Picturing Prevention
Using sonographic imaging, assistant professor Shawn Roll and his research team seek to detect the earliest signs of carpal tunnel syndrome.
By Breanne Grady MCM ’10
Shawn Roll has expertise in a specific type of “handiwork.”
This past September, he was awarded a $2.3-million research grant that will allow the researcher to study the early stages of carpal tunnel syndrome (CTS) in dental hygiene students.
A USC faculty member in his fifth year, Roll focuses primarily on research for the prevention, rehabilitation and assessment of musculoskeletal disorders like CTS.
Originally interested in athletic training, Roll changed his focus to occupational therapy, earning a bachelor’s degree in occupational therapy, a master’s degree in allied health professions, and in 2011, a PhD in health and rehabilitation sciences, all from the Ohio State University.
Roll refers to adults in the workplace as “industrial athletes” — a nod to his sports background — and treats them as such, working to prevent work-related injuries and helping adults be functional when they do sustain some sort of injury.
“The nice thing about occupational therapy that drew me in was its theoretical foundation,” he states, explaining his shift in interest. “It allows you to understand how to holistically view an individual and understand the way that you would intervene with that individual to improve their independence and their functional performance.”
According to Roll, what is known about CTS is largely from the clinical perspective, when somebody already has identifiable symptoms such as numbness, tingling or weakness in the hand.
“We’ve been studying carpal tunnel syndrome for more than 20 years, longer than that even, and we don’t understand what causes it,” he explains. “We have a collection of different ideas and know that repetitive motion, forceful gripping, vibration and those types of things can lead to it, but not always and not in every individual. You can put five individuals in the same job with the same physical exposures and three of the five will develop it while two will not.”
Shawn Roll, on right, examines graduate research assistant and doctoral student Mark Hardison’s wrist to demonstrate the way he collects data for his research | Photo by Christina Gandolfo
The four-year grant, which is funded by the Centers for Disease Control, National Institutes for Occupational Safety and Health, is titled “Sonographic Tissue Morphology in Early-Stage Work-Related Median Nerve Pathology.” It will run from September 2015 through September 2019.
As principal investigator, Roll and his team will be using sonography to examine populations of dental hygiene students at both USC and Loma Linda University.
Among Roll’s collaborators are co-investigator Jane Forrest, professor of clinical dentistry at the Herman Ostrow School of Dentistry of USC, and Wendy Mack, associate professor of preventative medicine at the Keck School of Medicine of USC, who will serve as statistician for the grant.
Roll and his collaborators determined that dental hygiene students were an ideal target population for the study.
“When students come into the program, they’re young and typically don’t have any problems, and less than 20 percent of them complain of any pain or discomfort in their hands,” he explains. “By the end of their two-year program, Dr. Forrest has documented up to 66 percent, or two-thirds of them, having some sort of pain in hands due to repetitive activities they’re doing in holding the scaling instruments. So, there is something going on there.”
Moreover, Roll describes how CTS in long-term dental hygienists is a known problem. In fact, he cites more than half of dental hygienists report having CTS at some point during their career.
In his preliminary work using sonographic imaging on chronic CTS patients, he determined that the median nerve — a major peripheral nerve in the upper limb of humans and other animals — is enlarged when compared to asymptomatic individuals, where the nerve is much smaller.
“Somehow, there has to be a transitional point to get from the small to the large,” he explains. “Using the imaging, we’ve actually done other preliminary work in an animal model where we’ve been able to replicate that progression in the size of the nerve, due to repetitive functional activities.”
Determining this tipping point could help target interventions and prevent CTS specifically in early-stage individuals.
The students in the study will be measured via imaging every four to five months to see if the median nerve tissues are actually changing in size or structure. The team will also use nerve conduction testing to see if the physiology of the nerve is working properly.
In addition, the team will collect symptom reports and functional reports from the student populations, comparing the imaging and changes in tissues of individuals complaining of symptoms or problems against those without symptoms.
In parallel, the study will collect the same data from a cohort population.
“We will collect data from a population of OT students, who also have a two-year professional program and very similar demographics, but do not engage in repetitive upper extremity tasks,” he says.
Using the sonographic images collected from both populations, his team will look for changes in median nerve morphology — the first signs of which could indicate the beginning of CTS.
At the end of the study, Roll hopes that the research will lead to earlier identification for individuals who might be progressing towards CTS. He stresses that research on the early stages is crucial to prevention.
“Our goal is to develop some sort of predictive model to show how imaging will show the progression of CTS, so we can develop this model and then implement it in the workplace where high-risk workers are screened every six months or year using the imaging,” he explains. “If we start to see the changes, we can then intervene.”
At the same time, the team will video-record the dental hygienists at work and look at the actual positions and postures they are using to be able to understand if there are certain positions and postures that are potentially leading to the symptoms.
“Hopefully, we can develop some sort of education program and preventive techniques,” he explains. “We won’t necessarily see CTS in our students across two years, but hopefully we’ll be able to continue following and measuring some of these individuals as they move into their professional careers long-term.”
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