Manual Needle Placement Versus EMG Guidance

More detail on this excellent paper on manual vs guided injection, published in October 2012, in the journal Muscle and Nerve, showed that both expert and novice injectors both did better when using EMG guidance compared to blind injections. 

  • Findings show a poor success rate, regardless of injector experience.
  • Muscle palpation and anatomical landmarks are insufficient to ensure the accuracy of BoNt-A injections, even for large, superficial muscles.

This study was carried out in very large skeletal muscle.  So this was more about locating the best site to inject rather than being able to find the muscle. Both groups did significantly better using EMG guidance.

MANUAL NEEDLE PLACEMENT: ACCURACY OF BOTULINUM TOXIN A INJECTIONS. October 2012; Muscle and Nerve 46 531-534; ALEXIS SCHNITZLER, MD,1 NICHOLAS ROCHE, MD,1 PHILIPPE DENORMANDIE, MD,2 CHRISTINE LAUTRIDOU, MD,2  BERNARD PARRATTE, MD, PhD,3 and FRANC¸ OIS GENET, MD1 

To Summarize

  • Confirm needle is actually in muscle:  >>  EMG yields an EMG signal and possible EMG audio; E-stim can result in a muscle twitch
  • Pre-injection EMG signal evaluation is possible
  • Numerous studies show EMG guidance improves outcomes
  • Recent study shows even experienced injectors do better injecting when using guidance into large muscles
  • E-stim can be essential for confirming sites in multi-segmented areas, such as the hand and foot. 
  • Low current stimulation capability improves nerve location and motor endplate location procedures, which typically need 0.1mA stimulation current steps.