HELIOSphan.com - The Health Blog » Epilepsy

TESTS IN EPILEPSY

admin — Mon, 07 Dec 2009 13:12:39 +0000

Epilepsy is a clinical diagnosis based on a detailed description of events. There is no single test which can always make, or exclude, a diagnosis of epilepsy. Moreover, as also explained in earlier chapters, epilepsy is not a single condition. There are many different types of epilepsy, and there are many different causes of epilepsy. Investigations may be useful to:

• add weight to, or support the clinical diagnosis of epilepsy;

• help ‘classify’ the type of epileptic seizure and epilepsy syndrome. This is important in predicting the likely outcome of the epilepsy in a given individual, and the treatment that should be used; and

• help detect or find a cause for the epilepsy.

The main investigations which may be used in epilepsy are the electroencephalogram (EEG) and brain imaging techniques, most commonly computerized tomographic scanning (CT scanning) or magnetic resonance imaging (MRI). Other investigations such as X-rays, blood tests, lumbar puncture (spinal tap), or tissue biopsy are much less commonly undertaken.

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THE FACTS-THE FIRST SEIZURE AND THE DIAGNOSIS OF EPILEPSY: OTHER CAUSES OF IMPAIRED OXYGEN SUPPLY TO THE BRAIN-OVERBREATHING

admin — Mon, 07 Dec 2009 13:11:52 +0000

Breathing in and out too fast and too deep is one bodily way in which, like palpitations, anxiety is manifested. This response seems to be particularly common in adolescent girls. If continued for more than a few minutes, excessive carbon dioxide is removed by the lungs from the blood, which becomes correspondingly alkaline. This affects the levels of calcium in the blood, and, in turn, the conduction of nerve impulses and the contraction of muscles. The net effect is that the subject experiences painful tingling in the hands and toes, which become flexed and contracted in a cramped posture. The lack of carbon dioxide also produces a feeling of light-headedness, and the total picture may be confused with a seizure. Treatment is simple and dramatically effective. A paper or polythene bag is placed (temporarily!) over the patient’s, nose and mouth, so that she re-breathes her own expired air, rich in carbon dioxide. The body chemistry and clinical state rapidly return to normal.

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THE FACTS-THE FIRST SEIZURE AND THE DIAGNOSIS OF EPILEPSY: OTHER CAUSES OF IMPAIRED OXYGEN SUPPLY TO THE BRAIN-RIGORS, NIGHT TERRORS, RAGE ATTACKS/OUTBURSTS OF TEMPER

admin — Mon, 07 Dec 2009 13:11:29 +0000

Occasionally the shivering associated with high fever, particularly frequent in infections of the urinary tract, may be confused with a convulsion.

Night terrors-These episodes are common in children between the ages of 5 and 10 years and frequently worry parents. Typically a child who has been in bed, asleep for 1-3 hours will waken suddenly, screaming. The child will be sitting up in bed, wide-eyed and unresponsive; they cannot be comforted. Within a minute or so, the child will lie down, turn over, and go back to sleep. There is no memory or recollection of the event the next morning. Reassurance (of the parents) is all that is required.

Rage attacks/outbursts of temper-Bizarre, semi-purposeful behaviour and confusion may rarely be part of a complex partial seizure arising from a temporal lobe. However, violent behaviour or uncontrolled rage are almost never a type of epileptic seizure. They are usually provoked by someone or something, even though the cause may be trivial.

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HOW COMMON ARE THE INDIVIDUAL CAUSES OF EPILEPSY?

admin — Mon, 07 Dec 2009 13:09:50 +0000

Causes of epilepsy that could be defined, with a fair degree of confidence, in each of two studies. The way in which the subjects were selected was different in each study, but the final

figure—the proportion in which a cause for epilepsy could be defined—varied within narrow limits, between only 34.5 per cent and 39.0 per cent.

The fact that 61.0-65.5 per cent of people with epilepsy have no discernible cause for their seizures certainly does not mean that the remainder have ‘idiopathic’ epilepsy. Since the advent of magnetic resonance imaging we know that a large proportion of subjects with such ‘cryptogenic’ epilepsy (epilepsy of hidden cause), have minor structural changes in the

brain—very commonly zones of atrophy in one or other temporal lobe. More recent studies show that nearly 90 per cent of those with temporal lobe epilepsy, for example, will have abnormalities on magnetic resonance imaging, though these abnormalities may be very minor, and only detectable with careful measurements on the scan.

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THE CAUSES OF EPILEPSY: ACQUIRED METABOLIC DISORDERS

admin — Mon, 07 Dec 2009 13:08:46 +0000

The pathways of chemical metabolism in the newborn are very unstable and vast changes in the serum concentrations of various substances can occur. A blood glucose concentration sufficiently low (hypoglycaemia) to cause seizures, for example, cannot be induced in older children or adults by starvation, or indeed by any means other than the injection of insulin. However, severe hypoglycaemia resulting in seizures may be seen in the newborn, particularly in premature infants, or in babies born to diabetic mothers.

Seizures due to a low serum calcium are also fairly frequent in the newborn period. One cause is early feeding with cow’s milk, which is very rich in phosphates, and which results in increased renal excretion of calcium and subsequent low levels of calcium in the blood.

In later stages of life, other acquired metabolic disorders may cause seizures. Chronic renal failure used to be one of the more common causes, but dialysis and successful transplantation of kidneys has reduced the frequency of seizures due to this cause.

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