Surgical treatment

This treatment should be considered when it has not been possible to control a person's epilepsy in the course of the first two years of treatment.

It is not possible to give a particular number of seizures per month as a definition of a medicine resistant epilepsy. The definition must partly rest on the number of seizures per month, and partly on to what degree they inconvenience the person. In the same way attention must be paid to the strain of the medical treatment. If a person is free of seizures, but chronically poisoned by the drug treatment he is receiving, surgical treatment should also be considered.

In order to achieve a good result it is important that the person's background is sufficiently stable. This means that support from his family and friends is strong enough to help him through the many examinations which have to take place before a possible operation. It is also important that he or she has support and understanding in connection with the operation and in the period which follows it.

Certain conditions must be met before one can be assessed with a view to an operation.

People with simple or complex partial seizures, with or without secondary generalized convulsions, where treatment with the currently marketed antiepileptic drugs have not been able to achieve control of their epilepsy, are typically those who can be considered for evaluation with a view to an operation.

At the most two years should be spent trying the different preparations before a decision is taken about possible surgical intervention. The reason for this is to avoid the possibility of the person becoming brain damaged from the many seizures, before the operation had been able to be carried out.

Who cannot be operated on?

Certain things can tell against the possibility of operating. People with epileptic changes which are located in both the right and left halves of the brain, and where it cannot be decided which focus starts all the seizures, cannot be operated on.

People with medical illnesses and who, because of this could not tolerate a neurosurgical operation, cannot be operated on. People with severe mental illnesses, in which case neurosurgical treatment might worsen their mental illness, cannot be operated on either.

People with psychogenic seizures in addition to their epileptic seizures cannot be operated on. If their psychogenic seizures cannot be treated by a psychiatrist, it can be difficult to differentiate between the psychogenic seizures and the epileptic. This is unfortunate, as the psychogenic seizures tend to increase in frequency, if the epileptic seizures no longer occur.

Examinations before the operation

EEG

Video-EEG

CT-scanning

SPECT-scanning

Spect-scanning is carried out to find the reduction in the blood flow in the epileptic focus between seizures.

At the same time as recording video-EEG during a seizure, SPECT-scanning is carried out to find the epileptic focus, which is shown, during seizure by an increase in the blood flow.

MRI-scanning

Psychiatric examination

Neuropsychological examination

Wada-test

An investigation is also made to find out which side of the brain controls the most used hand, and to find out where the speech center is located (Wada-test). This is particularly important if part of the outside of the temporal lobe is to be removed, as this is close to the speech center. If there is a suspicion that the epileptic area is located on the outside of the temporal lobe, investigations must be made with electrodes on the surface of the brain. The electrodes are surgically inserted onto the surface of the brain. Then the electrical discharges can be measured during and between seizures and thereby find out where the seizures start. Also by sending small electrical impulses through the electrodes can the neurophysiologist "map" the important areas on the surface of the brain dealing with language and movement. The operation can thereby be "tailored" to suit the individual. This is important, as no two brains are the same, and the speech center or the center that controls the hand are not the same size in all people.

In the cases where an operation on the inner side of the temporal lobe has not been effective, investigations will be taken with these inserted electrodes on the brain's surface in preparation for a "tailored" operation.

Examinations after the operation

EEG will be taken 3 months, 6 months and one year after the operation.

One year after the operation a neuropsychological examination is carried out to assess the effect of the operation. This examination may be repeated 2 years after the operation, and possibly again later.

Withdrawal of medicine

First after one and a half years have passed will a discussion as to whether to stop the antiepileptic drugs be initiated. The decision will be made together with the person and his family. If medicine is to be withdrawn, it must be done very slowly. If seizures reappear, the treatment must be resumed at once, as one goes a step backwards in the withdrawal program if the seizures start during withdrawal of the antiepileptic treatment.

After the operation control should be carried out for the first two years by the hospital where the operation took place. After that it can pass to the local special department.

Because of the development which is taking place all the time, it is important that people are followed up for at least five years. This follow up should look at the person's quality of life, and not just at whether or not he has had seizures or not.

Results of the operation

Side-effects of the operation

The most common side effect of this operation is loss of the sense of smell on one side. This can be noticed in the time following the operation, but by a year afterwards it cannot be noticed, as the other side has taken over the whole sense of smell. If the sense of smell is lost, it is a very irritating side effect, as one also loses interest in food and other things that smell good.

A small section of the field of vision may also be lost. If this happens, it is often that section which lies uppermost and out to the side, and is as such, less troublesome. One may still drive a car with this "blind spot". Very occasionally a loss of half the field of vision is seen. This is a serious side effect, as one may no longer drive a car.

A more serious side effect is depression which is seen in about 10% after the operation. It disappears again in many cases, but in isolated cases this has not happened.

Depression can be the result of the experience of suddenly being free of epilepsy. If one has lived with epilepsy for many years, it can be strange to be without it. In some cases psychological help should be given in the period just after the operation.

The intelligence quotient (IQ) can be lower just after the operation and in the first months. After that it tends to improve, and can end by being higher than before the operation. In some cases, however, memory can be permanently affected.

If the operation has taken place on the left side, there may be difficulties remembering words and the like, while in the case of an operation on the right side it may be remembering faces, and finding the way, that gives problems.

Paralysis is very rare after this type of operation.

Those thought suitable for this type of operation are examined in the same way as those who are to be operated on in the temporal lobe, except that the examination will always, in these cases, be carried out with electrodes surgically implanted on the brain's surface.

The follow-up will be the same as for the temporal lobe operation. The results are not as good as in the case of the temporal lobe operation.

The side effects are the same for the two types of operation.

This operation should be considered in cases of myoclonic-astatic epilepsy, where many disabling atonic seizures occur, which lead to lesions to the face or broken bones. This operation can also be considered in cases of epilepsy with many convulsive seizures which cannot be controlled by medicine. The reasons for considering the operation, and its side effects, must be thoroughly discussed with the person involved, or possibly with his guardian, if that is the case. In the first part of the operation a cutting through of two thirds of the corpus callosum is carried out. By this, some of the connections between the two halves of the brain are cut off. Only if this operation proves not to be successful, may a further operation be considered after six months, in which the rest of the callosal body be cut through.

The advantage in this operation is that generalized seizures are changed to partial seizures, which are contained in the one brain hemisphere. The seizures cannot spread to the entire brain, as many of the connections between the two halves have been cut. In this way, seizures with falling and injuries are avoided.

Who can be operated on?

The following people with epilepsy can benefit from such an operation:

People with myoclonic-astatic epilepsy, which cannot be controlled by medicine.

People with secondary generalized seizures, which cannot be controlled with medicine, particularly in those cases where the epileptic area is not located in the temporal lobe.

People with epileptic seizures which originate in many areas of the brain, which cannot be controlled by medicine, where the temporal lobe operation either has been carried out without effect, or where it is impossible to carry out this operation.

Who cannot be operated on?

There are some conditions which prevent a callosotomy from being carried out:

If the person has an illness which would make it dangerous to be under anaesthesia for many hours.

If the person has a medical condition which prevents him from undergoing brain surgery.

If the person has a severe mental illness, in which case neurosurgical treatment may lead to a worsening of his condition.

registering of seizures is continued, and the person and his family are questioned as to possible changes in the way he behaves.

Examinations before the operation.

An EEG examination is made, while the person sleeps. Sleep is induced with the help of a sleeping pill.

MRI-scanning is carried out before and after the operation to get a precise measurement of the size of the incision.

A neuropsychological examination is made to evaluate the person's condition before the operation, so that this can be compared with their condition after the operation.

A psychiatric examination evaluates if there is a psychiatric reason why the operation should not be carried out, and if it would prevent the person's condition being followed up, should the operation be carried out.

After the operation

After the operation the person should be systematically followed up by the center where the operation took place, for at least two years. After this time control can be partly or entirely passed to his local special department.

Because of the developments which is taking place at this time, it is important that results should be followed up for at least 5 years. Not only the number of seizures should be looked at, but the person's entire quality of life.

Results of the operation

Side effects of the operation

A detailed seizure description and registration is always carried out, and all the most important antiepileptic medicine should have been tried, for at least two years. After the operation

Side effects may consist of difficulty in controlling an arm, and stammering. These symptoms can be connected with the breaking off of contact between the two halves of the brain. In normally intelligent people this cutting off may lead to a disconnection syndrome, which is to say that the two brain hemispheres have lost the ability to work together. This complication is very rarely seen when the cutting through is carried out in two stages.

In very rare cases bleeding in the head can occur, which can be life-threatening. More side effects are seen after this operation than after the temporal lobe epilepsy operation.

Very few callosotomies are done after the introduction of vagus-stimulation.