Classifying subgroups of individuals with ALS: Acoustic and aerodynamic characteristics

H.A. Leeper, Michael Strong

Abstract


Amyotrophic Lateral Sclerosis (ALS) is a progressive degenerative neuromuscular disease that involves the upper and lower motor neurons. Damage to the lower motor neurons is manifested by muscle weakness, fatigue, muscle atrophy, and fasciculations, whereas upper motor neuron damage is manifested by spasticity, muscle weakness, cramping, increased tone, and hyperactive deep-tendon reflexes. Upper and/or lower motor involvement may occur during the course of the disease, but eventually, both systems are involved. At initial presentation, individuals are described primarily as being either bulbar or nonbulbar, as determined by presence or absence of neuromotor symptoms. Usually, bulbar signs are typified by rapid deterioration, while nonbulbar signs point to slightly slower deterioration, especially of the cranial nerves affecting oral-pharyngeal-laryngeal motor coordination and speech production. Progressive deterioration of the oral, velopharyngeal, and laryngeal subsystems serving speech leads to speech production difficulties and decreased speech intelligibility in individuals with ALS. Major characteristics of speech difficulties include imprecise articulation, hypernasality and nasal air emission, strained-strangled, harsh, breathy, low-pitch and low intensity voice production, and slow speaking rate. These characteristics may occur in different individuals at various times throughout the course of the disease. Acoustical and aerodynamic assessment of voice and speech production are useful in early detection, differential categorization, and the monitoring of deterioration of speech in individuals with ALS. Further, differential speech subsystem assessment of subgroups of individuals with bulbar and nonbulbar signs may lead to better management strategies of these groups of individuals relative to `quality of life' issues. This series of experiments characterizes acoustical and aerodynamic changes in speech deterioration of individuals with bulbar and nonbulbar signs which may allow for specific management strategies over time.

Keywords


Acoustics; Aerodynamics; Muscle; Neurophysiology; Pulmonary diseases; Speech analysis; Speech intelligibility; Amyotropic lateral sclerosis (ALS); Speech production

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