Vagus nerve stimulation reduces seizures in kids with LGS
Benefits of implanted device become clearer over time, review study shows
Written by |
A review study examined the effects of vagus nerve stimulation on seizures in children. (Photo by iStock)
Vagus nerve stimulation (VNS), a treatment that uses a small, implanted device to deliver electrical signals to the vagus nerve, was linked to fewer seizures in many children with Lennox-Gastaut syndrome (LGS), with the benefits generally becoming clearer over time, a review study found.
More than one year after VNS implantation, at least 40% of patients saw their seizures reduced by half or more. After 1.5 to two years, as many as 21% of patients were seizure-free.
The findings suggest that VNS “may represent a potentially useful therapeutic option for the management of [treatment-resistant] Lennox–Gastaut syndrome (LGS),” the researchers said.
The study, “Vagus nerve stimulation in pediatric patients with Lennox–Gastaut syndrome: a systematic review,” was published in Epilepsy & Behavior.
LGS is a rare, severe form of epilepsy that typically begins during early childhood. LGS symptoms include several types of seizures, sudden bursts of abnormal electrical activity in the brain that may affect the whole body. Because seizures can be frequent and difficult to control with medication, LGS can substantially impair cognitive and functional abilities, behavior, and quality of life. These challenges have led to interest in non-drug approaches such as VNS.
Researchers look at seizure frequency, intensity
VNS involves implanting a device that delivers intermittent electrical stimulation to the vagus nerve, which connects the brain with several organs, to help reduce seizure frequency and severity. But evidence of its benefits in children with LGS has been limited.
To learn more, the researchers conducted a systematic review of 28 studies involving 527 children and adolescents that aimed to assess the treatment’s safety, tolerability, and effectiveness.
Participants’ ages at the time of VNS implantation ranged from 1 month to 18. Some studies included people with other forms of epilepsy, but the researchers analyzed only data from participants with LGS who were 18 or younger at the time of implantation.
The review’s primary outcomes were seizure frequency and seizure characteristics after VNS. Across the studies, the proportion of patients achieving at least a 50% reduction in seizure frequency generally increased with longer follow-up, ranging from 18% to 58% during the first six months and from 39% to 81% after more than one year.
After 18–24 months, 30%–55% of patients achieved at least a 75% reduction in seizures, while 11%–21% were seizure-free. However, responses varied considerably across studies, and 10%–30% of patients showed benefit or saw their seizures worsen.
VNS also appeared to reduce several seizure types, with atonic seizures and drop attacks showing particularly consistent improvements. Atonic seizures cause a sudden, brief loss of muscle tone that can result in falls known as drop attacks.
Some studies reported reductions in seizure intensity and duration, as well as faster recovery after seizures, suggesting that VNS may provide benefits beyond reducing seizure frequency.
In some studies, participants saw improvements in alertness, attention, and sleep following VNS. Improvements in communication, social functioning, behavior, and school performance were also reported in some patients, while one study described a reduction in the number of antiseizure medications needed.
However, the studies were difficult to compare because they used different assessment methods, many of which were not validated and relied on caregiver reports. As a result, the researchers could not determine the overall magnitude of VNS’s effects on functional outcomes.
VNS was generally well tolerated, with most reported adverse effects being mild, transient, and manageable with adjustments to stimulation settings. Voice changes or hoarseness were the most common, affecting up to 44% of patients in the largest study, followed by cough, which affected 30%. Shortness of breath and tingling or altered sensation in the neck were also reported, particularly during the early period after implantation.
Surgical complications were less common and included pain at the implantation site and infections. Two adverse events across the reviewed studies led to device removal: one due to infection and another due to severe difficulty swallowing. Two deaths were reported during follow-up, but neither was considered related to VNS or its stimulation.
Overall, the review shows that “a considerable proportion of pediatric patients may experience a reduction in seizure frequency,” the researchers wrote. However, the team cautioned that current evidence is derived exclusively from observational studies, and further studies are needed to define VNS efficacy and safety in LGS.
