Off-State dyspnea induced by diaphragmatic-chest wall asynchrony in Parkinson's disease: A novel observation and review of the literature

In the clinical care of patients with Parkinson's disease (PD), dyspnea is a frequent symptom alongside the classic motor symptoms such as bradykinesia and rigidity. However, the underlying mechanisms of dyspnea in Parkinson's disease and how it is affected by dopaminergic medications like levodopa and dopamine agonists, which represent the mainstay treatment of motor symptoms in Parkinson's disease, are not yet fully understood. Various diagnostic tools exist to help clinicians evaluate patients with respiratory issues. In this case study, we report on the utilization of electromyography of the diaphragm, a previously not described diagnostic tool in the field of PD-related dyspnea, to study a patient with Parkinson's disease presenting with recurrent unexplained dyspnea when the dopaminergic medication wears off. We identified an altered sequence of respiratory motion, that is the contraction of diaphragm and excursion of the chest wall, during medication-off in this patient. We propose that the diaphragm-chest wall asynchrony, being a novel finding, likely leads to impaired mechanical output during breathing and contributes to the patient's experience of dyspnea when the medication wears off.