What is spinal stenosis?

Spinal Stenosis

Spinal stenosis is a narrowing of the spinal canal that may result in bony constriction of the cauda equina and emerging nerve roots, causing compression of neural elements and potentially leading to pain, sensory impairment, weakness, and neurogenic claudication. 1, 2

Pathophysiology and Types

Spinal stenosis occurs due to narrowing of the space within:

• The central spinal canal (central stenosis)
• The neural foramina (foraminal stenosis)
• The lateral recesses (lateral recess stenosis)

This narrowing can result from various causes:

• Degenerative changes (most common)
• Ossification of the posterior longitudinal ligament (OPLL)
• Disc herniation
• Facet joint hypertrophy
• Ligamentum flavum hypertrophy
• Spondylolisthesis

Clinical Presentation

Patients with spinal stenosis typically present with:

• Neurogenic claudication: Pain, numbness, and weakness in the legs that worsens with walking or standing and improves with sitting or spinal flexion 2
• Radicular pain following specific nerve root distributions
• Back pain (may or may not be present)
• Symptoms that worsen with extension and improve with flexion
• In severe cases, bowel or bladder dysfunction (cauda equina syndrome)

Diagnosis

The diagnosis of spinal stenosis requires consideration of:

1. Clinical history: Characteristic symptoms of neurogenic claudication
2. Physical examination: Neurological assessment, straight-leg raise test, gait evaluation
3. Imaging studies:
   • MRI without contrast: Preferred initial imaging study for evaluating neural foraminal stenosis and thecal sac compression 2
   • CT without contrast: Alternative when MRI is contraindicated; 50% thecal sac effacement reliably predicts significant stenosis 2
   • CT myelography: Useful for surgical planning in patients with significant stenosis 2
   • Dynamic imaging (flexion/extension): May be necessary to evaluate instability in cases of subluxation 2

Management

Conservative Management

Approximately 80% of patients experience symptom resolution with conservative treatment 2, which includes:

• Pain medications:

  • NSAIDs/COXIBs (naproxen 375-1100 mg/day, diclofenac 150 mg/day, or ibuprofen 1800 mg/day) for 2-4 weeks 2
  • Acetaminophen as an alternative for patients who cannot tolerate NSAIDs 2
  • Duloxetine as second-line therapy for chronic pain 2
  • Avoid long-term glucocorticoids due to potential adverse effects 2

• Physical therapy:

  • Delordosing exercises (flexion-based exercises)
  • Core strengthening
  • Activity modification

• Epidural steroid injections: May provide temporary relief for radicular symptoms

Surgical Management

Surgical intervention should be considered for:

• Patients with moderate to severe spinal stenosis who have failed conservative management for at least 6 weeks 2
• Disabling radicular pain preventing normal everyday tasks 2
• Severe spinal stenosis with multiple disc herniations and subluxation 2
• Clinically relevant motor deficits or cauda equina syndrome (absolute indications) 3

Surgical options include:

• Lumbar laminectomy with adequate decompression of neural elements
• Foraminotomy to address foraminal stenosis
• Fusion with instrumentation if instability is present 2

Prognosis and Follow-up

• Regular clinical and functional assessments are recommended after treatment 2
• Radiographic evaluation at 12 months post-surgery is recommended 2
• Delayed surgical intervention in severe cases can lead to irreversible neurological damage 2

Common Pitfalls and Caveats

1. Diagnostic challenges: Spinal stenosis on imaging doesn't always correlate with symptoms; asymptomatic degenerative changes are common 1

2. Differential diagnosis: Peripheral vascular disease can present similarly to neurogenic claudication and must be ruled out 4

3. Surgical timing: While surgery provides more rapid symptom relief compared to conservative treatment, the optimal timing remains debated 3

4. Conservative management duration: Guidelines suggest trying conservative management for at least 6 weeks before considering surgery, though this timeframe varies between guidelines 2

5. Imaging interpretation: The presence of anatomical stenosis on imaging in asymptomatic older adults is common and should be correlated with clinical findings 5