We read with great interest a recently published case report by Kim et al. [1] in Anesthesia and Pain Medicine. They reported that for neuromuscular transmission (NMT) monitoring, acceleromyography (AMG) or kinemyography (KMG) is superior to electromyography in a patient with Charcot-Marie-Tooth disease (CMTD). I greatly appreciate the authors' precise observations and excellent presentation of this case. Interestingly, the train of four (TOF) count and post-tetanic count (PTC) obtained using AMG after rocuronium administration remained at 0 throughout the monitoring period until the administration of sugammadex—although the TOF count using KMG spontaneously returned to 4. We describe our experience with the spontaneous recovery of the TOF ratio detected with AMG in a patient with CMTD.

A 33-year-old Japanese female (height, 162 cm; body weight, 55 kg) underwent submandibular gland tumor resection under general anesthesia. She had experienced muscle weakness since 10 years of age. Based on her medical history, the patient was diagnosed with CMTD at 28 years of age. Neurological examination revealed reduced strength in the anterior tibialis muscle, and the patient’s feet showed high arches and claw toes, a pes cavus foot deformity. Genetic testing was not conducted. General anesthesia was induced and maintained with propofol and remifentanil. After induction of general anesthesia, AMG (TOF-Watch®, MSD) was performed by stimulating the ulnar nerve at 50 mA for every 1-3 min. The TOF ratio prior to rocuronium administration was 129%. Rocuronium 10 mg was initially administered (0 min). Additional 10 mg of rocuronium was administered at 2 min because the TOF ratio was 98%. The TOF count reached 0 at 5 min, and the patient was intubated. The TOF counts were 1 at 21 min, 2 at 30 min, and 4 at 34 min. The TOF ratio recovered to 100% after 67 min (Fig. 1). The patient was managed uneventfully with propofol and remifentanil, and no additional rocuronium was administered intraoperatively. At the end of surgery, the TOF ratio was confirmed to be > 100%; therefore, the patient was extubated without sugammadex administration. The operative time was 111 min, and the anesthesia time was 183 min. The patient returned to the general ward postoperatively and was discharged on postoperative day 8 with no adverse events.

In Kim's case, they used a total of 0.6 mg/kg of rocuronium before intubation, twice the 95% effective dose. The TOF ratio of AMG reached 0 after approximately 60 min, whereas that of KMG was 34% [1]. In another case reported by Hiramatsu et al. [2], prolonged rocuronium-induced severe respiratory paralysis—despite the use of sugammadex—was observed in a patient with undiagnosed CMTD. They used 0.73 mg/kg of rocuronium for tracheal intubation. However, the present case was managed successfully with a total of 0.36 mg/kg and two doses of half the 50% effective dose (ED₅₀). Although we used AMG, the TOF count and TOF ratio spontaneously increased without sugammadex treatment. Although there have been reports of a case wherein the patient had received 0.6 mg/kg of rocuronium and that did not significantly prolong the efficacy of neuromuscular blockade [3], we believe that minimal use of rocuronium, by administering a divided dose, about half of ED₅₀, is essential, and AMG may be useful for NMT monitoring in a patient with CMTD.