Quantitative voice analysis in the assessment of bulbar involvement in amyotrophic lateral sclerosis

Bulbar and pseudobulbar symptoms are diagnostic criteria of amyotrophic lat eral sclerosis (ALS). One of the earliest symptoms of bulbar involvement is voice deterioration. Until now voice assessment in ALS patients has been d one mainly by perceptual analysis. The objective paramrters, including acou stic measures, one aerodynamic measure and the maximal phonation time. have been measured only in a fen small series of patients. The first purpose of this prospective study was to determine which vocal parameters discriminat e ALS patients with bulbar involvement from control patients. The second wa s to identify sensitive parameters for early detection of voice deteriorati on due to bulbar involvement in pre-symptomatic ALS patients. The voices of 63 female ALS patients. including 40 with bulbar symptoms (sALS patients) and 23 without bulbar symptoms (aALS patients). Were studied using an objec tive voice analysis system that allows simultaneous analysis of acoustic an d aerodynamic parameters. Measurements were compared with those obtained in 40 normal Female subjects (control patients). Five of right acoustic param eters were significantly different among the three groups: jitter, coeffici ent of variation for frequency, shimmer, number of harmonics, and maximum p honatory frequency range. Three aerodynamic parameters, phonatory airflow, cycle-to-cycle variation For phonatory airflow, and coefficient of variatio n for phonatory airflow were significantly different between sALS patients and control patients. No aerodynamic parameter allowed discrimination betwe en aALS patients and control patients. This study shows that acoustic param eters are more sensitive than aerodynamic parameters for early detection of bulbar involvement. Nevertheless. the measurements used can pl edict bulba r involvement in 73% of those in the sALS group, but only in 52% of those i n the aALS group.