Changing the Way Physical Therapists Measure Pain Pressure Threshold

Dhinu Jayaseelan

Physical therapists are all too familiar with the concept of pain. It is a condition that student PTs at the George Washington University (GW) School of Medicine and Health Sciences (SMHS) begin learning their first day of classes and something practitioners encounter daily in their patient care.

Dhinu Jayaseelan, DPT ’10, OCS, FAAOMPT, recognized that gaps exist in using patients’ information about pain to guide physical therapy treatment, and he’s addressing that situation through research. Jayaseelan, an assistant professor in the Department of Health, Human Function, and Rehabilitation Sciences at SMHS, is investigating and differentiating pain mechanisms involved in a patient’s condition. He hopes his research will better guide physical therapy interventions and treatment.

Dr. Jayaseelan in lab with studentA little background on pain science is helpful to understand Jayaseelan’s research. Generally, three pain mechanisms exist: nociceptive, peripheral neuropathic, and central sensitization. Nociceptive pain is often localized to the tissue that is damaged, while neuropathic pain involves nerve damage and may present with symptoms along the nerve’s pathway. Central sensitization involves a change in the central nervous system that contributes to the patient persisting in a state of high reactivity to stimuli (such as touch) on parts of the body where tissue damage may not even exist.

Evidence suggests that a patient with pain following a central sensitization mechanism would likely benefit from interventions that are different from those that address neuropathic or nociceptive pain. “Knowing which of these three pain mechanisms is most heavily involved may assist in guiding interventions to more efficiently treat the patient’s chief complaint and more accurately resolve the source of their pain,” Jayaseelan said. “It also will help us identify if other health professionals need to be involved in the patient’s care to facilitate best outcomes.”

One way to investigate which pain mechanisms may be primarily involved in a patient’s condition is to look at the pain pressure threshold (PPT) of a patient’s body in various locations. This requires applying pressure to a site on the patient and measuring how much pressure is applied before the patient initially notes they feel pain instead of pressure. Jayaseelan proposes that understanding where PPT values are altered — locally and/or distant to the site of pain — could further guide clinicians in understanding the dominant pain mechanism(s) at fault.

There are pressure algometers to measure patient PPT, but due to cost they are not readily available in many outpatient clinics. Jayaseelan proposes that using handheld dynamometers (HHD), which are more readily available in clinical practice, could provide valuable feedback on PPT. He’s working on a study to validate the HHD as an accurate measurement tool for PPT. He’s also collaborating with students in the Biomedical Engineering program at the GW School of Engineering & Applied Science to help develop an accurate and more cost-effective tool to measure PPT in clinics. Jayaseelan expects the device to be tested and ready for use in May 2018. In addition to the device development, part of his research has included the use of manual therapy to help reduce symptoms and improve function for individuals with musculoskeletal dysfunction.

Pain is one of the most common reasons individuals seek physical therapy services. And while pain is a complex and often frustrating impairment, Jayaseelan’s research could offer valuable insight into the pain experience, leading to more individualized and effective physical therapy treatments.