Seizure Diagnosis and Classification

Diagnostic Framework

The American College of Emergency Physicians provides a critical temporal distinction that must be documented in the diagnosis, distinguishing between provoked and unprovoked seizures, with the former occurring at the time of or within 7 days of an acute neurologic, systemic, metabolic, or toxic insult 1, 2
The American College of Emergency Physicians recommends documenting when the seizure occurs at the time of or within 7 days of an acute neurologic, systemic, metabolic, or toxic insult, such as hyponatremia, hypocalcemia, alcohol withdrawal, toxic ingestions, encephalitis, or acute CNS mass lesions 1, 2

The American College of Emergency Physicians emphasizes that metabolic abnormalities can be identified by history and physical examination in most cases, but not all, and recommends checking for hypoglycemia immediately in all seizure patients 4
The American Academy of Neurology recommends MRI as the preferred modality when neuroimaging is obtained, and documenting any mass lesions, stroke, hemorrhage, or structural abnormalities 4
Focal neurologic deficits are found in 81% of patients with focal CT lesions, but 17% with normal neurologic exams still had focal CT abnormalities 4
CT abnormalities are found in 34% of patients overall, highest in those >60 years, and the American College of Emergency Physicians recommends documenting any CT abnormalities 4

Hypoglycemia should be checked immediately in all seizure patients, as it is a common cause of seizures 6, 3
Hyponatremia is the most common electrolyte cause of seizures, and hypocalcemia can trigger seizures at any age, even without prior history 4, 3
Hypomagnesemia is particularly common in alcohol-related seizures, and uremia and hyperglycemia can also cause seizures 4, 3

The International League Against Epilepsy classification should be used to specify the seizure semiology based on the type of seizure, such as focal or generalized 1, 2
The American College of Emergency Physicians recommends documenting the seizure type, including whether it is a provoked or unprovoked seizure, and the underlying etiology 1, 2