What is epilepsy?
Epilepsy is the tendency to have recurrent seizures. It is the same thing as a seizure disorder. A single seizure does not constitute epilepsy.
The International League Against Epilepsy (ILAE) has recently classified epilepsy as a disease, instead of a disorder, to better convey that epilepsy is a serious medical condition.
How does our nervous system work?
As the diagram shows, nerves throughout the body act like telephone lines, allowing the brain to communicate with the rest of the body via signals. This is our nervous system, and it is critical to who we are:
“From the moment we are born to the moment we die, this communications network controls our every thought, our every emotion, every step we take, every impression we get. Without it we could not plan, feel, move a muscle, nor distinguish between pleasure and pain; we would be deprived of such amenities of life as the enjoyment of food, or music, or the colour of a painting, or the pressure of a friendly handshake.” The Body, Life Science Library, p141
In a person with epilepsy, the brain’s neurological system occasionally malfunctions.
How does our brain work?
One part is in charge of understanding what the eyes see; another part directs speech; a different part controls hearing; still another exercises reason. The left side of the brain controls movement on the right side of the body and receives sensation from the right side of the body, and vice versa.
Evidence suggests that the left hemisphere of the brain tends to deal with reasoning and communication and the right hemisphere with emotions and perception of shapes. All parts of the brain work and talk to each other over a network of cells called neurons and nerve fibres.
The brain works on electricity. The normal brain is constantly generating electrical rhythms in an orderly way. Millions of tiny electrical charges pass between a network of nerve cells in the brain and to all parts of the body via chemical messaging systems called neurotransmitters, which cause the nerve cells to fire or stop firing.
In simple terms, the nerve cells, called neurons, are the brains’s telephone system, sending electric charges from one point to another.
Normal human experiences occur when specialized parts of the brain responsible for taste, smell, movement, memory etc. are significantly excited. This is how we think, feel and move.
Move your finger now. When you do so, muscle fibres on each side of your finger joint are involved in the movement. Different groups of brain cells control different muscle fibres and their coordinated firing is what allows you to manipulate your finger smoothly.
What is a seizure?
A seizure occurs when the normal electrical balance in the brain is lost. The brain’s nerve cells misfire; they either fire when they shouldn’t or don’t fire when they should. The result is a sudden, brief, uncontrolled burst of abnormal electrical activity in the brain. Seizures are the physical effects of such unusual burst of electrical energy in the brain.
During a seizure, out-of-sync signals from the brain travel along the nervous system pathway to sensors, like the nerves that sense light in the eyes or the nerves that flex muscles. These misfiring signals may keep the brain from understanding what the eyes see, so the person stares during a seizure. Or they may affect leg muscle tone and cause a person to fall down. The type of seizure depends on how many cells fire and which area of the brain is involved. A seizure may be an alteration in behaviour, consciousness, movement, perception and/or sensation.
What is a seizure threshold?
A seizure threshold is the level of stimulation at which your brain will have a seizure. A very high fever, for instance, can sufficiently excite anyone’s brain to produce a seizure.
People with epilepsy have a lower-than-normal seizure threshold, meaning that only slightly increased excitement will cause them to have a seizure. Your seizure threshold is mostly genetically inherited, but other factors can affect this level. Young age and high fever are two factors that may lower one’s threshold, making a child more likely to have a seizure.
What causes epilepsy?
Epilepsy has many different causes. In any given individual, the cause is a combination of their genetically-determined seizure threshold, an underlying abnormality in the brain which predisposes them to epilepsy and factors which bring on epilepsy at that time.
Determining the specific cause for any one person’s epilepsy is usually difficult. In about 60 % of all cases, no specific cause is found, much to the frustration of the epilepsy patients involved. Epilepsy of an unknown origin is called idiopathic epilepsy. In many cases it is presumed to be genetic.
When the cause of a person’s epilepsy is identifiable, it is called symptomatic epilepsy. Basically, any lesion, scar, tangle of blood vessels or any other abnormality in the brain that can interfere with its delicate electrical workings can cause epilepsy. Common causes are head injury (eg. from a car accident); brain tumour, scar or lesion; brain injury during fetal development; birth trauma (eg. lack of oxygen during labour); aftermath of infectious diseases (eg. meningitis, encephalitis, measles); poisoning from substance abuse, like alcohol; and stroke.
If epilepsy is due to an acquired brain lesion which has not been identified, or the cause of which is unknown, its cause is termed cryptogenic (hidden).
Is epilepsy genetically inherited?
Some forms of epilepsy have now been linked to specific genes. In addition, scientists believe that everyone inherits a seizure threshold which determines how susceptible you are to seizures, but whether or not you ever develop epilepsy is another story. In fact, in most cases epilepsy develops without any family history of the condition.
If a parent has seizures, the likelihood of passing epilepsy on to their child is estimated to be about 6%, compared to a 1% or 2% risk of epilepsy in the general population. Basically, unless both parents have a strong family history of epilepsy, the chances that any of their children will inherit the tendency to have seizures are quite low.
Is epilepsy contagious?
No, epilepsy is not contagious. You cannot “catch” epilepsy from another person.
What is the history of epilepsy?
As far back as the historical record goes, people have always had epilepsy. Typically misunderstood and regarded with superstition, epilepsy has historically been mistreated in strange and horrific ways.
Exorcism, ointments, amulets and enemas were used as treatments in ancient Babylon, for example. Ancient peoples often believed that seizures were curses of gods and that people with epilepsy held prophetic powers. Attitudes of past societies toward epilepsy have left a legacy of stigma and damaging misconceptions that still persists today.
Some of the most exceptionally creative and talented people in history have had epilepsy, including: St. Paul, Alexander the Great, Julius Caesar, Dante, Joan of Arc, Isaac Newton, Molière, Napoleon Bonaparte, Handel, Beethoven, Flaubert, Paganini, Tennyson, Byron, Charles Dickens, Fydor Dostoyevsky, Vincent Van Gogh, Lewis Carroll, Alfred Nobel, Agatha Christie, Richard Burton.