Spinal Stenosis

Spinal Stenosis: Intro - Canal Calamity

• Spinal canal narrowing; causes nerve root/cord compression.
• Types:
  • Central stenosis
  • Lateral recess stenosis
  • Foraminal stenosis
• Sites:
  • Lumbar (commonest, esp. L4-L5, L3-L4)
  • Cervical
  • Thoracic (rare)
• Key Anatomy: Vertebral body, pedicles, laminae, intervertebral foramen, ligamentum flavum, facet joints, intervertebral disc.

⭐ Degenerative lumbar spinal stenosis most commonly affects the L4-L5 level, followed by L3-L4 and L5-S1.

Spinal Stenosis: Origins - The Narrowing Path

• Congenital: Achondroplasia (results in short pedicles), idiopathic short pedicles.
• Acquired (Most Common):
  • Degenerative (Spondylosis): Key factors include disc herniation/bulge, ligamentum flavum hypertrophy, and facet joint arthropathy/osteophytes.
  • Spondylolisthesis (vertebral slip).
  • Post-traumatic (e.g., fracture malunion).
  • Post-surgical (iatrogenic).
  • Paget’s disease.
• Pathophysiology: Involves mechanical compression of neural elements (nerve roots/cauda equina), associated vascular compromise (ischemia), and inflammatory mediators.

⭐ Hypertrophy of the ligamentum flavum is a key dynamic (buckling with extension) and static contributor to acquired lumbar spinal stenosis, significantly reducing canal diameter.

Spinal Stenosis: Symptoms - The Squeeze Sings

• Lumbar Stenosis:
  • Neurogenic claudication: Bilateral buttock/thigh/leg pain, numbness, weakness.
    • Worse: walking/standing (esp. downhill).
    • Relief: lumbar flexion/sitting (📌 'Shopping Cart Sign' / 'Stoop to Conquer').
  • Chronic low back pain; radicular pain if foraminal.
• Cervical Stenosis:
  • Neck pain.
  • Radiculopathy: Arm pain, paresthesia, weakness (dermatomal/myotomal).
  • Myelopathy: Gait disturbance (spastic, broad-based), clumsiness, UMN signs (Hoffmann's, Babinski), late bowel/bladder dysfunction.
• ⚠️ Cauda Equina Syndrome (RED FLAG):
  • Saddle anesthesia.
  • Bowel/bladder incontinence/retention.
  • Bilateral leg weakness.

⭐ Neurogenic claudication, characterized by pain relief upon lumbar flexion (e.g., leaning forward, sitting), is a hallmark symptom of lumbar spinal stenosis, distinguishing it from vascular claudication.

Spinal Stenosis: Unmasking - The Imaging Insight

• History: Symptom analysis (claudication distance, aggravating/relieving factors, red flags).
• Physical Exam:
  • Neurological: Motor, sensory, reflexes (normal/subtle deficits).
  • Gait assessment.
  • Special tests: SLR (often negative in central stenosis), Kemp’s, Romberg; Hoffman's/Babinski (cervical).
• Imaging:
  • X-rays (AP, lat, flex-ext): Alignment, instability, degeneration.
  • MRI (GOLD STANDARD): Canal dimensions, disc, lig. flavum, nerve/cord compression.
  • CT Myelogram: If MRI C/I; superior bony detail.

⭐ MRI is the imaging modality of choice for diagnosing spinal stenosis, providing excellent visualization of neural structures and soft tissue contributors to the narrowing.

Spinal Stenosis: Action Plan - Relieving the Rule

• Conservative Management (Initial):
  • Activity modification, analgesics (NSAIDs, acetaminophen).
  • Neuropathic agents (gabapentin, pregabalin), muscle relaxants.
  • Physiotherapy: flexion-based exercises, core strengthening.
  • Epidural steroid injections (short-term relief).
• Surgical Indications:
  • Failure of conservative treatment (typically 3-6 months).
  • Progressive/severe neurological deficits (e.g., significant weakness, myelopathy).
  • Cauda equina syndrome (EMERGENCY).
  • Intractable pain significantly affecting quality of life.
• Surgical Procedures:
  • Decompression: Laminectomy, laminotomy, foraminotomy, facetectomy.
  • +/- Instrumented Fusion (if instability, significant deformity, or extensive decompression).

⭐ The primary goal of surgery for spinal stenosis is decompression of the neural elements; fusion is added if there is associated instability or deformity.

High‑Yield Points - ⚡ Biggest Takeaways

• Neurogenic claudication (pseudoclaudication) is pathognomonic: buttock/leg pain with walking.
• Symptoms worsen with lumbar extension (standing, walking downhill), relieved by flexion (sitting, "shopping cart sign").
• Most common in lumbar spine, particularly L4-L5.
• MRI is the investigation of choice for diagnosis.
• Key acquired causes: ligamentum flavum hypertrophy, facet joint arthropathy, disc herniation.
• Definitive treatment for severe symptoms: surgical decompression (e.g., laminectomy).