Table 2.
Demographic information of participants.
| Healthy controls | Bulbar asymptomatic | Bulbar symptomatic | p-values | ||
|---|---|---|---|---|---|
| High speech function | Low speech function | ||||
| Stratification criteria | No history of speech, language, or neurological problems | Diagnosed with ALS; speaking rate >150 WPM; intelligibility >96% | Diagnosed with ALS; speaking rate <150 WPM; intelligibility >96% | Diagnosed with ALS; speaking rate <150 WPM; intelligibility <96% | N/A |
| Total N [number of males (M)] | 47 (23 M) | 60 (33 M) | 38 (20 M) | 28 (20 M) | N/A |
| Mean age in years (SD) | 60.80 (8.47) | 59.53 (10.22) | 56.74 (8.51) | 59.63 (9.92) | All groups: p = 0.25 |
| Symptom duration—mean months since symptom onset (SD) | N/A | 42.63 (27.95) | 42.78 (43.02) | 36.00 (33.11) | All ALS groups: p = 0.70 |
| Site of Onset = N | N/A | Spinal = 48 Bulbar = 1 Mixed = 3 Unknown = 8 |
Spinal = 30 Bulbar = 4 Mixed = 0 Unknown = 4 |
Spinal = 17 Bulbar = 7 Mixed = 2 Unknown = 0 |
N/A |
| Mean ALSFRS-R Total (SD) | N/A | 32.45 (8.07) | 32.10 (8.25) | 33.38 (10.27) | All ALS groups: p = 0.87 |
| Mean ALSFRS- R Bulbar (SD) | N/A | 11.06 (1.42) | 9.77 (1.76) | 8.55 (2.82) | All ALS groups: p < 0.001 |
| High speech-function and low speech-function groups: p = 0.07 | |||||
| Mean % Intelligibility (SD) | 99.25 (1.16) | 99.15 (1.03) | 98.44 (1.46) | 71.61 (29.93) | All ALS groups: p < 0.001 |
| High speech-function and low speech-function groups: p < 0.001 | |||||
| Mean speaking rate in WPM (SD) | 186.88 (21.61) | 182.65 (18.58) | 115.85 (24.24) | 109.20 (24.68) | All ALS groups: p < 0.001 |
| High speech-function and low speech-function groups: p = 0.61 | |||||
ALS, Amyotrophic lateral sclerosis; ALSFRS-R, Amyotrophic lateral sclerosis rating scale-revised; SD, standard deviation; WPM, words per minute.
p-values: derived from ANOVAs between participant groups.
Note: Stratification criteria were defined using currently accepted metrics of bulbar impairment based on previous literature, which is described in detail in the text.
Note: In the bulbar asymptomatic group, mean ALSFRS-R bulbar subscore was <12, indicating that at least a few participants reported some level of bulbar function impairment. However, we defined bulbar impairment on the clinical measures (i.e., speaking rate and speech intelligibility) used; we kept all participants who met these criteria in the bulbar asymptomatic group. All participants in this group were, therefore, very early on in disease progression and were asymptomatic based on our clinical metrics of speech.