Early diaphragmatic dysfunction in mild ALS patients: Ultrasound evaluation as a key tool for assessing pulmonary impairment

Abstract

Background: This study aims to evaluate ultrasound-based measures for detecting early diaphragmatic dysfunction in patients with mild amyotrophic lateral sclerosis (ALS), providing valuable indicators for ultrasound assessment.

Methods: A total of 36 ALS patients and 25 healthy controls were included. All participants underwent B-mode diaphragm ultrasound (DUS), recording indices such as diaphragm thickness and excursion. Clinical data, pulmonary function tests, and ALS Functional Rating Scale- Revised (ALSFRS-R) scores were collected for the ALS group. DUS indices were compared between the ALS group and controls, as well as between mild and non-mild ALS patients. Correlation analyses and Receiver Operating Characteristic (ROC) curve analysis were performed.

Results: Compared to the control group, the study group showed significantly lower Tdi-rest, Tdi-ins, Δins-exp, ΔTdi, DE-quiet, and significantly higher ΔTmax (P<0.05). In comparison to healthy controls, the mild ALS group had significantly lower ΔTdi and Δins-exp (P<0.05). The mild ALS group had significantly higher Tdi-rest, Tdi-ins, Δins-exp, ΔTdi, DE-quiet, and DE-max than the non-mild ALS group (P<0.05), while ΔTmax was significantly lower (P<0.05). The indices Tdi-rest, Tdi-ins, Δins-exp, ΔTdi, and DE-max were positively correlated with FVC, MVV, the ALSFRS-R score, and the respiratory subscore (P<0.05). ROC curve analysis demonstrated that these indices had high accuracy in monitoring pulmonary insufficiency (AUC≥0.811, P≤0.003).

Conclusion: DUS can identify pulmonary impairment in ALS patients and assess disease severity. Early pulmonary insufficiency exists in mild ALS patients, primarily assessed by ΔTdi and Δins-exp, with high accuracy in monitoring pulmonary dysfunction.