Tutorial on maximum inspiratory and expiratory mouth pressures in individuals with idiopathic Parkinson disease (IPD) and the preliminary results of an expiratory muscle strength program
Silverman E, Sapienza C, Saleem A, Carmichael C, Davenport P, Hoffman-Ruddy B. NeuroRehabilitaion 21 (2006) 71-79 IOS Press

Abstract. Respiratory symptoms are recognized as sequelae of motor dysfunction in idiopathic Parkinson’s disease (IPD) and these symptoms have the potential to cause problems with swallow, cough, voice and speech. Specifically, maneuvers that require rapid activation and coordination of upper airway and chest wall musculature become progressively impaired as motor dysfunction progresses during the natural course of the disease. This study reports on the maximum inspiratory and expiratory pressures produced by 28 participants (average age 64) diagnosed with moderate to severe IPD (average stage 2.5 with a range of 2.0-3.0). All measures were collected during the “medication on” state. Outcomes of a specific respiratory muscle strength training technique for improving maximum expiratory pressure are reported for three of the patients in this study, Techniques that focus on strengthening the respiratory muscles in patients with IPD (other than with low load breathing exercises), have not been previously reported. The results of this pilot study demonstrate that respiratory muscle weakness may be an important factor in the respiratory complications in IPD and that respiratory muscle strength training has the potential to improve expiratory muscle strength for this population. This improvement has the potential to positively impact high forced respiratory activities, such as forced breathing maneuvers, swallow, cough and speech functions that require greater magnitude and duration of expiration.

Introduction. Respiratory symptoms are recognized as sequelae of motor dysfunction in IPD and have the potential to cause problems with swallow, cough, voice and speech. Patients with IPD can, particularly in the later stages of the disease, become sedentary and develop problems with endurance, maximal fitness levels, and overall pulmonary function. While much of the research to date has focused on the motor symptoms of IPD (including tremor, rigidity, and bradykinesia), the pulmonary complications represent an important late stage and high morbidity consequence. Many individuals with IPD eventually succumb to pulmonologic complications, including aspiration pneumonia. The presence of aspiration pneumonia affords the highest mortality risk ratio among all comorbidities in patients with IPD living in nursing homes.

Observations of respiratory muscle weakness are consistent with the reduced ability to generate normal forced respiratory maneuvers and can be common to other types of neurological diseases. Past investigations in IPD have suggested that muscular weakness is exacerbated by increased chest wall rigidity. Weakness within the muscles of respiration will restrict the ability to overcome rigidity, and potentially contribute to reduced lung volumes and respiratory pressures which will impact swallow, cough and speech functions.

Conclusions. Measures of respiratory muscle strength, including MIP and MEP, are useful in quantifying the degree of respiratory impairment in individuals with IPD. It is unknown how these measures correlate with more functional assessments of perceived disability particularly in domains which rely heavily on respiratory muscle function (swallowing, cough and voice and speech). The current results suggest that expiratory muscle strength training may be a promising therapy in IPD. For individuals with IPD, this lessening of perceived disability may in effect “turn back the clock” on certain known consequents of respiratory muscle impairment. Potential ties between specific measures of respiratory muscle strength and perceived disability remain to be elucidated. Future studies should also examine larger numbers of individuals with IPD demonstrating greater variety in disease stages.