Epilepsy: Causes, Types, and Treatments

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  • 0:35 What Is Epilepsy
  • 2:06 Why Does Epilepsy Occur
  • 4:40 Clinical Signs,…
  • 7:02 Treatment of Epilepsy
  • 7:41 Lesson Summary
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Lesson Transcript
Instructor: Artem Cheprasov
This lesson will go over seizures and epilepsy. We'll define the difference, go over why it may occur, how it is diagnosed, and how some treatments work to stop the seizures that cause epilepsy.

Overexcitement in the Brain

It's great to get excited about things. Excited about a first date, a field trip, or going to grab some dinner with friends. This excitement makes us feel really good. Other times, being a bit too excited can actually be bad. Sometimes, we're even told to 'calm down' because we get so excited. This lesson will explore a similar process of overexcitement, but one that occurs in our brain; overexcitement that may sometimes be so severe that it can actually kill us.

What is Epilepsy?

The disorder that causes such an overexcitement is called epilepsy. It is a central nervous system condition where the brain experiences recurrent seizures. A seizure is the outward manifestation of the synchronous and excessive excitement of nerve cells. As a basic overview, a seizure is when someone experiences uncontrollable shaking of the body, loss of consciousness, and more. We'll get into the many different types of seizures later on.

About 1% of the United States population may have a seizure in their lifetime. However, one seizure does not epilepsy make. Again, epilepsy implies that someone is experiencing recurrent seizures. Someone can have one seizure as a result of a very high temperature but will never have one again otherwise.

The causes of epilepsy, or recurrent seizures, are unclear. Everything from infectious diseases, flashing lights, and strokes, to head trauma and drugs may lead to the development of epilepsy. Why one person with the same set of circumstances will develop epilepsy over another is uncertain; that's why a genetic cause is suspected as well. What we do know for sure is that epilepsy affects millions of people worldwide and causes serious economic implications in just the U.S. alone, where over $15 billion worth of direct and indirect costs related to epilepsy are accounted for.

Why Does Epilepsy Occur?

While we aren't exactly sure of the cause of epilepsy, we have a slightly better idea of what goes on in the brain that causes someone to have a seizure. The exact nature of what we believe goes on is highly detailed and way beyond this lesson's scope, but I'll try to boil everything down for you to some of the most important points.

Your brain is made up of billions of nerve cells called neurons. These nerve cells signal to one another via an electrochemical signal called an action potential. These neurons fire off electrochemical signals that depend on ions such as calcium, potassium and sodium, and also on chemical messengers such as glutamate. Glutamate is the major excitatory neurotransmitter in the brain. An important glutamate activated receptor responsible for the excitatory function of the central nervous system is known as the NMDA receptor.

When glutamate lands on structures such as the NMDA receptor of a nerve cell, it causes the cell to depolarize, that is to say become excited, and fire off a signal, known as the action potential. The depolarization, or excitation of the nerve cell, occurs thanks to the fact that sodium and calcium enter the cell while potassium leaves the nerve cell.

You can liken the glutamate to a ball that is thrown at a receptor, like a target on a dunk tank. As soon as the ball hits the target, a signal is sent to dump the person in the water. As soon as glutamate hits its receptors, including the NMDA receptor, the signal is sent to excite the nerve cell to fire off an excitatory signal.

If a nerve cell has a defect that causes it to keep firing off an action potential over and over again, a lot of glutamate is released into the surrounding area, causing other cells to begin firing off the action potentials uncontrollably all at the same time. These focal discharges can spread from one little spot in the brain to the entire brain, leading to generalized seizures, both of which are again a synchronous and excessive excitation of nerve cells.

Since your brain becomes overwhelmed with massive amounts of synchronous signaling, it loses control over its ability to interpret environmental cues, or stop itself from sending out erroneous signals to its body, resulting in the typical signs and symptoms of epilepsy.

Clinical Signs, Symptoms, and Diagnostics

Depending on the severity of the seizure, its propagation in the brain, and so forth, different types of signs and symptoms may be seen. There are:

  • Partial (focal) seizures, such as simple seizures which don't results in a person's loss of consciousness but may cause jerking of body parts, emotional changes, and changes in the way a person perceives light, sound, and touch.

There are also six main types of generalized seizures. These include:

  • Absence (petit mal) seizures that results in a person staring out into space for a few seconds even if they were in the middle of doing something
  • Tonic seizures that result in stiffness of a person's muscles, causing them to fall down
  • Clonic seizures that cause a person to repetitively move their body in a jerking motion
  • Myoclonic seizures which result in a person sporadically, as opposed to rhythmically, moving their legs, arms, or neck in a jerking motion
  • Atonic seizures where, in contrast to tonic or clonic seizures, a person loses muscle tone and therefore drops like a limp rag to the floor instead
  • Tonic-clonic (grand mal) seizures where a person loses consciousness, has muscle rigidity along with violent shaking, jerking, and loss of bladder and bowel control

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