Epilepsy Tổng quan về bệnh

Giới thiệu

Unprovoked seizures are seizures that occur without a potentially responsible clinical condition or beyond the interval estimated for the occurrence of acute symptomatic seizures. These are classified as either seizures of unknown etiology or seizures that occur due to a preexisting brain lesion or progressive nervous system disorder.  

Epilepsy is a clinical multiaxial diagnosis. It is a disorder of the brain characterized by an enduring predisposition to generate epileptic seizures and by the neurobiologic, cognitive, psychological and social consequences of this condition.  

Epilepsy may be defined by any of the following conditions:  

• At least two unprovoked (or reflex) seizures occurring >24 hours apart
• One unprovoked (or reflex) seizure and a probability of further seizures similar to the general recurrence risk (at least 60%) after two unprovoked seizures, occurring over the next 10 years
• Diagnosis of epileptic syndrome

Dịch tễ học

In the United States, an estimated 150,000 adults annually present with an unprovoked first seizure. Approximately 40-50% of these incident seizures recur and are classified as epilepsy. The lifetime cumulative risk of developing recurrent unprovoked seizures or epilepsy by the age of 80 years ranges from 1.4-3.3%. In adults, the incidence of epilepsy increases with advancing age.

Asia has a lower incidence of epilepsy compared to Latin America or Africa but has a higher incidence than Western nations due to endemic nervous system infections (eg neurocysticecosis, tuberculosis, cerebral malaria). In Asia, the International League Against Epilepsy (ILAE) classification reports that generalized seizures can be found in the range of 50-69%, while focal seizures are present in 31-50%.

Nguyên nhân

The etiologies of epilepsy based on the International League Against Epilepsy (ILAE) classification include structural (eg hippocampal sclerosis, brain tumors, vascular malformations, glial scarring, brain inflammation), genetic, infectious (cerebral infections caused by bacteria, viruses, fungi and parasites), metabolic (eg organ [kidney, liver, pancreas] failure, toxins), immune (eg autoimmune encephalitis), neurodegenerative (eg Alzheimer’s disease, Parkinson’s disease), and unknown. 

Sinh lý bệnh

An epileptic seizure is a transient occurrence of signs/symptoms brought about by abnormal excessive or synchronous neuronal activity in the brain. An epileptic seizure represents a disruption in the normal balance between excitatory and inhibitory currents or neurotransmission in the brain. Drugs or pathogenic processes that augment excitation or impair inhibition tend to be epileptogenic, while antiepileptic drugs tend to facilitate inhibition and dampen excitation.

Yếu tố nguy cơ

There is an increased risk of epilepsy following head trauma, stroke, degenerative changes in the brain (eg Alzheimer disease), central nervous system infections, a history of neurologic deficit from birth (eg cerebral palsy), migraine headache and neurocutaneous syndromes.