Diaphragm ultrasound assessments in newly diagnosed patients with spinal-onset amyotrophic lateral sclerosis

<bold>Introduction:</bold> Respiratory failure is a fatal stage of the disease progression in amyotrophic lateral sclerosis (ALS). Diaphragmatic involvement is considered a major cause of respiratory failure in ALS. <bold>Aim:</bold> This study aimed to examine the utility of diaphragm ultrasound (DUS) in detecting diaphragmatic dysfunction in newly diagnosed ALS patients. <bold>Materials and methods:</bold> Subjects diagnosed with spinal-onset ALS within the last 3 months prior to study procedures were included. B-mode DUS was performed in 14 ALS subjects and 13 healthy controls. Diaphragm thickness was measured at tidal volume (Tdi-rest), at residual volume (maximal expiration) (Tdi-exp) and at total lung capacity (maximal inspiration) (Tdi-insp) and thickening indices were calculated. ALS subjects further underwent spirometry testing in sitting position and assessments of functional ALS scales. DUS parameters were compared between ALS and healthy subjects. Correlations between clinical, spirometric and DUS data were investigated. <bold>Results:</bold> Diaphragmatic thickening indices significantly differed between ALS subjects and controls (all p<0.001). Tdi-insp was found significantly lower in ALS than healthy subjects (p=0.007), whereas no significant differences were detected for Tdi-rest and Tdi-exp. Strong relationships were shown between FVC, SVC and diaphragmatic thickening indices. DUS thickening indices also correlated with both the Milano Torino Staging and the respiratory subscore of ALS functional rating scale. <bold>Discussion:</bold> Diaphragmatic involvement can be present even in early stages of ALS and DUS is a valuable tool in evaluating respiratory capacity, in addition to spirometry.