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For us to understand the different types of seizures, we must first understand the brain itself. Our brain is like a team made up of many different workers, with each one having a job to do. As in any job communication between workers is very important. Each worker is responsible for different duties. One worker is in charge of understanding what the eyes see another for speech, and yet another controls the sense of smell.
Each worker in the brain is actually called a neuron. Neurons are like small telephone wires running through the brain. The wires send signals to different parts of the brain and this is what makes us think and move.
When a person has a seizure the neurons in the brain are either firing when they should not or they are not firing when they should. An uncontrolled discharge that affects several parts of the deep regions of the brain and then spreads to both sides is know as a generalized onset seizure. If the seizure happens in only an isolated part of the brain, it is known as a focal seizure. All types of epilepsy can be divided into these two categories.
Generalized-onset or convulsive seizures are what most people would think of when they think or epilepsy. In fact, about 90% of all people who suffer from this condition do have this type of epilepsy. The neuron discharge may begin in one part of the brain; it then travels throughout the brain. This type of seizure can cause muscle twitching, convulsions, salivating, rigidity: the person may urinate on themselves, or some other types of unnatural movement may occur.
This type of seizure can last for five minutes or more. A person having this type of seizure will lose consciousness during the seizure, but will wake up shortly after it is over. They will not remember what happened and will most likely be tired and dazed.
Tonic-clonic, which in the past were called grand mal seizures, is one type of general onset seizures. These happen when most to all of the neurons of the brain fire at the same time. The word tonic means to stiffen and clonic means to jerk. This type of seizure most often will involve convulsions, stiffening and jerking of the body, and a loss of consciousness.
Another type of general onset seizure is the absence or petit mal seizure. This type of seizure is non-convulsive. What happens here is that the part of the brain that makes a person aware can not communicate with the brain cortex. The person will lose awareness for a while, but is quick to regain it. The person can also lose muscle control and make some repetitive motions.
Examples of this would be; lip smacking, finger tapping, chewing, or pulling at clothing. The person generally looks like they have spaced out. For an inexperienced person this may look like the person is just not paying attention.
Myoclonic seizures involve discharges in the motor cortex. This is the part of the brain, which affects a person’s movement. They can cause a small amount of jerking of the arms and the leg. Most often this type of seizure will happen in the morning only. This is because they are triggered by lack of sleep. These are so mild that many people are having them without ever being diagnosed. This is because they are unaware that they are even having them.
A partial or focal seizure happens when abnormal discharges occur in small parts of the brain. If the seizure happens without the loss of consciousness, it is called a simple-partial. However, if a person has a change of awareness, but no actual loss of consciousness it is called a complex-partial.
Simple partial seizures usually only last for a short time. While this type of seizure is going on, the person might smell something peculiar. They may have a strange feeling or see flashing lights. Sometimes there will be some movement in the arms and hands. The person may also hear voices, which they do not understand. There are times when this type of seizure can happen with no visible reaction. This is called an aura and is a warning of bigger things to come.
A person who is having a complex-partial seizure can appear to be conscious, but is totally unaware of their surroundings. Warning signs to this type of seizure are rubbing of the hands, playing with an object, grinding teeth, or smacking lips. During this type of seizure the person will see and hear things that do not exist. Some may go back in time to events of the past.
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