Sciatica

Sciatica (also called radicular pain) is commonly used to describe radiating leg pain. It is caused by inflammation or compression of the lumbosacral nerve roots (L4-S1) forming the sciatic nerve. Sciatica can cause severe discomfort and functional limitation.

People with sciatica usually describe aching and a sharp leg pain radiating below the knee and into the foot and toes. The pain can have a sudden or slow onset and varies in severity. Most people report coexisting low back pain. Disc herniations affecting the L5 or S1 nerve root are more common and cause pain at the back or side of the leg and into the foot and toes. If L4 root is affected, pain is localised to the front and lateral side of the thigh. Tingling or numbness and loss of muscle strength in the same leg are other symptoms that suggest nerve root involvement.

How common is sciatica?

In the UK about 60% of patients with back and leg pain were clinically diagnosed with sciatica.

How is sciatica diagnosed?

Sciatica is a clinical diagnosis based on the person’s symptoms and findings on examination. Symptoms and signs suggesting sciatica:

• Unilateral leg pain more severe than low back pain;
• Pain most commonly radiating posteriorly at the leg and below the knee;
• Numbness and/or paraesthesia in the involved lower leg;
• Neurological deficit associated with the involved nerve root (muscle weakness/absence of tendon reflexes/sensory deficit);
• Positive neural tension test with provocation of pain in the affected leg (straight leg raise test/femoral nerve test/slump test).

Role of imaging

• Routine imaging is not advised in people with non-specific low back pain with or without sciatica
• Disc herniation is a common age related finding
• Consider imaging if symptoms progress for more than 12 weeks, or if the person has progressive neurological deficits (signs of urinary retention or decreased anal sphincter tone ) or worsening pain

Conservative treatment

• Encourage patients to remain active and avoid bed rest

What is the prognosis?

• Most people experience an improvement in symptoms over time with either conservative treatment or surgery
• For disabling symptoms lasting longer than 6 weeks with a lack of response to non-operative management, specialist referral (rheumatologist, rehabilitation physician, spinal surgeon) can also be considered
• Laminectomy surgery for radiculopathy may shorten the duration of symptoms, but outcomes at 12 months are similar to non-operative treatment and surgery is associated with increased risk of further surgery
• Decompression surgery for central lumbar canal stenosis may improve symptoms, but there is a lack of high -quality evidence for its superiority over non-operative management

References

• Diagnosis and treatment of sciatica, bmj 2019