Seizure (G40.909)

An epileptic seizure is a transient occurrence of signs and/or symptoms due to abnormal, excessive, or synchronous neuronal activity in the brain. Clinically, these events are classified into focal onset (localized to one hemisphere, with or without impaired awareness or evolution to bilateral tonic-clonic activity) and generalized onset (engaging bilateral networks symmetrically from inception, such as absence or tonic-clonic presentations). Presentations vary widely based on the cortical region involved, ranging from motor convulsions and automatisms to non-motor sensory, autonomic, or cognitive disruptions. While a provoked seizure stems from an acute systemic or metabolic insult (e.g., severe hypoglycemia, alcohol withdrawal, acute head trauma), epilepsy is characterized by an enduring predisposition to generate recurrent, unprovoked seizures. Evaluation requires distinguishing true ictal events from mimics like syncope or psychogenic non-epileptic seizures (PNES), typically guided by clinical history, electroencephalography (EEG), and neuroimaging.

Therapeutic area: Neurology