Use of Muscle Relaxants for Acute Postoperative Pain: A Practical Review.

Background: Skeletal muscle relaxants have emerged as a broad category of analgesic adjuncts, aiming to improve pain relief and reduce opioid reliance. These drugs induce muscle relaxation and reduce muscle spasms, and therefore, they are commonly used in surgical procedures involving muscle manipulation, such as abdominal surgery, breast surgery, and spine surgery. However, their analgesic efficacy and opioid-sparing effects are poorly explored. Methods: A scoping review of literature was performed with several electronic databases. We used a search string with a sequence of text words and word variants related to central muscle relaxants, pain management, postoperative pain, and specific muscle relaxants. Results: Review of literature shows significant heterogeneity among the studies in terms of surgical procedures, patient populations, choice of muscle relaxant, and timing and duration of administration, potentially limiting the generalizability of the findings and the ability for pooled analysis. Conclusions: Given the lack of evidence, we recommend that the use of skeletal muscle relaxants be reserved for patients in whom an optimal multimodal analgesic technique is not adequate. Also, there may be a limited role for these drugs in patients at high risk of postoperative pain undergoing surgical procedures with expected high opioid requirements. Due to the concerns of potential adverse effects, the decision to use muscle relaxants in vulnerable populations should be made carefully, weighing the benefits against the risks.