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

Abstract

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. Prospective observational, with H-reflex latency measurement and physical examination at baseline and at 10 minutes postinjection. Physical medicine and rehabilitation practice, outpatient surgical center, and community setting. 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. 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. 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. 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). 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.