Introduction
Lower motor neuron diseases are characterized by muscle weakness and progressive paralysis that often
results in death due to respiratory failure. General anesthesia with endotracheal intubation can ensure
adequate intraoperative ventilation, however abnormal response to muscle relaxants may result in
prolonged mechanical ventilation in the postoperative period.
The objective of this work is to present a case of general anesthesia in a patient with lower motor neuron
disease reviewing the latest evidence of the management of neuromuscular blockade in these pathologies.
Clinical case.
A clinical case of a woman of 45-year-old with progressive distal musculature weakness in inferior limbs and
right arm, as well as bulbar symptoms. She presented odynophagia for solids with weight loss in the last year
of 25 kg, dysphonia and fluctuating stridor. Bilateral paralysis of vocal cords in adduction was seen in
fibrolaryngoscopy by the ENT, so laryngeal microsurgery was needed.
Anesthesia was induced with fentanyl, propofol, rocuronium 30 mg and maintained with sevorane and
continuous perfusion of remifentanil. The neuromuscular response was monitored by train of four during all
the intervention. A new dose of rocuronium 10 mg after 30 minutes of induction was needed. After one
hour value of TOF ratio was 99% and was not required reversal of neuromuscular blockade. Awakening and
extubation was performed without complications. The patient does not have residual muscle blockade,
weakness, stridor or respiratory clinic.
Conclussions.
These patients with motor neuron diseases are hypersensitive to non-depolarizing neuromuscular blockers.
However, rocuronium has been demonstrated to be safe due to its rapid onset of action and the possibility
of antagonizing the blockade with Sugammadex. Depolarizing relaxants are extremely contraindicated in
these patients due to they may cause myotonic reactions and massive hyperkalemia.
The use of other non-neuromuscular relaxants is not recommended due to the risk of residual
postoperative blockade. Reversal with cholinesterase inhibitors is not indicated due to the unpredictable
effect and they may produced unwanted cholinergic effects that can lead to respiratory complications.

07 / Management of muscle relaxant in a patient with bulbar symptoms and advanced inferior motor neuron disease.