Orthopaedic Surgery - Spinal Stenosis

Basics

Spinal stenosis is:

Narrowing of the spinal canal, lateral recesses, or neural foramina

that results in compression of:

The spinal cord

Cauda equina

or

Spinal nerve roots.

In the lumbar spine, the condition is most commonly caused by:

Degenerative changes.

Degenerative Causes

Important degenerative abnormalities include:

Disc-space narrowing

Disc bulging

Facet-joint hypertrophy

Osteophyte formation

and

Hypertrophy or infolding of the ligamentum flavum.

Together, these changes reduce the space available for:

Neural structures.

Clinical Features

Lumbar spinal stenosis commonly causes:

Lower-extremity pain

Numbness

Paresthesia

Weakness

and

Neurogenic claudication.

Severe compression may occasionally produce:

Bladder

or

Bowel dysfunction.

Prevention

There are no established measures that reliably prevent:

Degenerative spinal stenosis.

However, maintaining:

General fitness

Healthy body weight

and appropriate management of musculoskeletal disease may improve overall:

Spinal function.

Epidemiology

Symptoms commonly develop during or after the:

Fifth and sixth decades of life

and may gradually progress with:

Advancing age.

Sex

Degenerative lumbar spinal stenosis overall has no strong:

Sex predominance.

However, degenerative:

Spondylolisthesis associated with stenosis

has historically been reported approximately:

Four times more frequently in women.

Incidence

Historical estimates suggest symptomatic spinal stenosis affects approximately:

1.7–8% of the population.

The prevalence increases substantially with:

Age.

Risk Factors

Important risk factors include:

Advancing age

Degenerative spinal arthritis

Disc degeneration

and conditions producing:

Spinal instability or deformity.

Genetics

There is no single established:

Genetic abnormality

responsible for typical degenerative spinal stenosis.

Some congenital skeletal disorders, however, may predispose to a:

Narrow spinal canal.

Pathophysiology

Lumbar spinal stenosis commonly develops through a progressive cascade of:

Disc degeneration

followed by secondary:

Facet and ligamentous changes.

Disc Degeneration

Degeneration leads to loss of:

Intervertebral disc height.

As the disc loses height, the annulus may:

Bulge posteriorly

into the spinal canal.

Ligamentum Flavum

Loss of disc height also allows the:

Ligamentum flavum

to buckle or infold into the:

Spinal canal.

The ligament may additionally become:

Hypertrophied.

Facet Loading

Loss of disc height transfers greater load to the:

Facet joints.

Facet Arthrosis

Increased mechanical loading produces:

Cartilage degeneration

Reactive sclerosis

Facet hypertrophy

and

Osteophyte formation.

These changes further narrow the:

Central canal

Lateral recesses

and

Neural foramina.

Neural Compression

The final result is reduced space for:

Nerve roots

and the:

Cauda equina.

Symptoms may be worsened dynamically when lumbar extension further decreases:

Canal dimensions.

Etiology

Spinal stenosis may be:

Congenital

or

Acquired.

Congenital Causes

Congenital causes include:

Skeletal dysplasias such as achondroplasia

and

Idiopathic developmental narrowing of the spinal canal.

Acquired Causes

Acquired causes include:

Degenerative disease

Spondylolisthesis

Spondylolytic abnormalities

Previous spinal surgery

Posttraumatic deformity

and

Paget disease.

Degenerative Stenosis

Degenerative disease is the:

Most common cause

in older adults.

Spondylolisthesis

Anterior translation of one vertebra relative to another may further decrease the dimensions of the:

Spinal canal

and

Neural foramina.

Diagnosis

Diagnosis is based on the combination of:

Characteristic symptoms

Physical examination

and

Imaging evidence of neural compression.

Imaging abnormalities alone do not establish symptomatic stenosis because degenerative narrowing is common in:

Asymptomatic older adults.

History

Symptoms generally begin:

Insidiously

and progress:

Slowly.

Back Pain

Patients may initially report longstanding:

Low-back pain

followed by progressive:

Buttock

Thigh

or

Lower-extremity symptoms.

Neurogenic Claudication

The characteristic syndrome is:

Neurogenic claudication.

Symptoms include:

Pain

Tightness

Numbness

Paresthesia

and subjective:

Weakness or heaviness of the legs.

Provoking Factors

Symptoms typically worsen with:

Standing

Walking

and

Lumbar extension.

Relieving Factors

Symptoms usually improve with:

Sitting

Lumbar flexion

or

Leaning forward.

Flexion increases the dimensions of the:

Lumbar spinal canal

and reduces neural compression.

Shopping-Cart Sign

Patients commonly report that they can walk farther while:

Leaning forward over a shopping cart.

This characteristic improvement with flexion is sometimes called the:

Shopping-cart sign.

Walking on an Incline

The historical description that symptoms worsen when walking:

Uphill

is not typical of classic lumbar stenosis because uphill walking generally places the lumbar spine into more:

Flexion.

Many patients instead tolerate uphill walking or cycling better than:

Level or downhill walking.

Cycling

Patients may tolerate a:

Stationary bicycle

relatively well because the flexed posture increases:

Spinal canal dimensions.

Physical Examination

The neurologic examination may be relatively:

Normal at rest

despite substantial symptoms during:

Walking.

Gait

Evaluate:

Walking pattern

Balance

and ability to:

Heel walk

and

Toe walk.

Abnormal Gait

Gait disturbance should also prompt consideration of:

Cervical myelopathy

Thoracic spinal disease

Hip pathology

or

Neurologic disease.

Lumbar Lordosis

Some patients demonstrate reduced:

Lumbar lordosis

because a flexed posture may lessen:

Symptoms.

Range of Motion

Lumbar range of motion may be:

Reduced.

Extension often aggravates:

Leg symptoms.

Motor Examination

Assess the major muscle groups supplied by:

L2 through S1 nerve roots.

Weakness may occur, with:

L5 involvement

being common.

L5 Weakness

Possible findings include weakness of:

Great-toe extension

Ankle dorsiflexion

or

Hip abduction.

Sensory Examination

Assess dermatomal sensation throughout the:

Lower extremities.

Deficits may correspond to the nerve roots affected by:

Central

Lateral recess

or

Foraminal stenosis.

Reflexes

Evaluate:

Patellar reflexes

and

Achilles reflexes.

Reduced reflexes may indicate:

Nerve-root dysfunction.

Straight-Leg Raise

The straight-leg-raise test may be:

Negative

in isolated spinal stenosis.

It may become positive when there is associated:

Disc herniation

or focal:

Nerve-root irritation.

Cauda Equina Examination

Patients with new:

Urinary retention

Incontinence

Saddle anesthesia

Bilateral severe weakness

or rapidly progressive neurologic deficits require urgent evaluation for:

Cauda equina syndrome.

Rectal Examination

A rectal examination may be considered in selected patients when evaluating suspected:

Cauda equina syndrome

although modern assessment relies on the overall neurologic picture, including:

Perineal sensation

and

Bladder function.

Laboratory Tests

Routine laboratory testing is generally:

Not required

for uncomplicated degenerative stenosis.

Infection or Malignancy Evaluation

When infection, inflammatory disease, or malignancy is suspected, laboratory studies may include:

Complete blood count

C-reactive protein

and

ESR.

Imaging

Plain Radiographs

AP and lateral lumbar radiographs may demonstrate:

Disc-space narrowing

Facet arthrosis

Osteophytes

Degenerative scoliosis

and

Spondylolisthesis.

Role of Radiographs

Radiographs are also useful for identifying or excluding:

Fracture

Gross deformity

and certain destructive:

Bone lesions.

They do not directly demonstrate:

Neural compression.

Flexion-Extension Views

Dynamic flexion-extension radiographs may be obtained when there is concern for:

Segmental instability.

They are particularly useful in patients with:

Spondylolisthesis.

MRI

MRI is the preferred advanced imaging examination for most patients with suspected:

Lumbar spinal stenosis.

MRI Findings

MRI can demonstrate:

Central canal stenosis

Lateral recess narrowing

Foraminal stenosis

Disc bulging or herniation

Facet hypertrophy

and

Ligamentum flavum thickening.

Clinical Correlation

The level and severity of compression on MRI should correspond reasonably with:

The patient’s symptoms and examination.

Severe-appearing radiographic stenosis can exist without:

Clinical symptoms.

CT Myelography

CT myelography can provide excellent visualization of:

Thecal sac and nerve-root compression.

Indications for CT Myelography

It may be useful when:

MRI is contraindicated

MRI quality is limited by metal instrumentation

or detailed evaluation of:

Bony stenosis

is needed.

Limitations

CT myelography is:

Invasive

because it requires intrathecal:

Contrast injection.

Possible adverse effects include:

Post-lumbar-puncture headache

and rare contrast or procedural complications.

Diagnostic Injections

Selective nerve-root blocks or epidural injections may sometimes help identify the principal:

Symptomatic level

when imaging demonstrates multiple possible sites of:

Neural compression.

Pathological Findings

Characteristic anatomical abnormalities include:

Loss of disc height

Annular bulging

Facet hypertrophy

Ligamentum flavum thickening

Central canal narrowing

Lateral recess stenosis

Foraminal narrowing

and sometimes:

Segmental instability.

Differential Diagnosis

The most important differential diagnosis is:

Vascular claudication.

Other considerations include stenosis elsewhere in the:

Cervical

or

Thoracic spine.

Vascular Claudication

Vascular claudication is caused by inadequate:

Arterial blood flow

to the lower extremities.

Distinguishing Features

Vascular symptoms typically correlate with:

Walking distance

and improve when the patient:

Stops walking

regardless of spinal posture.

In contrast, neurogenic claudication is strongly influenced by:

Lumbar position.

Leaning Forward

Improvement with:

Forward flexion

strongly favors:

Neurogenic claudication.

Pulse Examination

Patients with suspected vascular disease should undergo assessment of:

Peripheral pulses

and, when indicated,

Vascular studies.

Cervical or Thoracic Stenosis

Abnormal balance, upper-motor-neuron findings, or upper-extremity symptoms should raise concern for:

Cervical or thoracic cord compression

rather than isolated:

Lumbar stenosis.

Treatment

General Measures

Initial management is generally:

Nonoperative

unless there is severe or rapidly progressive:

Neurologic compromise.

Weight Management

Weight reduction may decrease mechanical load on the:

Lumbar spine

and improve general:

Mobility and conditioning.

Bracing

A lumbar brace or corset may occasionally provide:

Short-term symptomatic relief.

Long-term routine bracing is generally discouraged because prolonged dependence may contribute to:

Trunk muscle deconditioning.

Activity

Patients should remain:

As active as tolerated

provided there is no:

Unstable fracture

Gross instability

or other contraindication.

Prolonged bed rest is generally:

Avoided.

Physical Therapy

Physical therapy aims to improve:

Conditioning

Strength

Walking tolerance

and

Functional mobility.

Aerobic Conditioning

A:

Stationary bicycle

is often well tolerated because it places the lumbar spine in:

Flexion.

Aquatic Therapy

Aquatic exercise can improve conditioning while reducing:

Weight-bearing stress.

Trunk Strengthening

Therapy may include:

Abdominal strengthening

Hip and lower-extremity conditioning

and appropriate:

Lumbar stabilization exercises.

Back Extensor Strengthening

Back-extensor strengthening may be useful as part of general conditioning, but exercises that repeatedly provoke extension-related:

Claudication symptoms

should be modified.

Gait Training

Gait training may improve:

Balance

Walking efficiency

and appropriate use of:

Assistive devices.

Medication

First-Line Medication

Pain control may include:

NSAIDs

when not contraindicated

and

Acetaminophen.

NSAIDs

NSAIDs may help reduce:

Mechanical back pain

and associated inflammatory symptoms.

Their use should take into account:

Gastrointestinal

Renal

and

Cardiovascular risk.

Aspirin

Enteric-coated aspirin was historically used as an anti-inflammatory agent, although modern practice more commonly uses other:

NSAIDs

when appropriate.

Opioids

There is generally no role for sustained long-term:

Opioid therapy

for chronic lumbar spinal stenosis.

Epidural Steroid Injection

Lumbar epidural corticosteroid injections may provide:

Temporary symptom relief

in selected patients.

They do not reverse the underlying:

Structural stenosis.

Role of Injection

Injections may be useful to:

Reduce radicular symptoms

facilitate participation in:

Rehabilitation

or sometimes clarify the symptomatic:

Spinal level.

Surgery

Surgery is considered when symptoms remain:

Functionally intolerable

despite adequate nonoperative treatment.

Surgical Indications

Typical indications include:

Severe neurogenic claudication

Persistent radicular pain

Progressive neurologic deficit

and major reduction in:

Quality of life.

Urgent Surgery

Urgent or emergency assessment is required for:

Cauda equina syndrome

or rapidly progressive:

Motor weakness.

Preoperative Assessment

Because many patients are older and have medical comorbidities, preoperative evaluation may involve:

Primary care

Internal medicine

Cardiology

or

Anesthesiology.

Decompression

The principal surgical goal is:

Adequate decompression of neural elements.

Laminectomy

A:

Laminectomy

is commonly used to enlarge the central:

Spinal canal.

Foraminotomy

A:

Foraminotomy

may be added when compression involves the:

Neural foramen.

Lateral Recess Decompression

Hypertrophic facets and ligament may be removed to decompress:

Traversing nerve roots

within the:

Lateral recess.

Discectomy

A discectomy may be performed when a significant:

Disc herniation

contributes to neural compression.

Fusion

Fusion is not required for every patient undergoing:

Lumbar decompression.

Indications for Fusion

Fusion may be considered when there is:

Pre-existing instability

Symptomatic spondylolisthesis

Major deformity

or when decompression itself is expected to create:

Iatrogenic instability.

Facet Resection

Extensive removal of the:

Facet joints

or disruption of stabilizing posterior structures increases the likelihood that:

Fusion

will be required.

Historically, removal of more than approximately:

50% of the facets

has been considered a potential threshold for concern regarding instability.

Instrumentation

When fusion is indicated, fixation is commonly obtained using:

Pedicle screws

with or without:

Interbody support.

Follow-Up

Follow-up is individualized according to whether treatment is:

Nonoperative

or

Surgical.

Historical Postoperative Schedule

Traditional postoperative visits may occur at approximately:

6 weeks

3 months

6 months

1 year

and

2 years

with longer-term review as needed.

Prognosis

The natural history is:

Variable.

Some patients remain relatively stable for prolonged periods, while others experience:

Gradual worsening.

Spinal stenosis does not invariably progress to severe:

Disability.

Nonoperative Prognosis

Many patients can maintain acceptable function using:

Exercise

Activity modification

Medication

and occasional:

Injections.

Surgical Prognosis

In appropriately selected patients whose symptoms persist despite conservative treatment, decompressive surgery generally improves:

Leg pain

Walking tolerance

and

Neurogenic claudication.

Relief of:

Leg symptoms

is generally more predictable than relief of isolated:

Low-back pain.

Complications

Cauda Equina Syndrome

Severe central stenosis may rarely cause:

Bladder dysfunction

Bowel dysfunction

Saddle anesthesia

and

Bilateral lower-extremity weakness.

This requires:

Urgent evaluation and decompression.

Surgical Infection

Spinal surgery carries a risk of:

Superficial

or

Deep infection.

Neurologic Injury

Decompression and instrumentation may rarely cause:

Nerve-root

or

Dural injury

and, depending on level, other neurologic complications.

Dural Tear

Incidental:

Durotomy

may occur during decompression, particularly in:

Revision surgery

or severe stenosis.

Pseudarthrosis

When fusion is performed, failure to achieve solid union may result in:

Pseudarthrosis.

This can cause:

Persistent pain

Implant failure

or need for:

Revision surgery.

Recurrent or Adjacent-Level Stenosis

Degenerative disease may progress at:

The operated level

or

Adjacent spinal levels.

This can lead to recurrent:

Neural compression.

Persistent Pain

Some patients continue to experience:

Back or leg pain

despite technically adequate surgery.

Patient Monitoring

Patients should be monitored for:

Walking tolerance

Leg pain

Neurologic deficits

Bladder or bowel symptoms

and overall:

Functional status.

Fusion Monitoring

When arthrodesis has been performed, imaging may be used to evaluate:

Alignment

Instrumentation

and progression toward:

Fusion.

Red-Flag Monitoring

Patients should seek urgent evaluation for development of:

New urinary retention

Loss of bowel control

Saddle anesthesia

Rapidly progressive leg weakness

or severe bilateral:

Neurologic symptoms.

Key Principle

Lumbar spinal stenosis is narrowing of the spinal canal, lateral recesses, or neural foramina that compresses the cauda equina or nerve roots, most commonly because of age-related disc, facet, and ligamentum flavum degeneration.

The hallmark clinical syndrome is:

Neurogenic claudication, characterized by leg pain, numbness, heaviness, or weakness that worsens with standing and walking and improves with sitting or forward flexion.

MRI is the principal imaging study used to define:

Neural compression, while radiographs help identify spondylolisthesis, deformity, and instability.

Initial management usually consists of:

Activity modification, conditioning and physical therapy, analgesic or anti-inflammatory treatment, weight management, and selective epidural injections.

Surgery is reserved for:

Persistent function-limiting symptoms, progressive neurologic deficit, or cauda equina syndrome, with decompression as the primary procedure and fusion added only when instability or deformity requires it.