Respiratory rehabilitation in multiple sclerosis: A narrative review of rehabilitation techniques

Respiratory disorders in multiple sclerosis (MS) are an important issue. They can occur early during the course of the disease, are associated with the neurological impairment, and can lead to pneumonia and respiratory failure, which are the main causes of death in advanced MS. Prevailing impaired expiratory muscles and cough abilities has been demonstrated in this population and might constitute a specific target for rehabilitation interventions. However, international guidelines lack recommendations regarding respiratory rehabilitation in MS. Here we performed a systematic review of the published literature related to respiratory rehabilitation in MS.

We searched the databases MEDLINE via PubMed, PEDro and Cochrane Library for English or French reports of clinical trials and well-designed cohorts published up to December 2016 with no restriction on start date by using the search terms "multiple sclerosis", "respiratory rehabilitation", "respiratory muscle training", "lung volume recruitment", "cough assistance", and "mechanical in-exsufflation". Literature reviews, case reports and physiological studies were excluded. The Maastricht criteria were used to assess the quality of clinical trials. We followed the Oxford Centre for Evidence-Based Medicine guidelines to determine level of evidence and grade of recommendations.

Among the 21 reports of studies initially selected, 11 were retained for review. Seven studies were randomized controlled trials (RCTs), 2 were non-RCTs, and 2 were observational studies. Respiratory muscle training (inspiratory and/or expiratory) by use of a portable resistive mouthpiece was the most frequently evaluated technique, with 2 level-1 RCTs. Another level-1 RCT evaluated deep-breathing exercises. All reviewed studies evaluated home-based rehabilitation programs and focused on spirometric outcomes. The disparities in outcome measures among published studies did not allow for a meta-analysis and cough assistance devices were not evaluated in this population.

Although respiratory muscle training can improve maximal respiratory pressure in MS and lung volume recruitment can slow the decline in vital capacity, evidence is lacking to recommend specific respiratory rehabilitation programs adapted to the level of disability induced by the disease.