The success of modern surgery for epilepsy has caused a widespread interest in this type of treatment, with people seeing an operation as preferable to a lifetime on medication. However, only a small number of people with epilepsy are suitable for surgery and, even for those that are, there are no guarantees of success.

Suitability

The first thing a doctor has to establish when considering surgery as an option is to establish the patients suitability. Will surgery be possible and, if so, will it be beneficial?

There are a number of different types of surgery for epilepsy but the most common is the removal of a small part of the brain which is the underlying cause of the epilepsy; the focus. Only those patients whose seizures consistently begin in one small area of the brain are suitable for surgery. Sadly, this means that for the many people with epilepsy whose condition cannot be traced to a specific area of damaged tissue, surgery is not currently an option.

Another consideration is the nature of the person’s epilepsy. Surgery is always a risk so the benefits have to be significant. For this reason, doctors tend to only recommend those patients whose epilepsy has a very negative impact on their lives. These tend to be people who still have regular seizures despite trying a variety of medication. The doctor will want to know that surgery will greatly improve seizure control.

It is the quality of a person’s life that will be a main factor in the decision. In some people, a relatively small number of seizures can have a dramatic impact on their lives while others can tolerate a much higher number of seizures without it significantly affecting their well being. .

Pre-surgery tests

Because the surgeon will be removing a part of the brain, it is vital that as much as possible is known about the patient’s brain and their epilepsy before surgery takes place. After many tests the patient needs to be aware that they could then be told that surgery is not possible - not an easy thing to accept after hoping for change.

While most people with epilepsy will have had a standard EEG test, they will be asked to go into hospital for a much more detailed version. The aim is to study the person having several seizures while the EEG is connected. This usually involves coming off medication and having the EEG continually recorded, sometimes for several days. In some instances, the surgeon may have to insert special electrodes onto the surface of the brain itself, although this is only done in a small number of cases. This involves using natural holes in the skull or having to create them. Throughout this type of test the patient receives a great deal of support and help from the hospital staff.

The surgeon will also want to have an up-to-date image of the patient’s brain and this means having an MRI scan (magnetic resonance imaging). This machine creates a picture of the brain which put together with the results from the EEG often enables the surgeon to pinpoint the exact part of the brain which is causing the epilepsy.

These tests will need to show that a single area of only one side of the brain is causing seizures. Some functions of the brain are shared by both sides of the brain, so removing one part on one side does not usually lead to a loss of that function. However, other functions are controlled only by one side of the brain, and the surgeon will need to be confident that these areas are not going to be damaged during any operation.

Other tests include PET (positron emission tomography) and SPET (single positron emission tomography), which involve injecting tiny traces of radio active substances into the body and watching which part of the brain they reach.

Other tests are undertaken include neuropsychological tests, including IQ, memory and speech tests.

 After the tests the doctors will know whether an operation is the right way forward, offering the patient the best option for the future.

The assessment of any risks will be undertaken extremely carefully and will be discussed with the patient.

The operation

The type of surgery that a patient undergoes will depend greatly on what the surgeon hopes to achieve. The following is a list of some operations:

1. Selective amygdalo hippocampectomy - the removal of two structures in the temporal lobe which are commonly the site of seizure activity. Sometimes just the hippocampus part of the structure is removed.
2. Temporal lobectomy - a larger part of the temporal lobe is removed. This tends to be mainly the right side as the left side of the temporal lobe controls speech.
3. Sub-pial resection - fine cuts are made in the motor areas of the brain that do not affect the motor function but do prevent the spread of seizures.
4. Hemispherectomy - sometimes used to treat very severe epilepsy in children with damage to one whole side of the brain. The damaged side of the brain is removed.
5. Corpus callosotomy - again sometimes used to treat children with very severe epilepsy, this operation involves cutting the fibres that connect the two halves of the brain.
6. Removal of a lesion such as a tumour or a cyst.

After surgery

Despite the lengthy and very difficult nature of brain surgery, most patients make a rapid recovery and are usually up and about within a couple of days. Between eight and fifteen weeks later, most people are able to return to work. Some aspects, like waiting for the nerves that supply sensation to the skull, may take some time to recover.

The results

Some people may experience seizures just after the operation due to temporary swelling. This does not mean that the operation has failed.

Depending on the person’s own doctor, it may be some time before the patient can start reducing their medication. However, many patients notice a dramatic reduction in the number of seizures, many finding that their seizures appear to have stopped. They can then look at reducing or stopping their medication in consultation with their doctor.

One consequence of successful surgery that may surprise some people is the difficulty in coming to terms with life without seizures. Emotional reactions to this life change are common and can include quite severe temporary depression. Friends and family can also find it difficult to adjust to the person’s new found independence. This type of reaction will depend on how long the person has had epilepsy prior to having surgery.

As with most surgical techniques, there are no guarantees. Epilepsy surgery is no exception and a small number of people will find that surgery has not helped.

Reference: Epilepsy Action, 2003, British Epilepsy Association.