Amyotrophic Lateral
Sclerosis; Respiratory Assessment; Magnetic Stimulation; Respiratory
Muscles; Pulmonary Function.
Sclerosis; Respiratory Assessment; Magnetic Stimulation; Respiratory
Muscles; Pulmonary Function.
Introduction: Amyotrophic Lateral Sclerosis is a progressive
neurodegenerative disease that causes degeneration of central and
peripheral neuromotor control, leading to weakness and disorganized
recruitment of respiratory motor units, mainly of the diaphragm, reducing
ventilatory capacity and potentially leading to ventilatory failure. Thus, it is
essential to identify subclinical functional changes using objective methods
less dependent on volitional effort, integrating neurophysiological markers to
distinguish physiological and pathological patterns. Objectives: The main
goal of this study is to noninvasively assess contraction and relaxation
properties of the respiratory muscles in ALS patients using active and TMS-
assisted measures, and compare them with a healthy control group. As
secondary objectives, we aim to characterize these properties, analyze
corticospinal excitability by TMS, correlate findings with ventilatory and
respiratory strength measures, and investigate whether such changes may
indicate early neuromuscular dysfunction. Methods: In this observational
cross-sectional study, 28 individuals will be included, comprising ALS patients
(18–80 years, both sexes, FVC >50% and SNIP >40 cmH₂O) and healthy
controls. Participants will perform up to 5 PImax/PEmax maneuvers and 12
SNIP/SNEP maneuvers, with sEMG recording and supraliminal stimulation
synchronized to respiratory peaks via cervical and thoracic TMS. Statistical
analysis will be conducted in GraphPad Prism 8, adopting α = 5% and using
parametric or nonparametric tests according to normality (Shapiro–Wilk).
Expected Results: We expect to identify progressive reduction of respiratory
muscle strength and changes in inspiratory mechanics in ALS.
Neurophysiological measures obtained by TMS should reveal reduced
corticospinal excitability and altered diaphragmatic motor conduction. A
decrease in EMG activity and slowing of inspiratory pressure development
and relaxation are also expected. Biomechanical analysis should indicate
reduced diaphragmatic contractile efficiency. Together, these findings should
improve understanding of respiratory impairment and support clinical
monitoring of disease progression.