Maximum Tongue Pressure is Associated with Swallowing Dysfunction in ALS Patients

Maximum tongue pressure (MTP) measurement is a convenient, less invasive assessment that has been developed to quantify tongue strength; however, it is unclear whether MTP is useful for the detection of swallowing disorders in amyotrophic lateral sclerosis (ALS) patients. The purpose of this study was to clarify the relationship between MTP and the characteristics of swallowing disorders on videofluorography and to determine the usefulness of tongue pressure measurement for the assessment of swallowing function in ALS patients. Twenty-five ALS patients were evaluated according to the ALS functional rating scale-revised (ALSFRS-R), and their ability to swallow yogurt was observed via videofluorography. MTP was measured using a device (TPM-01, JMS, Hiroshima) equipped with a balloon probe. Then, the relationships between the ALSFRS-R score, swallowing function, and MTP were analyzed. MTP was significantly lower in the subjects with reduced tongue function (p = 0.002) or with pharyngeal residue (p = 0.006) than in the subjects with normal characteristics. Bolus formation and oral transit time and pharyngeal transit time were significantly prolonged among those with reduced MTP. MTP at a cut-off value of 21.0 kPa was associated with a full score on the bulbar-related items of the ALSFRS-R. MTP may serve as a new diagnostic tool for the early detection of swallowing dysfunction in ALS patients, because of its good relationship with their swallowing characteristics.