Epilepsy is a very common problem in brain-injured children. It is very distressing to watch and can be debilitating for the child. It is also exceptionally varied, ranging from a few unnatural blinks of the eye through to a ‘whole body’ convulsion. Just when I think, I have witnessed probably just about every variety of epileptic attack, up pops a child who produces something unique.
What is epilepsy?
Epilepsy is the tendency of specific brain-cells to misfire. There are three distinctions of epilepsy to bear in mind in understanding this problem. The first distinction is that an epileptic episode is either partial or generalised. The second distinction is that an epileptic episode is either simple or complex. The third distinction is that epileptic seizures are either grand mal or petit mal. Confused? – Don’t worry, read on and it will all become clear.
Normally, brain cells fire according to their being excited beyond a certain threshold of stimulation, or they are restrained from firing because they are inhibited from doing so. Sometimes in epilepsy, these inhibition and excitation thresholds are not applied successfully, causing brain cells to misfire very easily. When this happens, two things can occur:
1. The misfiring may be limited to a specific area of the brain, causing a very specific response from the individual such as a short absence or a twitching of one limb. These are known as partial seizures.
2. The misfiring may form a chain reaction, which spreads to a larger area of the brain, causing a more generalised response from the brain. Adams & Victor (1981) successfully demonstrated this phenomenon by measuring seizure activity with electrodes placed inside patients’ brains. (In Ropper, et al, 2000).
Partial seizures can be further subdivided by our second distinction of simple and complex.
Simple, partial seizures bring about changes in the level of consciousness, but never involve a loss of consciousness, whereas complex partial seizures do involve a loss of consciousness.
Sometimes, if the focus of the epileptic activity is in one of the temporal lobes of the brain, the child may experience an aura prior to the attack. This ‘aura’ may be an experience of positive or negative emotions, it may be a hallucination of one or more sensory modality, or the aura may trigger memories or stereotypical movements.
We now come to our third distinction of seizure activity, grand mal and petit mal seizures. Sometimes during a more dramatic ‘complex partial’ seizure, the child’s body may rhythmically shake. This is known as a grand mal or tonic - clonic seizure. Although this looks dramatic, it is nothing to be alarmed about and is usually over within a few minutes as a combination of structures in the brain, collectively known as the diencephalon act to suppress the seizure activity.
A petit mal seizure is less dramatic, usually very brief and is sometimes so shallow as to go unnoticed by parents, teachers and doctors. An example of such a seizure would be an absence, where the child simply stares vacantly for a second or two. I know a child who used to experience more than fifty such absences an hour and although they sound unobtrusive, when experienced at this magnitude the disruptive effect they can have upon life is easily underestimated.
Finally, and importantly, one aspect of epileptic activity, which it is important to discuss is a phenomenon known as status epilepticus. Usually seizure activity will dissipate within a few minutes and the child will recover with no harm done. However, rarely the seizure activity either will not stop, or the child emerges from one seizure, quickly to be consumed by another and another. This is a dangerous and potentially life threatening situation, which needs immediate medical intervention. In extreme cases such as this, seizures are capable of causing further brain-damage.
It has been demonstrated that some patients with seizure disorders display injury to a part of the brain called the hippocampus, the amount of damage being closely correlated with the number and severity of seizures, which the patient has experienced. The damage appears to be caused by the excessive release of a neurochemical called glutamate during the seizure. (Thompson et al, 1996). It is consequently vital that even if you only suspect your child to be experiencing seizure activity, that this is checked out and treated by a doctor.
What causes epilepsy?
Epilepsy has two causes, one is pathological, and the second is physiological in nature.
l Pathology: -When a brain suffers injury, millions of brain cells may die. Around the area of injury, there may also be cells, which have not been killed, but which are nevertheless injured. In addition, as I have previously alluded, the thresholds of excitation and inhibition, which normally control the firing of these cells, may have been disrupted. Therefore, these injured cells may not fire according to their normal patterns, but may more or less constantly misfire. The child in this situation may have more or less constant epileptic activity occurring in his brain.
l Physiology: - The environment in which the brain operates is by necessity oxygen and nutrient rich. Although the brain only comprises approximately 2% of the body’s weight, it consumes 25% of the body’s oxygen intake. When a brain suffers injury, the availability of the oxygen supply can be compromised. For instance, in many cases of brain-injury, the development of the rate and depth of breathing of the child, does not progress from that of a new-born, which is fast and shallow; - this places difficulties on the optimum levels of oxygen availability, thereby compromising the physiological environment of the brain. Similarly, uninjured children who are ill and develop a temperature may suffer an epileptic seizure as the temperature rise deprives the brain of oxygen, temporarily creating a poor physiological environment.
The young child with brain-injuries may also have trouble in taking in adequate nutrition, which could cause similar physiological effects. The brain’s response to this impoverished physiological environment is to produce a seizure reaction. When brain cells struggle to operate normally without the oxygen and the nutrition they need, they begin to misfire.
What can be done to combat epilepsy?
There are many approaches to combating epilepsy which may improve your child’s situation. Often a programme of developmental stimulation can reduce seizure activity. The reason for this is that if developmental gains can be produced in the child, it means the brain is operating at a more mature, efficient level. This ‘brain development’ can suppress seizure activity.
It is also important that children, who are predisposed towards epilepsy, be given good nutrition. This will help to maintain the physiological environment of the brain in as optimal a state as possible and hopefully keep seizure activity to a minimum.
There is a wealth of medical technology now available, which can help to combat seizure activity. Anti-convulsant medication always extracts a price from the child in terms of drowsiness and other side effects, but it is often necessary, if only temporarily to keep epilepsy under control. As long as the levels of medication are kept to the minimum needed to control the seizure, there is no harm in pursuing this path.
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