New-Onset Seizure in Adults and Adolescents: A Review.

Importance: Approximately 8% to 10% of the population will experience a seizure during their lifetime. Only about 2% to 3% of patients go on to develop epilepsy. Understanding the underlying etiology leading to an accurate diagnosis is necessary to ensure appropriate treatment and that patients with low risk for recurrence are not treated unnecessarily. Observations: Patients can present with new-onset seizure for a variety of reasons such as acute symptomatic seizures due to acute brain injury or metabolic derangements, or unprovoked seizures that are the initial manifestation of epilepsy. A patient history and physical examination may identify features more consistent with an epileptic event and laboratory studies and brain imaging can identify an acute insult contributing to the presentation. Patients diagnosed with first-time unprovoked seizure require electroencephalography and epilepsy protocol-specific magnetic resonance imaging of the brain, which includes thin-cut coronal slices to determine risk of recurrence and the need for long-term treatment. In patients who meet the criteria for diagnosis of epilepsy, a carefully selected antiepileptic medication with consideration of comorbidities, adverse effect profile, and type of epilepsy is essential along with appropriate counseling. Conclusions and Relevance: Approximately 3% of the population will develop epilepsy but 2 to 3 times as many patients will experience a single seizure or seizure-like event. A diagnosis of epilepsy has significant medical, social, and emotional consequences. A careful patient history and physical examination, electroencephalography, and brain imaging are necessary to separate patients with acute symptomatic seizures, single unprovoked seizures, and nonepileptic events from those with new-onset epilepsy.