From kids playing sports to battle damage to soldiers, traumatic brain injury can ruin lives
By Juan Siliezar, Brown University
Traumatic brain injuries are a pervasive yet elusive health problem, affecting millions worldwide. According to recent data, an estimated 2 million people experience a traumatic brain injury each year in the U.S.From kids and adults on playing fields, to soldiers and sailors on battlefields, the risk of brain injury includes everything from mild concussion to chronic traumatic encephalopathy (CTE) — a progressive disease often associated with football players who suffer repeated blows to the head.
Despite alarming trends about these types of injuries, they
remain frustratingly difficult to diagnose and even harder to prevent. The
applied mechanics laboratory at Brown University’s School of Engineering is part of
an effort to develop solutions. The 10-person team — which includes
postdoctoral researchers, graduate and undergraduate students — is led by
Haneesh Kesari, an associate professor of engineering. The lab’s focus is
centered on traumatic brain injury and blunt trauma the body can endure.
“We usually first become aware of injury through us feeling pain,” Kesari said. “In fact, through most of our evolutionary history, injury to the brain came via the skull, such as during falls or blows to the head, and not directly to the brain itself by means of chronic violent shaking of the head. It’s reasonable to speculate that this is one of the reasons why the skin and the muscles around the skull have pain receptors, but the brain itself does not. The lack of pain receptors inside the brain’s tissues means it is not possible to ‘feel the pain’ of mild traumatic brain injury, at least not in the traditional sense that we do with other types of traumatic injuries — making it particularly insidious.”
To address that challenge, the Kesari lab has been
developing wearable devices for use in experimental settings to measure the
stresses and strains associated with blows to the head, blast trauma, or
violent thrashing of the head and neck. Working with collaborators at Brown and
beyond, the U.S. Office of Naval Research-funded effort is part of a long-term
project called PANTHER that is studying brain and bodily injury. It’s led
by researchers at the University of Wisconsin-Madison and includes Kesari’s lab
as well as Brown researchers Diane Hoffman-Kim and David Henann.
The multi-institution collaboration looks to link damage occurring at the cellular level in the brain with the forces and motions involved in blows to the head. This is where the Kesari group’s wearable devices come into play.
“We have Fitbits and other types of sport watches that
monitor our body’s health, like how many steps we take in a day or our calories
burned, so the thought was why not create a Fitbit-type device that does this
for the brain’s mechanical health,” Kesari said.
Introducing the accelo-hat
Known as the accelo-hat, the accelerometer-laced helmet the
team has developed is meant to take the guesswork out of brain injury. The
helmet — designed and built in Kesari’s lab — uses both commercial
accelerometers and sensors manufactured by the team to capture raw motion data
from any movement in the head of a user so that researchers can extrapolate
that data into a virtual model. Using the model, the team then recreates that
motion and simulates what would happen inside the brain as a result.
For example, the lab has recreated impacts to the brain from
a person heading a soccer ball and from riding on a high-speed motorboat as it
slams into the water repeatedly — a type of potential injury of
increasing concern to the Navy. Those studies revealed dramatic spikes
in stress applied to the brain because of these activities. The success of the
accelo-hat has led the team to expand it to encompass a human-sized dummy
implanted with accelerometer sensors throughout.
The system serves as a scientific tool to measure and
analyze the severity of accidents too dangerous to test on humans — such as
falling down stairs or surviving a plane crash. The National Institute for
Aviation Research, for example, has used the accelo-hat in efforts to develop
safer aircraft seats. The research involves dropping an airplane fuselage
several feet to simulate a landing gear failure while human models wearing
accelo-hats sit in the seats.
“We could see what happened injury wise if they changed the
height of the seat or if they increased the cushioning in the back seat,”
Kesari said. “Do those changes make it more safe or less safe? Those questions
couldn't really be answered before, but now with the theory and algorithms that
we developed, they can be.”
A cross-team effort
The accelo-hat and the mathematical theory that powers it
stem from the collective expertise and dedication of the team both in the
Kesari lab and via its collaborators at Brown. Each team member brings a unique
skill set to the table and plays a part in a much larger effort, including
developing complex algorithms to decode accelerometer data and translating raw
numbers into meaningful insights about how forces impact the human body.
Brown postdoctoral research associate Yang Wan, for instance, helped take Kesari’s initial theory of how to extract the accelerometer data from the sensors into actual experimental measurements capturing accelerations and stresses the human body experiences using the accelo-hat. The work not only involved statistical analysis and highly advanced decoding techniques, but also some boots on the ground. Wan and team members visited various Navy-supported research labs and bases to help run many of the experiments.
Beyond data interpretation, the lab’s success has also relied on partnerships with Brown researchers like Hoffman-Kim, a neuroscientist and engineer, to enhance the team’s ability to connect mechanical insights with biological realities. Hoffman-Kim’s lab creates 3D brain cell cultures, or mini-brains, that mimic real neural tissue and provide invaluable data about cellular responses to trauma.
Senior research associate Rafael González-Cruz plays a key
role in this partnership, bridging the gap between engineering and
neuroscience.
“Members of the Kesari lab design sensors that can detect
changes in acceleration and position of the head after receiving an injury and
use that to be able to determine whether the metrics compiled by these sensors
are indicators of injury — I look at the biological response of these forces in
actual living cells,” González-Cruz said.
To perform the injury experiments on the mini-brains,
González-Cruz uses a centrifuge that rotates at fast speeds to create an
enormous amount of force —which is traditionally used to separate cells by
size and density. Most recently, he and Wan led a test that allowed the team to
measure what happens to mini-brains when they applied different levels of
sustained force. This allowed the team to measure, with precision, the cell
damage not only caused by different amounts of force but the amount of damage
that unfolds over longer periods of time, which mimics the effect of brain
compression injuries. The information is critical for understanding how it
might be possible to prevent, diagnose and treat these types of compression
injuries.
For González-Cruz, the challenge of the issue and ultimate
purpose of helping protect people against concussions is part of what draws him
into the work and keeps him motivated. Class of 2024 graduate Hana
Butler Gutiérrez, who joined the Kesari lab while she was an undergraduate
and now serves as a research associate, feels the same motivation.
One of the newest members of the lab, she works on the
materials side and spends her days creating and testing silicone lattice
structures designed to absorb impact. The designs are small and flexible and
made to slip into protective gear like helmets that the lab designs, but are
intricate and involve a lot of trial and error, especially determining which
designs will best
dissipate energy.
Keeping the ultimate goal top of mind helps keep her
focused, she said.
“The whole time you're thinking about how you are designing
these structures for a purpose,” Gutierrez said. “You're thinking about the use
that it's going to have and how you're spending all this time making something
very precise for a very specific goal. Its validating and gives you a reason to
continue — because while my work is sheerly mechanical, it has a place
somewhere further in a much bigger project.”