosphorus, BUN, creatinine and glucose
• Transaminases
• Thyroid function tests and PT/PTT
• Toxicology screen
• ABG or pulse oximetry

• Check a pregnancy test in women of childbearing age.
• Check an ammonia level if hepatic encephalopathy is possible.
• An ECG is worth doing in everyone, to look for QT prolongation or arrhythmia presenting as seizure-like events.
• Serum prolactin (drawn 10 to 20 minutes after the event) and lactate can support the diagnosis but are not required.

3. Lumbar puncture

• LP is not routine. Do it if meningitis or encephalitis is suspected. That means fever, meningismus, immunosuppression, or persistent altered mental status.
• In a febrile child, do an LP if intracranial infection is suspected. Children under 12 to 18 months may lack typical signs, so the threshold is lower. Consider partially treated meningitis if the child is already on antibiotics. (Textbook of Family Medicine 9e)
• Get a head CT first if there is a mass lesion or raised ICP concern. If a patient is empirically treated for meningitis or encephalitis, antibiotics and acyclovir should not wait for imaging or LP. (Goldman-Cecil Medicine)

4. Neuroimaging

• In the emergency department: a non-contrast head CT is high-yield for a first seizure in adults. Rosen's Emergency Medicine says most guidelines recommend it. A 2024 systematic review found a number needed to scan of 10 to 19 for management-changing findings such as hemorrhage, infarct and tumor.
• MRI (outpatient) is preferred over CT. It is better at showing cortical malformations, the temporal lobes, gliomas and cavernous malformations. (Textbook of Family Medicine 9e)
• If the patient is seen in the office shortly after a first seizure, imaging doesn't need to be immediate unless there is focal injury or marked cognitive impairment. (Textbook of Family Medicine 9e)
• PET and SPECT are only for presurgical or localization work. They are not routine.
• Children: neuroimaging is not routine after a simple febrile seizure. For a first unprovoked seizure, the Harriet Lane Handbook says MRI isn't routinely indicated and CT is not recommended.

5. EEG

• Order an EEG for all new-onset unprovoked seizures. Ideally do it within 24 to 48 hours, and a sleep-deprived study raises the yield.
• It helps classify the seizure type and epilepsy syndrome, and it informs recurrence risk.
• A 2025 ILAE/IFCN meta-analysis found that interictal epileptiform discharges imply an increased risk of recurrence after a first unprovoked seizure.
• Get an urgent EEG for persistent altered mental status to exclude nonconvulsive seizures or status epilepticus. (Goldman-Cecil Medicine)
• Use video-EEG monitoring if the diagnosis is unclear, for example to separate epileptic from psychogenic events.
• Febrile seizures usually need no EEG. (Textbook of Family Medicine 9e)

6. Disposition

• Injury, or concern about an underlying illness
• Poor clinical progress
• Inadequate observation or social support
• Unreliable follow-up

Quick algorithm

1. Fingerstick glucose, ABCs, then confirm it was a seizure.
2. Labs, ECG and pregnancy test.
3. Non-contrast head CT in the ED if there is a first seizure, focal findings, trauma, or immunosuppression.
4. LP if infection is suspected.
5. EEG, then MRI brain with an epilepsy protocol as an outpatient.
6. Refer to neurology. Give counseling on driving and safety.

Recent evidence flag