Effects of voice rehabilitation in people with MS: A double-blinded long-term randomized controlled trial.

Background: Hypophonia is a prevailing problem in people with multiple sclerosis (PwMS). However, evidence supporting the effectiveness of voice rehabilitation is lacking.

Objective: The aim of this study was to identify the most effective method to reduce hypophonia.

Methods: In this randomized controlled trial, 44 PwMS were randomized to intensive and high-effort voice treatment groups, the LSVT-LOUD^®, and conventional treatment group. Subjects received 16 treatments (4 sessions/week) lasting 45 minutes. The primary outcome was voice intensity (dB) in monologue, vocalization, and sentences while voice handicap index (VHI) measured voice self-perception. Outcomes were assessed by a blinded observer at baseline, post-treatment, and 15-month follow-up (FU).

Results: Linear models revealed a significant post-intervention between-group mean difference in favor of LSVT-LOUD for monologue: +6.3 dB (95% CI: 2.5 to 10.1); vocalization: +7.4 dB (95% CI: 2.3 to 12.5); and sentences: +9.5 dB (95% CI: 4.7 to 14.3). However, 43.7% PwMS in the LSVT-LOUD and 10% in the conventional treatment group obtained a full recovery of voice intensity (>60 dB) post-treatment, Fisher's test = 13.3, p < 0.01. However, these improvements were not maintained at FU. Between-group differences at VHI were -10.8 (95% CI: -21.2 to -0.4) and -11.3 (95% CI: -24.3 to -1.7) in favor of LSVT-LOUD at post and FU.

Conclusion: LSVT-LOUD can be a valid treatment to increase voice intensity in PwMS. However, results suggest the need for FU interventions targeting maintenance.