Barcelona-Parkinson treats refractory epileptic patients

In Barcelona-Parkinson we offer medical services to patients with epilepsy by means of vagal stimulation and electrical stimulation.

What is epilepsy?

Epilepsy is a frequent chronic disease due to a general electrical disorder, and may be focal or generalized. It involves a high level of disability, due to the difficulty in controlling the crises.

Focal epilepsy consists of sensory or sensory-motor crises. When there is loss of consciousness it is referred to as complex. Sometimes it is very difficult to control with the usual drugs.

Generalized epilepsy consists of tonic, chronic/tonic, or myoclonic seizures that cause great difficulties in daily life and for participation in the workplace.

What can cause epilepsy?

Epilepsy can have various causes: symptomatic causes, vascular issues, traumatic brain injury, perinatal hypoxia, brain tumor, etc.

Many epileptic patients, despite anti-epilepsy drugs, which are increasingly more effective and well-tolerated, are not able to improve their quality of life due to the high frequency of seizures. These cases are referred to as refractory epilepsy.


What is vagal electrical stimulation?

Electrical stimulation of the vagus nerve (VNS) is a procedure that has proven effective in decreasing the frequency and severity of seizures in patients with difficult-to-control epilepsy. It is used in patients with epilepsy that is refractory to treatment with antiepileptic drugs who are not candidates for surgical resection or do not wish to undergo surgical treatment of the brain. It is important to remember that resective surgery is much more effective than VNS in appropriate candidates, in which case VNS is considered a palliative procedure.

The apparatus for vagal stimulation consists of a programmable generator of a size similar to that of a cardiac pacemaker and which, like the latter, is placed on the chest wall. This generator is connected to a helical bipolar electrode that is placed around the vagus nerve at the level of the fifth or sixth cervical vertebra.


What does the surgical procedure for implantation and programming of the stimulator consist of?

The surgical procedure requires a lateral incision in the pectoralis major to implant the generator and another in the neck to apply the electrodes to the vagus nerve. The procedure lasts a total of 1 to 2 hours and is usually done under general anesthesia. Afterwards, in the doctor´s office, the stimulation parameters are programmed. It is usually started with periods of stimulation of 30 seconds repeated at intervals of 5 minutes, using electrical pulses of 0.5 milliseconds duration and at a frequency of 30 pulses per second. It starts with an intensity of 0.25 mA, which increases every two weeks. The benefit is usually obtained with intensities of 1.5 to 3 mA. The stimulation frequency and the frequency or duration of the electrical pulses can also be varied. The patient and his / her relatives have a magnet that can be used to stop the stimulation or to activate it outside of the programmed cycle in case the patient notices that he is going to have or is having a seizure. The generator battery lasts between 7 and 10 years, after which it is necessary to change the generator, usually through an even simpler operation, which can be performed under local anesthesia.

Is stimulation of the vagus nerve effective in epilepsy?

The first time that Vagus Nerve Stimulation (VNS) was used in humans was in 1988. Subsequently, two randomized, double-blind, controlled, multicenter clinical trials and another prospective, multicenter trial (open design and not blind), as well as numerous projects in individual centers, were carried out. These demonstrated the efficacy and safety of VNS in the treatment of epilepsy. As a summary of the results of these studies, we can conclude that between one-third and half of the patients treated with VNS experience a greater-than-50% reduction in the number of seizures, although very few obtain complete control over them. VNS is effective in children and adults with a wide variety of both focal and generalized drug-resistant epileptic syndromes. Patients should continue to take AEDs, but doses can often be reduced, thus decreasing drug-related adverse effects.


Is stimulation of the vagus nerve safe? Does it have adverse effects?

Vagus nerve stimulation (VNS) is a safe procedure. Complications of the procedure, such as infection or injury to the vagus nerve, are very rare. Episodes of bradycardia and even asystole have been described during stimulation at the time of surgery, but in all cases these were resolved without clinical consequences. The most common side effects are those that may appear during the stimulation phases, and include cough, dysphonia, tingling in the neck, and feeling of shortness of breath. It does not cause systemic or CNS-related adverse effects, such as dizziness, drowsiness, bradypsychia, irritation or nervousness, which are common with AEDs. The incidence of sudden death (SUDEP) is similar in patients with VNS to other patients with refractory epilepsy.

Are there any contraindications to vagus nerve stimulation?

Vagus nerve stimulation (VNS) cannot be used in patients after a bilateral or left cervical vagotomy. Short-wave diathermy, microwave diathermy, or therapeutic ultrasound diathermy should not be used. Ultrasound diagnosis is not included in the contraindications.

Special precautions should be taken when performing magnetic resonance imaging in these patients, although most can be performed without significant risk. However, magnetic resonance imaging of the neck is contraindicated.

Domestic devices such as microwaves or mobile phones do not interfere with the device.


What types of epilepsy surgery by brain resection are practiced?

The main objective of the surgery is to leave the patient free of seizures by removing epileptogenic tissue and injury. To achieve this, the following types of epilepsy surgery can be performed:

Resective surgery

This involves eliminating the focus (or foci) that are considered responsible for the seizures: epilepsy surgery of the temporal, temporal-medial basal, or lateral temporal lobes; epilepsy surgery of the extra-temporal, extra-temporal frontal, extra-temporal parietal, or extra-temporal occipital lobes; and functional hemispherectomies.

Disconnective surgery

It is a question of disconnecting the epileptogenic zone so that the seizure does not occur: callosotomy or lobular disconnection.

Re-operative Surgery

Before surgery, it is important to ensure that it does not cause aftereffects in the patient, such as permanent motor deficit (conditions that limit physical abilities), permanent language deficits (conditions that limit language skills) or loss of visual field.