Quantitative Assessment of Tongue Atrophy in Amyotrophic Lateral Sclerosis Using Transoral Tongue Ultrasonography (TOTU): A Retrospective Single-Center Study.

INTRODUCTION/AIMS: Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease accompanied by bulbar dysfunction, in which tongue atrophy contributes to dysarthria and dysphagia. Conventional tongue assessments rely on inspection, palpation, or electrophysiological testing but are limited by subjectivity and invasiveness. A rapid, objective, and repeatable imaging-based method for evaluating tongue size would be valuable. We quantified tongue atrophy in ALS using a standardized protocol for transoral tongue ultrasonography (TOTU) and assessed discrimination.

METHODS: This retrospective, cross-sectional study included 15 patients with ALS and 15 controls who underwent TOTU. Using standardized mid-sagittal images, tongue cross-sectional area (cm2) and tongue thickness (mm) were measured three times per subject and averaged. Associations with age, body mass index (BMI), disease duration, and ALS Functional Rating Scale-Revised (ALSFRS-R) scores were explored. Discrimination was evaluated using receiver operating characteristic (ROC) analyses.

RESULTS: Both tongue cross-sectional area (6.26 ± 1.37 vs. 9.44 ± 1.02 cm2) and tongue thickness (31.47 ± 3.0 vs. 39.44 ± 1.39 mm) were significantly lower in the ALS group than in controls (both p < 0.001). These indices showed no significant associations with age, BMI, disease duration, or ALSFRS-R scores. ROC analyses showed high discriminative ability, with an area under the curve of 0.982 for tongue cross-sectional area and 1.000 for tongue thickness.

DISCUSSION: Standardized TOTU enables rapid, quantitative, noninvasive assessment of tongue size and reliably detects tongue atrophy in ALS, supporting bedside evaluation of bulbar involvement.