Comparison of the Neuromuscular Profile of the First Dorsal Interosseous Muscle and the Flexor Hallucis Brevis Muscle as Measured by Electromyography

Lower limb muscles recover faster than upper limb muscles following administration of nondepolarizing neuromuscular relaxants until the train-of-four ratio (TOFR) reached 0.7. However, no study has been conducted to evaluate the recovery time of the flexor hallucis brevis muscle (FHBM), up to a TOFR of 0.9, which indicates satisfactory recovery of neuromuscular blockade. The aim of this study was to determine electromyographically the relationship between the TOFRs of the FHBM and the first dorsal interosseous muscle (FDIM), following 0.1 mg/kg of vecuronium. Eighteen patients were enrolled in this study. Electromyography of the FDIM and the FHBM was monitored. Onset times and recovery times to TOFRs of 0.7 and 0.9 of both muscles after administration of vecuronium were measured. The onset time in the FDIM was not different from that in the FHBM (P = 0.10). Recovery time to TOFR 0.7 was significantly faster in the FHBM than in the FDIM (P < 0.013). There was no significant difference in the meantime to reach TOFR 0.9 between the FDIM and the FHBM (P = 0.11). There is no clinical importance in the difference of neuromuscular recovery between the FHBM and the FDIM after TOFR reached 0.9 following administration of vecuronium.