Biology 202
1998 Second Web Reports
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Zach Hettinger


Epilepsy is a neurological disorder in the brain that effects millions of people in the United States alone. It can manifest in several ways, but all forms exhibit uninduced seizures(not immediately induced from drugs, alcohol, head trauma, or high fever). Seizures can also vary in intensity, ranging from mild occurrences to life threatening attacks. Most cases of epilepsy begin in childhood with a substantial number disappearing in adulthood for various reason, including treatment. Treatment can vary from antiepilepsy medications to certain cases which call for the removal of pieces of the brain.

In an attempt to greater understand epilepsy, a classification system was developed that groups seizures according to how they effect the body. These groups are not hard and fast, but do tend to have distinct symptoms. It is important to keep in mind that it is also possible for an episode of seizures to start as one type and then evolve into another. A common example of this is that some people experience what are referred to as auras, which are precursors to full blown seizure. The auras are only minor seizures, but they can be very helpful in allowing people to prepare for the impending episode.

The classification system initially groups seizures as either partial and generalized. Partial seizures are localized in one part of the brain while generalized seizures effect the entire brain. Partial seizures can then be further divided into simple partial and complex partial. Simple partial seizures can consist of sudden and jerky motions of body parts, problems in hearing and seeing, stomach discomfort, and/or a sense of fear, all depending on what part of the brain the epilepsy is located in(1). It is interesting to note that during a partial seizure episode the person is fully aware of what is going on and will have a complete memory of the occurrence. Auras are a manifestation of this group of seizures. Complex partial seizures differ from the simple variety in several ways, but one of the most striking is that the person has no memory of the event afterwards. The symptoms of a complex partial seizure often consist of the person having a very automated appearance(a result of a lack of conscious awareness), aimless walking, mumbling, head turning, and pulling at clothing(1).

I found the differences between the complex and simple seizures to be intriguing in regards to our conversations of the I-function. It seems that the I-function is being effected by the seizures because the simple partial allows the person to experience and remember the occurrence, whereas the complex seizure leaves the person with no memory, even though they are still exhibiting complex physical behavior. This also provides further evidence that the I-function does not have to be "present" in order for the body to perform complex behavior.

There are also two commonly found generalized seizures referred to as absence and tonic-clonic, formerly known as petit mal and grand mal. Absence seizures consist of lapses in consciousness for 5 to 15 seconds and have no effect on the person once they are done. These are most often observed in childhood, with most children outgrowing them, although some cases develop into more serious situations(1). Tonic-clonic seizures consist of the person first losing consciousness and going rigid(tonic phase), a series of violent convulsions(clonic phase), and then consciousness is regained over time(2).

The last group of seizures, tonic-clonic, is what most people think of when epilepsy comes to mind, but they only account for a small percentage of what most epileptic people experience, they are just the most visible. 62% of people suffering from epilepsy have partial seizures and complex partial seizures make up 30% of reported cases.(1) So it's important to not let popular opinion effect how one approaches what is a common and very often controllable neurological disorder.

Now that the framework for evaluation and treatment of epilepsy is in place it's important to understand where epilepsy comes from. Which is a difficult problem because somewhere close to 65% of cases are idiopathic, meaning they have no know cause(1). Of those that are known, symptomatic, there are many different explanations for the disorder, including:

Although the above list is made up of environmental causes, scientists are finding that more and more types of seizures(there are upwards of 40 types) can be explained in terms of genetics. In the past it was said that people had a "seizure threshold"(1) that could be effectively lowered or raised according to ones genetics. This threshold consisted of some point where a certain level of environmental stimuli were necessary to cause seizures, but that genes did not directly cause epilepsy. Yet as genetic research builds up in this area, more and more types of seizures are being attributed to genetic causes. It was recently discovered in mice that a certain protein involved in the storage of calcium ions could cause epileptic behavior in mice that had a damaged gene for that protein(3). It seems amazing that a small defect in the genome could cause such drastic behavioral abnormalities. But when considering the importance of charged particles in the nervous system it makes perfect sense. Seizures are basically uncontrollable electrical activity in the nervous system and a lack of control of ions would easily lead to widespread problems. In recent times two more genes were found to be linked to epilepsy, including a protein that is instrumental in preventing other vital proteins from being degraded. When this key protein is damaged, epilepsy is found in that individual, it seems to play some sort of antiepilepsy function, whether through design or by default(4). Another gene was found in a particular family that is potentially linked to the occurrence of partial seizures, the most common type of seizure(5). While each of these new discoveries are small in their scope of whom they directly effect, they are aiding in establishing the biochemical pathways in the body and nervous system that are involved in epilepsy. This importance of genetic factors is very evident when looking at the prevalence of epilepsy in different cultural groups. The research done on the protein that has antiepileptic properties was performed because that particular form of epilepsy is very prevalent in Finland, whereas the same disorder is very rare in the United States(4). Epilepsy is also known to be very prevalent in Tanzania where 4% of the population suffers from it, compared to Canada where only 1-2% of the country is afflicted. Thus genetic factors can not be disregarded.

Treatment can vary depending on the type of seizures that a person is experiencing. If the seizures are mild than one can elect to give them time to see if they will go away on their own, which happens to a lot of childhood cases. If the seizures are more severe or persist over time then the next step is to use antiepileptic drugs. A large majority of the time the drugs can be used for a period of a year and then have the patient slowly weaned off them, and then never suffer from another seizure. In some cases the drug treatment must go on indefinitely and possibly have to rely on a combination of antiepileptic drugs. The last alternative in the most severe of cases is surgery. This technique consists of identify the particular part of the brain that is damaged and then removing it. Because of it's nature, surgery is only possible on those that suffer from partial seizures because the problem must be isolated, otherwise it would do no good to only remove a piece of the brain. In addition to the formal methods of treatment above, there has also been growing consideration of using marijuana in treating epilepsy(6).B ut this is still being debated and has not been accepted into standard treatment.

Over the course of the semester we talked about the nervous system in terms of boxes and how they are connected to one and other to produce behavior. Brain(box)=behavior. But for the most part we kept the resolution of our boxes at the level of large groups of neurons, never getting any smaller then the neuron itself. But now with the incorporation of "epilepsy genes" the line between neurobiology and genetics has become unclear. It continually amazes me that we can observe a behavior and then work at breaking it down to neurological activity and then genetics. Obviously not all behavior is a result of genetics, for each of the genes that have been found only effect a small number of people suffering from epilepsy, but it points to the presence of a strong relationship between, genetics, neurobiology and behavior. At some point we will not only completely understand how and why the nervous system works, but we will be able to help heal and mend it in its entirety.



1-Epilepsy FAQ

2-Seizures and Epilepsy-Frequently asked Questions

3-Identifying Epilepsy Inhibiting Protein

4-New Epilepsy Gene

5-Common epilepsy Discovered Linked to Chromosome 10

6-Panel Recommends Testing Medical Use of Marijuana

7-General Epilepsy information[links]

8-Comprehensive Epilepsy Program-Recent News

9-Mike's Epilepsy Home Page[links]



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This paper reflects the research and thoughts of a student at the time the paper was written for a course at Bryn Mawr College. Like other materials on Serendip, it is not intended to be "authoritative" but rather to help others further develop their own explorations. Web links were active as of the time the paper was posted but are not updated.

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