For a healthy person, the exchange of electrical and chemical signals between nerve cells in the brain is precisely coordinated. For patients who suffer from epilepsy, this coordination can get 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
More than 30 percent of patients suffer from continued occurrence of seizures, despite appropriate treatment with anticonvulsive drugs (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.
A promissing therapy option for patients suffering from epilepsies is transcutaneous Vagus Nerve Stimulation (t-VNS®).
- 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.
NEMOS® - for treatment of drug-resistant epilepsy
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