By Blake Eligh
Working without scans or X-rays, physical therapists rely on their hands to tell them what lies beneath the skin. With their fingertips, they trace the line of a tendon, probe the edge of a kneecap, or cup an elbow joint to feel for the telltale swelling or warmth that indicates an injury.
Touch is an invaluable tool in Tricia Twogood’s work as a physical therapist and assistant professor in the Temerty Faculty of Medicine’s Department of Physical Therapy.
Tricia Twogood (MScPT ’09) primarily treats musculoskeletal conditions in her clinical practice, providing physical therapy for patients who may have multiple diagnoses, such as a history of cardiovascular disease or stroke, and previous injuries. She depends on touch to confirm a diagnosis and during therapy as she works to bring her clients’ attention to a specific body part or movement.
“Touch is fundamental to what we do and who we are as physical therapists,” she says.
But our broad understanding of the sense of touch is only just beginning to be understood. In 2021, California-based researchers Ardem Patapoutian and David Julius won the Nobel Prize in Physiology or Medicine for their groundbreaking research in sensory biology.
Patapoutian, a molecular biologist at San Diego’s Scripps Research, identified Piezo1 and Piezo2, the pressure-sensitive channels crucial for detecting the pressure of touch. Julius, a physiology professor at University of California San Francisco, discovered a nerve cell protein that responds to high temperatures.
Their independent yet complementary studies shed light on the fundamental physiological process underlying the perception of touch, pressure, temperature and pain.
It’s something that drives the work of neuroscientist Min Zhuo, a professor in Temerty Medicine’s Department of Physiology. Zhuo, who holds the Michael Smith Chair in Neuroscience and Mental Health, studies the relationship between pain and cognition.
Zhuo’s research shows that emotions such as fear and anxiety can activate chronic pain by releasing a surge of neurotransmitters from the brain’s frontal lobes to the spine. His research highlights the crucial role of the anterior cingulate cortex (ACC) in processing and regulating sensory and emotional experiences related to acute and chronic pain.
Thanks to ACC, how the brain registers touch and pain are closely intertwined, he says. When someone touches your hand, the mechanical stimulus triggers tiny electrical signals that travel through the body’s somatosensory system. The signals move from skin to spinal cord, where glutamate neurotransmitters relay the information to the brain’s cortex for conscious perception. This process, known as ascending sensory transmission, loops in the visual centre to recognize the touch and its source, and activates ACC in the process.
“Human imaging studies show that the ACC is activated if you have an injury or suffer an acute pain, like burning a finger,” Zhuo says.
By activating the body’s emotional response, the neurons become conditioned to respond and can increase or suppress the brain’s response to mechanical stimuli, including touch.
“For people with chronic pain, like neuropathic pain or spinal cord injuries, this ACC activity may enhance or even cause a pain response,” he says. “When circuitry is highly activated, even a gentle touch can trigger a strong response.”
This emotional response of ACC can also influence how the brain responds to touch, Zhuo says.
“If it’s the touch of a friend, or a lover touches your hand, the brain will understand this and respond accordingly. If the touch conveys dangerous information, the brain will amplify the sensation and cause you to withdraw your hand,” he says.
“The body’s system produces feedback control in response to peripheral sensory stimulation. It can make the whole body become super-sensitive to touch.”
As researchers unravel the science of touch at the molecular level, questions remain about the role of touch in social situations, including clinical settings.
This is an area of practice that Pier Bryden (PGME ’97, PGME ’01) has often considered in her work as a staff psychiatrist at The Hospital for Sick Children and as Temerty Medicine’s associate dean of clinical affairs and professional values. Bryden says that touch can be a delicate subject in health care, especially when it comes to interactions with young patients. Training has traditionally discouraged nonclinical touch between practitioner and patient, even when a child actively seeks comfort.
“In my practice as a child psychiatrist, I would never initiate nonclinical touch of any kind,” she says. “A child may not be able to tell me if they don’t like it, or they may be intimidated by the fact that I am an adult and a doctor. A significant number of child and adolescent psychiatry patients may have histories of trauma, so when it comes to touch, we are very careful.”
However, Bryden notes, there are times when touch may be appropriate or even necessary. She points to the work of Austrian psychoanalyst René Spitz, whose post-war study of children raised in foundling hospitals revealed the critical role of touch in a child’s physical and emotional development.
“The children who weren’t touched were significantly developmentally delayed, which raised the question of what children need [in order] to develop — social interaction and, arguably, touch,” she says. The answer to the question of contact with patients requires reflection, says Bryden.
“What do you do when a young child gives you an unexpected hug or asks for comfort?” she asks. “Particularly with younger children, you have to consider what rejecting touch means and how cognitively capable they are to understand the rationale.”
Bryden recommends preparing boundary-setting phrases that offer a neutral option.
“I might say, ‘I’m more of a handshaker’ or offer a high-five,” she says. “But there are times when I’ve been taken off guard, and rejection would be significant. Sometimes you have to make in-the-moment decisions.”
In residency training, Bryden notes that there are clear lines around consent and communication.
“You cannot touch someone without first explaining the purpose,” she says.
Bryden points out that complaints to medical oversight boards often cite practitioner touch that the patient didn’t feel adequately prepared for. The College of Physicians and Surgeons of Ontario’s “Boundary Violations” and “Advice to the Profession” documents set out clear physician obligations in such interactions.
“Patients might not know they would be touched in that way, when it was coming or were taken by surprise because the physician didn’t take the time to explain it,” Bryden says, adding that the more intimate the exam, the more important it is to explain what you will be doing and why, and to get patient consent.
Bryden says it’s critical to discuss scenarios in training and prepare boundary-setting phrases to offer a neutral option. For example, if a paediatric patient asks for a hug, Bryden suggests that practitioners can take cues from their relationship with the family. If a hug is provided, it is with explicit consent and in the safety of a public space.
“The younger they are, the more you have to be guided by parents. It should always be in public — never in private — for me, that’s an absolute. Preferentially, it should be observed by parents, and the longer you have known the patient and the family, the better,” she says.
The issues that Bryden brings up are also on Twogood’s mind. For Twogood’s learners, who will rely on touch as part of their practice, navigating these areas is a skill that must be learned.
“It can be a very big deal to make physical contact with another person, and physiotherapists must never lose sight of this,” she adds. “It’s a huge part of the training for the students I work with.”
Equally important are consent and communication.
“In practice, the early part of our encounters always begins with a verbal conversation, and then there is the transition to physical contact,” says Twogood. “There isn’t a recipe for how that occurs — it should be a dialogue between the patient and the practitioner.”
For Twogood, it’s undeniable that touch plays an integral part in clinical practice. Clients may hold themselves differently when touched, standing up a little straighter or moving differently, she adds. “Touch changes the dynamics of the social interaction.”
There are also times when Twogood strategically withholds or removes touch to deliberately reduce the amount of feedback she is providing while a client practises a movement or exercise.
“Clients may not remember a lot of what we tell them,” she says. “If I really want someone’s attention, I might pick the moment that I am touching them to deliver certain information.”
Ultimately for Twogood, the role of touch is greater than the sum of physiological or anatomical parts.
“Touch changes the dynamics of the social interaction,” she says. “It goes beyond mechanics and anatomy. As physiotherapists, we are deliberate about targeting specific tissues of the body when we use touch in clinical practice, but at the end of the day, it’s also a connection between two people.” •