SURGICAL THERAPIES FOR LENNOX-GASTAUT SYNDROME
Surgery may be recommended to those patients who do not respond to the usual seizure medications or other therapies available. The most common surgical procedures for patients with Lennox-Gastaut Syndrome include the corpus callosotomy and the Vagus Nerve Stimulator. (1) Some literature has argued that resective surgery may also be an options for patients with Lennox-Gastaut Syndrome (1, 2).
A comprehensive list of surgical options is listed below. Click on each option to learn more.
The Vagus Nerve Stimulator or VNS, is a small device which is implanted through surgery to help control seizures through electrical impulses. (read more)
Corpus callosotomy is most effective for atonic seizures ("drop attacks"), tonic-clonic seizures, and tonic seizures. Seizure frequency is reduced by an average of 70% to 80% after partial callosotomy and 80% to 90% after complete callosotomy. (3) (read more)
The RNS Stimulator consists of a small neurostimulator implanted within the skull under the scalp. The neurostimulator is connected to one or two wires (called electrodes) that are placed where the seizures are suspected to originate within the brain or on the surface of the brain. (4) (read more)
Deep brain stimulation (DBS) is a medical therapy in which an implanted device delivers electrical stimulation to regions deep in the brain. Although not FDA approved, DBS has shown to reduce seizures in some patients with refractory epilepsy. (read more)
Trigeminal Nerve Stimulation (TNS) is a novel medical treatment in which mild electrical signals stimulate branches of the trigeminal nerve in order to modulate the activity of targeted brain regions.
VAGUS NERVE STIMULATOR
The Vagus Nerve Stimulator or VNS, is a small device which is implanted through surgery to help control seizures through electrical impulses. The device, which is implanted under the arm or near the chest, automatically sends electrical impulses to the vagus nerve. The vagus nerve then sends impulses to the brain which help control the electrical disturbances that cause a seizure.
Although the impulses are set automatically (your doctor will determine the frequency), the VNS is also accompanied by a magnet which can be used to prevent or control a seizure before or during its occurrence. The magnet sends an extra dose of therapy into the nerve and can also decrease the severity or length of a seizure.
The VNS surgery usually takes about an hour and is usually performed under general anesthesia. The surgeon will make two incisions; one under the arm or near the upper chest area to insert the VNS therapy generator, and another incision on the left side of the neck to attach the wires to the vagus nerve.
In a study conducted by Cornell University in 2000, 13 patients with Lennox-Gastaut syndrome between the ages of 4 and 44 years were treated with vagus nerve stimulation. During the first 6 months of treatment, the VNS produced a median seizure rate reduction of 52%. At 6 months of follow-up, three patients had a greater than 90% reduction in seizures, two had a greater than 75% reduction, one had a greater than 50% reduction, and six had at least a 25% reduction. One patient did not improve. No patient worsened after initial improvement. Side effects, including hoarseness, coughing, and pain in the throat, were transient and tolerable.(6)
When patients with generalized seizures, and drop attacks in particular, fail multiple seizure medications, a corpus callosotomy may be considered. Corpus callosotomy is a procedure that severs the membrane that divides the right and left cerebral hemispheres. (1)
When performing corpus callosotomy, the surgeon cuts the corpus callosum, the large fiber bundle that connects the two sides of the brain. (2) Partial callosotomy (anterior two-thirds) is effective in 50-75% of cases, while complete callosotomy (posterior one-third) may reach 80-90% reduction of drop attacks (2).
Surgery is often a difficult decision for families to make. It is important to speak with your doctor about the risks and benefits associated with the corpus callosotomy surgery.
1. NYU Langone Epilepsy Center, Corpus Callosotomy
2. Epilepsy.com. Everything you need to know about Lennox-Gastaut Syndrome, Newsletter, February 2012.
DEEP BRAIN STIMULATION (DBS)
DBS is currently approved in the United States to treat Parkinson’s disease and other movement disorders but has not been approved by the U.S. FDA for the treatment of epilepsy. The procedure involves the insertion of electrodes that measure approximately one millimeter thick into a deep part of he brain called the anterior nuclei of the thalamus (2)(ANT). A small programmable stimulator containing a battery (that lasts 3 to 5 years) is inserted under the clavicle in the chest wall. A wire is inserted under the skin, up one side of the neck, behind the ear, and to the top of the head, where, guided by computer magnetic resonance imaging, it is positioned through two small drill holes to the thalamus. When switched on, the device delivers steady pulses of low voltage-electrical pulses to the brain (3).
On March 18th, 2010 results from a pivotal study for DBS for epilepsy, known as the SANTE® trial (Stimulation of the Anterior Nucleus of the Thalamus in Epilepsy), were published in the medical journal Epilepsia. Results from the study showed that after completion of an initial 3-month placebo phase, there was a 40.4% reduction in seizures in patients receiving deep brain stimulation (DBS) compared with 14.5% in a control group who had a stimulator device implanted but did not receive any stimulation. Two years after implantation of the DBS device, seizures were reduced by a median 56% compared with baseline, and 14 patients (12.7%) became seizure free for at least 6 months (4). According to a recent study completed at the Mayo Clinic where a 3-year-old patient with Lennox-Gastaut syndrome received DBS, seizures were noted to be improved and are no longer impeding the patient's development (6). The results of this study have not yet been published but are available on the Mayo Clinic's website. Although it appears that the efficiency of DBS to reduce seizures is demonstrated in a sufficiently large population, the exact determinants of its success (physical parameters, syndromes) remain unknown. (5)