Neurostimulation is an exciting new treatment approach for epilepsy. It can prevent seizures or help control them by using electrical stimulation to change how brain cells function. The goal is to disrupt the network that propagates the start of a seizure throughout the brain. Neurostimulation for epilepsy is a rapidly growing field, with clinical studies of different neurostimulation techniques showing promising results. This article reviews those trials and also considers challenges and future developments in the field.
Neuromodulation for Epilepsy
The nervous system controls functions that are not under voluntary control, such as heart rate and breathing. The vagus nerve, part of the autonomic nervous system, carries messages between the brain and other parts of the body. In people with epilepsy, fast changes in the vagus nerve can occur before seizures, which may be picked up by VNS devices. When this happens, the device can send an extra burst of stimulation to help stop a seizure.
VNS is an implantable device that consists of a generator (like a pacemaker) and leads (wires that connect to the generator). The generator is placed in the chest, usually under the skin on the left side of the chest. The leads are coiled around the vagus nerve in the neck. The generator and the leads carry intermittent electrical pulses, according to adjusted preprogrammed settings. The device can be activated by patients or their families if they think a seizure is coming on.
This treatment is for people with refractory focal epilepsy and who have tried at least two antiepileptic medications without success. The VNS device has been shown to help reduce the frequency of seizures and improve quality of life in a large number of people. A study of 65 people who received VNS for more than 10 years found that seizures decreased by about 28% in the first three months after implantation. Seizure rates continued to decrease over time, and the average duration of a seizure was reduced.
For the most difficult to treat epilepsies, surgery can be performed to place electrodes inside the brain to monitor and stimulate brain cells. This is called deep brain stimulation or DBS. Several trials have been conducted to test this treatment for a wide variety of epilepsies, including mesial temporal lobe epilepsy (MTLE), Lennox-Gastaut syndrome, occipital lobe epilepsy, and frontal lobe epilepsy.
The results from these studies vary, depending on the type of epilepsy, where the stimulation was targeted, and the parameters of the therapy. For this reason, it is hard to draw definitive conclusions about the effectiveness of DBS in these disorders. Further research is needed to develop therapies that better target the epileptogenic network, rather than just a specific location in the brain. This will require a deeper understanding of how the different regions of the brain communicate with each other, and how epileptiform discharges spread from one region to another. In the meantime, a variety of other therapies are available to help manage epilepsy.
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