There’s a cautionary tale in the story of radiological investigations for ‘musculoskeletal’ pain. As imaging improved and the pictures got clearer and shinier, those referring for scans, reporting on scans and interpreting scans for patients, grew more and more confident that they could visualise the ’cause’ (or lack thereof) of an individual’s pain experience. This tumescent confidence has not been without its problems, and every therapist will have first hand experience of a person whose pain has been derided and denied as a result of “nothing showing up on the scan”, or equally, the patient who falls off the precipice after 6 weeks of steady progress because their long awaited MRI demonstrated a ‘bulging disc’.
There are attempts now to put out the dumpster fire that imaging for low back pain has become, such as the Choosing Wisely initiative and research into the possible consequences of the way radiology reports are written.
But it seems a different chapter of the radiology-for-pain guild haven’t got the memo and are possibly hurtling down the track towards problems.
Of bulges and blobs
In a review article in the current Clinical Journal of Pain, Evaluation of Chronic Pain Using Magnetic Resonance (MR) Neuroimaging Approaches, What the Clinician Needs to Know (Kumbhare et al 2017), the authors suggest
“…most clinicians are not aware of the capabilities of advanced MRI methods in assessing cortical manifestations of chronic pain. In addition, many clinicians are not aware of the cortical alterations present in individuals with chronic pain.“
The basic idea (well intentioned I’m sure) is to begin to set out a path for clinicians to use fMRI imaging of the brain to help diagnose, track and treat pain.
But in the same issue Karen Davis, the great debunker of fMRI and pain overstatement, and David Seminowicz have written a commentary on the Khumbhare et al (2017) paper; Insights for Clinicians From Brain Imaging Studies of Pain (Davis and Seminowicz 2017) noting some fundamental issues with the idea
Neuroimaging has taught us a lot about the brain in chronic pain, but individual variability means that these findings cannot be generalized across conditions
The first point to take away from the Kumbhare et al review is that there were no specific abnormalities in common across the studies, likely owing to the variability between studies, including differences in chronic pain condition, age, sex, and co-occurring symptoms and diseases.
The effect of sex differences is not always often fully considered in brain imaging studies despite chronic pain conditions being more prevalent in women (eg, fibromyalgia, irritable bowel syndrome, temporomandibular disorder) or more prevalent in men (eg, back pain, anklyosing spondylitis).
Thus, it is important for a clinician to know that there is vast intersubject variability (including sex differences) in the general response to and coping with painful stimuli, brain circuitry, and connectivity.
Can brain biomarkers replace pain ratings?
Kumbhare et al state that “compared with self-reporting approaches, objective imaging techniques are expected to potentially lead to better pain management.” We find this statement problematic for several reasons. We argue that pain ratings are the best outcome measure we have for treating chronic pain and will likely always remain that way – imagine for example a patient who’s brain is deemed “recovered” based on our neuroimaging techniques, but still reports suffering intolerable pain most of the day. (emphasis added)
The last comment above (in bold) is the telling one.
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