Primary lateral sclerosis (PLS) is a neurodegenerative motor neuron disorder that is characterized by corticospinal and corticobulbar dysfunction. In this disease, muscle relaxants in general anesthesia should be used with extreme caution. A 67-year-old woman with a history of PLS was scheduled for laparoscopic gastrostomy due to long-term dysphagia. In the preoperative assessment, she presented a tetrapyramidal syndrome with generalized muscle weakness. A priming dose of 5 mg of rocuronium was administered and the train-of-four (TOF) ratio (T4/T1) after 60 seconds was 70% so induction was followed with fentanyl, propofol, and additional 40 mg of rocuronium. After 90 seconds when T1 was lost, the patient was intubated. During surgery, the TOF ratio increased progressively until 65%, 22 minutes after a final bolus of 10 mg of rocuronium. Prior to emergence, 150 mg of sugammadex was given and neuromuscular block reversal was evidenced with a TOF ratio > 90%. As it was decided to perform the surgery laparoscopically, general anesthesia with a neuromuscular blockade was necessary. Since it is reported that patients with motor neuron diseases show an increased sensibility to non-depolarizing muscle relaxants (NDMR), these agents should be used cautiously. Adversely to what studies document, no augmented responsiveness was shown in TOF monitoring, so the standard dose of 0.6 mg/kg of rocuronium was safely given. A final bolus of NDMR was administered after 54 minutes, demonstrating a similar pharmacokinetics profile in terms of duration of action as reported in several studies (45-70 minutes). In addition, a full and rapid neuromuscular blockade recovery with 2 mg/kg of sugammadex was seen, as previously demonstrated in a case series.
Keywords: motor neuron disease; non-depolarizing neuromuscular blocking agents; primary lateral sclerosis; rocuronium; sugammadex dosing and timing.
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