Disclosures: Maryam Hosseini, MD: Nothing to disclose

Case Description: A 54-year-old man presented with severe bilateral sciatica. MRI revealed Grade I-II anterolisthesis and disc herniation (HNP) at L4 – L5. Conventional electrodiagnostic testing (EMG) demonstrated L4-5 and L5-S1 radiculopathy. It was unclear whether spondylolisthesis, HNP or stenosis was the predominant pain generator, making it difficult to select optimal treatment. EMG did not relate symptoms to a specific pathology. We supplemented conventional EMG with dynamic testing of the posterior tibial and peroneal H reflexes in lumbar extension. Based upon findings the subject was treated for spinal stenosis (LSS) with exercise in flexion.

Setting: Outpatient

Patient: 54-year-old man with severe bilateral sciatica with two sources for pain generation.

Assessment/Results: On the more symptomatic right side posterior tibial and peroneal H reflex values increased after 3 minutes in lumbar extension from 31.5 to 33 milliseconds (ms) and 28.6 to 30.0 ms, respectively. On the less symptomatic side latencies increased from 30.7 to 32.1 ms and from 27.5 to 28.6 ms. The subject improved by 70% in pain and by 40% in strength after 6 weeks of flexion bias exercise.

Discussion: Flexion bias exercises are beneficial for LSS and extension bias exercise can be problematic as stenosis increases with bulging of the ligamentum flavum. Cadaveric studies demonstrate 63% narrowing of the spinal canal in extension. Dynamic EMG with LSS has demonstrated soleus H-reflex latency prolongation after walk-loading subjects. We selected 3 minutes in extension as prior study by the examiner suggested that for LSS subjects there is at least a 1-ms prolongation of latency after 2.5 minutes in extension. We compared H-reflex latencies in neutral position with those following 3 minutes of lumbar extension.

Conclusion: Identifying the primary pain generator is important in selecting the most appropriate treatment. Dynamic electrodiagnostic studies can help optimize outcomes in patients with LSS by increasing diagnostic specificity.

Level of Evidence: Level V

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PM&R Meeting Abstracts - https://pmrjabstracts.org/abstract/a-challenging-case-of-sciatica-and-the-value-of-dynamic-emg/