Dextromethorphan/quinidine (DMQ) for reducing bulbar symptoms in amyotrophic lateral sclerosis - assessment of treatment experience in a multicenter study

Abstract

Background: In amyotrophic lateral sclerosis (ALS), dextromethorphan/quinidine (DMQ) has been reported to reduce bulbar symptoms, including dysarthria and dysphagia. However, data on patients' perceptions of DMQ treatment are limited.

Methods: Data on DMQ treatment were collected from 1065 ALS patients treated at 13 ALS centers between 10-2015 and 06-2025. Patient-reported outcome measures (PROM) of 179 participants were remotely assessed via the "ALS App". PROM included the self-explanatory version of the ALS Functional Rating Scale (ALSFRS-R-SE), the Net Promoter Score (NPS); and Treatment Satisfaction Questionnaire for Medication (TSQM-9).

Results: Mean disease duration was 29.3 months (SD 38.1). ALS progression before treatment was 0.82 points/month (ALSFRS-R). Mean DMQ treatment duration was 8.4 months (SD 10.8), including 35.2% (n = 374) of shorter (<3 months), 35.3% (n = 375) of longer (3-9 months), and 29.5% (n = 313) of very long DMQ treatment (>9 months). Patients' recommendation (n = 178) was positive (NPS: +23) with higher scores after very long DMQ treatment (NPS +37) compared to longer (NPS +15) and shorter treatment (NPS +7.5), respectively. TSQM-9 scores (n = 163) demonstrated high satisfaction for effectiveness 60.0 (SD 25.9), convenience 73.8 (SD 18.2), and global satisfaction 63.4 (SD 29.8).

Interpretation: The positive perception in PROM underscores the value of DMQ as an individualized treatment option for bulbar symptoms in ALS. However, shortage of clinical data, online assessment, and selection biases are among the limitations of this study that need to be addressed in further investigations.

Keywords: Amyotrophic lateral sclerosis; bulbar symptoms; dextromethorphan/quinidine (DMQ); dysarthria; dysphagia; patient-reported outcomes.