Levodopa-induced respiratory dysfunction confirmed by levodopa challenge test: A case report

Parkinson disease is associated with various nonmotor symptoms, including rare respiratory dysfunction events. However, patients with Parkinson disease often have comorbid medical problems, such as respiratory distress, and differentiating nonmotor symptoms can be difficult. A 78-year-old male presented with repetitive shortness of breath. He was diagnosed with Parkinson disease and chronic obstructive pulmonary disease (COPD) several years prior. His symptoms were ambiguous between acute COPD exacerbation and levodopa-related nonmotor symptoms of Parkinson disease. To clarify the underlying cause, we performed the levodopa challenge test. After the patient complained of dyspnea following levodopa administration, levodopa-induced respiratory dysfunction was diagnosed. After adjusting antiparkinson medication, the patient's respiratory symptoms gradually improved. Respiratory dysfunction as a nonmotor symptom of Parkinson disease can be caused by levodopa medication. To determine whether the symptoms are induced by levodopa, the levodopa challenge test may be useful in clarifying symptoms related to antiparkinson medication.