Orthopaedic Surgery - Sciatica

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Basics

Sciatica refers to:

Pain radiating from the lower back or buttock into the lower extremity along the distribution of a lumbosacral nerve root.

The sciatic nerve is formed mainly from the:

L4–S3 nerve roots, although higher lumbar radiculopathies involving L2–L4 can produce related anterior-thigh symptoms.

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Typical Pain Distribution

Sciatic or radicular pain may be experienced in several regions.

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Low Back

Pain may begin in the:

Midline or paraspinal lumbosacral region

and then radiate toward the hip or leg.

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Buttock

Patients may describe:

Deep, cramping, aching pain

within the buttock.

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Posterior or Lateral Thigh

Compression of the:

L5

or

S1

nerve roots commonly causes pain in the:

Posterior or lateral thigh.

Some patients experience symptoms in both regions.

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Anterior Thigh

Higher lumbar radiculopathy involving:

L2

L3

or

L4

may cause pain in the:

Anterior or medial thigh.

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Epidemiology

Sciatica is relatively common.

Historical estimates suggest that approximately:

2% of the general population

may be affected at a given time, with a lifetime occurrence approaching:

40%.

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Etiology

The most common cause is:

Lumbar intervertebral disc herniation

with compression and inflammation of a:

Lumbosacral nerve root.

The most frequently affected disc levels are:

L4–L5

and

L5–S1.

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Pathophysiology

The:

Nucleus pulposus

may protrude or extrude through a weakened or torn:

Annulus fibrosus.

The resulting disc material can compress or chemically irritate an adjacent:

Nerve root.

Both:

Mechanical compression

and

Inflammatory mediators

contribute to radicular pain.

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Diagnosis

Diagnosis is based primarily on:

History

Neurologic examination

Nerve-root tension signs

and selective imaging.

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Signs and Symptoms

Most patients have some history of:

Low-back pain

before the onset of leg symptoms.

A precipitating event may occur, such as:

Bending

Lifting

Straining

or sudden twisting.

Symptoms may begin:

Gradually

or

Abruptly.

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Leg Pain

Leg pain is often:

More disabling than the back pain.

The distribution generally follows the affected nerve root.

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Root-Specific Pain Patterns

L1

Pain may localize to the:

Groin.

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L2

Symptoms may occur in the:

Medial or anterior thigh.

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L3

Pain typically affects the:

Anterior thigh

and may extend toward the:

Medial knee.

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L4

Pain may involve the:

Anterior thigh

Medial knee

and

Medial shin.

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L5

Pain commonly travels through the:

Lateral thigh

Lateral calf

and

Dorsum of the foot.

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S1

Symptoms commonly involve the:

Posterior thigh

Posterior calf

and

Lateral aspect of the foot.

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Pain Below the Knee

In classic lower lumbar radiculopathy, pain frequently extends:

Below the knee.

This can help distinguish nerve-root pain from some forms of nonspecific referred back pain.

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Foot Symptoms

Paresthesia is a common distal symptom.

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L5

Tingling or numbness commonly affects the:

Dorsum of the foot

and may extend toward the:

Great toe.

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S1

Sensory symptoms may occur over the:

Lateral foot

and

Little-toe region.

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Motor Symptoms

Weakness may occur but is usually less prominent than:

Pain

or

Paresthesia.

Marked or progressive weakness should prompt evaluation for:

Severe nerve compression

or another neurologic disorder.

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Aggravating Factors

Symptoms may worsen with:

Bending

Stooping

Lifting

Coughing

Sneezing

Straining

Prolonged sitting.

These activities may increase:

Intradiscal pressure

or nerve-root tension.

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Relieving Factors

Some patients obtain relief with:

Standing

Gentle walking

Rest

or lying with the:

Hips and knees flexed.

Sleeping with a pillow beneath the knees may also reduce discomfort.

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Physical Examination

A complete examination should include:

Lumbar spine assessment

Motor testing

Sensory testing

Reflexes

and

Nerve-tension maneuvers.

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Spinal Posture

Patients with acute radiculopathy may demonstrate:

Flattening of lumbar lordosis

and maintain the knees in slight:

Flexion.

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Sciatic Scoliosis

An antalgic lateral shift may occur in which the patient leans away from or occasionally toward the painful side.

This is sometimes termed:

Sciatic scoliosis

or

Antalgic list.

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Lumbar Range of Motion

Lumbar motion may be limited, especially:

Extension

Forward flexion

and

Lateral flexion toward the affected side.

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Motor Examination

Strength should be systematically tested and documented for comparison over time.

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Hip

Assess:

Flexion

Extension

Abduction

Adduction.

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Knee

Assess:

Flexion

and

Extension.

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Ankle

Assess:

Dorsiflexion

Plantarflexion

Inversion

Eversion.

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Great Toe

Assess:

Flexion

and particularly:

Extension, which is useful for evaluating L5 function.

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Typical Motor Deficits

Common patterns include:

L3–L4: Quadriceps weakness

L4: Possible ankle dorsiflexion weakness

L5: Weak great-toe extension and dorsiflexion

S1: Weak plantarflexion

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Sensory Examination

Test sensation throughout the lower-extremity:

Dermatomes

and compare with the:

Opposite side.

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Reflexes

Important reflexes include:

Patellar reflex – predominantly L3–L4

Achilles reflex – predominantly S1.

Asymmetric reduction may help identify the affected nerve root.

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Gait

Observe for:

Antalgic gait

Foot drop

Weak push-off

Pelvic tilt

or other compensatory patterns.

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Trendelenburg Sign

Weakness involving the hip abductors, especially with:

L5 dysfunction, may produce:

Pelvic drop

or a compensatory trunk lean during walking.

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Straight-Leg Raise

The straight-leg-raise test is a classic maneuver for evaluating:

L4–S1 nerve-root irritation.

With the patient supine:

Keep the knee extended

and gradually flex the:

Hip.

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Positive Straight-Leg Raise

The test is considered positive when it reproduces the patient’s characteristic:

Radiating leg pain

typically between approximately:

30° and 70° of hip flexion.

Isolated hamstring tightness or low-back discomfort is less specific.

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Crossed Straight-Leg Raise

The crossed straight-leg-raise test is positive when elevation of the:

Unaffected leg

produces radicular pain in the:

Symptomatic leg.

This finding is relatively specific for:

Lumbar disc herniation.

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Lasègue Maneuver

During straight-leg raising, forced:

Ankle dorsiflexion

may further increase nerve tension and reproduce symptoms.

Pain usually decreases when the:

Hip or knee is flexed.

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Bowstring Sign

After straight-leg raising reproduces sciatica:

Flex the knee slightly

then apply pressure in the region of the:

Popliteal fossa or hamstring insertion

to retension the nerve.

Reproduction of the characteristic leg pain supports:

Nerve-root irritation.

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Femoral Nerve Stretch Test

This test evaluates higher lumbar nerve roots, particularly:

L2–L4.

With the patient prone or side-lying, knee flexion combined with hip extension may reproduce:

Anterior thigh pain.

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Muscle Wasting

Visible muscle atrophy is uncommon in:

Acute radiculopathy.

It generally suggests a more:

Chronic lesion.

Marked or disproportionate muscle wasting should prompt consideration of:

Tumor

Peripheral neuropathy

or another neurologic disorder.

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Red-Flag Findings

Urgent evaluation is required for:

Progressive motor weakness

Bilateral neurologic symptoms

Saddle anesthesia

Urinary retention

Urinary or fecal incontinence

Fever

Known malignancy

Unexplained weight loss

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Laboratory Tests

Routine laboratory studies are not required for uncomplicated sciatica.

Testing may be appropriate when there is concern for:

Infection

Malignancy

Inflammatory disease

or another systemic process.

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Evaluation for Myeloma

In older patients with unexplained or atypical spinal pain, selected tests may include:

CBC

ESR or CRP

and

Serum protein electrophoresis

when:

Multiple myeloma

is suspected.

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Imaging

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Plain Radiographs

Routine radiographs are usually not required for uncomplicated acute radiculopathy.

They may be useful when there is concern for:

Fracture

Spondylolisthesis

Scoliosis

Tumor

or other structural disease.

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Lateral Radiograph

A lateral lumbar view may demonstrate:

Compression fracture

Spondylolisthesis

or degenerative changes.

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AP Radiograph

An AP view may identify:

Scoliosis

Pedicle destruction

or other findings suggesting:

Metastatic or destructive disease.

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Pelvic Radiographs

Pelvic imaging may be helpful when considering:

Pelvic tumor

Hip pathology

or other nonspinal causes of symptoms.

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MRI

MRI is the preferred advanced imaging study for evaluating:

Lumbar disc herniation

Nerve-root compression

Spinal stenosis

Vertebral fracture

Bone marrow tumor

Spinal cord or epidural lesions.

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Indications for Early MRI

MRI is particularly appropriate for:

Progressive neurologic deficit

Cauda equina syndrome

Concern for infection

Concern for malignancy

or persistent disabling symptoms despite appropriate conservative treatment.

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CT

CT may be useful in patients who:

Cannot undergo MRI

or when detailed:

Bony anatomy

needs to be assessed.

CT myelography is another option in selected patients when MRI is contraindicated or nondiagnostic.

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Pathological Findings

The classic finding is:

Extrusion or protrusion of the nucleus pulposus through a disrupted annulus fibrosus.

This can compress the adjacent:

Nerve root.

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Differential Diagnosis

Important alternatives include:

Diabetic neuropathy

Discitis

Spinal epidural abscess

Lumbar spinal stenosis

Lumbar muscle strain

Spinal tumor

Peripheral nerve entrapment

Hip pathology

Sacroiliac pathology

Psychogenic or nonanatomic pain syndromes

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Diabetic Neuropathy

Diabetic neuropathy usually produces:

Symmetric distal sensory symptoms

in a:

Stocking distribution

rather than a single dermatomal radicular pattern.

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Spinal Infection

Discitis or epidural abscess should be considered when symptoms occur with:

Fever

Systemic illness

Elevated inflammatory markers

or significant risk factors for infection.

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Lumbar Spinal Stenosis

Lumbar stenosis more commonly causes:

Neurogenic claudication

with symptoms aggravated by:

Standing or walking

and relieved by:

Sitting or forward flexion.

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Treatment

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General Principles

Most cases of acute sciatica are treated:

Nonoperatively.

The goals are to:

Control pain

Maintain mobility

Preserve neurologic function

and allow natural recovery.

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Patient Education

Patients should temporarily reduce:

Heavy lifting

Repeated bending

and movements that clearly aggravate symptoms.

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Bed Rest

Prolonged bed rest should be avoided.

If pain is severe, a short period of approximately:

1–3 days

may be reasonable before progressively increasing activity.

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Activity

Patients should resume:

Walking and normal daily activity

as tolerated.

Prolonged inactivity can lead to:

Deconditioning

Muscle weakness

and delayed recovery.

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Exercise

Long-term management should emphasize:

Core strengthening

Back conditioning

Aerobic fitness

and proper:

Lifting mechanics.

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Physical Therapy

Physical therapy may include:

Lumbar stabilization

Directional exercises

Flexibility

Core strengthening

Aerobic conditioning

and education regarding:

Posture

and

Healthy-back mechanics.

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Medication

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NSAIDs

NSAIDs may provide short-term relief of:

Pain

and

Inflammation

when medically appropriate.

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Muscle Relaxants

A short course of muscle relaxants may be useful in patients with prominent:

Muscle spasm.

Adverse effects such as:

Sedation

should be considered.

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Acetaminophen

Acetaminophen may be used for:

Analgesia

when appropriate.

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Opioids

Routine opioid therapy should generally be:

Avoided

because most sciatica improves spontaneously and opioids have significant adverse effects and dependence risks.

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Epidural Steroid Injection

Epidural corticosteroid injection may provide:

Temporary relief of radicular pain

in selected patients with:

Disc herniation

or inflammatory nerve-root compression.

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Role of Injection

The goal is primarily to improve:

Pain control

Mobility

Sleep

and tolerance of:

Rehabilitation

while the underlying lesion resolves.

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Surgery

Surgical treatment is considered when:

Appropriate nonoperative management fails

or when significant neurologic compromise is present.

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Persistent Symptoms

For persistent disabling radicular pain, surgery may be considered after approximately:

6 weeks or more

of appropriate conservative treatment, depending on clinical circumstances.

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Neurologic Deficit

Earlier surgery may be indicated for:

Progressive motor weakness

or severe neurologic deficit.

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Cauda Equina Syndrome

Cauda equina syndrome requires:

Urgent surgical decompression.

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Microdiscectomy

The standard operation for a symptomatic lumbar disc herniation is:

Lumbar discectomy

commonly performed through:

Laminotomy and microdiscectomy.

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Minimally Invasive Discectomy

Tubular or expandable retractor systems may be used to perform:

Minimally invasive microdiscectomy.

The goal is to remove the compressive disc fragment while minimizing:

Soft-tissue injury.

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Follow-Up

Patients should be reassessed periodically to document:

Pain

Motor strength

Sensation

Reflexes

and

Functional recovery.

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Monitoring Interval

During the acute recovery phase, reassessment at approximately:

2–4-week intervals

may be useful.

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Prognosis

The overall prognosis is:

Good.

Most patients improve without surgery.

Historical studies suggest that more than:

70%

recover with:

Nonoperative treatment.

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Natural History

Improvement may occur because the herniated disc fragment undergoes:

Dehydration

Shrinkage

and sometimes:

Spontaneous resorption.

Inflammation surrounding the nerve root also gradually decreases.

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Complications

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Persistent Pain

Some patients develop:

Chronic or recurrent radicular pain.

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Progressive Spondylosis

Underlying disc degeneration may progress to:

Lumbar spondylosis

with additional:

Mechanical pain

or

Spinal stenosis.

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Cauda Equina Syndrome

A large central disc herniation can compress multiple lumbosacral roots and produce:

Urinary retention or incontinence

Bowel dysfunction

Saddle anesthesia

Bilateral leg weakness.

This represents a:

Surgical emergency.

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Persistent Motor Deficit

Prolonged nerve compression may result in:

Permanent weakness

Foot drop

or other residual neurologic dysfunction.

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Patient Monitoring

Follow-up should document:

Pain distribution

Strength

Sensation

Reflexes

Gait

Return to work and daily activity.

Any development of:

Progressive weakness

Saddle anesthesia

or

Bowel or bladder dysfunction

requires immediate reassessment.

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Key Principle

Sciatica is radiating lower-extremity pain caused most commonly by irritation or compression of a lumbar or lumbosacral nerve root, usually from a disc herniation at L4–L5 or L5–S1.

Characteristic findings include:

Dermatomal leg pain, paresthesia, possible weakness or reflex change, and reproduction of symptoms with nerve-tension tests such as the straight-leg raise.

Most patients improve with:

Activity modification, short-term analgesic treatment, early mobilization, and rehabilitation, while surgery is reserved for:

Persistent disabling pain, progressive neurologic deficit, or cauda equina syndrome.