Posted on Mar 16, 2011 under Epilepsy |
Since episodic electrical events can occur in different areas of the brain, the types of seizures that they produce will differ depending on what area is affected.
You heard a loud noise and ran to Johnny’s room. Your son was stiff, his back was arched, he didn’t seem to be breathing and he was turning blue. Then he started shaking violently, and he was foaming at the mouth. Your first thought was that he was about to die!
Mary was sitting with you at the dinner table when suddenly she stopped eating and stared into space. You called her, but she didn’t respond, and you had to call her several times. “Why does she daydream so often?” you wondered.
William comes running to you with a frightened look on his face. He is pale and then has a glassy look to his eyes. You call him, but he doesn’t respond. You notice that he is smacking his lips and fumbling with his clothes. Then as you hold him, he stiffens and begins to shake violently.
Trina began to have jerking at the corner of her mouth. “It’s just a habit,” your doctor said, but it’s gotten worse. Now the jerking is there all the time and sometimes it spreads to involve the whole side of her face.
All of these are seizures, and yet each differs. Each may require a different evaluation by your physician. Each may require different medication. Each may have a different outcome. The type of seizure depends largely on where in the brain it starts and on the direction and speed of the spread of the electrical activity.
Seizures are divided into two major groups, “partial seizures” and “generalized seizures.” “Partial seizures” (simple or complex), those that begin focally—that is, in one place—-are also called “focal” or “local” seizures. It is important to identify partial seizures because, since they begin focally, there may well be a specific problem in that area of the brain, one that may need special attention. The physician looks for a scar, a tangle of blood vessels, or a tumor as the cause of such seizures. If focal seizures cannot be controlled with medication, then surgery can be considered. “Generalized seizures,” on the other hand, seem to start all over the brain at once. We are unable to detect either by clinical signs or symptoms, and sometimes not even from the EEG, where this widespread electrical activity begins.
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Posted on Apr 28, 2009 under Epilepsy |
Any patient’s response to treatment with anti-epileptic drugs is based first on whether the seizures have reduced in frequency or stopped completely, and secondly whether there have been any side-effects. If a patient has good seizure control but unacceptable side-effects then the dose of the drug should be reduced slightly in the expectation that seizure control will continue, but the adverse effects become less prominent. If the patient has some, but not complete seizure control and no side-effects, then the dose is increased. Therefore, a patient is receiving the correct dose of the drug when the seizures have stopped and there are no side-effects. In the past, doctors used to emphasize the importance of blood tests to measure the amount of drug in the blood (called ‘therapeutic blood level monitoring’). This is because there is some relationship between the blood level of the drug and its therapeutic and toxic effects. That is to say, there are blood levels of anti-epileptic drugs below which therapeutic effects do not occur (the drug is unlikely to be effective), and above which no further benefit is achieved without causing toxicity. However, the ‘lowest’ and ‘highest’ levels in the blood are only approximate guidelines. For an individual patient the optimal or satisfactory blood level may lie outside these ranges. Up to 50 per cent of patients may be controlled with blood levels well below the lower limit of the range previously considered to be therapeutic, and up to 15-20 per cent of patients may be controlled with no side-effects with blood levels that are higher than the upper limit.
There are many factors which affect the blood levels of anti-epileptic drugs, including the chemical structure of the drug and how it is carried in the blood (usually attached to proteins); the age and sex of the patient; an individual’s metabolism of the drug (by either the kidney or liver, and whether there is any disease of these organs); and how regularly and reliably the drug is taken. Because of all these factors, the lack of a clear correlation between blood levels and effectiveness or toxicity, and the fact that a blood test may be distressing (particularly for children), doctors are now less inclined to monitor anti-epileptic drug blood levels. However, there are certain situations where measuring blood levels may be important, including:
* where there is the possibility of the patient not taking the drug as prescribed. This is one of the common reasons for poor seizure control. Measuring the blood level of the drug will go some way to confirm or exclude this possibility;
* if the patient presents in status epilepticus, that is, in a prolonged fit;
* if the patient has severe learning difficulties and is not able to tell the doctor of side-effects;
* if the patient is taking phenytoin, particularly with another anti-epileptic drug. This is because the metabolism of phenytoin is different from all other anti-epileptic drugs. A small change in dosage, either up or down, may respectively result in toxicity or loss of control of seizures.
* special situations, including pregnancy, or when there is a disorder of the kidney or liver. This is because these three situations may significantly affect how the drug is metabolized in the body.
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