Saturday, October 20, 2012

Digesting the Moose Jaw adventure: Part VI Sensory testing 2

Older posts in this series:
Digesting the Moose Jaw adventure: Part I
Digesting the Moose Jaw adventure: Part II NERVES, baby
Digesting the Moose Jaw adventure: Part III Sensory testing for pain
Digesting the Moose Jaw adventure: Part IV Nature of Pain
Digesting the Moose Jaw adventure: Part V Mindfulness

"What we know now that we didn't know 5 years ago" 
Pam Squire
This post belongs with Part II and Part III in this series. There didn't seem to be much "new" here I hadn't already seen and stumbled over multiple times; as a PT on the outskirts of medicine, completely familiar with working in the dark, with the shadows, with uncertainty [hampered by clunky unwieldy and largely irrelevant tissue-based explanatory models], and as an aging human in a HumanAntiGravitySuit, I figured out a long time ago that peoples' pain presentations are more about them, and their own nervous system glitches, than about some maddeningly elusive definitive diagnosis that may have been missed. It seems to me this title and the content it contained suggested that news of this unknowability has begun to dawn on the medical profession, that they are starting to learn how to be more comfortable with uncertainty, starting to learn how to grapple with the idea that pain is its own phenomenon, not just a symptom of something else they've not been able to get their finger quite on. Good on them. More interactive, less operative, maybe.

Criterion 1: "Pain with a distinct neuroanatomically plausible distribution" refers to "a region corresponding to a peripheral innervation territory or to the topographical representation of a body part in the CNS", Pam Squire said.  She said, have your patient draw a pain diagram. She suggested using the colour key as described in Part III.

Criterion 2: "A history of relevant lesion or disease affecting the peripheral or central somatosensory system", i.e., the "lesion or disease is reported to be associated with pain, including a temporal relationship typical for the condition." She said, medical history plus or minus neuropathic pain scales will help establish this criterion. Various scales include LANSS, Neuropathic Pain Diagnostic Questionnaire (DN4), Neuropathic Pain Scale (NPS), Neuropathic Pain Questionnaire (NPQ), Neuropathic Pain Symptom Inventory (NPSI, in French).

Criterion 3: "Demonstration of the distinct neuroanatomically plausible distribution by at least one confirmatory test"; "as part of the neurological exam, these tests confirm the presence of neurological signs concordant with the distribution of pain."
 E.g., quantitative sensory testing, using the "kit" as described in Part III. Other ways include electrophysiology (not very practical in the clinical setting) or a clinical neurological exam (I'm thinking, reflex hammers etc.). Testing for hot and cold sensation can be done with a metal object, which is going to feel cold to the touch, usually, unless it's been sitting in the sun or on a radiator. 
Back in PT school we used hot and cold water in test tubes.
Other tools: clinical neurological exam, electroneurography (sensory nerve conduction), evoked potentials (SEP, LEP)

Criterion 4: "Demonstration of relevant lesion or disease by at least one confirmatory test" These included more specific pathoanatomical tests such as biopsy, MRI, CSF analysis etc. Challenges to pinning down a diagnosis of neuropathic pain include the reality that "the pain system is dynamic and changes unpredictable", and that "signs and symptoms may change over time." 
Well, yeah... this has been a huge confound for PT all along. We have pretty much never been able to get beyond tooth fairy science, haven't been able to show our interventions to have much credibility beyond "non-specific effects." 
Not that there is anything wrong with non-specific effects of the relieving sort - they are better than nothing, and way better than nocebo. 

This included sensory testing and pain diagraming as in Part III. DN4 with its 7 sensory descriptors was recommended as the best questionnaire to use, validated, and free from . 
Questions to ask: OPQRST:
O = onset (Sudden? Gradual? Trauma? Surgery?)
P = provoking factors, palliative factors. What makes it worse or better? Spontaneous pain is a hallmark of NeP, also sensory avoidance symptoms like avoiding certain kinds of clothes, or lights, or toothbrushing.
Q = qualities of the pain, its intermittence or constancy
R = region, radiation
S = severity on visual analogue scale
T = time duration, especially how long it's been the way it is now. 
If CRPS is suspected, check for 5 "S"s: 
Skin colour change, swelling (intermittent or constant), sweating, spasms/dystonia, shaking/focal tremors/clonus/tics. 

Check for body perception disorders - if present they might be evaluated using the Recognize App from NOI for hands and feet

Handouts included several pages of useful tips on sensory testing for and interpreting results of light brush, vibration, cool, warm, cold, hot, punctate, pin prick, deep pressure - getting it just right; what kind of fiber is tested in each case, what results mean re: which "pain" mechanism is being revealed. 
All that is still a bit too nerdy, even for me - useful though, for anyone setting up an actual study that incorporates sensory testing. 

1. Editorial; The Neuropathic Pain Scales Regional Anesthesia and Pain Medicine, Vol 30, No 5 (September–October), 2005: pp 417–421 (full access pdf)

2. Michael I. Bennett, Blair H. Smith, Nicola Torrance, and Jean Potter; The S-LANSS Score for Identifying Pain of Predominantly Neuropathic Origin: Validation for Use in Clinical and Postal Research. The Journal of Pain, Vol 6, No 3 (March), 2005: pp 149-158

3. Krause SJ, Backonja MM. Development of a neuropathic pain questionnaire. Clin J Pain. 2003 Sep-Oct;19(5):306-14.

4. Troels S. Jensen and Ralf Baron; Translation of symptoms and signs into mechanisms in neuropathic pain. Pain 102 (2003) 1–8 (open access pdf)

5. Alban Latremoliere and Clifford J. Woolf; Central Sensitization: A Generator of Pain
Hypersensitivity by Central Neural Plasticity. J Pain. 2009 September; 10(9): 895–926.

6. Didier Bouhassira, Nadine Attal, Haiel Alchaar, François Boureau, Bruno Brochet, Jean Bruxelle, Gérard Cunin, Jacques Fermanian, Patrick Ginies, Aurélie Grun-Overdyking, Hélène Jafari-Schluep, Michel Lantéri-Minet, Bernard Laurent, Gérard Mick, Alain Serrie, Dominique Valade, Eric Vicaut; Comparison of painsyndromesassociated with nervous orsomaticlesions and development of anewneuropathicpaindiagnosticquestionnaire (DN4). Pain Volume 114, Issues 1–2, March 2005, Pages 29–36

7. Johan Marinus, G Lorimer Moseley, Frank Birklein, Ralf Baron, Christian Maihöfner, Wade S Kingery, Jacobus J van Hilten;  Clinical features and pathophysiology of complex regional
pain syndrome. Lancet Neurol. 2011 Jul;10(7):637-48. (Full pdf)

8. Backonja, Miroslav-Misha; Walk, David; Edwards, Robert R.; Sehgal, Nalini; Moeller-Bertram, Toby; Wasan, Ajay; Irving, Gordon; Argoff, Charles; Wallace, Mark; Quantitative Sensory Testing in Measurement of Neuropathic Pain Phenomena and Other Sensory Abnormalities. Clinical Journal of Pain: September 2009 - Volume 25 - Issue 7 - pp 641-647

9. Walk, David; Sehgal, Nalini; Moeller-Bertram, Tobias; Edwards, Robert R.; Wasan, Ajay; Wallace, Mark; Irving, Gordon; Argoff, Charles; Backonja, Misha-Miroslav; Quantitative Sensory Testing and Mapping: A Review of Nonautomated Quantitative Methods for Examination of the Patient With Neuropathic Pain. Clinical Journal of Pain: September 2009 - Volume 25 - Issue 7 - pp 632-640

10. Maija L. Haanpää, Misha-Miroslav Backonja, Michael I. Bennett, Didier Bouhassira, Giorgio Cruccu, Per T. Hansson, Troels Staehelin Jensen, Timo Kauppila, Andrew S.C. Rice, Blair H. Smith, Rolf-Detlef Treede, Ralf Baron; Assessment of NeuropathicPain in PrimaryCare. The American Journal of Medicine Volume 122, Issue 10, Supplement, October 2009, Pages S13–S21

11. Ann-Sofie Leffler, Per Hansson; Painful traumatic peripheral partial nerve injury-sensory dysfunction profiles comparing outcomes of bedside examination and quantitative sensory testing. European Journal of Pain Volume 12, Issue 4, pages 397–402, May 2008.

12. Peter Vestergaard Rasmussen, Søren Hein Sindrup, Troels Staehelin Jensen, Flemming Winther Bach; Symptoms and signs in patients with suspectedneuropathicpain.  Pain Volume 110, Issues 1–2, July 2004, Pages 461–469

13. Scott, David; Jull, Gwendolen; Sterling, Michele; Widespread Sensory Hypersensitivity Is a Feature of Chronic Whiplash-Associated Disorder but not Chronic Idiopathic Neck Pain. Clinical Journal of Pain: March/April 2005 - Volume 21 - Issue 2 - pp 175-181

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