Spinal and Referred Pain Terminology

Transcription

1 Spinal and Referred Pain Terminology Concepts and Terms Jim Borowczyk and John MacVicar South GP CME 2017

2 Low Back Pain

3 Lumbar Spinal Pain Is pain perceived as arising anywhere within a region bounded superiorly by a horizontal line through the last thoracic spinous process, inferiorly through a line through the tip of the first sacral spinous process, and laterally by vertical lines tangential to the lateral borders of the lumbar erector spinae muscles

4 Sacral Spinal Pain Is pain perceived as arising anywhere within a region bounded by an imaginary transverse line through the tip of the first sacral spinous process, inferiorly by an imaginary transverse line through the posterior sacrococcygeal joints, and laterally and laterally by imaginary lines passing through the posterior superior and posterior inferior iliac spines

5 Acute and Chronic LBP Acute Low back pain is low back pain that has been present for less than three months Subacute low back pain is pain that has been present for more than 5 to 7 weeks, but not longer than 12 weeks Chronic low back pain is low back pain that has been present for at least 3 months

6 Radicular Pain

7 Cross Section Spine

8 Spinal Nerve

9 Definition Pain arising from irritation of a spinal nerve or its roots May or may not be associated with radiculopathy It is shooting (lancinating) and band like It tends to involve the whole of the limb It is episodic It tends to be caused by chemical irritation from extruded disc material

10 Mediators of Inflammation Disc material is highly inflammatory Phospholipase A 2 (cell wall breakdown) Metalloproteinases (nucleus Tumour necrosis factor α (TNF-α) Nitric oxide Leukotrienes Prostaglandin E 2

11 Radiculopathy Conduction is blocked in a spinal nerve or its roots It caused by compression or ischaemia Conduction block in sensory nerves causes numbness Conduction block in motor nerves causes weakness Radiculopathy does not cause pain It is a state of neurological loss

12 Somatic Pain As Opposed to Radicular

13 Definition Pain arising from deep tissue structures (including intervertebral discs and facet joints) Constant in position Poorly localised Diffuse Aching in quality

14 Referred Pain Definition and Mechanisms

15 Definition Referred pain is pain perceived in a region innervated by nerves other than those that innervate the source of the pain MSMX 704

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17 Referred Pain Best current explanation is convergence the economical use of neurons 2 nd order neurons (dorsal horn) have inputs from other deep organ and skin neurons Ambiguity arises as ongoing traffic does not specify which tissue is nociceptive This is amplified at each synapse Some evidence for branching

18 Joint Pain Convergence Cortex Thalamus Higher nuclei 2 nd order neuron Incoming impulses Joint Spino-reticulothalamic pathway Other Structures MSMX Muscle, Joint and Visceral Pain 18

19 Distinguishing Between Radicular and Somatic Referred Pain Hints and Tips

20 Feature Pain in the buttock or proximal thigh is unlikely to be radicular Explanation Somatic referred pain from the lumbar facet joints is most commonly perceived in the gluteal region and proximal thigh. When radicular pain is produced experimentally is perceived distally in the lower limb

21 Feature Pain extending below the knee is not necessarily radicular pain Explanation Although radicular pain characteristically extends into the leg, somatic referred pain can also be perceived below the knee, and sometimes into the foot

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24 Feature Pain extends across a relatively wide region, and is felt deeply in a relatively constant or fixed location is somatic referred pain. Its boundaries may be hard to define, but its centroid is clearly perceived by the patient Explanation These are characteristic features of somatic referred pain that have been produced experimentally, and relieved by anaesthetising structures in the lumbar spine

25 Feature Pain that travels along the length of the lower limb, along a narrow band, will be radicular pain Explanation This is the distinguishing topographic feature of radicular pain that has been evoked in volunteers by stimulating nerve roots. Distribution along a narrow band has not been produced by stimulating somatic structures, nor shown to be relieved by anaesthetising somatic structures

26 Feature A patient does not necessarily have to exhibit neurological features to be suffering from radicular pain, but the presence of neurological features favours radicular pain, provided that the above features have been satisfied Explanation Neurological features imply radiculopathy but are not themselves diagnostic of radicular pain. However, pain of a radicular nature combined with neurological features implies a common origin of both sets of features

27 Feature Deep aching pain indicates somatic referred pain. Lancinating or shooting pain is radicular Explanation Dull aching pain is characteristic of somatic referred pain as produced experimentally. Shooting pain is characteristic of pain produced by stimulating nerve roots

28 Facet Joint Pain Patterns AOA Convocation August 2017

29 AOA Convocation August 2017

30 2007 Cervical Pain Pattern Data Bailey et al, Pain Physician, 2007 Over 200 consecutive patients with putative cervical facet joint pain All received diagnostic MBB All had successful relief of their index pain The following pain patterns emerged AOA Convocation August 2017

31 Updated Cervical Pain Patterns AOA Convocation August 2017

32 Sources of Low Back Pain What Structure is Causing the Pain

33 Tissue Specific Pain All innervated structures may cause pain Causes of Low Back Pain (Schwarzer et al, Kalichman et al) Intervertebral Disc Zygapophysial (Facet) Joint Sacroiliac Joint 40% 15 40% 15 30%

34 Natural History How Benign is Back Pain Traditional wisdom is that most get better eg 90% at 2 months Various studies show recovery at 4 weeks to be 62%, 28%, 33% One study showed only 7% had pain at 12 months Von Korff et al 40% still have pain at 6 months 62% suffer a relapse within the first year

35 Natural History Outcome at 12 months Onset Proportion of patients by pain status at 12 months (von Korff) No pain LD/LI LD/HI HD/ML HD/SL Recent 21% 55% 10% 6% 8% Non-recent 12% 52% 16% 11% 9% Australian Musculoskeletal Initiative Data 648 Patients with Acute Low Back Pain Fully recovered 3 Months 12 Months MSM Care 67% 71% Usual Care 49% 56%