epileptiformie

Epileptiformie is the French term used to describe patterns of brain electrical activity associated with epilepsy, visible on electroencephalography (EEG). It denotes abnormal hyperexcitability and synchronization of cortical neurons. Epileptiform patterns include spikes, sharp waves, and spike-and-wave discharges. They can occur between seizures (interictal) or during seizures (ictal) and may be focal or generalized.

Spikes are brief waveforms lasting less than 70 milliseconds; sharp waves last 70–200 ms. Spike-and-wave complexes are bursts of spikes followed by a slow wave, often seen in generalized epilepsy, notably around 3 Hz in childhood absence seizures. Interictal epileptiform discharges (IEDs) are observed between clinical seizures and point to an epileptogenic zone.

Pathophysiology involves an imbalance between excitatory and inhibitory mechanisms, including dysfunction of inhibitory interneurons and increased neuronal excitability due to ion channel abnormalities. Clinically, epileptiform patterns support the diagnosis of epilepsy and help localize epileptogenic regions, but they are not necessary for diagnosis and can occur in other brain disorders. Their presence informs prognosis and treatment decisions, but not all patients with epilepsy show IEDs on EEG.

Associated conditions include acute brain injuries, infections (encephalitis), tumors, metabolic disturbances, and genetic epilepsies. Patterns may be influenced by sleep, medications, age, and underlying pathology; sleep deprivation and certain sedatives can increase the yield of epileptiform discharges.

Interpretation and limitations: EEG findings must be integrated with clinical history. A normal EEG does not rule out epilepsy, and treatment decisions rely on the overall clinical context. In some cases, long-term video-EEG monitoring or additional imaging is used to clarify the significance of epileptiform patterns.