H-reflex latency and nerve root tension sign correlation in fluoroscopically guided, contrast-confirmed, translaminar lumbar epidural steroid-bupivacaine injections.

OBJECTIVES

To examine the correlation between physical examination parameters, commonly referred to as "nerve root tension signs," and H-reflex latency measurements both pre- and postepidural steroid-bupivacaine (Marcaine) injection, and to propose mechanisms of pain alleviation.

DESIGN

Prospective observational, with H-reflex latency measurement and physical examination at baseline and at 10 minutes postinjection.

SETTING

Physical medicine and rehabilitation practice, outpatient surgical center, and community setting.

PARTICIPANTS

Ten consecutively recruited patients (6 women, 4 men; age range, 40-71 y) with clinical radiculopathy and compatible magnetic resonance imaging findings, who were unaware of the outcome measures.

INTERVENTIONS: Patients received a fluoroscopically guided, contrast-confirmed, paramedian translaminar lumbar epidural injection of 120 mg of methylprednisolone acetate (80 mg/mL) and 2.0 mL of .25% preservative-free Marcaine.

MAIN OUTCOME MEASURES: Seated slump testing (SST), straight-leg raising (SLR), and H-reflex latency were measured bilaterally both pre- and postinjection. Differences were measured by using the paired t test in an A-B design.

RESULTS

All SST of the affected (injected) side improved from pre- to postinjection, with 3 patients reporting discordant hamstring pain and 7 reporting no pain. SLR ability increased by an average of 29 degrees +/-12 degrees, corresponding to an average relative increase of 54% on the affected side. A statistically significant difference was found (Student t test, P=.02) between pre and post H-reflex latency on the affected side but not when comparing changes between affected and unaffected sides (Student t test, P=0.6).

CONCLUSIONS

Significant improvements in SST and SLR result from low volume epidural injection of Marcaine, with questionable prolongation of the H-reflex to the gastrocnemius-soleus complex on the affected side.