TLE

An Overview of Epilepsy

A Bit of Background

      Epilepsy is a neurological disorder that affects the abilities of brain cells to transmit their messages to brain cells in other areas. A disruption in the brain causes the neurons to give off abnormal electrical signals amongst the cells. Epilepsy was written about as early as 2000 B.C. and mentioned in various ancient Greek, Chinese, and Indian texts as well as in the Bible. It wouldn't be until Hippocrates that its origin as a neurological disorder would be characterized. In the mid 1800's, extensive scientific studies were applied to epilepsy research. Accurate medicinal treatment did not begin until 1857 when Sir Charles Locock used a sedative to control epileptic seizures. Since then, the study of epilepsy, as well as the methods of control and treatment, has expanded tremendously into the great amount of information that is known about the disorder today (Patrick, 2009).


Modern Data and Statistics

     Epilepsy is one of the most common brain disorders in the world today, afflicting over 50 million people worldwide. Nearly 50% of all epilepsy cases affects those under the age of ten, making it a one in ten chance that a person will experience an epileptic seizure at least once in their lifetime (Engel, 2007). Cultural differences or a possible hereditary genes are possible factors that make epilepsy a more frequent occurrence in some parts of the world. Tanzania and Canada are two of the nations with the highest percentage of epileptic occurrences--at least four percent of the Tanzanian population and two percent of Canada's suffer from the disorder (Patrick, 2009).

      In their everyday functioning, people with epilepsy may experience emotional or psychological distress, perceived and experienced stigmas, social isolation, academic underachievement, sexual dysfunctions, and higher rates of suicide (McLin, 1992). In various nations around the world epilepsy is thought to be contagious and can be spread through saliva similar to rabies. It is often thought that a person should not marry, work alongside, or even associate with someone with epilepsy. A study in Henan, China, for example, found that over half of the people surveyed would object to having their children play with others with epilepsy (Engel et al., 2009).

Electrodes in Brain
Neurons. Image from http://www.flicker.com

Neurology of Epilepsy

     The National Institute of Neurological Disorders and Stroke has defined epilepsy to be "a brain disorder that causes people to have reoccurring seizures" (Engel, 2007) while the International League Against Epilepsy defines an epileptic seizure as "a transient occurrence of signs and/or symptoms due to abnormal excessive or synchronous neuronal activity in the brain."

     Though the causes are still uncertain, epilepsy has been linked with prenatal factors such as a premature birth and a higher age of the mother at birth (Engel, 2007). Head injuries, central nervous system infections, cerebrovascular disease (disease in the blood vessels supplying the brain), and drug withdrawal all can increase a person's susceptibility after birth. Unfortunately, between 60 and 70 percent of cases of epilepsy have no identifiable cause (Baker & Jacoby, 2000).

     The actual occurrence of a seizure is due to a substantial disruption of the electrical communication between neurons, leads to a temporary excess of energy in the brain. Neuronal communication is also controlled by the release of excitatory or inhibitory neurotransmitters that are sent from an axon through the synaptic space between neurons and picked up by the dendrites of another neuron. An excitatory neurotransmitter will activate the nervous system into action while an inhibitory neurotransmitter will prevent activity (Cotman et al., 1988). A seizure is induced when too many excitatory neurotransmitters are produced, or too few inhibitory transmitters are produced, both of which leads to hyperactivity in the brain.

Types of Seizure

      Seizures can range in form from large scale episodes to smaller brief disturbances, and can affect a person in parts of the body in many different ways. The modern classification system separates types of seizures into over 30 different sub-categories. The main two groupings divide the type of seizure into either a partial seizure, where only a confined area of the brain has a disruption of activity, or a generalized seizure, where throughout the brain neurons will have excessive electrical discharge. If the neuronal hyperactivity occurs in an area of the motor cortex, the section of the brain involved with movement, shaking or twitching will occur, whereas if the neurons typically have a sensory function the result may be a tingling sensation (Baker & Jacoby, 2000). Essentially, the symptoms someone feels from having a seizure depends on the original function of the neurons in that part of the brain.

     A simple partial, or focal seizure is one in which a person experiences sudden jerky movements of certain body parts while remaining conscious throughout the episode. This type of episode, also referred to as an aura, generally lasts only a short time and affects the functioning of sensation located in only certain parts of the brain. Auras contribute to many of the different sensations we will be describing in this website.

     A complex partial seizure instead, will cause impaired consciousness along with aimless actions that often cannot be recalled by the patient. Random walking, head or mouth movement, or mumbling are often the visible symptoms of a complex partial seizure. Often a complex partial seizure will begin as a simple partial seizure before the disruption in activity spreads to other areas of the brain (Epilepsynl.com).

*In temporal lobe epilepsy, these types of seizures often include other unique behavioral and perceptual symptoms that will be discussed on the following page.

     A generalized seizure is a seizure that isn't localized in a certain part of the brain. The major generalized seizures fall into two categories: tonic-clonic (formerly grand mal) or absence (petit mal). The term tonic-clonic was created because tonic means to stiffen, while clonic means jerking, so the term works as an account of what occurs during this type of seizure. In a tonic-clonic seizure a patient will fall to the ground, lose consciousness, become rigid and then quake for a short duration. Absence seizures mainly occur in children and can turn into tonic-clonic or complex partial seizures if they persist with age. In an absence seizure there is a lose of consciousness where the child will appear to stare blankly into space for around ten seconds, after which he will return to a normal state and often be unaware that a seizure has just occurred (Epilepsynl.com).

Diagnosis and Treatment

     Epilepsy can be diagnosed in a person if he or she has experienced a seizure and a scan with an electroencephalograph (EEG) shows abnormal brain activity, as an EEG can help to classify the seizure type. Problems with cognitive and memory functioning have been associated with certain anti-seizure drugs, though. Preventative measures for epilepsy range from antiseizure drugs to brain surgery in more severe cases. There is still no cure for epilepsy but modern innovations have made the disease a more than manageable condition (Black, 1995). Lifestyle changes such as getting enough sleep on a regular schedule, getting routine exercise, eating well-balanced and nutritious meals, avoiding caffeine, artificial sweeteners, alcohol and illegal drugs all can help to prevent seizures (Epilepsynl.com).  

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