Impact of Levodopa in Lung Functions in Patients with Parkinson Disease

BACKGROUND: Parkinson's disease (PD) is the second-most common neurodegenerative disorder known primarily by its motor symptomatology. These motor manifestations are also hypothesised to affect the respiratory muscular function of PD patients contributing to restrictive pattern of ventilatory dysfunction. Previous reports attempting to detect these abnormalities through spirometric assessments have been inconclusive. Attempts at reversal of the restrictive abnormalities by levodopa therapy too, have yielded conflicting results. OBJECTIVES: This study aims to classify spirometric abnormalities in asymptomatic PD patients after levopopa withdrawal and document changes after levodopa replacement. METHODS: Thirty-six non-smoker PD patients without pre-existing respiratory abnormalities were enrolled. Their standard spirometric values- FEV1, FVC and FEV1/FVC, were noted before and after their morning levodopa dose. RESULTS: Nineteen patients had abnormal PFT values at baseline - 14 restrictive and 5 obstructive defects. Fourteen patients showed improvement in their pulmonary performances after dopamine administration with 6 showing complete reversibility. Statistically significant improvement in the post-levodopa FVC values was seen in patients with restrictive disorder (P value=0.04) but not for obstructive disorders. DISCUSSIONS: This pilot study characterised that 39% of PD patients had restrictive ventilatory defects prior to morning dopamine administration. Of these, 40% showed improvement after levodopa administration. CONCLUSION: Restrictive defects are common in PD patients which are evident on routine spirometric screening. These defects are reversible on levodopa administration.