Sprains and the Brain

Most people don’t think a sprained ankle is serious, but Erik Wikstrom disagrees. The UNC exercise and sports scientist studies the mechanisms and long-term impacts of lateral ankle sprains — exploring not only how they affect local tissues, but how they change the way the brain programs movement.

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April 16th, 2019

A sea of blue t-shirts surges across Franklin Street, only broken by the occasional, celebratory fire. One person climbs a nearby lamppost, bellowing into the night: “TAR!” Those below cheer heartily in response: “HEELS!”

For most Carolina fans, the 2017 NCAA National Championships is surrounded by memories like this. Memories of victory. And while the UNC Men’s Basketball team’s struggle for redemption is one for the history books, at the time, one of its star players, Joel Berry, was facing a different kind of struggle. The junior point-guard had sprained his left ankle in a game against Kentucky just before the semi-finals. Earlier that same season, he sprained his right ankle ­­–– twice.

He played through these sprains, returning to the courts just minutes after injury and eventually helped lead his team win the NCAA title. And while Berry had the support of professional medical staff, the question remains as to how these injuries affect the body in the long-term, especially for those who don’t have easy access to physical rehabilitation.

Lateral ankle sprains are the most common musculoskeletal injury in both sports and daily life, but they’re also one of the most overlooked. What many don’t realize is that these sprains can lead to life-long medical conditions if not treated properly.

UNC exercise and sport scientist Erik Wikstrom emphasizes that one of the biggest issues with ankle sprains is the public’s lack of concern for them. “These injuries that are perceived to be inconsequential have long-lasting consequences,” he says. “Just a single ankle sprain can lead to the development of ankle osteoarthritis.”

Only about half the people who sprain their ankle seek medical attention, and just 20 percent of those that do follow it up with some form of physical rehabilitation. The other half go back to sports and regular use, often on the same day they got the injury.

“If we look at the longer-term issues, about 40 percent of everyone who sprains their ankle will go on to develop chronic ankle instability,” Wikstrom explains. “And about 70 to 80 percent of those individuals will develop post-traumatic ankle osteoarthritis.” This condition is characterized by degradation of the ankle cartilage following traumatic injury, causing pain and difficulty during both physical activity and daily movements like walking or climbing stairs.

Peripheral pathways

But these injuries don’t have to have such major consequences. Some methods of physical rehabilitation are effective in treating ankle injury. Manual therapies such as massage and joint mobilization can relieve symptoms and improve outcomes for those with chronic ankle instability. But Wikstrom is trying to get at the bigger picture. “We want to understand why this works,” he says. “If we understand those mechanisms, we can better tailor treatments to the individual patients.”

Ankle sprains affect the body’s nervous and sensory system, from the level of nerve receptors in the ankle all the way up to the brain. Signals from these nerve receptors allow the brain to assess the current state of the body, integrate that information with past experience, and create a plan for how to move next. Following injury, these systems compensate for damaged receptors, ligaments, and muscle — resulting in adaptations to the brain’s movement plan and often increasing risk for reinjury.

“Most people don’t realize that those compensations have even occurred. They’re very subtle changes that we can’t see with the naked eye,” Wikstrom says.

To better understand these neural shifts, he and his team use technologies like transcranial magnetic stimulation (TMS) and electroencephalography (EEG) to measure changes happening at various levels of the nervous system. TMS allows them to measure the brain’s capacity for sending information to the ankle muscles, an ability that is decreased in those with recurrent sprains. EEG measures the activation of different regions of the brain during physical therapy tasks.

“It’s very unlikely that any treatment would impact one level of the neuromuscular system and one level only,” he explains. “So by assessing changes at the brain, spinal, and in the peripheral level, not only can we measure those individually, but we also can look at the interactions among them.”

Back in the game

Ultimately, a better understanding of how sprains impact both the ankle and the body’s nervous system will improve how clinicians can treat these injuries. Wikstrom hopes it will also emphasize the importance of such treatment to the public.

“People trust their primary care providers, so if those providers learn more about the central nervous system impacts and effective treatment options — and then make strong recommendations — we might have better results,” he says.

Progress in treating these injuries means more people staying active and more athletes back in the game — perhaps not on the same day, but ensuring a longer, healthier career.

Erik Wikstrom is an assistant professor in the Department of Exercise and Sport Science within the UNC College of Arts & Sciences.