Succinylcholine, a depolarizing neuromuscular blocking agent, is frequently used in anesthesia for rapid sequence intubation due to its fast onset and short duration of action. Despite its efficacy, one of its most commonly reported adverse effects is postoperative myalgia, which is often described as muscle soreness similar to that experienced after vigorous exercise. The timeline for developing succinylcholine-induced myalgia depends in part on physiological and procedural factors, such as patient demographics, anesthesia techniques, and the use of premedications or adjunct agents.

Most cases of succinylcholine-induced myalgia manifest on a timeline of 6 to 24 hours postoperatively, although reports have indicated onset as early as 30 minutes after recovery from anesthesia and as late as 48 hours. The pain usually peaks within the first postoperative day and gradually subsides over 2 to 3 days, rarely persisting beyond 72 hours (1). The underlying mechanism involves depolarization of the muscle endplate, resulting in fasciculations (transient, uncoordinated muscle contractions) and microtrauma to the muscle fibers. This local damage causes an inflammatory response, which explains the delayed onset of muscle soreness rather than immediate pain (2).

The intensity and timing of myalgia varies across patients. Young adults, ambulatory individuals, and females report a higher incidence and earlier onset compared to elderly or immobile patients. Fasciculations appear within seconds of administration, while biochemical evidence of muscle injury, such as elevated serum creatine kinase levels, peaks 12 to 24 hours later, which correlates with the timeline of symptom onset (3). Studies indicate that the degree of muscle damage is proportional to the intensity of fasciculations, which can be influenced by dosage and adjunctive medications that modulate neuromuscular activity (4).

Preventive pharmacological strategies have provided insights into the timeline of myalgia development after succinylcholine administration. During precurarization, a small dose of a non-depolarizing neuromuscular blocker, such as atracurium, is administered before succinylcholine. This technique has been shown to significantly reduce the severity and earlier onset of myalgia (2). Similarly, when administered prior to induction, pregabalin and nonsteroidal anti-inflammatory drugs (NSAIDs) have demonstrated efficacy in delaying or mitigating the development of symptoms (1). Due to its antioxidant properties, selenium has also been reported to attenuate both fasciculations and the resultant inflammatory cascade, leading to a reduced incidence and delayed onset of myalgia (4).

Although the physiological processes leading to myalgia begin immediately after succinylcholine is administered, clinical symptoms only emerge after muscle inflammation develops. Thus, the onset of this condition can be conceptualized as occurring in two phases: an initiation phase, which occurs within minutes due to fasciculations, and a symptomatic phase, which emerges hours later as the inflammatory response peaks. Variability in the timing and intensity of symptoms is further accounted for by interindividual differences in metabolism, oxidative stress response, and muscle fiber composition (1).
Postoperative myalgia is an unfortunate but well-documented side effect of succinylcholine administration that follows a consistent timeline of effects, though with some individual variation. Preventive approaches such as precurarization and the use of anti-inflammatory, anticonvulsant, or antioxidant agents have demonstrated consistent benefit in reducing both the incidence of this condition and the severity of associated symptoms.

References

1. Srivastava VK, Agrawal S, Nimbhorkar VK, Mishra A, Sharma S, Panda PK. Prophylactic use of pregabalin for prevention of succinylcholine-induced fasciculation and myalgia: a randomized, double-blinded, placebo-controlled study. Braz J Anesthesiol. 2016;66(2):165-170. doi:10.1016/j.bjane.2014.08.004
2. Tirkey A, Kumar M, Haque E, Kumar T, Lakra L, Suwalka U. Premedication with Diclofenac and Precurarization with Atracurium on Succinylcholine-Induced Myalgia in Laparoscopic Cholecystectomy: A Double-Blinded Randomized Study. Anesth Essays Res. 2022;16(1):89-93. doi:10.4103/aer.aer_35_22
3. Simard C, Paquin A, Schwartz BC. A Paralyzing Case of Myalgias. Am J Case Rep. 2020;21:e922568. Published 2020 May 13. doi:10.12659/AJCR.922568
4. Mostafa MF, Osman EA, Elkasem MMA, Seddik MI, Herdan R. The Antioxidant Effect of Selenium on Succinylcholine-related Myalgia After Adult Sinuscopies: Randomized Controlled Double-Blind Trial. Pain Physician. 2021;24(6):E743-E751.