How can epilepsy be treated?

Epilepsy is a condition that can severely affect quality of life, causing recurrent seizures and even loss of consciousness in some cases. Professor Matthew Walker is a leading neurologist with expertise in treating this condition. There are several treatment options for epilepsy with antiepileptic medications available, surgery, nerve stimulation therapy and even the ketogenic diet.

How do antiepileptic drugs work?

The excitability of the brain changes on a day by day, hour by hour, minute by minute basis. If the excitability increases too much and crosses a certain threshold, then all the nerve cells will start to “fire” together resulting in a seizure – an "electrical” storm. Every brain, whether it is a human brain or a fly brain, will have such a threshold and that threshold can be exceeded for many reasons, such as consumption of certain recreational drugs, brain infections, alcohol withdrawal or a sudden brain injury. The threshold for any brain to have a seizure is genetically set and for some people that threshold is lower than the natural fluctuations in brain excitability, and so spontaneous seizures occur – this is a so-called genetically determined epilepsy.

For other people, damage to a part of the brain through, for example, head injury or stroke can lead to the threshold in that brain area being lowered and the seizures will then start in that part of the brain. Sometimes seizures occur because some of the nerve cells in a particular part of the brain have not connected up and have developed properly.

The drugs we have increase the threshold, hopefully preventing seizures from occurring. There are over 20 different antiepileptic drugs and they increase the threshold in different ways. If one does not work, then another, that perhaps works differently, will be tried. Sometimes they will be used in combination. These drugs have side-effects but are generally very effective with about 70% of people with epilepsy becoming seizure free. However, the drugs have no permanent effect on the threshold, so that if someone comes off the medication the threshold would be the same as if they had not taken medication. However, this does not mean that the seizures will be permanent and that the person will always have to take medication because for many people the threshold naturally changes over time and then the person may be able to come off medication and stay seizure free.

What if medications do not work?

When the drugs are not effective, then there are alternative options including the ketogenic diet, vagus nerve stimulation and epilepsy surgery.

The ketogenic diet was developed in the 1920s when the only effective antiepileptic drugs that were available were bromides and phenobarbital (both rarely used now because of their side-effects). Based on the observation (dating back to Hippocrates) that starvation or fasting often reduced seizure frequency, a high-fat, low-carbohydrate diet was developed to mimic fasting by reducing blood glucose and increasing ketone levels (the acetone smell on people’s breath who have been starving themselves). The diet lost favour with the discovery of phenytoin in the late 1930s, only to experience a renaissance in the 1990s as a treatment in drug-resistant epilepsy in children. The diet is difficult to maintain and is probably more effective in severe epilepsy in children than in adults. However, recently we have been working to produce better tolerated forms of the diet by understanding better how the diet works.

Another approach that can help is vagus nerve stimulation. The vagus nerve is a nerve that runs down the inside of the neck and carries signals to the brain, lungs and gut. By putting a pacemaker-like device under the skin of the chest with a wire under the skin to the vagus nerve, it is possible to stimulate the vagus nerve and help seizures. This is because the vagus nerve goes up into the brain, and stimulation of the nerve can change the seizure threshold of the brain.

Perhaps the most successful way of preventing seizures in those with seizures that are resistant to medication is epilepsy surgery.

How does epilepsy surgery work?

Epilepsy surgery can work through three different approaches by:

1. Removing the “bad” part of the brain
2. Cutting the connections of the “bad” part to other brain areas
3. Implanting an electrical stimulator which, through electrical stimulation, reduces the excitability of the “bad” part(s) of the brain.

The brain consists of 100 billion nerve cells with trillions of connections. Seizures may arise in a small area of the brain but then, through these many connections, spread to other areas and eventually to the whole brain. Epilepsy surgery works through identifying the main area from where seizures arise and removing that area (provided it is not critical for important functions such as speech and movement). This is termed “curative, resective surgery”. Resective surgery is not always successful because we are not always able to localise where the seizures arise, or once one area of the brain is removed, the seizures start to arise from a different area. Sometimes it is not possible to remove the area from where seizures arise, because it is in an area that is crucial for brain function. The surgeon may then decide instead to cut the connections by which the seizure spreads, however, this operation is generally far less successful.

If the seizures arise from multiple brain areas (multifocal seizures) or from the whole brain (generalised seizures), then resective surgery is not usually possible. Instead, operations are used with the aim of improving or lessening the seizures with a much lower chance of stopping the seizures. When someone is having severe falls or generalised seizures, cutting the connection between the two halves of the brain (a “corpus callosotomy”) can sometimes be successful by restricting the seizures to one half of the brain; this stops the seizure spreading to the whole brain and so can prevent falls and generalised convulsions. Another approach is to stimulate deep areas of the brain with an implanted stimulator (deep brain stimulation), which results in the brain becoming less excitable. Brain stimulation is far less successful than these other surgical approaches and is only suitable in very selective cases.

To discuss treatment options for epilepsy, make an appointment with an expert.