Spinal Stenosis
Chapter notes (PDF)PDFNarrowing of the spinal canal causing compression of the spinal cord or nerve roots, most commonly in the lumbar spine. Characterised by neurogenic claudication relieved by flexion/sitting.
Key Facts
- Neurogenic claudication: bilateral leg pain, heaviness, numbness on walking; relieved by sitting or leaning forward (flexion - 'shopping trolley sign')
- Lumbar stenosis: most common; usually degenerative (facet hypertrophy, ligamentum flavum thickening, disc bulging, osteophytes)
- Cervical stenosis: myelopathy (spastic gait, hyperreflexia, Lhermitte sign, hand clumsiness)
- Distinguishes from vascular claudication: neurogenic relieved by flexion/sitting (not just stopping); vascular relieved by standing still
- MRI: gold standard for diagnosis - shows degree of stenosis, nerve root compression
- Conservative: physiotherapy, flexion-based exercises, analgesia; effective for many patients
- Surgical decompression: laminectomy for severe/progressive neurogenic claudication or myelopathy (SPORT trial)
- Age: predominantly >60 years; degenerative in ~90%
Overview
Key Facts
Spinal stenosis is narrowing of the spinal canal, lateral recess, or neural foramen, leading to compression of neural structures. The lumbar spine is most commonly affected.
Epidemiology
- Symptomatic lumbar stenosis: ~8–11% of >60 years
- Most common indication for spinal surgery in >65 years
- Cervical stenosis less common but potentially more serious (myelopathy)
Aetiology
- Degenerative (~90%): facet joint hypertrophy, ligamentum flavum thickening, disc bulging, osteophytes
- Congenital: short pedicles, congenitally narrow canal (predisposes to earlier symptoms)
- Other: spondylolisthesis, Paget disease, post-surgical, trauma
Pathophysiology
- Narrowing of central canal/lateral recess → compression of cauda equina (lumbar) or spinal cord (cervical)
- Venous congestion hypothesis: stenosis impairs venous drainage → nerve root ischaemia during exercise
- Extension narrows canal further → symptoms worse with standing/walking
- Flexion opens canal → symptoms relieved by sitting/bending forward
Clinical Presentation
Lumbar Stenosis - Neurogenic Claudication
- Bilateral (or unilateral) leg pain, heaviness, weakness, numbness on walking
- Relieved by sitting down, leaning forward, flexion ('shopping trolley sign')
- Walking distance progressively decreases
- Symptoms in multiple dermatomes (multilevel)
- Back pain may be present
- May be able to cycle (flexed position) even when unable to walk
Cervical Stenosis - Myelopathy
- Insidious onset clumsy hands (difficulty with buttons, writing)
- Gait disturbance (broad-based, spastic)
- Lhermitte sign (electric shock sensation down spine on neck flexion)
- Upper motor neuron signs in legs, lower motor neuron signs in arms
- Bowel/bladder dysfunction (late)
Red Flags
- Progressive neurological deficit
- Bladder/bowel dysfunction (cauda equina in lumbar; myelopathy in cervical)
- Upper motor neuron signs (cervical myelopathy - surgical urgency)
- Rapid deterioration
Differential Diagnosis
| Diagnosis | Key Features | Investigation |
|---|---|---|
| Vascular claudication | Calf pain, relieved by standing still (not flexion), absent pulses, ABPI reduced | ABPI, duplex USS |
| Disc herniation | Radiculopathy, single dermatome, positive SLR | MRI |
| Peripheral neuropathy | Stocking-glove, symmetrical, sensory > motor | Nerve conduction, HbA1c |
| Hip OA | Groin pain, reduced ROM, antalgic gait | X-ray hip |
| Cauda equina syndrome | Acute bilateral legs, saddle anaesthesia, urinary retention | Emergency MRI |
Diagnosis / Investigation
Imaging
- MRI lumbar/cervical spine: gold standard; shows canal narrowing, ligamentum flavum hypertrophy, disc bulging, nerve root compression, cord compression (cervical)
- CT: if MRI contraindicated; good for bony stenosis
- X-ray: spondylosis, spondylolisthesis, alignment; poor for soft tissue
Vascular Assessment
- ABPI: if vascular claudication differential (>0.9 is normal)
Special Tests
- Treadmill test: objective walking distance assessment
- EMG/NCS: if diagnostic uncertainty; can confirm multilevel radiculopathy
Management
Non-pharmacological
- Physiotherapy: flexion-based exercises, core strengthening, stationary cycling
- Activity modification: avoid prolonged standing/extension
- Walking aids: walking stick, rollator (maintains flexed posture)
- Weight loss: if overweight
Pharmacological
- NSAIDs: short course for pain relief
- Neuropathic pain: gabapentin 300–1200mg TDS, pregabalin, amitriptyline
- Epidural steroid injection: limited evidence; short-term relief for radicular symptoms
Surgical
- Decompressive laminectomy: gold standard for severe neurogenic claudication (SPORT trial: surgery superior to conservative at 4 years for quality of life and function)
- Laminotomy, foraminotomy: less extensive decompression
- With fusion: if associated spondylolisthesis or instability
Cervical myelopathy:
- Surgical decompression: anterior (ACDF) or posterior (laminoplasty/laminectomy) - recommended for progressive myelopathy
Referral Criteria
- Spinal surgery: progressive neurological deficit, refractory neurogenic claudication, cervical myelopathy
- Emergency: cauda equina syndrome
Prognosis
- Natural history: variable; many patients stable over years
- ~30% improve with conservative management
- ~30% remain stable; ~30% slowly deteriorate
- Surgical decompression: ~65–80% good outcomes for neurogenic claudication
- Cervical myelopathy: progressive without surgery; early surgery gives better outcomes
- Post-surgical: walking distance typically improves significantly
- Complications of surgery: dural tear (~5–10%), infection, recurrence of stenosis
Other Relevant Information
Neurogenic vs Vascular Claudication
| Feature | Neurogenic | Vascular |
|---|---|---|
| Pain distribution | Bilateral, diffuse | Calf, unilateral |
| Relieved by | Sitting, flexion | Standing still |
| Cycling | Usually possible | May reproduce symptoms |
| Pulses | Normal | Reduced/absent |
| ABPI | Normal | Reduced |
| Onset with walking | Variable distance | Fixed distance |