Is intraoperative neurophysiologic monitoring (IONM) medically indicated for a patient in their late 50s with a history of low back pain, severe constant pain in their right leg, spondylolisthesis, degenerative changes, and an incarcerated fragment at L5-S1, who is scheduled to undergo L5-S1 discectomy?

IONM is NOT Medically Indicated for This L5-S1 Discectomy

For a straightforward single-level L5-S1 microdiscectomy without fusion or instrumentation in a patient with isolated radiculopathy and no documented instability, intraoperative neurophysiologic monitoring (IONM) is not medically necessary. 1, 2

Rationale for IONM Not Being Indicated

Procedure Complexity Does Not Warrant IONM

• Microdiscectomy at L5-S1 is a standard decompressive procedure that does not involve spinal cord manipulation, instrumentation, or correction of deformity—the primary indications where IONM demonstrates clinical utility 3

• IONM is specifically designed to assess functional integrity of the spinal cord, nerve roots, and peripheral nervous system structures during complex spinal surgery where there is risk of emerging insult to neural structures 3

• The underlying principle of IONM is to identify emerging insult before irreversible neural injury occurs during procedures that involve extensive manipulation of neural elements or correction of spinal alignment 3

This Case Involves Isolated Radiculopathy Without Instability

• The patient has an incarcerated disc fragment at L5-S1 causing right-sided radiculopathy with no back pain, which is appropriately treated with discectomy alone 1, 2

• The surgeon correctly identified that despite the grade 1 spondylolisthesis at L4-5, the patient's symptoms are focused on the incarcerated fragment at L5-S1, making a smaller decompressive surgery appropriate rather than fusion 4

• Discectomy alone without fusion is the correct surgical approach for primary disc herniation causing radiculopathy when there is no documented instability requiring stabilization 1, 2

Standard Visualization Techniques Are Sufficient

• Lumbar discectomy procedures are routinely performed using surgical loupes or standard visualization techniques, not requiring the microsurgical technique that would justify additional monitoring 4

• The procedure involves direct visualization of the nerve root and disc fragment removal through a standard posterior approach, where anatomical landmarks and direct inspection provide adequate safety 1, 2

Clinical Context Supporting This Decision

Patient Presentation Supports Straightforward Discectomy

• The patient demonstrates classic L5-S1 radiculopathy with weakness of dorsiflexion and plantar flexion on the right, sensory alteration along L5 dermatome, and imaging showing incarcerated fragment with mass effect 4

• Conservative management has been appropriately exhausted with epidural steroid injection providing only temporary relief, and the patient has constant leg pain affecting function 4, 5

• The absence of back pain and presence of isolated leg symptoms indicates nerve root compression rather than instability, supporting decompression alone 4, 1

Surgical Plan Appropriately Excludes Fusion

• The surgeon's decision to perform microdiscectomy rather than the more aggressive decompression with fusion at L4-5 demonstrates appropriate surgical judgment based on symptom localization 4

• The static 8mm anterior listhesis at L4-5 that does not change with flexion-extension indicates stable spondylolisthesis that does not require fusion at this time 4, 5

When IONM Would Be Indicated

Complex Procedures Requiring Monitoring

• IONM is appropriate for complex spinal surgery involving spinal cord manipulation, multilevel instrumented fusion, deformity correction, or procedures with high risk of neural injury 3

• Multimodality monitoring techniques permit assessment of dorsal sensory spinal cord tracts, ventral motor tracts, and nerve roots during procedures where these structures are at significant risk 3

• Combined monitoring modalities provide complementary information during complex cases where real-time feedback can prevent irreversible neural injury 3

This Case Does Not Meet Those Criteria

• A single-level discectomy at L5-S1 without instrumentation or fusion does not involve the surgical complexity, spinal cord manipulation, or deformity correction that justifies IONM 1, 2, 3

• The procedure should be performed in an outpatient or 23-hour observation setting, further supporting that this is a routine decompressive procedure not requiring intensive monitoring 1, 2

Critical Pitfall to Avoid

• Do not conflate the presence of spondylolisthesis at an adjacent level with the need for IONM during a straightforward discectomy at the symptomatic level 4, 1

• The grade 1 listhesis at L4-5 is stable and asymptomatic, and the surgical plan appropriately addresses only the symptomatic L5-S1 level with decompression alone 4, 5

• IONM adds unnecessary cost and complexity to a procedure where standard surgical technique with direct visualization provides adequate neural protection 4, 3