Vibration sense testing with a 128-Hz tuning fork as a tool to determine recovery from epidural neuraxial block

Vibration sense testing using a 128-Hz tuning fork is a commonly used test in the diagnosis of dorsal horn dysfunction and polyneuropathy. In this open, prospective study, we tested the hypothesis that vibration sense testing is a sensitive and specific method to assess recovery from epidural block.

Recovery from epidural block was evaluated in 81 patients undergoing cesarean delivery or vein stripping by comparing the use of a 128-Hz tuning fork with the results of conventional evaluation of block recovery. Conventional block recovery testing included Bromage-Score, formal muscle power testing according to the British Medical Research Council, pinprick testing, and warm/cold testing. Epidural blocks were performed by the same anesthesiologist using ropivacaine and sufentanil via an epidural catheter. After obtaining baseline values, an epidural anesthetic was performed and patients were tested every 30 minutes until complete recovery from the block was documented with all examined methods. Statistical analysis was performed to compare the results of the different methods to the time at which baseline values of vibration sense were reached.

At the time vibration sense testing returned to baseline, there was no residual motor block according to the Bromage Score in 100% of the patients and no residual block for foot flexion and extension. Twelve percent of the patients showed a minimal lack of strength in the quadriceps muscle and 11% had residual sensory anesthesia to pinprick below L5/S1.

Based on our observations, recovery of vibration sense corresponds with recovery of motor block after epidural anesthesia and may serve as an easy means of documenting recovery with a single test before discharge.