In Part 2 of this series, we looked at the patient interview through a pain sensitivity lens. This process helps determine whether pain sensitivity is less or more likely to be a priority for the physical examination. Now we arrive at the examination itself.

Clinical pain sensitivity testing

Let’s consider clinical pain sensitivity testing first. If the patient interview suggests that pain sensitivity is more likely to be a significant contributing factor in their presentation, pain sensitivity becomes a priority during the physical examination.

There are many, many ways to test different aspects of pain sensitivity. What we describe here is a simple test protocol for somatosensory sensitivity that can be performed without the need for specific or expensive equipment and in a timely manner.

This protocol can provide considerable insight into how someone is processing different types of stimuli that under ‘normal’ circumstances would not be painful (or only mildly locally painful with sharp stimuli) for most people.

The tests are (with links to examples in a clinical context):
•    light touch—using a tissue or a piece of fishing line as a substitute for a monofilament (watch here)
•    blunt pressure—using digital pressure as a substitute for a pressure algometer (watch here)
•    sharp—using a toothpick (watch here)
•    cold—using an ice cube (watch here).

What to look for

Test order can be important. The above order will generally take you from least to potentially most provocative testing. If the person you are testing has severe allodynia with light touch testing, it may be unhelpful to continue testing.

On other occasions, you might test all modalities to get a broader picture of the somatosensory sensitivity of the nervous system.

Most physiotherapists should be familiar with doing a version of these tests in neurological screening for loss of sensation or full neurological examination protocols.

It is natural to assume with pain sensitivity that you are looking for heightened responses. Pain with light touch. Exaggerated pain with sharp. Increased coldness or pain with cold.

However, reduced sensory responses can also be a feature of the altered processing of sensory information (as opposed to reduced response due to compromised nerve conduction) that may occur with pain sensitivity.

There could therefore be a mix of heightened and reduced responses. This mixed response might be across tests, such as reduced sensitivity to light touch but a heightened response to sharp and cold stimuli in the same body site. Or there may be mixed findings for a single test.

For instance, consider the patient who has heightened sensitivity to light touch on a surgical incision but reduced sensitivity to light touch on an area adjacent to the scar.

Compare side to side. Compare proximal to distal. Ask about differences in response between sites. It is most helpful to compare areas with similar skin, such as two arms or two legs, the upper and lower back or either side of the spine.

The response might not just be pain; comparison to other sites is critical. Is the sensitivity localised to the region with symptoms or is it more widespread? Does a specific stimulus provoke symptoms locally and/or does it provoke a distal response?

For example, ice application to the low back might provoke symptoms down the leg. Or sharp stimulus to the neck might be heightened but also provoke pins and needles in the arm. If symptoms are provoked, how long do the symptoms remain once the stimulus is removed?

If the stimulus is applied in a repeated manner, do symptoms stay the same or is there a build-up of the response (temporal summation)? See the videos referenced earlier for examples.

A helpful tip is to initially observe different findings in different people rather than provide an exact explanation for the differences.

This testing protocol is a perfect opportunity to use reflective questioning. Imagine that a person tests as sensitive to cold on their problematic knee but feels a normal response on the other knee.

On completion of the testing, asking them ‘What do you think that means?’ would be a helpful prompt, followed by some education or an explanation of the findings. This does not need to be hours of education on pain neurophysiology.

A simple, patient-specific explanation might be just as powerful in transforming patient understanding—watch here and here for examples.

Warnings of possible negative responses may be important prior to testing.

In rare circumstances, pain sensitivity testing can result in the patient experiencing acute anxiety and/or feelings of being overwhelmed.

In such instances, the physiotherapist should be empathetic, maintain a calm demeanour, support the patient through the episode and ultimately use this as a reflective and learning exercise for the patient.

The influence of pain sensitivity on other aspects of the physical examination

If a patient has increased sensitivity, this may have implications for other elements of the physical examination and for the interpretation of the examination findings.

Firstly, what effect might further assessment have on a person with increased sensitivity? Consider the patient with allodynia to light touch, temporal summation with repeated light touch stimulus and sharp, blunt pressure and cold hyperalgesia.

What might their tolerance be to other aspects of a physical examination? Geoff Maitland spoke eloquently about the concept of patient ‘irritability’. Perhaps the neuroscience is catching up to Geoff. Certainly, pain sensitivity can be a significant factor in reducing patient tolerance to the assessment as a whole.

For those further assessment components deemed necessary, modification may be required in terms of the manner and intensity with which they are performed.

Think about how you might modify aspects such as passive range testing, functional testing, strength testing or palpation techniques for the patient with significant pain sensitivity.

Secondly, imagine a person who received a knee twisting injury when working on a construction site. They have significant, constant knee pain and pins and needles from the knee to the medial ankle. Pain is 7/10 at best. They can’t tolerate clothes rubbing against the knee.

Pain sensitivity testing indicates that they have allodynia to light touch, temporal summation with repeated light touch stimulus and sharp, blunt pressure and cold hyperalgesia. How valid might the results of specific orthopaedic testing to try to identify a pathological source of symptoms be in this scenario?

A valgus stress test might be applied and might provoke pain in the knee. Is there injury to the medial collateral ligament?

With further testing, all orthopaedic tests are provocative of knee pain, with very mild pressure applied. Is this routine of orthopaedic testing going to provide any helpful insight into potential pathology or are the tests just provocative because of significant pain sensitivity?

In the scenario above, the validity of the orthopaedic testing would be questionable.

This knee injury scenario has been presented from a pain sensitivity perspective.

Now let’s look at the very same presentation through a pathoanatomical lens. The diagnostic process considers mechanism of injury, site of pain, range of motion and a single orthopaedic test: a valgus stress test. What would the conclusion be?

Potentially, this narrow assessment view could result in a medial collateral ligament strain diagnosis with management being bracing of the knee for two to four weeks. If you don’t think about pain sensitivity, you could be missing an important contributing factor and providing management that is harmful or not helpful.

Ever done this before? We have. But with evolving knowledge we are able to learn from this and to provide helpful care for both the mechanical sprain presentation and the increased pain sensitivity presentation.

Resources

Like to hear Tim and Darren casually chat about the physical assessment of pain sensitivity? Click here.

Like to read about our take in a scientific journal? Beales et al. ‘Masterclass: A pragmatic approach to pain sensitivity in people with musculoskeletal disorders and implications for clinical management for musculoskeletal clinicians.’ Musculoskeletal Science and Practice, 2021. Click here. 

Listening to pain stories might be helpful? Click here.

Want the bigger picture? Click here. 

Like something short and fun? (Yes, it’s Tim and Darren again.) Click here.

>> Darren Beales FACP is a Specialist Musculoskeletal Physiotherapist (as awarded by the Australian College of Physiotherapists in 2008) and a director at Pain Options in Perth, WA. As a senior research fellow at Curtin University, Darren is undertaking broad research into clinical pain, from the mechanistic understanding of clinical pain to efforts to enhance the management of persistent pain and implementation of knowledge into practice.

>> Tim Mitchell FACP is a Specialist Musculoskeletal Physiotherapist (as awarded by the Australian College of Physiotherapists in 2007) and a director of Pain Options. Tim has completed a PhD in the area of low back pain and has a special interest in the translation of logical reasoning into clinical practice. He holds positions with the Australian Physiotherapy Council and the Australian College of Physiotherapists.