Public health | ICD 11 | Anatomically based terminology | Pain generator principle | Flag system in compensable injury | Neuroanatomy of spine | Referred pain | Somatic referred pain | Predicting chronicity |
Discuss the public health dimensions of the problem of spinal pain, including but not limited to: prevalence, demography, personal and community costs
In 2014-15 - 3.7 million Australians (1 in 6 people) (4 million in 2018) had chronic back problems
Prevalence increases with ag from <1% for 0-14 to 27% in 65-74 then declines slightly >75y
3/4's of people with chronic back problems are of working age
In 2008-2009 - Total health expenditure for back pain was >$1.2 billion
Indigenous Australians suffer chronic back pain at the same rate as non-indigenous populations
Low back pain is more common in lower socioeconomic regions, but not more common rurally
Lower back pain is the most common musculoskeletal complaint seen in general practice in Australia
Chronic back problems were almost equal between the genders
Risk factors included: age, physical fitness, smoking, being overweight, and type of occupation
Back and leg pain is the leading cause of disability worldwide. It contributes to more disability adjusted life years than any other chronic disease cause.
QOL is signficantly impacted with higher levels of general ill health, psychological distress, and functional limitation
Among other people with chronic pain, those with chronic back pain are more likely to report disability with restrictions in mobility, self cares, employment and social interactivity
Back pain and arthritis are two of the most common health conditions causing premature retirement between 45-64yo (40% of cases)
References:
AIHW - Impacts of Chronic back problems (2016) https://www.apsoc.org.au/pdf/publications/20160816_aihw_impacts_of_chronic_back_pain.pdf
Wheeler, L. P., Karran, E. L., & Harvie, D. S. (2018). Low back pain: Can we mitigate the inadvertent psycho-behavioural harms of spinal imaging?. Australian journal of general practice, 47(9), 610-613.
A.I.H.W. (2020, August 25). Back problems, What are back problems? Australian Institute of Health and Welfare. https://www.aihw.gov.au/reports/chronic-musculoskeletal-conditions/back-problems/contents/what-are-back-problems
Identify the application of the ICD-11 taxonomy to spinal pain syndromes.
Chronic primary pain ('non-specific' chronic low back pain)
- Subgroup - Chronic primary musculoskeletal pain (if there are no red flags)
- Subgroup - Chronic secondary musculoskeletal pain (if there were flags/a clear other disease cause)
ICD-11: MG 30.02
Description
Chronic primary musculoskeletal pain is chronic pain in the muscles, bones, joints or tendons that is characterised by significant emotional distress (anxiety, anger/frustration or depressed mood) or functional disability (interference in daily life activities and reduced participation in social roles). Chronic primary musculoskeletal pain is multifactorial: biological, psychological and social factors contribute to the pain syndrome. The diagnosis is appropriate independently of identified biological or psychological contributors unless another diagnosis would better account for the presenting symptoms. Other chronic musculoskeletal pain diagnoses to be considered are those listed under chronic secondary musculoskeletal pain.
Inclusions
Chronic primary low back pain
Chronic primary cervical pain
Chronic primary thoracic pain
Chronic primary limb pain
ICD-11: MG 30.3
Description
Chronic secondary musculoskeletal pain is chronic pain arising from bone(s), joint(s), muscle(s), vertebral column, tendon(s) or related soft tissue(s). It is a heterogeneous group of chronic pain conditions originating in persistent nociception in joint, bone, muscle, vertebral column, tendons and related soft tissues, with local and systemic aetiologies, but also related to deep somatic lesions. The pain may be spontaneous or movement-induced.
Exclusions
Acute pain (MG31)
Chronic neuropathic pain (MG30.5)
Chronic primary pain (MG30.0)
Chronic secondary visceral pain (MG30.4)
Coding Note
If the pain is related to visceral lesions, it should be considered whether a diagnosis of chronic visceral pain is appropriate; if it is related to neuropathic mechanisms, it should be coded under chronic neuropathic pain; and if the pain mechanisms are non-specific, chronic musculoskeletal pain should be coded under chronic primary pain.
THIS HAS SUBGROUPS:
- From persistent inflammation (e.g infection, crystal arthropathies, inflammatory arthropathy)
- Associated with structural changes (e.g. on imaging, examination features of clear OA)
- Due to disease of the nervous system (e.g. Parkinson's, MS, Peripheral neuropathy)
- Other specified (
- Other non-specified
ICD-11: MG 30.5
Description
Chronic neuropathic pain is chronic pain caused by a lesion or disease of the somatosensory nervous system. The pain may be spontaneous or evoked, as an increased response to a painful stimulus (hyperalgesia) or a painful response to a normally nonpainful stimulus (allodynia). The diagnosis of chronic neuropathic pain requires a history of nervous system injury or disease and a neuroanatomically plausible distribution of the pain. Negative (for example, decreased or loss of sensation) and positive sensory symptoms or signs (for example, allodynia or hyperalgesia) indicating the involvement of the somatosensory nervous system must be compatible with the innervation territory of the affected nervous structure.
Discuss the limitations of anatomically-based diagnostic terminology in spinal pain syndromes.
Anatomically-based diagnostic terminology has attempted to be used in spinal pain syndromes to help classify patient presentations into increasingly homogenous groups to be able to apply grouped therapeutics to those most likely to benefit.
However, sadly this approach has been foiled by several factors. Firstly, historical and examination techniques to define pathology have had very little success and poor evidence of correlation with anatomical-pathological disease (Petersen, Laslett & Juhl, 2017). Secondly, imaging has also not correlated the visualisation of pathology with symptom based outcomes (Maher, Underwood, & Buchbinder, 2017). Thirdly, because of the inaccuracies of making a clear pathological diagnosis, aiming to apply certain therapeutics to narrowed groups has not been possible.
This has led to terms such as 'non-specific' lower back pain. Up to 90% of low back pain is now described as 'non-specific' (Maher, Underwood, & Buchbinder, 2017). Defining mechanisms for lower back pain is more important to rule out sinister and concerning causes of back pain such as leaking aortic aneurysms. There may also be some benefit to defining axial versus radicular pain - as these can have different therapeutic modalities. However, these terms are being use to help group patients with similar symptom presentations and provide them with generic therapeutics aimed to improve short, intermediate, and long-term outcomes.
It is important to keep in mind that despite our efforts to define serious or life-threatening causes of back pain, we are not very good at it. For example, of the 23 'red-flag' symptoms and signs associated with diagnosing malignancy in back pain, only 1 had evidence supporting its use (previous diagnosis of cancer) (Henschke et al., 2013).
References:
Hancock, M. J., Maher, C. G., Latimer, J., Spindler, M. F., McAuley, J. H., Laslett, M., & Bogduk, N. (2007). Systematic review of tests to identify the disc, SIJ or facet joint as the source of low back pain. European Spine Journal, 16(10), 1539-1550.
Henschke, N., Maher, C. G., Ostelo, R. W., de Vet, H. C., Macaskill, P., & Irwig, L. (2013). Red flags to screen for malignancy in patients with low‐back pain. Cochrane database of systematic reviews, (2).
Maher, C., Underwood, M., & Buchbinder, R. (2017). Non-specific low back pain. The Lancet, 389(10070), 736-747.
Petersen, T., Laslett, M., & Juhl, C. (2017). Clinical classification in low back pain: best-evidence diagnostic rules based on systematic reviews. BMC musculoskeletal disorders, 18(1), 1-23.
Discuss the clinical validity of the concept of a ‘pain generator’ in spinal structures.
There have been many attempts to simplify back pain to 'pain generators' - sources of pain for patients. If these pain generators can be identified, then therapeutics directly addressing the cause may alleviate suffering.
Patients are still largely treated on a 'trial and error' basis (Vardeh, Mannion & Woolf, 2016). Diagnostic tools lack accuracy to cleanly delineate a 'pain generator' to target. Even in very experienced hands, correlation between experts regarding the mechanism or 'pain generator' can be very poor (Smart & Doody, 2006; Smart et al., 2011).
The problem for chronic low back pain is the myriad of anatomical, physiological, molecular and neurological components that can contribute to pain experience. Further, it is rare that one single structure is pathological but rather that multiple features are damaged at one point in time.
Using 'degeneration' as an example, there are clearly identified markers of degeneration seen on imaging. However, these rarely correlate with symptoms and being of older age does not correlate directly with worsening pain experience (Hildebrandt, Bongers, Dul, & Kemper, 2000).
References:
Fillingim, R. B., Loeser, J. D., Baron, R., & Edwards, R. R. (2016). Assessment of Chronic Pain: Domains, Methods, and Mechanisms. The journal of pain, 17(9 Suppl), T10–T20. https://doi.org/10.1016/j.jpain.2015.08.010
Hildebrandt, V. H., Bongers, P. M., Dul, J., van Dijk, F. J., & Kemper, H. C. (2000). The relationship between leisure time, physical activities and musculoskeletal symptoms and disability in worker populations. International archives of occupational and environmental health, 73(8), 507–518. https://doi.org/10.1007/s004200000167
Smart, K. M., Blake, C., Staines, A., & Doody, C. (2011). The discriminative validity of “nociceptive,”“peripheral neuropathic,” and “central sensitization” as mechanisms-based classifications of musculoskeletal pain. The Clinical journal of pain, 27(8), 655-663.
Smart, K., & Doody, C. (2006). Mechanisms-based clinical reasoning of pain by experienced musculoskeletal physiotherapists. Physiotherapy, 92(3), 171-178.
Vardeh, D., Mannion, R. J., & Woolf, C. J. (2016). Toward a mechanism-based approach to pain diagnosis. The Journal of Pain, 17(9), T50-T69.
Describe the “flag” system in relation to the compensable injury
This are a list of psychosocial prognostic factors for the development of persistent pain and work disability following the onset of musculoskeletal conditions
The flags model is a framework for identifying factors that can become obstacles in a patient's recovery and return to work following an MSK injury. Early identification of these can allow them to be overcome and addressed to help prevent persistent pain and long term disability
Red Flags: (0-4 weeks)
Serious medical pathology (eliminate serious pathology e.g. cancer) as a cause of MSK pain
Co-morbidity - Assess the interplay of other diseases to MSK presentation (e.g. RA)
Orange Flags: (0-4 weeks)
Mental health disorders
Personality disorders
(remember to manage compensable and non-compensable medical issues separately)
Yellow Flags: (4-12 weeks)
Perceptions (High pain intensity, high psychological distress)
Beliefs (High perceived disability, poor belief in self management, lowered resilience)
Behaviours (Participation in work, home social etc is impacted. Passive role in recovery)
Blue Flags: (4-12 weeks)
Work (Perception that supervisor and co-workers are un-supportive)
Social (Non-English speaking, Low social support)
Black Flags: (4-12 weeks)
Compensation and complexities navigating the system
Financial strain (e.g. dispute about liability)
Continued need to prove claim validity
Describe the neuroanatomy and function of the spine.
Radiological planes
"Scotty Dog" - Oblique plain X-ray view
Lumbar lateral plain X-ray view
Xray Lumbar - Sagittal
Axial Vertebral Anatomy
Axial anatomy of vertebrae
Medial branch anatomy (Reference: Sandeep Kapur - https://www.researchgate.net/figure/Z-joint-anatomy-A-Relevant-anatomy-NR-nerve-root-IAP-inferior-articular_fig3_275304790)
Dorsal root anatomy (Reference: Sandeep Kapur - https://www.researchgate.net/figure/Z-joint-anatomy-A-Relevant-anatomy-NR-nerve-root-IAP-inferior-articular_fig3_275304790)
Epidural space anatomy
Medial branch anatomy in more detail
Target spots for MBB on LS Xray
Anatomy of upper cervical spine
Coronal plain Xray of cervical spine
Lateral Xray of the cervical spine
Cervical MBB Target anatomy
Discuss current concepts of referred pain and radiation of pain in relation to spinal pain.
The physiologic basis for referred pain is the convergence of afferent neurons onto common neurons within the central nervous system. The central nervous system may not be able to distinguish which part of the body is responsible for the input into these common neurons
In the case of the lumbar spine, afferents from the innervated somatic structures, including the muscles, ligaments, synovial joints, and discs, converge on the same neurons in the dorsal horn as the afferent nerves from the lower extremity.
Critically appraise the concepts of radicular pain radiculopathy somatic referred pain with respect to limb girdle or limb pain associated with spinal pain.
Definition: The pain spreads into the lower limbs, and is perceived in regions innervated by nerves other than those that innervate the site of noxious stimulation
Somatic referred pain:
Pain coming from the somatic structures of the spine (so not radicular or visceral referred pain). It does NOT involve stimulation of nerve roots. It comes from stimulation of small nerve endings in discs, zygapophyseal joints, or sacroiliac joints.
Theory: Convergence of nociceptive afferents on second-order neurons in the spinal cord that also subtend to regions of the lower limb. Somatic referred pain is perceived in regions thta share the same segmental innervation as the source. There are NO neurological signs as there is not compression of nerve roots.
Somatic referred pain is dull, aching and gnawing. Sometimes expands to areas that are difficult to localise. It is difficult to outline the area, but can usually work out a central pain area. The pattern of referral is NOT dermatomal.
BUT - although pain from different segments in the lumbar spine refers to different regions in the lower limb, patterns are not consistent amongst subjects or between studies
Moreover, although somatic referred pain tends most often to centre over the gluteal region and proximal thigh, it can also extend as far as the foot
To be consistent with these experimental data, when dull aching pain that spreads into the lower limb and settles into a relatively fixed location occurs in patients, it should be recognized as somatic referred pain, when it occurs in patients.
Radicular Pain
Pain evoked from ectopic discharges emanating from a dorsal root or its ganglion
Disc herniation is the most common cause. Inflammation of the affected nerve seems to be the most critical pathological process
Radicular pain was tested by tying sutures around a nerve and pulling on it after the operation!! Pain was distinctive - lancinating quality travelling the whole length of the lower limb in a band 2-3 inches wide.
Interestingly, pulling on normal nerve roots does not cause pain - only those that have previously been inflamed. If there is just compression, this needs to involve the dorsal root ganglion (only tested in animals).
The term 'sciatica' comes from a time when pain was less understood. The better term - 'radicular pain' should be used instead.
Radiculopathy
Neurological state
Referred or radiation of pain describes the sensation of experiencing pain in an area of the body further away from where the noxious disease or trauma is occurring.
In spinal pain, this occurs usually through direct trauma, injury, or local inflammation around a nerve or nerve root, causing stimulation of the nerve and firing of axons. These nerves may innervate other areas of muscle and skin. Messages may be sent to the brain to describe injury or damage to the nerve supplying these areas. As the brain has no distinct way of determining the exact location of injury to the nerve, the brain will perceive the noxious stimuli anywhere that the nerve innervates. This gives rise to referred, or radiation of pain in areas of the body where damage is not occurring.
Critically appraise the concept of somatic referred pain with respect to:
- SIJ origin pain
Referred pain from SIJ sections is referred to the: 0 = Upper buttock, 1 = region around the posterosuperior iliac spine, 2 = pain in the middle buttock area, or 3 = pain in the lower buttock
Zero =
One =
Two =
Three =
Reference:
Kurosawa, D., Murakami, E., & Aizawa, T. (2015). Referred pain location depends on the affected section of the sacroiliac joint. European Spine Journal, 24(3), 521-527.
Disc origin referred pain
Can't find much. Most articles just talk about 'centralised' back pain for disc origin pain.
Reference:
O’Neill, C. W., Kurgansky, M. E., Derby, R., & Ryan, D. P. (2002). Disc stimulation and patterns of referred pain. Spine, 27(24), 2776-2781.
Fujii, K., Yamazaki, M., Kang, J. D., Risbud, M. V., Cho, S. K., Qureshi, S. A., ... & Iatridis, J. C. (2019). Discogenic back pain: literature review of definition, diagnosis, and treatment. JBMR plus, 3(5), e10180.
Facet joint origin pain
Cervical
Causes parasagittal cervical and cervicothoracic pain
Rarely causes midline cervical or arm pain
Does not cross to the other side
Can be unilateral or bilateral (if both sides involved)
Lumbar
Commonly causes parasagittal lumbar and buttock pain (40-70%), lateral hip (10-30%), and occasionally posterior thigh (10-30%) and groin pain (5-10%).
Rarely causes midline lumbar pain or leg pain
Does not cross to the other side
Can be unilateral or bilateral
If pain is severe - can involve a larger area
Reference:
Dwyer A, Aprill C, Bogduk N. Cervical zygapophyseal joint pain patterns. I: A study in normal volunteers. Spine. 1990;15(6):453‐457
Pain of musculoskeletal origin secondary to gait or usage abnormality
Not sure what this means...
Discuss factors predictive of chronicity after acute spinal pain, including but not restricted to the “flag” system.
Increasingly there is a challenge to the old adage 'acute LBP resolves within 3 months'. A systematic review suggested 2- 48% of patients with acute lower back pain (LBP) in primary care transition to chronic pain
Tools have been developed to try and risk stratify patients who may go on to develop chronic LBP following an acute LBP episode. The Subgroups for Targeted Treatment (STarT) Back Tool (SBT).
Key factors that were highly predictive identified by Stevans et al., 2021, were:
- Baseline disability
- Having health insurance
- Elevated BMI
- Smoking status
- Diagnosis at the index visit
- Psychological co-morbidities
These were discussed in more detail above.
Reference:
Stevans, J. M., Delitto, A., Khoja, S. S., Patterson, C. G., Smith, C. N., Schneider, M. J., ... & Saper, R. B. (2021). Risk Factors Associated With Transition From Acute to Chronic Low Back Pain in US Patients Seeking Primary Care. JAMA network open, 4(2), e2037371-e2037371.
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