Back pain is one of the most frequent reasons for outpatient visits and emergency department presentations worldwide. While the majority of cases are benign and self-limiting, a small but critical subset represents medical or surgical emergencies.
For learners, back pain is a classic example of a symptom where pattern recognition, red-flag identification, and focused examination matter far more than ordering routine imaging.
The key clinical question is always the same:
Is this routine mechanical back pain, or is something dangerous hiding underneath?
Definition of Back Pain
Back pain refers to pain arising from the spine or paraspinal structures and may involve:
- Cervical spine
- Thoracic (mid-back) spine
- Lumbar spine
Pain may be localized or radiate to the limbs, chest, or abdomen depending on the underlying pathology.
Epidemiology and Clinical Significance
- Around 80–85% of people experience back pain at least once in their lifetime
- Non-specific mechanical back pain accounts for nearly 85% of cases
- Less than 5% are due to serious causes such as malignancy, infection, or vascular emergencies
Despite this, missing the dangerous 5% can have devastating consequences.
Pathophysiology: Why Does Back Pain Occur?
Back pain can originate from multiple structures, including:
- Intervertebral discs
- Facet joints
- Ligaments and muscles
- Nerve roots
- Vertebral bodies
- Referred pain from visceral organs
Understanding this helps explain why back pain is not always a “spine problem.”
Red Flags in Back Pain (Never Miss These)
Certain features strongly suggest serious pathology and must never be ignored.
Key red flags include:
- History of cancer
- Fever or systemic illness
- IV drug use or immunocompromised state
- Progressive neurological deficits
- Saddle anesthesia
- Urinary retention or fecal incontinence
- Unexplained weight loss
- Significant trauma or minor trauma in elderly patients
- Severe point tenderness over the spine
The presence of even one red flag changes the entire approach to evaluation.
Anatomical Approach to Back Pain
A simple and highly effective way to think about back pain is by location.
Lower Back Pain
Common causes include:
- Non-specific mechanical back pain
- Herniated intervertebral disc with sciatica
- Cauda equina syndrome
Lower back pain associated with saddle anesthesia, urinary retention, or bilateral leg weakness strongly suggests cauda equina syndrome and is a neurosurgical emergency.
Mid-Back (Thoracic) Pain
Thoracic back pain is more concerning because it is less commonly mechanical.
Important causes include:
- Abdominal aortic aneurysm rupture
- Renal colic
- Pancreatitis or peptic ulcer disease
- Pyelonephritis
Always consider referred pain in mid-back presentations.
Upper Back Pain
Upper back pain may reflect intrathoracic pathology such as:
- Pneumothorax
- Pulmonary embolism
- Aortic dissection
- Pneumonia
A chest examination and chest X-ray are often crucial here.
Common Causes of Back Pain
Non-Specific (Mechanical) Back Pain
This is the most common type and is usually due to muscle strain or ligamentous injury.
Typical features include:
- Pain worsened by movement
- No neurological deficits
- Normal systemic examination
Imaging is not required in most cases.
Herniated Intervertebral Disc
Occurs when disc material compresses nerve roots.
Key features:
- Radicular pain (sciatica)
- Positive straight-leg raise test
- Neurological symptoms in a dermatomal pattern
Most cases improve with conservative management.
Vertebral Compression Fracture
Seen commonly in:
- Elderly patients
- Osteoporosis
- Chronic steroid use
Patients often have point tenderness over the affected vertebra.
Epidural Abscess
A rare but life-threatening condition.
Classic risk factors include:
- IV drug use
- Fever
- Immunosuppression
Importantly, only a minority have fever, so absence of fever does not exclude it.
Cauda Equina Syndrome
Caused by compression of the cauda equina nerve roots.
Classic features:
- Saddle anesthesia
- Urinary retention
- Reduced anal tone
- Bilateral leg weakness
This is a true surgical emergency.
Referred and Non-Spinal Causes
Not all back pain originates from the spine.
Examples include:
- Kidney stones
- Pyelonephritis
- Abdominal aortic aneurysm
- Pancreatitis
- Pulmonary embolism
Always think beyond the spine when symptoms don’t fit.
History Taking in Back Pain
A focused history should include:
- Onset and duration of pain
- Trauma history
- Radiation of pain
- Neurological symptoms
- Bladder or bowel changes
- Fever or weight loss
- IV drug use
- Past history of cancer or osteoporosis
History often provides more diagnostic value than imaging.
Physical Examination
A systematic exam is essential.
Key components include:
- Inspection and posture
- Palpation for spinal tenderness
- Range of motion
- Neurological examination of lower limbs
- Straight-leg raise test
- Perianal sensation if red flags present
Documentation of a normal neurological exam is crucial.
Diagnostic Workup
When Imaging Is NOT Needed
In uncomplicated mechanical back pain:
- No red flags
- Symptoms < 6 weeks
- Normal neurological exam
Reassurance and conservative management are sufficient.
When Imaging IS Required
Imaging is indicated when red flags are present.
Common modalities include:
- X-ray for suspected fractures
- MRI for neurological deficits, epidural abscess, cauda equina
- CT scan for trauma or vascular causes
MRI is the gold standard for most serious spinal pathology.
Management of Back Pain
Non-Specific Back Pain
Mainstay of treatment includes:
- Reassurance
- NSAIDs or paracetamol
- Early mobilization
- Physical therapy
Prolonged bed rest is discouraged.
Specific Causes
Management depends on etiology:
- Herniated disc: conservative treatment initially
- Compression fracture: pain control and orthopedic consultation
- Epidural abscess: IV antibiotics and neurosurgical consult
- Cauda equina: urgent surgical decompression
- AAA rupture: emergency surgery
Treat the cause, not just the pain.
Common Pitfalls in Back Pain Evaluation
Some frequent mistakes include:
- Ordering imaging for every patient
- Missing red flags due to anchoring bias
- Assuming absence of fever rules out infection
- Ignoring urinary symptoms
- Failing to document neurological findings
Back pain rewards careful thinking and punishes shortcuts.
Key Learning Pearls
Most back pain is benign, but serious causes must be actively excluded. Red flags matter more than pain severity. Imaging is a tool, not a reflex. Always consider non-spinal causes. Cauda equina syndrome and epidural abscess are diagnoses you must not miss.
FAQs
Is imaging required for all patients with back pain?
No. Most cases of acute mechanical back pain do not need imaging.
When should MRI be ordered?
MRI is indicated when neurological deficits, infection, malignancy, or cauda equina syndrome is suspected.
Can back pain be caused by abdominal disease?
Yes. Conditions like kidney stones, pancreatitis, and AAA can present as back pain.
Is fever always present in spinal infections?
No. Many cases of epidural abscess do not present with fever.
What is the most dangerous cause of back pain?
Cauda equina syndrome and ruptured abdominal aortic aneurysm are among the most life-threatening.
