Botulinum Toxin A Injection and Perianesthesia Neuromuscular Monitoring: Case Report and Review

The popularity of looking younger has been facilitated by the availability of botulinum toxin (BoNT) injection. In 2019, over 7.7 million injections of BoNT occurred, making it the number one minimally invasive cosmetic procedure in the United States. With the ease of patients obtaining BoNT in an outpatient setting, coupled with the fact that it is considered a minimally invasive procedure, most patients do not disclose the use of BoNT during the preoperative anesthesia evaluation. This case report involves a female whose recent BoNT injections interfered with neuromuscular (NM) monitoring during anesthesia. Neuromuscular monitoring was performed using the orbicularis oculi muscle with repeated train-of-four (TOF) 0/4. It was not until completion of procedure when the arms were accessible that the adductor pollicis muscle was assessed with a TOF of 2/4. During postoperative follow up, the patient revealed she had received BoNT injections prior to surgery. A review of BoNT pharmacology, barriers to NM monitoring and use of sugammadex are discussed. This case demonstrates the importance of ascertaining BoNT injection history in any case in which access to the ulnar nerve or tibial nerve is not available.