Back Pain

Differential diagnosis

Mechanical
- Non-specific LBP: 85 %
- PID: posterior / lateral
- facet joint hypertrophy (bilateral): spinal stenosis (causes 'cauda equina claudication')
- facet joint hypertrophy (unilateral): lateral recess stenosis

Systemic illness
- Vertebral body fracture: 2^o cancer / myeloma / osteoporosis / Paget's disease of bone
- Inflammatory arthropathies: ankylosing spondylitis / psoriatic arthropathy / Reiter's
- Infection: epidural abscess / TB

Visceral pain
- AAA (abdo. aortic aneurism)
- pancreatitis
- renal colic

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Red flag features

Patient
- < 20 yrs old
- > 55 yrs old

Back pain
- non-mechanical, progressive
- nocturnal
- thoracic

Back examination
- localised bony tenderness

Neurology
- alternating / bilateral sciatica
- gait disturbance
- saddle anaesthesia
- sphincter disturbance

Systemic
- weight loss
- prev. history of cancer
- prev. history of HIV
- prev. use of steroids

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History: features and questions to ask

Pain
- what % is back pain vs leg pain
- what is the effect of sitting, standing, lying, walking

Sensory symptoms
- nerve roots: warm / icy pain at level
- dorsal columns: ataxia
- cord: sensory level (paraesthesia / anaesthesia)

Sphincters
- do you know when you have a full bladder?
- can you feel urine passing down your urethra?
- can you feel it when you have stopped passing urine?
- have you recently become impotent?
- can you differentiate between fluid and flatus?

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Examination: features to elicit

Back
- any bony tenderness?
- Schober's index

Legs
- Lasegue's sign (painful straight leg raise < 45^o)
- crossed straight leg raising pain

Motor
- UMN signs at level
- LMN signs below

Sensory

- sensory level below lesion - classically: intrinsic lesion = sacral sparing / extrinsic lesion = saddle anaesthesia

PR (per-rectal examination)
- loss of anal tone
- loss of perianal sensation

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Investigation

Bloods
- FBC
- CRP, ESR
- Ca²⁺, PO₄^3-, ALP
- serum electrophoresis
- PSA
- cultures

Imaging
- MRI
- AXR: missing pedicle sign = mets
- Technecium bone scan: mets

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Management

GP
- analgesia ladder: NSAIDs
- encourage exercise
- manipulation in 1st 6 weeks: PT, osteopathy, etc.
- holistic approach: consider depression, occupation etc.

Office procedures
- facet joint injection: LA / steroids
- nerve root blocks: confirm level prior to surgery

Surgery
- laminectomy
- discectomy

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Prognosis

- at 4weeks: 75 % resolved
- at 3months: 90 % resolved
- persisting > 2months: poor prognosis

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Referral

Refer if...
- Emergency: cauda equina syndrome
- Urgent: red flag features
- Neurology: weakness, sphincter disturbance, other symptom failure to resolve within 4weeks

NB: no need to refer if sciatic pain only (unless not resolving by 4 weeks)

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