Does cervical interlaminar epidural steroid injection with low-dose lidocaine cause objective upper extremity weakness? A preliminary study

Objective. Low-dose local anesthetic is often used in cervical interlaminar epidural steroid injections (CIESI), yet its effect on upper extremity strength has not been studied. The presence of consequent weakness has potential implications for postprocedure safety. This study aimed to determine whether low-dose lidocaine in a C7-T1 CIESI causes objective weakness. Design. Prospective case series. Setting. Academic pain center. Subjects. Adults, cervical radicular pain. Methods. Participants underwent CIESI with 1mL of 1% lidocaine (3mL total injectate). Elbow flexion (EF), wrist extension (WE), elbow extension (EE), and handgrip strength were measured by dynamometry at baseline, 15 minutes, and 30 minutes postinjection. Changes in strength from baseline and the proportion of participants with a minimum perceptible change in EF, WE, EE, and handgrip strength (≥20%) and 95% confidence intervals (CIs) were calculated. Results. Twenty-seven participants were included. At 15 and 30 minutes postinjection, there was no within-participant difference in EF, WE, EE, and handgrip strength from baseline overall. Nonetheless, five (19%, 95% CI54-33) of the participants demonstrated a 20% or greater strength decrease in at least one myotomal distribution. A 20% or greater decrease in strength was present in left EF 4% (95% CI50-11%), right EF 7% (95% CI50-17%), left WE 4% (95% CI50-11%), and right WE 7% (95% CI50-17%). Conclusions. The present data suggest that CIESI with an injectate volume of 3mL that includes 1mL of 1% lidocaine may result in objective upper extremity weakness that is above the minimum threshold of perception in a subset of patients.