Table 2.
Tools to measure bulbar dysfunction severity and disease progression.
| Tool | Description | Advantages | Limitations | Recommendations |
|---|---|---|---|---|
| 1. ALSFRS-R, bulbar sub-score | Tracks bulbar disease progression; 3 “bulbar” questions; 0 (no function)−4 (normal function) | Quick and easy to perform; patient and caregiver versions available; well validated as a total score; (66) recent studies suggest using “domain-specific” subscores instead of a total score; (67, 68) declines linearly; an accepted end point in clinical trials | Limited assessment of bulbar dysfunction; symptom report; may underestimate sisease severity; (69) changes relatively late in the disease; skewed to detection of the LMN impairment (70) | Recommended for use in clinic and clinical trials but caution due to limited nature of bulbar assessment |
| 2. Center for Neurologic Study-Bulbar Function Scale (CNS-BFS) | Reports solely on bulbar symptoms, 21 questions regarding speech, swallowing and salivation | Validated-high criterion and construct validity, (71) good reliability, responsive to change over time and improved in a clinical trial (72) | Symptom report; potentially not sensitive to early phases of the disease; need further validation against VFSE | Recommended for bulbar evaluation in clinic and clinical trials |
| 3. Appel scale | Includes 5-point ratings of functional status of speech and swallowing (scores 6–30) and bulbar disease progression | Reliable; responsive to disease progression (linear decline); the composite score distinguishes slow from fast progressors, predicts survival, provides bases for clinical classification with management recommendations depending on severity (73) | Validation is limited to date; includes only 2 questions related to bulbar function-−1 speech and 1 swallowing | Requires further evaluation of measurement properties; limited for the assessment of bulbar dysfunction |
| 4. Norris scale | 34-item ranking system; (74) 6 items in the “bulbar” category (i.e., chew, swallow, speak, jaw jerk, atrophy face/ tongue, lability) on a 3-point scale for each item | Quick and easy to administer; includes a range of bulbar items; has been used in clinical trials (75) | All items (functional and non-functional) rated equally; 3-point scale might be too coarse to detect change; limited information on the development and validation of the tool; responsiveness not established | Requires further evaluation of measurement properties; limited for the assessment of bulbar dysfunction |
| 5. ALS Severity Scale (ALSSS) | 10-point staging scale; was designed to supports management/rehabilitation practices in ALS; includes 1 speech and 1 swallowing item (0 to 10) | Easy to perform; clear description of each stage; adequate reliability; sig correlations with timed tests and speech intelligibility; responsive to change over time (76) | Ordinal scale; includes only 1 speech and 1 swallowing item | Requires further evaluation of measurement properties |
| 6. Neuromuscular Disease Clinical Status Scale (NdSSS) | 8-stage dysphagia severity scale to track the development of symptoms of dysphagia over time | Quick and easy to administer by a trained clinician; reliability, concurrent validity relative to other scales and responsiveness reported (77) and adequate | Focused predominantly on description of intake/ diet; not validated against VFSE | Although promising, requires further evaluation of measurement properties in other cultures |
| 7. Oral Secretion Scale (OSS) | 5-point scale to evaluate the severity of sialorrhea in ALS | Quick and easy to administer; validated against ALSFRS-R bulbar subscore and SSS; adequate reliability; can be used by different professions (78) | Floor effect in the more severely involved individuals; responsiveness not assessed; not linked to dysphagia outcomes | Recommended for evaluation of severity of sialorrhea in clinic and in clinical trials |
| 8. Sialorrhea Scoring Scale (SSS) | 9-point scale to evaluate the severity of sialorrhea | Quick and easy to administer; validated against ALSFRS-R bulbar subscore and OSS; adequate reliability; can be used by different professions; better spread of scores across the severity range compared to OSS (78) | Responsiveness not assessed; reliability was somewhat lower than for OSS; not linked to dysphagia outcomes | Recommended for evaluation of severity of sialorrhea in clinic and in clinical trials |
| 9. Sentence Intelligibility Test—Speech Intelligibility and Speaking rate | % of words understood by a listener during a sentence transcription task, and number of words produced per minute (WPM) | Easy to perform; supported by software; validated in multiple studies with respect to ALSSS (79) and ALSFRS-R; decline in rate to 125 WPM predicts intelligibility drop and is used to time AAC interventions; WPM changes linearly with disease progression (80, 81) | Requires a trained SLP; requires a trained transcriber; low sensitivity to early bulbar disease; (61) declines over 12% in sentence intelligibility and 37 WPM are outside of measurement error (82) | Speaking rate is recommended to be tracked during clinic in order to plan AAC interventions for those at risk for loss of speech intelligibility |
| 10. Timed tests: Speech and pause durations in a passage* | A passage reading task (e.g., Bamboo) (83) allows a separation between speaking and pause events; gives a detailed picture of the components of speaking rate | Easy to perform; allows practice to minimize reading errors; distinguished patients with ALS with bulbar and respiratory signs; (84) showed sensitivity to change in a drug trial (85) | Currently requires time consuming, by-hand measurements; requires training; measurement properties (e.g., responsiveness, measurement error) are not well established; bulbar effects need further differentiation from respiratory and cognitive effects | Requires further standardization as well as better testing of measurement properties; subsequently would benefit from automation |
| 11. Times tests: DDK* | A syllable repetition task (pa; ta; ka; pa-ta-ka) in syllables per second (syl/sec) that is used to detect slowing of the oral movements | Easy to perform; clinicians are familiar with the task; easily measured instrumentally; free of cognitive-linguistic effects; distinguishes slow from fast progressors; (86) cut off 4.6 syl/s 91% sensitivity and 54% specificity in detecting bulbar signs in pre-symptomatic patients (61) | Requires training/ modeling and maximum effort from patients; measurement properties are not fully established (e.g., responsiveness; error of measurement) | Requires further standardization as well as better testing of measurement properties; subsequently would benefit from automation |
| 12. Maximum Tongue Pressure (MTP)* | A measure of tongue strength using a commercially available devices | Affordable easy to use clinical tool; validated against ALSFRS-R bulbar subscore and VFSE; cut off < 21 KPa has sensitivity 80% and specificity 100% for detecting bulbar dysfunction on ALSFRS-R (87) and oral dysphagia; adequate reliability; independent prognostic factor of survival (88) | Requires training of the clinician and patient prior to measurement—results are placement dependent; (89) requires max effort; insufficient data on responsiveness; (90) not associated with dysarthria and speech intelligibility loss | Requires further standardization as well as testing of measurement properties |
*
May be used for diagnostic purposes.