Radiating Leg Pain: Differentiating True Sciatica from Other Causes

A man in his mid-forties walks into the clinic, supporting his lower back with one hand while tracing a sharp line with his finger from the buttock down along his leg to the foot. He describes the pain as an electric-like spark shooting through his leg whenever he coughs or sits for a long time.

A question naturally arises:Is this true sciatica caused by compression of a spinal nerve root?Or is it one of the many conditions that produce radiating leg pain without involving the nerve root?

This article offers clinicians a precise, direct method to distinguish true sciatica from its mimics, drawing on anatomical understanding, clinical reasoning, and targeted physical examination.

First: What Happens in True Sciatica?

Sciatica is not simply back pain—it is a nerve root disorder, most often affecting the fifth lumbar or first sacral nerve root.

The most common cause is:Lumbar disc herniation, which compresses the nerve root and triggers inflammation around it.

Other causes include:

• Spinal canal narrowing

• Vertebral slippage

• Nerve-root cyst

• Space-occupying lesions such as tumors

• Abscess or hemorrhage inside the spinal canal

Outcome:Radiating neuropathic pain, sensory disturbance, weakness in muscles supplied by the affected root, and altered reflexes.

How Do We Diagnose Sciatica Clinically?

1. Pain Pattern

Sciatica has a distinct signature:

• Leg pain is more prominent than back pain

• Pain typically radiates below the knee

• The radiation follows a clear dermatomal path:

  • L4: Front of thigh and inner leg

  • L5: Side of leg and top of foot

  • S1: Back of thigh, outer leg, and outer edge of the foot

Pain is usually described as sharp, shooting, electric, or “traveling in a single line.”

2. Neurological Signs

• Tingling or numbness following the same distribution

• Specific muscle weakness:

  • L5: Difficulty lifting the foot or big toe

  • S1: Difficulty standing on tiptoes

• Reflex changes:

  • L4: Reduced knee reflex

  • S1: Reduced Achilles reflex

A matching pattern of pain, sensory loss, muscle weakness, and reflex change strongly supports a nerve-root lesion.

3. Key Examination Tests

Straight Leg Raise Test

• Positive when radiating pain appears below the knee between 30–70 degrees of leg elevation.

• A negative test lowers the likelihood of true sciatica.

Cross-Leg Straight Leg Raise

• Less sensitive but highly specific, usually indicating a large disc herniation.

Seated Neurodynamic Test

• More sensitive; identifies cases missed by the straight leg raise test.

• Pain should ease when neural tension is reduced—otherwise the test is not truly positive.

Conditions That Mimic Sciatica Without Being Sciatica

1. Lumbar Facet Joint Pain

• Lower back pain radiating to the buttock or thigh

• Rarely extends below the knee

• No dermatomal pattern, weakness, or reflex change

• Worsens with back extension or rotation

This is referred pain from the joint—not nerve-root pain.

2. Sacroiliac Joint Dysfunction

• Buttock pain that may radiate backward

• A clear tender point over the joint

• Three or more positive provocative tests increase diagnostic likelihood

• No neurological deficits

Can resemble S1 involvement but lacks genuine nerve-root signs.

3. Piriformis Muscle Syndrome

• Deep buttock pain radiating sometimes down the leg

• Worsens with prolonged sitting

• Stretch tests of the muscle are positive

• Spinal imaging usually normal

Compression occurs outside the spine—not at the nerve root.

4. Spinal Canal Narrowing (Neurogenic Claudication)

• Leg pain and heaviness during walking

• Improves immediately with sitting or bending forward

• Often affects both legs

• Not dermatomal

A distinct pattern that differs from sciatica.

5. Vascular Claudication

• Calf pain during walking

• Improves simply by stopping, without needing to sit

• Weak pulses and low ankle pressure index

Differentiation from neurogenic claudication is crucial, as treatment differs completely.

6. Peripheral Nerve Entrapment

Lateral Thigh Sensory Entrapment

• Tingling and numbness over the outer front thigh

• No back pain, no weakness

• A peripheral (not root-related) sensory problem

• 
  

7. Hip Disorders

Hip Osteoarthritis

• Groin pain

• Radiates to the front of the thigh and may reach the knee

• Worsens with hip rotation

• No neurological signs

Greater Trochanteric Pain Syndrome

• Pain on the outer side of the hip

• Worse when lying on the affected side or climbing stairs

• Radiates to the thigh but not the lower leg

  
  

Red Flags Not to Miss

1. Cauda Equina Syndrome

• Bilateral weakness

• Loss of sensation in the saddle area

• Urinary retention or incontinence

• Loss of bowel control

Requires urgent imaging and surgical intervention.

2. Spinal Tumor

• Persistent night pain unrelieved by rest

• Unexplained weight loss

Progressive weakness

3. Spinal Infection

• Fever

• Increased inflammatory markers

• Severe continuous pain

  
  

How Clinicians Approach the Case Systematically

1. Exclude red flags

2. Analyze the radiation pattern

3. Conduct a full neurological examination

4. Perform neural-tension tests

5. Assess hip, sacroiliac joint, and vascular status

6. Decide whether imaging is needed

7. Use electrodiagnostic tests when the picture is unclear

Conclusion

Radiating leg pain is not always sciatica.True sciatica has a very specific signature:Radiation below the knee, a clear dermatomal path, targeted muscle weakness, altered reflexes, and positive neural-tension tests.

Many mimicking conditions arise from joints, muscles, the hip, blood vessels, or peripheral nerves—each requiring a different management strategy.

Accurate differentiation leads to correct treatment and prevents diagnostic delay and unnecessary interventions.