VAGUS NERVE STIMULATION (VNS)
This treatment method, known as epilepsy pacemaker, was first used in 1988 and has become a widely used treatment method all over the world, since it has shown effective results in drug-resistant epilepsy patients in the following years.
In this treatment, a spiral-shaped cable is placed around vagal nerve in the neck region, and the other end of the cable is integrated into a battery placed in the chest.
The vagal nerve is the longest nerve that runs between the brain and the trunk.
The vagal nerve is a very important structure that regulates our heartbeats, breathing patterns and bowel movements.
In addition, stimulation of this nerve with very low current electrical energy; It regulates the uncontrolled electrical activity in the brain that causes epileptic seizures and ensures that seizures are controlled in epilepsy patients.
Frequently Asked Questions About VNS
Assoc, Prof. Dr. Sait OZTURK, MD / Neurosurgeon
- Despite using epilepsy drugs for a sufficient period of time (at least 2 years) and in an appropriate variety (at least 2 different drugs); It is a surgical treatment used in patients whose seizures cannot be controlled and which we define as drug-resistant epilepsy. This surgery is not performed in patients newly diagnosed with epilepsy and in patients who have had epilepsy for a long time and whose seizures are under control with drugs, unless undesirable side effects due to drugs have developed. In addition, if the cause of epilepsy is a lesion in the brain or a space-occupying cause in the brain, craniotomy should be performed for this problem first.
- VNS surgery is an operation with a very low risk. The most common post-operative problems are temporary hoarseness, voice problems and stiffness in the throat. However, these complaints usually regress within weeks.
- The operation is performed under general anesthesia from two different areas in the chest region and neck region. An incision of approximately 5 centimeters in length is made in the neck region, and the vagal nerve is reached from here, and a cable is attached to the nerve. Then, a second incision is made in the chest area and a pocket is created where the battery will be placed. The end of the cable, which is attached to the nerve in the neck region, is delivered to the pocket in this chest region and system connections are made. Then, both incision areas are closed and the surgery is finished by suturing the aesthetic sutures. It is an operation that takes an average of 1 hour.
- Studies have shown that seizures can be controlled by different factors. It has been revealed that very low current electrical energy sent to the brain via the vagal nerve suppresses seizures by regulating impaired EEG signals. In some studies, it has been shown that the rate changes in the chemicals that enable the communication of millions of nerve (neuron) cells in our brain among themselves suppress the seizure. However, there is still no clearly proven and globally accepted mechanism of action.
- 4 hours after the operation, the patients are walked and they start feeding. On the 1st day of the surgery, they can be discharged and return to their normal lives.
- Patients discharged on the 1st day of the operation can continue their normal lives.
- The generators of the patients are activated on the 14th day after the surgery and the stimulation parameters are gradually increased every two weeks. Generator settings are completed in an average of 3 months. In this process, it is not recommended to make any changes to the drugs until the generator settings are completed. They should be followed up regularly by neurologists after the surgery. The long-term effectiveness of this surgery is on average 50-60%. However, it is known that 80% efficiency is seen in some patients, 30% in some patients, and it does not provide any benefit in a very limited patient group. Generally, the effects of the VNS on epilepsy appear in the 3rd month after the operation. In the following months and years, the effectiveness continues to increase. Drug usage and dosages are decided by evaluating under the control of a neurologist. VNS therapy should be considered as an adjunct to medication. Average daily drug use decreases by half at the end of the first year.
- Generator settings are made via an electronic tablet . By the programmer, which is brought closer to the generator in the patient’s chest area, adjustment is made in a very short time.
- This time varies, as different generator adjustments will be made for each patient. However, it will have an average generator life of 4 to 7 years. When the generetor level decreases, only the former wound in the chest area is opened, the generator is removed and replaced with a new one, under local anesthesia. Patients are discharged one hour after the procedure.
- The VNS system is a MR compatible battery. However, there is a very low risk of damage to the battery during MRI. For this reason, whole body MRI is not recommended. It is recommended that the battery be turned off immediately before the MRI scan, and the battery powered up again after the acquisition. There are no restrictions on X-ray or computed tomography; necessary shots can be taken without the need to turn off the battery.