Epilepsy – a background
Information on epilepsy and the types of treatment
For a healthy person, the exchange of electrical and chemical signals between nerve cells in the brain is precisely coordinated.
In patients who suffer from epilepsy, this coordination can be temporarily disturbed, resulting in pathological electrical discharges. Subsequent nerve cells then respond by sending sudden, uncontrolled signals, creating a sort of “electrical storm in the brain”.
This spreads and activates individual brain areas – or even the whole brain – in an unnatural way. The symptoms and expressions of the resulting epileptic seizure depend on the areas affected.1
Not all seizures however are due to epilepsy. Seizures can occur in life for many different reasons, such as diabetes or a heart condition but on this website we use the term ‘seizure’ to mean an epileptic seizure.
There are many different types of epileptic seizures. Seizures are divided into two main types:
- Focal seizures (also called partial seizures)
- Generalised seizures
Epileptic seizures always have their origin in the brain.
More than half a million people in the UK suffer from epilepsy. This is around 1 in 100 people. Anyone can develop epilepsy, and it happens in all ages, races and social classes. Epilepsy is most commonly diagnosed in children and people over 65 and there are over 40 types of recognised epilepsy.
The most common treatment for epilepsy is medication – anti-epilepsy drugs (AEDs). There are many different types of AEDs. The AED prescribed is dependent on the individual’s situation: the likely cause of the epilepsy, the type of seizure experienced, or any other medical conditions present.
More than 30 percent of patients suffer from continued occurrence of seizures, despite appropriate treatment with anticonvulsive drugs (AEDs drugs to treat epilepstic seizures).2,3
Few treatment options are currently available for these patients. These involve:4
In principle, one can distinguish between two neurosurgical methods: Removing the brain area causing the seizures, or the surgical interruption of nerve tracts through which the seizures spread.
Deep brain stimulation
For deep brain stimulation, electrodes are implanted in the brain. These electrodes are connected to a battery-powered stimulator, which is normally implanted below the patient’s collarbone. This can produce an electrical stimulus that influences the epileptic activity at its source specifically.
Invasive vagus nerve stimulation
The cervical branch of the vagus nerve in the neck is exposed in a surgical procedure, and an electrode is wrapped around the nerve. The electrode is connected to a stimulator implanted under the skin, below the collarbone.5,6
An electrical current is passed through the vagus nerve to the brainstem, from where it activates higher centres of the brain.
transcutaneous Vagus Nerve Stimulation (t-VNS®)
Represents a promising therapy option for patients suffering from epilepsies
Kwan P, Arzimanoglou A, Berg AT, Brodie MJ, Allen HW, Mathern G, Moshe SL, Perucca E, Wiebe S, French J: Definition of drug resistant epilepsy: consensus proposal by the ad hoc Task Force of the ILAE Commission on Therapeutic Strategies. Epilepsia 2010;51:1069-1077.
Kwan P, Brodie MJ: Early identification of refractory epilepsy.N Engl J Med 2000;342:314-319.
Alotaibi FA, Hamani C, Lozano AM: Neuromodulation in Epilepsy. Neurosurgery 2011;69:957-979.
Beekwilder JP, Beems T: Overview of the clinical applications of vagus nerve stimulation. J Clin Neurophysiol 2010;27:130-138
Amar AP, Levy ML, Liu CY, Apuzzo MLJ: Vagus Nerve Stimulation; in Krames ES, Peckham PH, Rezai AR, (eds): Neuromodulation. London, Academic Press, 2009, pp 625-637.