From the Guidelines
The most common cause of a first-time seizure in adults is an acute symptomatic seizure, which occurs secondary to an acute brain insult, with stroke being the leading cause, accounting for approximately 30-45% of first-time adult seizures. This is based on the evidence from various studies, including 1, which highlights the importance of identifying and treating the underlying cause of the seizure. Other significant causes of first-time seizures in adults include alcohol withdrawal, drug toxicity or withdrawal, metabolic disturbances (such as hypoglycemia, hyponatremia, or hypocalcemia), central nervous system infections (meningitis or encephalitis), brain tumors, and head trauma.
When evaluating a patient with a first-time seizure, immediate management should include:
- Ensuring airway protection
- Obtaining basic laboratory studies (including electrolytes, glucose, toxicology screen)
- Neuroimaging (preferably MRI, though CT may be used initially)
- An electroencephalogram (EEG) to assess for epileptiform activity
It's essential to note that a single seizure does not necessarily indicate epilepsy, which is defined as having two or more unprovoked seizures. Treatment decisions should be individualized based on the underlying cause, with correction of metabolic abnormalities, treatment of infections, or management of withdrawal syndromes as appropriate. Antiseizure medication is not always initiated after a first seizure unless there is a high risk of recurrence or an underlying structural abnormality, as suggested by 1.
The evidence from 1 and 1 also supports the idea that laboratory testing is of low yield in patients with a new-onset seizure who have returned to baseline, and that the history and physical examination can predict the majority of patients who will have a laboratory abnormality. However, the most recent and highest quality study 1 provides the most relevant guidance on the management of first-time seizures in adults.
From the Research
Causes of First-Time Adult Seizure
- Acute symptomatic seizures are the most common cause of first-time adult seizures, accounting for about 40% of all first seizures 2
- These seizures are closely related to neurological or systemic insults, such as:
- Acute stroke
- Traumatic brain injury
- Central nervous system infections
- Medication
- Alcohol and illicit drugs
- Electrolytic and metabolic disorders
- Anoxic encephalopathy
- Eclampsia
- Reversible posterior leukoencephalopathy
- Limbic encephalitis 2
- Traumatic brain injury is also a significant cause of first-time adult seizures, with post-traumatic epilepsy accounting for 10-20% of epilepsy cases in the general population 3
Diagnosis and Management
- Careful history and clinical examination should guide clinicians' management plans for first-time adult seizures 4
- Electroencephalography and brain imaging, preferably with epilepsy-specific magnetic resonance imaging, may help characterize both etiology and risk of seizure recurrence 4
- Antiepileptic drugs should be initiated in patients with newly diagnosed epilepsy, and the decision to prescribe drugs in patients without an epilepsy diagnosis depends on individual risk factors for seizure recurrence and possible complications from seizures 4