What Is Epilepsy?
Epilepsy is one of the most common and disabling brain disorders. It causes seizures. Seizures can occur cyclically but with repetitive onset of sudden attacks. It happens when there is abnormal electrical activity in your brain cells called neurons. This abnormality involves the excessive, hypersynchronous firing of neurons in your brain. Hypersynchronous means there is firing of neurons together that propagates from one group of neurons to the next leading to a strong build-up of activity.
Put in another way, an epileptic seizure is caused by abnormal neuronal firing. The term epilepsy is defined as a condition in which you have recurrent and unprovoked seizures. If you've had two or more seizures in your lifetime, there is a good chance that you may be epileptic. An epilepsy syndrome is a group of characteristics that consistently occur together. Patients may have similar seizure types, age of onset, triggering factors, genetics, EEG findings, natural history, prognosis, and response to antiepileptic drugs.
We will be looking at how common epilepsy is, its classification, diagnosis, a few epilepsy syndromes, and its treatment in this article.
How Common Is Epilepsy?
Epilepsy is relatively common. It has an incidence of about 50 new cases per year per 100,000 population. About 1% of the population is affected. One-third of patients have drug-resistant epilepsy. Roughly 75% of epilepsies start during childhood.
Classification: Generalized, Focal, and Epileptic Spasms
Seizures are separated into three categories: generalized, focal and epileptic spasms. Focal seizures originate in and are limited to one cerebral hemisphere. Generalized seizures begin in and affect both hemispheres. A seizure can start off focally and later generalize.
There are four types of generalized seizures: generalized tonic-clonic (GTC), absence, myoclonic, and atonic.
In GTC seizures, you lose consciousness. You also experience bilateral symmetric convulsive movements, stiffening followed by jerking, of all limbs.
With absence seizures, you may stare or sometimes blink your eyes or nod your head. You become unresponsive to external stimuli.
Myoclonic seizures involve sudden, brief, lighting fast, movements. These short-lived involuntary muscle contractions may affect one or several of your muscles. Hence, myoclonic seizures can be generalized or focal. You may not lose consciousness while this is happening.
Atonic seizures cause you to lose your body tone. Often it results in a head drop or fall.
The characteristics of focal seizures depend on the area of the cortex affected. For instance, a focal seizure arising from the occipital lobe may involve visual phenomena. One arising from the precentral gyrus may present with rhythmic clonic or tonic motor activity. When the postcentral gyrus is involved, there may be sensory symptoms such as paresthesias (tingling or prickling sensation). When you lose consciousness during a focal seizure, the seizure is classified as dyscognitive. Seizures originating in the temporal lobe are often dyscognitive.