Respiratory difficulties are a less common symptom of multiple sclerosis. Problems with breathing may be associated with more advanced disease, however problems can occur at any stage of the disease, even in patients who do not complain of respiratory problems. Just as weakness of leg and hip muscles can affect walking ability, weakness of the respiratory muscles can affect breathing/pulmonary function.
Problems related to breathing in patients with MS can be caused by respiratory muscle weakness, bulbar dysfunction (involving muscles which control speech and swallowing), or abnormalities with breath control. Reduced muscle strength and spasticity can result in lower lung volumes (less air in the lungs) and eventually stiffness of lung tissue and chest wall due to diminished range of motion.
As a musician, the ability to breathe deeply and control my air flow is vital to accomplishing my job. From the beginning stages, band students learn to take in a lot of air and move it forcefully through a narrow instrument to create a beautiful sound. It takes a great deal of effort and power to do so. But outside of performing on an instrument, even musicians may breathe shallowly and fail to utilize their full lung capacity on a regular basis.
In addition to reduced lung volume, MS patients who experience problems with breathing may have a weaker cough which may interfere with clearing the airway. Peak cough flow (PCF) is a common measurement used to assess respiratory muscle weakness. Persons who are unable to clear their airway are at increased risk of pneumonia and respiratory tract infections.
In a recent study, researchers in Canada studied 79 patients with MS who experience pulmonary function abnormalities (i.e. problems related to breathing and lung function) who were referred to a respiratory neuromuscular rehabilitation clinic from February 1999 through December 2010. The goal of the study was to describe the rate of decline of pulmonary function and peak cough flow (PCF) in this select group of MS patients, and to describe the effect of lung volume recruitment (LVR) on pulmonary function in this group.
Patients with neuromuscular diseases such as MS may experience a decrease in a number of measures of pulmonary function. One such measure is the forced vital capacity (FVC) which refers to the total volume of air which can be forcibly exhaled after a person takes in the deepest breath possible. Larger lung capacity can help to improve peak cough flow (PCF) in patients with neuromuscular disease.
Of the 79 patients included in the Canadian study, 35 (44.3%) were seen more than once with a median follow-up of 13.4 months. Patients were significantly disabled with a mean EDSS of 7.33, but no patient was on invasive ventilation during the follow-up period. Fifty patients (67.6%) were on medication for spasticity. Few were on disease-modifying therapy, which included glatiramer acetate and interferon b-1a, and no patient was on chronic corticosteroid therapy.