Back pain
Most back pain is mechanical. Your job is to find the few that aren't: cauda equina, cord compression, infection, spinal TB, AAA and fractures.
A 35-year-old labourer has low back pain for 5 days after lifting a heavy sack, radiating down the back of his left leg to the outer foot. He has no bladder or bowel change and no saddle numbness. Power is normal, the left ankle reflex is reduced, and straight leg raise is positive at 40°.
A 30-year-old woman from a rural area has had mid-back pain for 3 months, worse at night, with evening fevers and 5 kg weight loss. There's a small angular bump on her spine.
What does each need?
- Ask the cauda equina questions every timeSaddle numbness, bladder or bowel change, sexual dysfunction, both legs. Write the answers down.
- Screen for red flagsCancer, fever, weight loss, TB, drug injection, trauma, osteoporosis, age, night pain.
- ExamineSpine, straight leg raise, lower limb power, reflexes, sensation, saddle sensation if any neuro symptoms.
- Over 50Abdomen and femoral pulses for AAA. Temperature in everyone.
- No red flagsNo imaging. Stay active, NSAID for a short time, exercise.
- Red flagsBloods, imaging and the right specialist.
- Written safety-netCauda equina symptoms: come back immediately.
- Saddle numbness or new bladder or bowel problems
- Sciatica in both legs or worsening weakness
- Known cancer, thoracic pain, night pain, weight loss
- Fever, drug injection, immunosuppression
- Over 50 with sudden pain, pulsatile mass or low BP
- Significant trauma or osteoporotic fracture
- Cauda equina syndrome
- Metastatic cord compression
- Spinal TB (Pott's disease)
- Epidural abscess or discitis
- Leaking AAA
- Vertebral fracture
- Pyelonephritis or renal colic
- Ankylosing spondylitis
- Brucellosis
| Mechanical back pain | Most improve within 6 weeks |
| Sciatica | Most settle in 6–12 weeks |
| Imaging | Not needed without red flags |
| Ibuprofen | 400 mg 3 times daily with food, shortest time |
| Naproxen | 250–500 mg twice daily, with a PPI if needed |
| Emergency MRI | Suspected cauda equina or cord compression |
| Spinal TB treatment | Usually 9–12 months of anti-TB drugs |
Check every dose against a current drug reference and your hospital protocol.
On this page
Why it matters
Low back pain is one of the commonest complaints in OPD and the emergency department. Over 9 in 10 cases are non-specific (mechanical) and improve within weeks. The skill is to screen every patient for the few serious causes, and to give the rest good advice. In Pakistan, spinal TB is an important cause in young adults.
Red flags
- CCauda equinaSaddle numbness, bladder or bowel change, bilateral sciatica
- IInfectionFever, IV drug use, recent spinal procedure, TB contact, diabetes
- TTumourCancer history, weight loss, night pain, over 50
- TTraumaFall, osteoporosis, steroids
- AAortaOlder, smoker, low BP, pulsatile mass
| Red flag | Think of |
|---|---|
| Saddle numbness, bladder or bowel change, both legs | Cauda equina syndrome |
| Known cancer, thoracic or night pain, weight loss | Metastases, cord compression |
| Fever, night sweats, weight loss, TB contact | Spinal TB or infection |
| Drug injection, immunosuppression, recent procedure | Epidural abscess, discitis |
| Significant trauma, osteoporosis, steroids | Vertebral fracture |
| Over 50, sudden pain, pulsatile mass, low BP | Leaking AAA |
| Under 20 or over 55 with new pain | Serious pathology more likely |
The cauda equina questions
Ask and document the answers:
- "Any numbness around your bottom or private parts, like sitting on a saddle?"
- "Any new problem passing urine, or controlling your bladder or bowels?"
- "Any change in sexual function?"
- "Pain or numbness down both legs?"
Examination
- GeneralTemperature, weight, lymph nodes.
- SpinePosture, deformity (gibbus in spinal TB), tenderness, movement.
- Nerve rootsStraight leg raise, power, reflexes and sensation in the legs.
- SaddleSaddle sensation and anal tone if any neuro symptoms (with a chaperone).
- AbdomenOver 50: pulsatile mass, femoral pulses. Loin tenderness.
Which nerve root?
| Root | Weakness | Reflex | Sensation |
|---|---|---|---|
| L4 | Knee extension, ankle dorsiflexion | Knee | Medial shin |
| L5 | Big toe extension, foot dorsiflexion | None reliable | Top of foot, big toe |
| S1 | Foot plantarflexion (tiptoe) | Ankle | Sole, lateral foot |
Differential diagnosis
| Condition | Clues |
|---|---|
| Mechanical back pain | Pain with movement, no red flags |
| Sciatica (disc prolapse) | Leg pain worse than back pain in a dermatome, positive straight leg raise |
| Spinal stenosis | Older, leg pain on walking, relieved by bending forward or sitting |
| Spinal TB (Pott's) | Weeks to months, night sweats, weight loss, gibbus, cold abscess |
| Metastases or myeloma | Cancer history, night pain, anaemia, high calcium |
| Vertebral fracture | Osteoporosis, steroids, trauma, point tenderness |
| Ankylosing spondylitis | Young man, morning stiffness over 30 minutes, better with exercise |
| Leaking AAA | Older, pulsatile mass, low BP |
| Renal colic or pyelonephritis | Loin pain, urinary symptoms, fever |
| Brucellosis | Raw milk, animal contact, sacroiliitis, fever |
Spinal TB in Pakistan
- Thoracic and lumbar spine; weeks to months of pain, night sweats, weight loss.
- Gibbus (angular deformity), paraspinal or psoas abscess, leg weakness from cord compression.
- MRI, chest X-ray, and tissue for GeneXpert or histology where possible.
- Anti-TB treatment through the national TB programme, often 9–12 months. Surgery for cord compression, instability or large abscess.
Investigations
| Situation | Tests |
|---|---|
| No red flags | None |
| Infection or cancer suspected | CBC, ESR, CRP, calcium, ALP; MRI |
| Trauma or osteoporosis | X-ray or CT |
| Cauda equina or cord compression | Emergency MRI |
| TB suspected | MRI, chest X-ray, GeneXpert or biopsy |
| Myeloma suspected | Protein electrophoresis, calcium, kidney function |
| AAA suspected | Bedside ultrasound or CT, vascular surgeon |
Management of mechanical back pain and sciatica
- ReassureMost improve within 6 weeks. Hurting doesn't mean harm.
- Stay activeKeep working if possible. Avoid bed rest.
- NSAIDLowest dose, shortest time, with a PPI if needed.
- Exercise and physiotherapyIf not improving after 2–4 weeks.
- SciaticaMost settle in 6–12 weeks; refer if progressive weakness or not settling.
Paracetamol alone, gabapentin, pregabalin and antidepressants are not recommended for low back pain. Avoid strong opioids.
Common mistakes
- Not asking (or not writing down) the cauda equina questions.
- X-raying every back pain.
- Advising bed rest.
- Missing spinal TB in a young adult with night sweats.
- Calling a leaking AAA "back strain" in an older man.
- Prescribing long-term opioids or pregabalin for simple back pain.
Follow-up
- Written advice: come straight back with saddle numbness, bladder or bowel problems, or leg weakness.
- Physiotherapy if not improving after 2–4 weeks.
- Review if not better in 6 weeks, or sooner if worse.
Frequently asked questions
What are the red flags in back pain?
Saddle numbness, bladder or bowel problems, leg weakness, cancer history, weight loss, night pain, fever, drug injection, significant trauma, osteoporosis or steroid use, and age over 50 with new pain.
What is the best painkiller for back pain?
An NSAID such as ibuprofen or naproxen at the lowest effective dose for the shortest time. Paracetamol alone is not recommended.
Does back pain need an X-ray or MRI?
Not usually. Imaging is for red flags, neurological deficit, or pain not improving after about 6 weeks.
How does spinal TB present?
Weeks to months of back pain, night sweats, weight loss, and sometimes a gibbus deformity, an abscess or leg weakness.
Test yourself
Exam-style questions on this guide, from our two question banks. Choose an answer to see why each option is right or wrong.
1. A man with low back pain and sciatica has no red flags. What is the best management?
Answer: Stay active with simple analgesia. Most mechanical back pain and sciatica improve within weeks with activity and analgesia.
- Surgery referral: Not first.
- Urgent MRI: Not needed without red flags.
- Strong opioids long term: Harmful.
- Bed rest for 2 weeks: Slows recovery.
2. A patient with sciatica has weak big toe extension and numbness over the top of the foot. Which root is affected?
Answer: L5. L5 supplies big toe extension and sensation over the top of the foot.
- L4: Knee extension, medial shin.
- L3: Thigh.
- S1: Plantarflexion, ankle reflex, lateral foot.
- S2: No.
3. Which symptom in back pain needs emergency assessment?
Answer: New saddle numbness. Saddle numbness suggests cauda equina syndrome: emergency MRI.
- Stiffness in the morning only: Usually not urgent.
- Pain after lifting: Common.
- Muscle spasm: Common.
- Pain on bending: Mechanical.
4. A 40-year-old has low back pain radiating down the back of the leg to the sole, with a reduced ankle reflex and weak plantarflexion. No red flags. What is the initial management?
Answer: Analgesia, stay active. S1 radiculopathy from L5/S1 disc prolapse (sole pain, reduced ankle jerk, weak plantarflexion) usually improves with conservative management: analgesia (NSAIDs, neuropathic agents for sciatica per guidance), staying active and physiotherapy. Imaging if symptoms persist > 6 weeks, progressive neurological deficit, or red flags. Red flags (cauda equina, cancer, infection, fracture) need urgent investigation.
- Immediate discectomy: Only if persistent or progressive.
- Strict bed rest for 2 weeks: Bed rest delays recovery from sciatica; staying active is advised.
- Urgent MRI within 24 hours: Only with red flags or persisting symptoms.
5. A 35-year-old has acute back pain and sciatica in the posterior thigh and lateral foot, weak plantarflexion and an absent ankle reflex. No red flags. Which root is affected?
Answer: S1. Root signs: L4 — anterior knee/medial leg, knee jerk, ankle dorsiflexion (tibialis anterior); L5 — dorsum of foot/big toe, extensor hallucis longus, no reflex (hamstring); S1 — lateral foot/sole, plantarflexion, ankle jerk. L4/5 disc → L5 root; L5/S1 disc → S1 root (posterolateral prolapse). Most improve with analgesia and staying active within 6–12 weeks; MRI and surgery for progressive deficit or persistent pain; emergency for cauda equina.
- L4: L4 affects the knee reflex and medial leg.
- L5: L5 affects the dorsum of the foot and big toe extension, not the ankle reflex.
- L3: L3 affects the thigh and knee reflex.
6. Which dermatome supplies the skin around the umbilicus?
Answer: T10. Key dermatomes: C5—lateral arm (regimental badge); C6—thumb; C7—middle finger; C8—little finger; T4—nipple; T7—xiphisternum; T10—umbilicus; L1—inguinal region; L3—medial knee; L4—medial leg and big toe area; L5—dorsum of foot; S1—lateral foot and sole; S2–S4—perineum (saddle area). Herpes zoster follows a dermatome. Abdominal surgery incisions and spinal anaesthesia levels are described by dermatomes.
- T4: Nipple.
- T7: Xiphisternum.
- L1: Groin.
- S1: Lateral foot.
7. Which condition typically produces a loud first heart sound (S1)?
Answer: Mitral stenosis with mobile cusps. S1 is closure of the mitral and tricuspid valves. It is loud when the cusps are still wide open as the ventricle contracts: mitral stenosis with pliable leaflets, a short PR interval and fast heart rates (exercise, fever, thyrotoxicosis, anaemia). It is soft with a long PR interval, mitral regurgitation, a calcified immobile valve and poor ventricular function.
- Long PR interval: Cusps drift closed before systole: soft S1.
- Mitral regurgitation: Incomplete closure: soft S1.
- Calcified, rigid mitral valve: Rigid cusps barely move: soft S1.
- Severe heart failure: Weak contraction: soft S1.
References and dose sources
- NICE NG234
- NICE NG156 — AAA
- NICE NG41 — spinal injury
- NICE NG59 — low back pain and sciatica
- GIRFT — National suspected cauda equina pathway
- Ibuprofen dosing: Drugs.com: Ibuprofen dosage (see also our ibuprofen dose page)
- Naproxen dosing: Drugs.com: Naproxen dosage (see also our naproxen dose page)
- Omeprazole dosing: Drugs.com: Omeprazole dosage (see also our omeprazole dose page)
International guidance is linked where it reflects good practice. Where your hospital’s protocol differs, follow your hospital.