What is the diagnosis and recommended treatment for a patient with narrowing of the L5-S1 intervertebral disc space, as shown on radiographs of the lumbar spine, with no evidence of lysis or listhesis, and normal lumbar vertebrae alignment, height, shape, and bony density?

Diagnosis and Management of L5-S1 Disc Space Narrowing

Diagnosis

The radiographic finding of isolated L5-S1 disc space narrowing without lysis, listhesis, or other structural abnormalities represents degenerative disc disease, which is the most common cause of low back pain and frequently occurs at the L5-S1 level. 1, 2

• L5-S1 is the most frequently affected level for decreased disc height in degenerative spinal disease 1
• Disc space narrowing at this level is more strongly associated with low back pain than osteophytes, particularly when present at 2 or more levels (though this case shows single-level involvement) 3
• Plain radiography cannot visualize disc pathology, nerve compression, or accurately evaluate spinal stenosis—MRI is required for complete assessment if symptoms persist or surgical intervention is considered 4

Initial Conservative Management

Provide evidence-based reassurance about the generally favorable prognosis and advise the patient to remain active, as this is more effective than bed rest for acute or subacute low back pain. 4

First-Line Treatment Approach:

• Inform the patient that acute low back pain has a high likelihood for substantial improvement within the first month, with or without specific treatment 4
• Recommend remaining active rather than bed rest—activity is more effective for recovery 4
• Provide self-care education materials (such as evidence-based back books) as an inexpensive method that approaches the effectiveness of costlier interventions like supervised exercise, acupuncture, or massage 4

Conservative Treatment Requirements Before Imaging:

• Complete formal physical therapy for at least 6 weeks to 3 months 5
• Trial of NSAIDs and consideration of neuropathic pain medications (gabapentin or pregabalin) if radicular symptoms develop 5
• Structured home exercise program with compliance monitoring 6

When to Obtain Advanced Imaging

Order MRI (preferred) or CT only if the patient has persistent symptoms beyond 4 weeks AND is a potential candidate for surgery or epidural steroid injection. 4

Red Flags Requiring Immediate MRI:

• Severe or progressive neurologic deficits 4
• Suspected cauda equina syndrome 4
• History of cancer (strongest predictor of vertebral cancer) 4
• Signs of vertebral infection 4
• Age >50 with risk factors for cancer (consider ESR ≥20 mm/h, which has 78% sensitivity and 67% specificity for cancer) 4

Routine Imaging is NOT Recommended Because:

• Early imaging does not improve patient outcomes 4
• It cannot identify a precise cause in most cases 4
• It incurs additional expenses without changing management 4
• The natural history of lumbar disc herniation with radiculopathy shows improvement within the first 4 weeks with noninvasive management in most patients 4

Surgical Considerations (If Conservative Treatment Fails)

Fusion is NOT routinely indicated for isolated disc space narrowing without documented instability, spondylolisthesis, or nerve compression requiring extensive decompression. 4, 5, 7

Fusion Should Only Be Considered When:

• Documented instability or spondylolisthesis is present 4, 5
• Extensive decompression (>50% facet removal) might create iatrogenic instability 4, 5
• Chronic axial low back pain persists after comprehensive conservative management for 3-6 months with significant functional impairment 5
• Patient is a heavy manual laborer with significant degenerative changes and chronic axial back pain in addition to radicular symptoms 4

Evidence Against Routine Fusion:

• There is no compelling evidence that routine fusion improves outcomes for primary disc herniation with radiculopathy 4, 7
• Discectomy alone results in 70% return-to-work rate compared to 45% with fusion 7
• Fusion increases morbidity, cost, and potential complications (31-40% complication rates versus 6-12% for decompression alone) without proven benefit in cases lacking clear instability 4, 5

Common Pitfalls to Avoid

• Do not order MRI or other advanced imaging in the first 4 weeks unless red flags are present—this does not improve outcomes and increases costs 4
• Do not perform fusion for isolated disc space narrowing without documented instability—Level III and IV evidence shows no benefit and increased complications 4, 5
• Do not misinterpret disc bulge on MRI as equivalent to nerve compression—findings like bulging disc without nerve root impingement are often nonspecific 4, 6
• Do not proceed to surgery without completing comprehensive conservative treatment including formal physical therapy for at least 6 weeks—this is a critical requirement 5, 6