Back Pain and Sciatica

Low back pain is very common and has many causes. Lumbago is another term for low back pain. Non-specific or mechanical lower back pain refers to the majority of patients who do not have a specific disease causing their lower back pain. 

Sciatica refers to the symptoms associated with irritation of the sciatic nerve.

Acute low back pain should improve within 1-2 weeks. Recovery can take longer (4-6 weeks) for sciatica.

Chronic lower back pain can have a massive impact on the patient’s quality of life and be difficult to manage. 

There are several challenges with managing patients with lower back pain:

  • Identifying serious underlying pathology
  • Speeding up recovery
  • Reducing the risk of chronic lower back pain
  • Managing symptoms in chronic lower back pain

 

Causes of Mechanical Back Pain

The causes of mechanical back pain include:

  • Muscle or ligament sprain
  • Facet joint dysfunction
  • Sacroiliac joint dysfunction
  • Herniated disc
  • Spondylolisthesis (anterior displacement of a vertebra out of line with the one below)
  • Scoliosis (curved spine)
  • Degenerative changes (arthritis) affecting the discs and facet joints

 

Causes of Neck Pain

The causes of neck pain include:

  • Muscle or ligament strain (e.g., poor posture or repetitive activities)
  • Torticollis (waking up with a unilaterally stiff and painful neck due to muscle spasm)
  • Whiplash (typically after a road traffic accident)
  • Cervical spondylosis (degenerative changes to the vertebrae)

 

Red-Flag Causes of Back Pain

It is essential to look out for features that may indicate underlying:

  • Spinal fracture (e.g., major trauma)
  • Cauda equina (e.g., saddle anaesthesia, urinary retention, incontinence or bilateral neurological signs)
  • Spinal stenosis (e.g., intermittent neurogenic claudication)
  • Ankylosing spondylitis (e.g., age under 40, gradual onset, morning stiffness or night-time pain)
  • Spinal infection (e.g., fever or a history of IV drug use)

 

Other Causes of Back Pain

Keep in mind that back pain may not always be related to the spine. There is a long list of abdominal or thoracic conditions that can cause back pain, including:

  • Pneumonia 
  • Ruptured aortic aneurysms
  • Kidney stones
  • Pyelonephritis
  • Pancreatitis
  • Prostatitis
  • Pelvic inflammatory disease
  • Endometriosis

 

Sciatica

The spinal nerves L4 – S3 come together to form the sciatic nerve. The sciatic nerve exits the posterior part of the pelvis through the greater sciatic foramen, in the buttock area on either side. It travels down the back of the leg. At the knee, it divides into the tibial nerve and the common peroneal nerve. 

The sciatic nerve supplies sensation to the lateral lower leg and the foot. It supplies motor function to the posterior thigh, lower leg and foot.

Sciatica causes unilateral pain from the buttock radiating down the back of the thigh to below the knee or feet. It might be described as an “electric” or “shooting” pain. Other symptoms are paraesthesia (pins and needles), numbness and motor weakness. Reflexes may be affected depending on the affected nerve root.

The main causes of sciatica are lumbosacral nerve root compression by:

  • Herniated disc
  • Spondylolisthesis (anterior displacement of a vertebra out of line with the one below)
  • Spinal stenosis

 

Bilateral sciatica is a red flag for cauda equina syndrome.

 

History and Examination

When assessing any pain, you can use the SOCRATES mnemonic:

  • S – Site
  • O – Onset
  • C – Character
  • R – Radiation
  • A – Associations
  • T – Timing
  • E – Exacerbating and relieving factors
  • S – Severity

 

Key symptoms in the history are:

  • Major trauma (spinal fracture)
  • Stiffness in the morning or with rest (ankylosing spondylitis)
  • Age under 40 (ankylosing spondylitis)
  • Gradual onset of progressive pain (ankylosing spondylitis or cancer)
  • Night pain (ankylosing spondylitis or cancer)
  • Age over 50 (cancer)
  • Weight loss (cancer)
  • Bilateral neurological motor or sensory symptoms (cauda equina)
  • Saddle anaesthesia (cauda equina)
  • Urinary retention or incontinence (cauda equina)
  • Faecal incontinence (cauda equina)
  • History of cancer with potential metastasis (cauda equina or spinal metastases)
  • Fever (spinal infection)
  • IV drug use (spinal infection)

 

Key findings on examination are:

  • Localised tenderness to the spine (spinal fracture or cancer)
  • Bilateral neurological motor or sensory signs (cauda equina)
  • Bladder distention implying urinary retention (cauda equina)
  • Reduced anal tone on PR examination (cauda equina)

 

The sciatic stretch test can be used to help diagnose sciatica. The patient lies on their back with their leg straight. The examiner lifts one leg from the ankle with the knee extended until the limit of hip flexion is reached (usually around 80-90 degrees). Then the examiner dorsiflexes the patient’s ankle. Sciatica-type pain in the buttock/posterior thigh indicates sciatic nerve root irritation. Symptoms improve with flexing the knee.

TOM TIP: It is worth remembering the main cancers that metastasise to the bones. A history of these in an exam patient presenting with back pain should make you think of possible cauda equina or spinal metastases. You can remember them with the PoRTaBLe mnemonic:

  • Po – Prostate
  • R – Renal 
  • Ta – Thyroid
  • B – Breast
  • Le – Lung

 

Investigations

Generally, patients with mechanical/non-specific lower back pain can be diagnosed clinically and do not require further investigations.

X-rays or CT scans can be used to diagnose spinal fractures.

An emergency MRI scan is required in patients with suspected cauda equina (within hours of the presentation). 

Investigations for suspected ankylosing spondylitis are:

  • Inflammatory markers (CRP and ESR)
  • X-ray of the spinal and sacrum (may show a fused “bamboo spine” in later-stage disease)
  • MRI of the spine (may show bone marrow oedema early in the disease)

 

STarT Back Screening Tool

The STarT Back tool was developed by Keele University to stratify the risk of a patient presenting with acute back pain developing chronic back pain. This helps guide the intensity of the initial interventions (e.g., referral for group exercises, physiotherapy and cognitive behavioural therapy).

It involves 9 questions that assess the patient’s function and psychological response to the back pain. It gives a:

  • Total score (out of 9)
  • Subscore on the 4 psychosocial questions (out of 4)

 

The interpretation gives a risk of developing chronic back pain:

Low Risk

Medium Risk

High Risk

Total Score

3 or less

More than 3

More than 3

Subscore

3 or less

3 or less

More than 3

 

Managing Acute Lower Back Pain

First, exclude serious underlying causes. If concerned about symptoms or signs of an underlying condition, arrange further investigations and refer appropriately. For example:

  • Same-day referral to the on-call orthopaedic team for an urgent MRI scan if cauda equina is suspected
  • Inflammatory markers and an urgent rheumatology review if ankylosing spondylitis is suspected
  • Full in-line spinal immobilisation, admission to a trauma unit and x-rays/CT scans for spinal injury after major trauma

 

Patients with neurological symptoms or signs on examination, particularly if progressive or severe, may require referral to orthopaedics or neurosurgery (potentially urgently). 

The StarT Back tool can be used to stratify the risk of developing chronic back pain. 

The NICE clinical knowledge summaries (updated 2020) give the options for managing non-specific low back pain based on the outcome of risk stratification, as briefly summarised below (always check the latest guidelines when treating patients). 

Patients at low risk of chronic back pain can generally be managed with: 

  • Self-management
  • Education
  • Reassurance
  • Analgesia
  • Staying active and continuing to mobilise as tolerated

 

Additional options for patients at medium or high risk of developing chronic back pain include:

  • Physiotherapy
  • Group exercise
  • Cognitive behavioural therapy

 

The NICE clinical knowledge summaries advise for analgesia:

  • NSAIDs (e.g., ibuprofen or naproxen) first-line
  • Codeine as an alternative
  • Benzodiazepines (e.g., diazepam) for muscle spasm (short-term only – up to 5 days)

 

They specifically state not to use opioids, antidepressants, amitriptyline, gabapentin or pregabalin for low back pain.

Patients need safety-net advice to report red flag symptoms, such as saddle anaesthesia or incontinence.

Radiofrequency denervation may be an option in patients with chronic low back pain originating in the facet joints. Radiofrequency is used to target and damage the medial branch nerves that supply sensation to the facet joints associated with the back pain. This is done under a local anaesthetic.

 

Management of Sciatica

The initial management of sciatica is mostly the same as acute low back pain. 

The NICE clinical knowledge summaries (updated 2020) state not to use medications such as gabapentin, pregabalin, diazepam or oral corticosteroids for sciatica. They state not to use opioids for chronic sciatica. 

They suggest considering a neuropathic medication if symptoms are persisting or worsening at follow up, but not gabapentin or pregabalin, leaving at the main choices of:

  • Amitriptyline
  • Duloxetine

 

Specialist management options for chronic sciatica include:

  • Epidural corticosteroid injections
  • Local anaesthetic injections
  • Radiofrequency denervation
  • Spinal decompression

 

Last updated August 2021