Comparison of TOF scan neuromuscular monitoring on adductor pollicis vs. corrugator supercilii and flexor hallucis brevis

The TOF-Scan is used for neuromuscular monitoring during general anesthesia. Standard placement involves the adductor pollicis muscle, but alternative sites have been proposed for specific clinical scenarios. This study aimed to compare neuromuscular blockade parameters on the palm vs. eyelid, and the palm vs. toe. This study included cohorts A (n = 14; palm vs. eyelid) and B (n = 20; palm vs. toe). Neuromuscular blockade was induced with mivacurium, and TOF-Scan measurements were recorded until recovery. Parameters were analyzed using paired comparisons, correlations, and Bland-Altman charts. In cohort A, time to onset of neuromuscular blockade was shorter on the eyelid than on the palm (median: 60 vs. 187.5 s, p = 0.00098). Relaxation and recovery times were also shorter on the eyelid (p = 0.0023, p = 0.0064). In cohort B, time to onset was delayed on the toe compared to the palm (median: 300 vs. 195 s, p < 0.001), but relaxation and recovery times were shorter on the toe (p = 0.028, p = 0.0076). Strong correlations between measurement sites were observed, indicating reliability. TOF-Scan provides consistent results across alternative measurement sites, but site-specific differences in neuromuscular blockade dynamics reflect the varying sensitivity of these muscles to mivacurium. These findings underscore the importance of tailored neuromuscular monitoring in clinical practice.Clinical trial number NCT04845386.