What is the next best step for a patient with a large synovial cyst at L4-5 on the left with associated nerve root compression and radiculopathy, who has not responded to medical therapy and injection therapy, and has a history of previous spinal fusions at L2-3 and L5-S1?

Surgical Intervention is Indicated for Synovial Cyst with Nerve Root Compression and Failed Conservative Treatment

For a patient with a large synovial cyst at L4-5 causing left L5 nerve root compression and radiculopathy who has failed medical therapy and injections, surgical decompression via laminectomy is the next best step in management.

Clinical Scenario Analysis

The patient presents with:

• Large synovial cyst at L4-5 on the left compressing the left L5 nerve root
• Grade 1 anterolisthesis at L4-5
• Spondylosis at L3-4
• Previous fusion surgery at L2-3 and L5-S1
• Failed response to both medical therapy and injection therapy
• Left radiculopathy symptoms

Treatment Algorithm

1. Indications for Surgical Intervention

• Nerve root compression causing radiculopathy 1, 2, 3
• Failed conservative management (medications and injections) 3
• Presence of neurological symptoms (radiculopathy) 4

2. Recommended Surgical Approach

• Laminectomy/hemilaminectomy with cyst excision is the standard surgical approach 1, 2, 3
• Limited laminotomy is sufficient in the majority of cases 1
• Surgical exploration should include:
  • Hemi-laminotomy
  • Flavectomy
  • Minimal facet joint excision 2

3. Consideration for Fusion

• The presence of grade 1 anterolisthesis at L4-5 raises the question of whether fusion is needed
• According to research, concomitant fusion is only required in select cases with clinical evidence of instability 3
• In a large Mayo Clinic series of 194 patients, only 18 patients (9.3%) required concomitant fusion, and only 4 patients (2%) required subsequent fusion for symptomatic spondylolisthesis 3
• Given the patient's previous fusions at L2-3 and L5-S1, the biomechanical stress on L4-5 may be increased, potentially warranting consideration of fusion

Expected Outcomes

Surgical removal of lumbar synovial cysts has demonstrated excellent results:

• 91% of patients report good relief of pain 3
• 82% experience improvement in motor deficits 3
• In another study, 15/32 patients (47%) were completely free of complaints, and 13/32 (41%) had marked improvement 1
• Only 3/32 patients (9%) had considerable remaining complaints 1

Potential Complications

Surgical risks that should be discussed with the patient include:

• Cerebrospinal fluid leak (1.5%) 3
• Discitis (0.5%) 3
• Epidural hematoma (0.5%) 3
• Seroma (0.5%) 3
• Deep vein thrombosis (0.5%) 3
• Development of instability requiring subsequent fusion (2%) 3
• Local recurrence or contralateral cyst formation (12.5%) 1

Important Considerations

1. Adjacent Segment Disease: The patient already has fusions at L2-3 and L5-S1, making L4-5 a potential site for adjacent segment disease. The presence of a synovial cyst and anterolisthesis supports this theory.

2. Surgical Complexity: Previous fusion surgeries may make the current surgical approach more challenging, requiring careful preoperative planning.

3. Monitoring for Instability: Even if fusion is not performed initially, close monitoring for development of instability at L4-5 is essential during follow-up.

4. Timing of Surgery: Given the failure of conservative measures and the presence of neurological symptoms, prompt surgical intervention is warranted to prevent further neurological deterioration 5.

Surgical decompression with cyst excision offers the best chance for symptom resolution and improved quality of life in this patient who has failed conservative management for a symptomatic lumbar synovial cyst causing nerve root compression.