Researchers test vagus nerve stimulation to teach premature babies to take a bottle
Eager expectant parents often hear that newborns eat, dirty their diapers and sleep — and not much else for several months. But what should come naturally – eating – can be difficult, if not impossible, for premature babies or babies who suffer a lack of oxygen to the brain during birth. Their muscles are weak, and they have difficulty coordinating the pattern of “suck, swallow, breathe” to successfully eat.
Some of these babies end up going home with a gastrostomy tube — a surgically implanted port that sends food directly to their stomachs. Although the tube does allow them to get the nutrition they need to grow, it requires surgery and, of course, extra care by the parents. In addition, babies who have feeding difficulties are more likely to have language delays later on.
A group of researchers and doctors at MUSC want to see if they can help babies develop proper oral feeding skills before leaving the hospital so they can avoid the G-tube.
They’ve been working on a small preliminary study to see if stimulating a baby’s vagus nerve while the baby actively sucks on a bottle will help rebuild the motor pathway that enables the baby to eat. An electrode attached to the baby’s ear sends a mild pulse that the vagus nerve picks up. The vagus nerve runs from the brain to the colon and provides sensory information from the ear and throat; it’s also responsible for motor functions in the neck related to swallowing and speaking, among multiple other functions throughout the body.
Doctors have used vagus nerve stimulation to help people with epilepsy reduce the number and severity of seizures. Early studies have indicated it could help reduce the severity of tinnitus by decreasing brain hyperactivity and help stroke survivors regain motor function when it’s paired with physical rehab.
The pairing is key, said Bashar Badran, Ph.D., who along with Dorothea Jenkins, M.D., professor in the College of Medicine, led a team from multiple disciplines, including psychiatry, occupational therapy, pediatrics and imaging, as well as members of the Department of Biomedical Engineering at City College of New York, to develop the study, which began last fall. It is funded through a discovery pilot project from the National Center of Neuromodulation for Rehabilitation at MUSC, which is supported by the National Institutes of Health.
Stroke survivors who do physical therapy get results, but slowly. Performing the therapy while getting vagus nerve stimulation speeded up the results, Badran said.
Those studies were on adults. The MUSC study is working with the youngest group of patients to get brain stimulation.
“I think MUSC is the only place you could do this kind of work,” Badran said, referring to the way the health care providers teamed up with researchers to try to improve patient outcomes.
The team has published the results from the first five babies to participate. The early results are promising, with three babies going home without the tube. A fourth baby was able to eat but got a tube at the mother’s request during a hernia repair, in case feeding went downhill after the surgery.
Though the results are good, the main focus of this early study is to show the therapy is safe. All the babies are getting the treatment, so the study isn’t as rigorous as one that has a control group.
Jenkins said they haven’t seen the treatment cause any problems for the babies.
“It seems to be very well tolerated,” she said.
The bigger problem is in miniaturizing the treatment to fit the tiny patients. Badran said they fabricate the electrodes by hand to fit the babies’ ears. They’ve gone through five prototypes so far.
On Aug. 22, the team crowded into the special needs nursery to try the treatment on baby No. 8 — Emaree Haskell. Emaree was born Aug. 2 when her mom, Jayne Johnson, was 36 weeks pregnant. That’s a late preterm birth — 37 weeks is considered full-term — but Jenkins said Emaree suffered hypoxic ischemic encephalopathy, or lack of oxygen, and hasn’t been able to pick up feeding.
Johnson said she agreed to the treatment because her daughter is having problems with the concept of sucking.
“It can only help her, not hurt her,” she said.
Right now, they laboriously turn the stimulation on manually whenever they observe she’s successfully sucking on her bottle. The goal, however, is to develop an automated system using an intelligent baby bottle that can sense when she’s sucking properly and synchronize the stimulation with the sucking. The MUSC Foundation for Research Development has already filed a provisional patent for such a device on behalf of the core team of researchers.
Normally, occupational therapists work with the babies, but that usually happens only once per day. Similarly, because providing the nerve stimulation manually is so labor-intensive, the team can get together only once daily. An automated system would allow a nurse or occupational therapist to easily provide the therapy. Ideally, a baby would receive the treatment two or three times each day, Jenkins said.
After Emaree’s session, she’s drunk about 15 cc of formula from a 60 cc bottle. Nurses feed the remainder to her through a nasogastric tube. Teaching the brain how it should work takes time, Badran said. So far, they’ve been giving babies the treatment for 14 days and have started seeing improvements after the first week, Jenkins added.
And a week and a half later, Jenkins reported good results for Emaree: she had improved from taking only 20 percent of her feeds by mouth at the start of treatment to taking 80 percent by mouth after two weeks of treatment. Jenkins expected her to be completely bottle-fed within the week —a big step for the little girl.
The team plans to work with 20 to 25 babies in this stage of testing.