Sudden, recurrent bursts of excessive neuronal activity produce the seizures that define epilepsy. The discharges can remain localized or spread to involve both hemispheres, generating symptoms that range from brief lapses of awareness to full convulsive episodes.

Causes include genetic mutations affecting ion channels or synaptic proteins, structural lesions such as scars or tumors, developmental malformations, and in many cases remain unknown. Diagnosis relies on clinical history, EEG, and imaging to identify the seizure type and any underlying focus. Treatment begins with antiseizure medications that modulate excitability; when drugs fail, surgery, neuromodulation, or dietary therapies may be considered.

The impact of epilepsy extends beyond the seizures themselves to effects on mood, cognition, and social participation. Research into the basic mechanisms of seizure generation and into closed-loop stimulation systems continues to expand therapeutic options.

Accurate classification of seizure type remains the starting point for effective management.