Epilepsy

Treatment

There is continuous debate over which patients should be treated with an antiepileptic drug. A single seizure is not generally treated unless the patient is at high risk of experiencing further seizures, eg post-stroke seizures or seizures in patients with brain tumours. Some neonatal seizures are not treated with antiepileptic drugs, eg febrile convulsions. However, people who have experienced two or three seizures within a short time period should be prescribed medication.

The majority of cases of epilepsy cannot be cured and most people are prescribed an antiepileptic drug to help prevent the onset of further seizures. Not everyone will respond to medication; an estimated 70% will experience symptom relief. In the remaining 30%, some may experience a reduction in seizures, others may be treated with several antiepileptic drugs and in select cases, surgery may be used to relieve further seizures.

Antiepileptic drugs work by restoring the normal electrical activity in the brain. This can be done by enhancing the activity of the inhibitory neurotransmittergamma aminobutyric acid (GABA), or reducing the activity of excitatory neurotransmitters  such as glutamate. These approaches help to inhibit excessive neuronal firing and prevent a seizure from spreading throughout the brain. Some drugs act on neuronal membranes and help to stabilise them, while others block sodium channels to stop the seizure from spreading across the brain. The mechanisms of action of these drugs are complex; several antiepileptic drugs act via different mechanisms.

Different drugs are used to treat different types of seizure and some commonly prescribed antiepileptic drugs are shown below:

An antiepileptic drug will only work if it is maintained at a certain level in the body. If the drug level in the blood gets too high, it may lead to excessive sleepiness and other unwanted side effects.

Those with severe forms of epilepsy that do not respond to medication may receive surgery to treat their illness. This can be performed if the area of the brain affected by seizures can be identified, and removed without significant side effects. Several types of surgery can be used, including:

• Temporal lobe surgery
  This type of surgery removes part of the temporal lobe, especially the hippocampus  and amygdala .
• Cortical resections outside the temporal lobe, eg the frontal, parietal  or occipital  lobe.
• 'Split brain' operation
  The corpus callosum  is cut to separate the right and left hemispheres to prevent the seizure from spreading throughout the whole brain. This type of surgery is seldom performed in selected cases with daily multiple severe seizures.
• Hemispherectomy
  One whole hemisphere of the brain is removed in this type of surgery. This procedure is very seldom performed.