Lumbar Stenosis vs Sciatica: How to Tell the Difference
Leg pain originating from the lumbar spine is one of the most common reasons for consultation in spine neurosurgery. Two conditions dominate: lumbar spinal stenosis and sciatica caused by herniated disc. While both can cause radiating leg pain, their mechanisms, symptoms, and treatments differ significantly.
Dr Christian Dimitriu, neurosurgeon specializing exclusively in spine surgery, explains how to distinguish these two conditions and why differential diagnosis is essential for proposing the appropriate treatment.
Lumbar spinal stenosis and sciatica from herniated disc are two distinct conditions that can cause leg pain. Lumbar stenosis results from progressive narrowing of the spinal canal, while sciatica is caused by compression of a nerve root, most often by a herniated disc. Differential diagnosis is essential because treatments differ.
Two Conditions, Two Mechanisms
Lumbar Spinal Stenosis: Progressive Narrowing
Lumbar spinal stenosis is a narrowing of the spinal canal through which the cauda equina nerves pass. This narrowing is generally related to aging and spinal osteoarthritis.
The main causes are:
• Facet joint osteoarthritis which hypertrophies over time
• Thickening of the ligamentum flavum at the back of the canal
• Disc degeneration with disc bulging
• Spondylolisthesis (vertebral slippage)
• Constitutionally narrow canal (present from birth)
This narrowing progressively compresses the nerves innervating the legs, causing characteristic symptoms during walking.
Sciatica: Acute Radicular Compression
Sciatica, or lumbosciatica, results from compression of a nerve root, most often by a herniated disc. The intervertebral disc ruptures and allows part of the gelatinous nucleus (nucleus pulposus) to escape, which compresses the sciatic nerve (L5 or S1 root).
Unlike lumbar stenosis which develops over several years, sciatica from herniated disc generally occurs suddenly, often after exertion, lifting, or a false movement. The compression is local, unilateral, and affects a single nerve root.
Comparison Table: Lumbar Stenosis vs Sciatica
Neurogenic Claudication: The Key Symptom of Stenosis
The characteristic symptom of lumbar spinal stenosis is neurogenic claudication (or neurogenic intermittent claudication). The patient describes pain, heaviness, or cramping in both legs that appears during walking and forces them to stop.
Characteristics of neurogenic claudication:
• Limited walking distance: the patient can only walk 100 to 500 meters before having to stop
• Rapid relief when stopping: sitting down or bending forward relieves pain within minutes
• Improvement with flexion: the patient spontaneously adopts a forward-leaning posture ("shopping cart posture")
• Worsening with extension: walking uphill, arching the back, or standing still worsens symptoms
• No decreased arterial pulse: unlike vascular claudication (arteritis), pedal pulses are present
This symptom allows Dr Dimitriu to suspect lumbar stenosis from the medical history, even before clinical examination and imaging.
How Dr Dimitriu Makes the Diagnosis
1. Medical History: The Crucial Step
Diagnosis begins with a thorough medical history. Dr Dimitriu looks for:
• Mode of onset: sudden (herniated disc) or progressive (stenosis)
• Triggering circumstances: exertion, lifting, no triggering factor
• Pain characteristics: unilateral/bilateral, precise/diffuse path
• Aggravating and relieving factors: walking, sitting position, flexion, extension
• Walking distance: limited or not
• Evolution: acute or chronic
2. Clinical Examination
Physical examination confirms diagnostic hypotheses:
For sciatica:
• Lasègue sign: pain on straight leg raising
• Motor deficit: foot weakness (foot dorsiflexion, toe standing)
• Sensory deficit: hypoesthesia in L5 territory (dorsum of foot) or S1 (sole)
• Absent Achilles reflex (if S1 affected)
For lumbar stenosis:
• Walking test: symptom reproduction after a few minutes of walking
• Neurological examination often normal at rest
• Pain on lumbar extension (patient arches backward)
• Relief with flexion (patient bends forward)
3. Imaging: Lumbar MRI
Lumbar MRI is the gold standard examination. It visualizes:
For lumbar stenosis:
• The spinal canal diameter (normally greater than 12 mm)
• Ligamentum flavum hypertrophy
• Facet joint osteoarthritis
• Circumferential disc bulging
• The presence of associated spondylolisthesis
For herniated disc:
• The herniated disc itself (extrusion, protrusion)
• The level of herniation (most often L4-L5 or L5-S1)
• Disc-root conflict: visible nerve compression
• Exclusion of other causes of sciatica (tumor, infection)
Dr Dimitriu emphasizes: "MRI does not decide treatment. It is the correlation between clinical symptoms and imaging that guides therapeutic decision-making. Minimal stenosis on MRI can be very symptomatic, and vice versa."
Treatments: Different Approaches
Treatment of Lumbar Spinal Stenosis
Conservative treatment (first-line):
• Physical therapy: abdominal strengthening, lumbar flexion work
• Pain medication and anti-inflammatories: paracetamol, NSAIDs, gabapentinoids
• Epidural injections: corticosteroids to reduce inflammation
• Lifestyle adaptation: using a shopping cart, walking downhill
• Weight loss if necessary
Surgical treatment (if conservative treatment fails):
Surgery is proposed if walking distance becomes too limited (less than 200-300 meters) despite 3 to 6 months of medical treatment. The procedure consists of decompression laminectomy: the surgeon widens the spinal canal by removing bony and ligamentous structures compressing the nerves.
In some cases, lumbar fusion (spinal fusion) is necessary if the spine is unstable.
Treatment of Sciatica from Herniated Disc
Conservative treatment (60-90% spontaneous recovery):
• Relative rest (avoid prolonged bed rest)
• Pain medication: paracetamol, NSAIDs, oral corticosteroids
• Physical therapy after the acute phase
• Foraminal or epidural injections: cortisone injected near the compressed nerve
Surgical treatment (specific indications):
Surgery is indicated in case of:
• Cauda equina syndrome (absolute emergency)
• Severe or progressive motor deficit
• Hyperalgesic pain resistant to all treatments
• Conservative treatment failure after 6 to 8 weeks
The standard procedure is microdiscectomy: removal of the herniated disc fragment under microscope, through a 3-4 cm incision. Endoscopic techniques allow even smaller incisions (less than 1 cm).
When Stenosis and Herniation Coexist
It is not uncommon for both conditions to be present simultaneously, especially in patients over 50 years old. A constitutionally narrow spinal canal can be "decompensated" by the appearance of a herniated disc.
In this case, the clinical picture combines:
• Bilateral neurogenic claudication (stenosis)
• Predominant unilateral sciatica (herniation)
• More severe walking limitation
MRI shows both canal narrowing and the herniated disc. Dr Dimitriu explains: "In these complex situations, surgery must address both problems: wide canal decompression and herniation removal. This is why the neurosurgeon's experience is essential for planning the optimal surgical procedure."
The prognosis remains excellent: more than 80% of patients operated on for stenosis with associated herniation are satisfied and regain normal walking distance.
Frequently Asked Questions
Yes, both conditions can coexist, especially after age 50. A constitutionally narrow spinal canal can be decompensated by a herniated disc. In this case, the clinical picture combines symptoms of both conditions: bilateral neurogenic claudication and predominant unilateral sciatica. MRI allows visualization of both conditions and planning of appropriate treatment.
No. Neurogenic claudication is bilateral leg pain triggered by walking and relieved by sitting or bending forward. It is characteristic of lumbar spinal stenosis. Sciatica is unilateral pain following a precise nerve path (from buttock to foot), caused by compression of a nerve root by a herniated disc. The mechanisms and treatments are different.
No. Conservative treatment (targeted physical therapy in flexion, epidural injections, pain medication, lifestyle adaptation) is effective in many cases and should always be tried first. Surgery is considered if symptoms significantly limit walking (distance less than 200-300 meters) despite well-conducted medical treatment for 3 to 6 months. Surgical indication is functional: it depends on impairment in daily life.
Lumbar MRI is the gold standard examination. It shows both spinal canal narrowing (stenosis) and the presence of a herniated disc with disc-root conflict. CT scan can be an alternative if MRI is contraindicated. However, clinical examination remains fundamental: it is the correlation between the patient's symptoms and abnormalities visible on imaging that allows correct diagnosis and proposing appropriate treatment.
There is no fixed timeframe. Surgical indication depends on functional impairment and response to conservative treatment. Surgery is generally proposed if: walking distance is reduced to less than 200-300 meters, pain is disabling despite well-conducted medical treatment for 3 to 6 months, neurological deficit appears or worsens. The goal of surgery is to improve quality of life by restoring normal walking distance.
Learn more about the mentioned conditions:
• Lumbar Spinal Stenosis — causes and treatments
• Lumbar Disc Herniation — sciatica and lumbosciatica
• Spondylolisthesis — vertebral slippage associated with stenosis
Sources: HAS (French National Authority for Health), SFCR (French Society of Spine Surgery), NASS (North American Spine Society), The Lancet (2019) — Lumbar spinal stenosis.