DEFINITIONS
Epileptic seizure: A paroxysmal event characterized by a series of recurrent electrical discharges ("short circuit") of a pathologically synchronized population of cerebral cortex neurons and manifests with a sudden onset of consciousness disturbance and / or other neurologic manifestation.
Epilepsy: A disease characterized by a tendency of the brain to produce seizures. A single seizure may be sufficient for the diagnosis of epilepsy to be assigned, as long as it can be accounted for by an identifiable brain disorder (anatomical, biochemical and / or genetic) and is 'unprovoked', that is, it is not immediately preceded by an event known to be harmful to the brain. A distinction must be drawn between the terms 'epilepsy', which is a disease and 'epileptic seizure', which is an event that may or may not occur in the context of epilepsy.
Focal seizures & epilepsy: Clinical manifestations and electroencephalographic abnormalities demonstrate abnormally synchronized electrical neuronal discharges of a cortical area of one of both cerebral hemispheres (epileptic seizure). They are due to anatomical (or less frequently to a purely neurochemical and / or genetic) pathology.
Generalized seizures & epilepsy: Clinical manifestations and electroencephalographic abnormalities demonstrate a pathological series of recurrent electrical neuronal discharges synchronized in both hemispheres. They are usually due to neurochemical and / or genetic (or rarely anatomical) damage that predisposes to abnormal bihemispheric electrical synchrony, which presupposes simultaneous seizure activity of central brain structures, notably the thalamus.
Status Epilepticus: According to the classical definition, 30 or more minutes of continuous or recurrent seizures without recovery of consciousness and/or other neurologic functions between the seizures. According to current practice, even 5 minutes of epileptic activity should be considered and treated as 'status epilepticus'. The most dangerous form is generalized tonic-clonic status epilepticus.
INCIDENCE AND PREVALENCE
About 50 million people worldwide suffer from epilepsy. The highest incidence is in people under 2 years of age and over 65. Taken together, the prevalence of the disease is 1% up to the age of 20, reaching 3% up to the age of 75 and, by this age, the probability of having suffered at least one seizure is estimated at around 10%. Up to 5% of the population will have at least one seizure during their lifetime. In Greece, it is estimated that 100-120 thousand people suffer from the disease.
ETIOLOGY & CLASSIFICATION
Any process that damages the structure or function of the cortex may cause epilepsy. A lesion can be identified, usually demonstrated in imaging studies (CT or MRI) in about 70% of epilepsy cases. In cases of childhood onset epilepsy, the most common causes are cortical malformations and other congenital disorders, perinatal events and infections. Among adult onset epilepsy, about half are due to a stroke, while other common causes are brain tumors and post-traumatic epilepsy. Hippocampal sclerosis (or more generally mesial temporal sclerosis) is also common, a condition of unclear etiology, possibly related to a viral infection in childhood or infancy.
In about 30% of cases the etiology of epilepsy is thought to be related to the intrinsic (usually of polygenic etiology) sensitivity of neural circuits to epileptic activity, and the disease is characterized as 'idiopathic'. Most idiopathic epilepsy are generalized.
ANCILLARY DIAGNOSTIC TESTS IN EPILEPSY
The main ones are electroencephalogram (EEG) and neuroimaging.
EEG has an important auxiliary role. Identifying epileptic ("sharp") abnormalities in EEG increases the probability that the episode being investigated was indeed epileptic. It should be kept in mind that EEG may be normal in people with epilepsy. When EEG reveals epileptic abnormalities consistent with the observed episodes, it practically confirms the diagnosis of epilepsy and contributes decisively to its classification. If not, its diagnostic value is relative and is taken into account with the rest of the data.
Neuroimaging (CT, MRI, etc.) helps identify anatomical brain injury (when present) that causes epilepsy.