300 Section - The predictive nature of diagnostic nerve blocks for spasticity management with chemodenervation and neurotomy: a systematic review

Objectives : Diagnostic nerve blocks (DNBs) involve the injection of anesthetic around peripheral nerves to temporarily reduce motor tone. Although they are used clinically to inform spasticity treatment with chemodenervation or nerve-based procedures such as neurotomy, there is little research exploring the predictive nature of DNBs. The purpose of this systematic review was to explore the research on DNBs and their ability to predict clinical response to botulinum toxin or neurotomy.

Design: A systematic search of the literature was completed using MEDLINE, EMBASE, and Scopus. The full search strategy was based on components “spasticity” and “nerve block”, and either “botulinum toxin” or “neurotomy”.

Results: In total, nine eligible articles were analyzed, with five studies involving neurotomies and four studies involving chemodenervation. These studies focused exclusively on lower limb spasticity. There were different DNB protocols used across the eligible articles. DNBs resulted in similar clinical outcomes after neurotomy on gait and spasticity measurements. DNBs resulted in reduced agonist muscle strength as compared to neurotomy outcomes, particularly those collected a year or longer after surgery.

Conclusion: In lower extremity spasticity DNBs resulted in comparable gait and spasticity outcomes as compared to neurotomy, with less consistency as compared to chemodenervation. DNBs resulted in a greater loss of agonist muscle strength compared to neurotomies when exploring outcomes at a year or later post-surgery. DNBs were less predictive of clinical response to chemodenervation and to range of motion assessments. DNBs may have a larger role to play in surgical decision-making for procedures such as neurotomy given their superior predictability and the more permanent nature of surgery versus chemodenervation.