[Masseter strength in patients with motor neuron disease].

Although masseter muscles play an essential role in digestion, masseter strength in patients with motor neuron diseases has not been well studied. The purpose of this study is to evaluate the masseter strength in healthy volunteers (n = 13, mean age +/- S.D.: 58 +/- 10 years) and in patients with motor neuron diseases (n = 16, mean age +/- S.D.: 61 +/- 10 years) using a device for the measurement of occlusal forces (Nihon Koden, Co. Ltd., Japan). Masseter strength values in the healthy volunteers and the patients with motor neuron diseases including amyotrophic lateral sclerosis (ALS) were 24.6 +/- 13.4 kg (mean +/- S.D.) and 21.9 +/- 16.4 kg (ALS: 26.2 +/- 14.6 kg), respectively, and this difference is not statistically significant. Further, there was no relation between masseter strength and the severity of clinical signs including bulbar palsy. These results suggest that masseter strength is not particularly vulnerable in patients with motor neuron diseases.