What Determines Severity of Neuropathic Pain – The Neuropathicity, Not the Mood – and Good-Bye Fear Avoidance Model(FAM)

Factors such as pain on light touch (allodynia) and excessive pain on pinprick (hyperpathia) were strong indicators of pain severity. “Female gender, age, and history of serious mental disorders were found to be weaker indicators.”  Psychological factors are played up as being the prime indicator of chronic pain – much to the delight of insurers who would like to be off the hook for compensation if they could deem client’s problem as psychological and hence of their own doing. This has always been rubbish – pain severity has always been the unmost important factor and each victim has a breaking point where psychological decompensation will be evident. That does not mean that coping strategies don’t help – its just that it still is a pain problem, not a psychological one. Recent review of Fear Avoidance Model states it has not worked out well and needs to be re-vamped with multidimensionality.

Pain. 2013 Jan;154(1):141-6. doi: 10.1016/j.pain.2012.10.001.
Predictors of severe pain in a cohort of 5271 individuals with self-reported neuropathic pain.
Butler S, Jonzon B, Branting-Ekenbäck C, Wadell C, Farahmand B.
http://www.ncbi.nlm.nih.gov/pubmed/23140908

Causes of pain included:
Diabetic perripheral neuropathy 813
Post traumatic neuropathy 3718
Post herpetic neuropathy 293
Lumbosacral radiculopathy 2794
Meralgia paresthetica 643
Myofascial pain syndrome 659
Other NP 2327
Nondiabetic polyneuropathy 1512
Spinal cord injury 766
Stroke 147 
Trigeminal neuralgia 171
Type I complex Regional pain – 312
Type II complex regional pain – 132
Unknown (nerve pain) – 1578
Other 1217 
Fibromyalgia 947

Neuropathic pain descriptors were: stabbing, shooting, aching and burning pain . 
How useful are they? – not at all – Even in severe pain the chances of having any of these descriptors was very low:

Number of descriptors in severe pain cases:
None – 2,699
One – 88
Two – 167
Three – 365

This means only 16% of subjects had neuropathic pain descriptors -  a finding I have noticed - 
Better pain predictor is the severity of the pain: - 2/3 will have severe pain

mild – 128
moderate – 1658
severe – 3419

 Major mood disorders were well represented:

mild pain – 29.9%
moderate pain – 36.4%
severe pain – 40%

Hyperpathia was common (2944) and allodynia as well (2797) – in over 85% of cases.

Presence of hyperpathia or allodynia gives a 3.3 times risk of neuropathic pain. Having both – a 11.8 times risk. Maybe not a realistic measure give tnat they would have had to have these features in order to be diagnosed with such. What is important is that mood disorders only increased risk by 1.4 times. One neuropathic pain descriptor doid not increase chances of neuropathic pain; two increased it to 1.4 times. If 2/3 of neuropathic subjects were found to have severe pain, it would follow that chances are at least 2 times for those with severe pain.

Comment – everyone likes to ignore the importance of pain severity but it comes out near top as an indicator of neuropathic pain. Presence of skin sensitivity to pain is very useful. Finding neuropathic pain descriptions are useful when found but don’t count on it – only 1/6 will have it. Mood issues don’t factor in prominently risk wise.

The fear-avoidance model took a hit recently with a report in press stating the model did not work as diagramed and needed to be revamped:

Re-Thinking the Fear Avoidance Model: Toward a Multi-Dimensional Framework of Pain-Related Disability
Timothy H. Wideman, Gordon G.J. Asmundson, Rob J.E.M. Smeets, Alex J. Zautra, Maureen J. Simmonds, Michael J.L. Sullivan, Jennifer A.Haythornthwaite, Robert R. Edwards
Pain 2013 in press
http://www.ncbi.nlm.nih.gov/pubmed/23748115       (sorry no abstract)

Given there is no abstract I have pulled a few quotes to boost my biased opinion of the FAM:

  • “The lack of empirical support for the cyclical relationships in the FAM may stem from incorrect theoretical assumptions inherent to the model.”
  • “Contrary to FAM predictions, pain intensity is a robust and unique predictor of disability [27,39], and maladaptive changes in sensory processing have been linked to the development and
    persistence of disabling musculoskeletal pain conditions.”
  • “There are grounds for questioning the relevance of a phobia-based conceptualization of fear for individuals with persistent musculoskeletal pain.”
  • “Contrary to prediction, findings suggest that many individuals with chronic pain don’t report significant levels of catastrophizing, fear or disability.”

Another issue was voiced at the Canadian Pain Society meeting in Winnipeg 2013 – at pain clinics, clinicians do not see fear advoidance – instead the see 2/3 of clients overdoing themselves and protentially hurting themselves that was.

As for behavioural issues causing chronic pain – apparently it is easy to extinguish these pain behaviours by ignoring them but paying attention to them DOES NOT significantly elevate them – suggesting thesse behaviours are more self -soothing rather than attentional

I never liked that model and am glad to see it gone…

This entry was posted in Insurer issues, neuropathic, pain mechanisms, psychology. Bookmark the permalink.

Leave a Reply

Your email address will not be published.

You may use these HTML tags and attributes: <a href="" title=""> <abbr title=""> <acronym title=""> <b> <blockquote cite=""> <cite> <code> <del datetime=""> <em> <i> <q cite=""> <strike> <strong>