Low Back Pain Diagnosis – Simplified approach

A) DEFINITION OF LOW BACK PAIN

  • Pain, muscle tension or stiffness localized below the costal margin and above the inferior gluteal folds, with or without leg pain
  • Types of Low back pain:
    1. Acute (<6 weeks)
    2. Subacute (6-12 weeks)
    3. Chronic (>12 weeks)
  • Sciatica refers to the pain in the distribution of the lower lumbar spinal roots

B) RED FLAG SIGNS IN LOW BACK PAIN

Red flag signs are the indicators of serious spinal pathology.

DisorderSymptomsSigns
AllDuration of pain > 1 month
Bed rest with no relief
CancerAge ≥ 50 years
History of cancer
Unexplained weight loss
Neurologic findings
Lymphadenopathy
Compression fractureAge ≥ 50 years (> 70 years is more specific)
Significant trauma
History of osteoporosis
Corticosteroid use
Substance abuse
InfectionFever or chills
Recent skin or urinary tract infection
Immunosuppression
Injection drug use
Fever (temperature > 100°F or 38°C)
Tenderness over spinous processes
Cauda equina syndromeSaddle anesthesia
Bilateral sciatica or leg weakness
Difficulty urinating
Fecal incontinence
Progressive motor or sensory deficit

C) YELLOW FLAG SIGNS IN LOW BACK PAIN

Yellow flag signs are psychological factors shown to be indicative of long-term chronicity and disability.

  • A negative attitude that back pain is harmful or potentially severely disabling
  • Fear avoidance behavior and reduced activity levels
  • An expectation that passive, rather than active, treatment will be beneficial
  • A tendency to depression, low morale, and social withdrawl
  • Social or financial problems

D) ETIOLOGY OF LOW BACK PAIN

1. Non-specific/Simple Mechanical low back pain: Commonest cause

Mckenzie classification:

  • Postural syndrome: due to a mechanical deformation of normal soft tissue from prolonged end range loading of periarticular structures (static deformation of spine).
    • Pain may be local and reproducible when end range positions, such as slouching, are maintained for sustained periods of time.
    • Treated by improving posture and avoiding provocative posture
  • Dysfunction syndrome: due to adaptive shortening, scarring or adherence of connective tissue causing discomfort.
    • Consistent movement loss and pain at the end range of movement.
    • Treated by mobilization in the direction that reproduces pain (remodelling of tissues)
  • Derangement syndrome (commonest):
    • Due to disturbance in the normal resting position of the affected joint surfaces
    • May show one direction of repeated movement which decreases or centralizes referred symptoms – preferred direction.

Disc origin pain is aggravated by flexion and has a gradual onset while, the facet origin pain is aggravated by extension and has a more sudden onset.

2. Specific low back pain:

a. Mechanical:

  • Degenerative: Spondylosis, Intervertebral disc degeneration, Lumbar non-spondylolytic spondylolisthesis, Ankylosing spinal hyperostosis, Lumbar spina canal stenosis
  • Trauma: Lumbar intervertebral disc herniation, Vertebral fractures
  • Congenital: Spina bifida, Severe kyphosis, Severe scoliosis, Transitional vertebra

b. Non-mechanical:

  • Neoplasia: Multiple myeloma, Metastatic carcinoma, Spinal cord tumors, Lymphoma and leukemia, Retroperitoneal tumors, Primary vertebral tumors (Osteoid osteoma, Eosinophilic granuloma)
  • Inflammatoy arthritis: Ankylosing spondylitis, Reiter syndrome, Psoriatic spondylitis, Enteropathic spondyloarthritis (IBD)
  • Infection: Osteomyelitis (TB, Purulent), Paraspinous abscess, Septic diskitis
  • Osteochondrosis: Scheuermann disease

c. Referred: Renal, GI, Pelvic pathology or Aortic aneurysm

3. Psychogenic causes:

  • Anxiety
  • Depression
  • Fibromyalgia
  • Adjustment disorders at home, work, etc.

E) HISTORY TAKING FOR LOW BACK PAIN

1. Look for red flag signs in Acute Low Back pain and yellow flag signs in Chronic Low Back Pain

2. Where does it hurt?

  • Usually, dull steady ache over lower lumbar spine
  • Localized severe point tenderness in fractures
  • Pain radiating down a leg may suggest nerve impingement:
    • Disc herniation: younger patients
    • Osteophyte: older patients

3. When does it hurt?

a. Disc related back pain:

  • Symptoms often worsened by sitting or standing for prolonged periods
  • Symptoms aggravated by coughing or sneezing
  • Symptoms often alleviated by lying flat

b. Lumbar spinal canal stenosis:

  • Symptoms improved by forward flexion of the back (opens up the narrowed spinal canal foraminal spaces) – “Shopping cart sign” (relief of pain when leaning forward to push shopping cart)
  • Symptoms worsened by standing for prolonged periods

4. How does activity affect the pain?

  • Improved by rest, minimal on morning arising and worsened with activity: Disc herniation or Spinal stenosis from osteoarthritis
  • Improved by activity, worse on morning arisising and worsened with inactivity: Inflammatory spondyloarthropathy (ankylosing spondylitis, psoriatic arthritis or inflammatory bowel disease)

inflammatory vs mechanical back pain

5. Does the pain radiate?

  • Radiation of pain down one leg (sciatica): nerve impingement by disc herniation or osteophyte
  • Pain or dysethesias in perenium: cauda equina syndrome

radicular pain vs referred pain

6. What relieves the pain?

  • Benefit noted or not with NSAIDs and acetaminophen: helpful in developing management strategy for pain control

F) PHYSICAL EXAMINATION OF LOW BACK PAIN

low back pain examination

 

examination of back

1. Look – café-au-lait spots (? neurofibromatosis), hairy patches (? spina bifida)

2. Feel – spinous process tenderness (? fracture, tumor, infection), SI joint pain (? ankylosing spondylitis), chest expansion <2.5cm (? ankylosing spondylitis), step at L5 (? spondylolisthesis)

3. Move – pain on bending toward affected side, or on flexion (? Lumbar disc disease), pain on extension (? Facet joint or spinal stenosis), range of motion

4. Special Tests

a. Schober’s Test: assesses the amount of lumbar flexion. Make two pen-marks, one at 10cm above the PSIS, the other 5cm below it. Upon flexion, the distance should increase >5cm. Decreased ROM of lumbar spine suggests ankylosing spondylitis.

b. Straight Leg Raise: assesses the presence of radiculopathy – if pain is reproduced and radiates down into affected leg when the leg is raised between 10 and 60 degrees elevation. If the opposite leg produces a positive response, it is indicative of a large herniation.

  • Lasegue’s test involves dorsiflexing the foot during the SLR.

c. Wadell’s sign indicating psychological distress: 3 out of 5 is significant

  • Inappropriate tenderness that is superficial or widespread
  • Pain on simulated axial loading by pressing on the top of the head or simulated spine rotation
  • Distraction signs such as inconsistent performance between straight-leg-raising in the seated position vs the supine position
  • Regional disturbances in strength and sensation that do not correspond with nerve root innervation patterns
  • Overreaction during the physical examination.

5. Complete a thorough neurological exam, including gait, ankle reflex (S1), knee reflex (L4), strength, sensation (look for saddle anesthesia and anal sphincter tone, plus check dermatomes along lower limb).

Signs associated with specific nerve root impingement:

Nerve rootWeaknessAltered sensationAltered reflexe
L2Iliopsoas (Hip flexor)Anterior thigh, groinNone
L3Quadriceps (Knee extensor)Anterior and lateral thighPatellar
L4Tibialis anterior (ankle dorsiflexion; subtalar inversion)

AND Limitation of femoral stretch

Medial ankle and footPatellar
L5Extensor hallucis longus an Extensor digitorum longus (Great-toe dorsiflexion and other toe dorsiflexion) – Inability to heel walk

AND Limitation of SLRT

Lateral calf and 1st web spaceNone
S1Tendo-achilles, Flexor hallucis longus, Flexor digitorum longus (Ankle plantar flexion and plantar flexion of toes) – Inability to toe walk

AND Limitation of Bowstring/Sciatic nerve strect test (Perform SLRT; allow patient to flex knee back until pain is relieved; apply pressure to popliteal fossa; reproduction of pain indicates positive bowstring test)

Lateral plantar footAchilles

G) INVESTIGATING A CASE OF LOW BACK PAIN

 

low back pain investigations

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