Deviant speech characteristics in motor neuron disease.

Speech and language characteristics of motor neuron disease (MND) change with disease progression. In this study, symptoms most prevalent in general also occurred in the early stages of the disease. These were not the most characteristic or severe in later stages, although present. As neurological symptoms became more severe, the predominant speech and language characteristics changed to severe abnormalities. It is, therefore, difficult to assign specific patterns of speech and language symptoms characteristic of all MND patients at all stages of the disease. A low but positive correlation existed between length of illness and number of shared (co-occurring) dimensions (severity). Neurological symptoms of tongue atrophy and dysphagia were most strongly related to decrease in intelligibility of speech; abnormal pulmonary function and difficulty breathing were least involved with speech disorders.