A first seizure in adulthood is a common reason for emergency department evaluation and subsequent follow-up in primary care. Family physicians are often responsible for confirming the diagnosis, identifying reversible causes, ordering appropriate diagnostic tests, and counseling patients regarding prognosis and safety issues. The evaluation of an event suspected to be a first seizure requires an understanding of seizure epidemiology, common etiologies, and risk factors that influence recurrence and long-term outcomes. The diagnostic approach includes a careful history and physical examination; laboratory studies as clinically indicated for any possible seizure; electroencephalography for all patients with a suspected unprovoked seizure; and neuroimaging for most after a first unprovoked seizure. Treatment considerations after an initial seizure include indications for antiseizure medication in the acute setting, maintenance antiseizure medication, hospitalization, and referral to neurology. Prognostic issues such as recurrence and mortality risks, return to work, driving restrictions, and counseling regarding emotional and financial impacts are important to consider after a first seizure.
Mullur K, Burbank K. Seizure Disorders in Adults: Evaluation of a First Seizure. FP Essent. 2026;568:7-11.
Case 1. KZ is a 24-year-old accountant who experienced a seizure at work 1 week ago. Coworkers report that she collapsed at her desk, developed stiffening of her limbs followed by rhythmic jerking movements, and was confused for several minutes afterward. She was evaluated in a local emergency department and treated for minor head injuries; history, medication review, and basic laboratory testing at that time did not identify any provoking factors. She has no history of seizures and presents today to discuss further evaluation and next steps.
Background and Epidemiology
Seizures are a relatively common neurologic event in adulthood. Approximately 8% to 10% of adults will experience at least one seizure during their lifetime, although active epilepsy affects about 1.1% of US adults.1–3 The incidence of first seizures demonstrates a bimodal distribution, with peaks in early adulthood and later life.2 In younger adults, first seizures are more often unprovoked, whereas in older adults, they are frequently related to cerebrovascular disease or other structural brain pathology.1,4
Among adults presenting with a first seizure, generalized tonic-clonic seizures are the most commonly recognized type at initial presentation, particularly when events occur in public settings and are witnessed by others, although focal seizures are the most common seizure type overall.1,2 Tonic-clonic seizures are characterized by loss of consciousness, generalized stiffening, and rhythmic jerking of the extremities, often followed by a postictal period of confusion or fatigue.1,2 Focal seizures with impaired consciousness (previously focal impared awareness) are also common but may be underrecognized or misclassified as syncope, panic attacks, or psychiatric events, particularly when motor manifestations are subtle.2 Accurate recognition of seizure type is important because it influences diagnostic evaluation, recurrence risk assessment, and treatment decisions.
Epilepsy is a chronic disease of the brain characterized by a predisposition to generate recurrent seizures, with associated neurobiologic, cognitive, psychological, and social consequences.5 It is clinically defined as the occurrence of at least two unprovoked seizures more than 24 hours apart, one unprovoked seizure with at least 60% risk of recurrence over 10 years, or the diagnosis of an epilepsy syndrome.5
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