Nicole Dodds first noticed her son, Rowan, was having trouble using the right side of his body when he was about 6 months old. Babies typically use both hands to pick up toys and lift their chest off the floor at that age, but Rowan was mostly using his left arm and hand, keeping his right hand balled in a fist.

That started a string of doctor visits. Around Rowan’s first birthday, doctors did an MRI and diagnosed his one-sided weakness as hemiplegia, probably caused by a stroke he sustained in utero. This surprised Dodds, since as far as she knew she’d had a totally normal pregnancy and birth

Perinatal stroke — when an infant loses blood supply to the brain in late pregnancy, during birth or in the first month of life — is one of the most common causes of hemiplegia in infants, affecting anywhere from 1 in 2,500 to 1 in 4,000 live births in the United States every year.

Like adult stroke, perinatal stroke is usually caused by a blood clot that jams brain arteries, or else by bleeding in or around the infant’s brain. Babies with heart disease, clotting disorders such as hemophilia, and bacterial infection among other factors have a higher risk of perinatal stroke, but the exact cause is often unknown.

As in the case with Rowan, there are often no outward signs for up to a year that something is amiss, resulting in delayed or inconclusive diagnosis. It’s nearly impossible to detect a stroke in utero, or even in the first few weeks after birth, since the symptoms can seem within the norm for infants: favoring one side, extreme sleepiness, mild seizures that seem like shivering or sudden stiffening. More obvious behaviors such as trouble walking and talking don’t usually become apparent until the child turns 2, and are associated with other childhood problems.

And because these strokes are relatively uncommon, doctors aren’t always on the lookout for them.

“A lot of these babies can look like they are doing really well in the first three months after a stroke. But by the time they’re 6 or 8 months old, one hand might be advancing and developing skills — like picking up a Cheerio from a tabletop — but the other hand is not able to do that,” said Gabrielle deVeber, a senior scientist at the University of Toronto who specializes in pediatric stroke.

When deVeber was just starting her medical career in 1992, doctors had a “wait and see” approach to treating infant stroke, she said. Since newborns’ brains have more plasticity and can develop around, or compensate, for problems more easily than an older child’s brain, the thought was that they should be able to “bounce back” from the injury with little to no intervention.

“Now we know that’s really not true,” she said. “With these kids, it’s really important to identify that a stroke has occurred as soon as possible so we can begin treatment.”

Research shows that about half of all perinatal stroke patients have lasting motor impairments, such as weakness or paralysis and muscle spasms, and half have minor or no lasting physical impacts. About 60 percent have some cognitive symptoms — including impaired language development and other developmental and behavioral disorders — later in life.

And yet, other than singling out and treating specific symptoms, there is no standardized protocol on how to treat infants identified as having had a perinatal stroke.

In 2013, a review of 166 studies outlining 64 approaches to treating childhood cerebral palsy found that less than a third merited further investigation. Many were shown to be ineffective, and a few — such as inhaling pure oxygen in a hyperbaric chamber, which can cause seizures or eardrum damage — were even shown to be harmful. The review found just 15 approaches were both safe and effective.

One that got the green light, known as constraint-induced movement therapy, uses a cast or other restraint on the unaffected side to encourage the use of the other impaired limb. This approach is the primary focus of a phase-three clinical trial taking place at 12 sites across the United States, which began enrolling participants up to age 2 in October 2019 and will continue for five years.

Warren Lo, a pediatric neurologist at Nationwide Children’s Hospital in Columbus, Ohio, who is co-leader of the constraint-induced movement study, said such efforts are vital because “there is really no consensus on how to rehabilitate infants who have suffered perinatal stroke.”

His co-leader, Sharon Landesman Ramey, a developmental psychologist at Virginia Tech, has spent the past 20 years adapting a form of constraint-induced movement therapy for adult stroke patients, making it more effective for children.

“An adult stroke patient has a mental image of the correct way to turn a doorknob, or how to eat with a spoon,” she said. “But a little baby who’s never even held a spoon doesn’t know anything about that.”

As a result, she said, their recovery process is very different.

Children enrolled in the study use a lightweight cast specially made to fit on their unaffected arm and hand, hampering the use of that side. Combined with activities employed by physical therapist, the cast encourages the children to use their affected side instead. It’s a lot like how doctors treat children with blurry vision in one eye by having them wear a patch over their good eye and perform exercises with the affected eye (such as looking up, down and side-to-side). Over time, the child’s brain adapts to better interpret signals sent from the blurry one, allowing both eyes to see clearly without the patch.

Nicole Dodds’s son, Rowan, received earlier versions of the therapy while participating in two previous trials led by Landesman Ramey — one when he was almost 2 years old; the second when he was almost 3. While those trials included children with hemiplegia from various causes, the current trial is enrolling only children who have had a perinatal stroke and is limited to children between 8 to 24 months old.

In past clinical experiences with 30 infants who received an intensive version of the therapy before age 2, Landesman Ramey said, more than 90 percent had better movement when assessed after one month of therapy. Some of these infants also showed improvements in language, cognition, and social and emotional development

Landesman Ramey said she hopes starting the therapy earlier will help participants respond better, just as children who are deaf and receive cochlear implants before 18 months of age are generally able to hear more sounds and often speak more fluently as a result than those who get one later on.

“A baby’s brain is developing a whole repertoire of skills in their first year of life,” including speech, hearing, social, emotional and motor functions, she said.

Although some of the activities for participants in the new constraint study may seem like play — beating a drum, rolling a ball or hugging a teddy bear — they are intensive components of the therapy.

The potential impacts are profound. The enrolled infants and toddlers will be asked to reach, pinch, grab, point, wave and practice other motions. Some will get the therapy for six hours a day, some for three hours, and one control group will continue their usual therapy regimen. The last three days of treatment will be cast-free, so the babies can practice using both arms and hands together. Trained assessors will evaluate their motor skills within a week after the one-month therapy session, and then again after six months.

Landesman Ramey said the research team hopes to get parents involved in activities with their children “during non-therapy hours — at home, on the playground or wherever the child is — about 45 minutes every day,” she said. That way, they can help their child practice skills learned in therapy, even after the trial has ended.

That is clearly something that Dodds has embraced.

At home in Florida, Dodds continues to work with Rowan, now 4 years old and in prekindergarten. The constraint-induced movement therapy he went through, she said, definitely made a difference. His gross and fine motor skills have improved, just on a longer timeline than is typical: He crawled at 13 months old and walked at 20 months old.

He still uses his left side more than his right, and he struggles to use both together — say, to open a jar of peanut butter or walk down a flight of stairs. But he is able to do the majority of things kids his age do, said Dodds: “He runs, he jumps, he will talk your ear off.”

It wasn’t always easy, she said, “but it’s worth it. My son experienced gains that I don’t think he would have achieved with the typical therapy regimen.”