Cerebral vasomotor reactivity in de novo unilateral Parkinson's disease: a comparison of hemodynamic parameters among affected and healthy hemisphere

Background: Cerebral vasomotor reactivity (CVR) evaluation has provided contrasting results in patients with idiopathic Parkinson's disease (PD). We assessed CVR to hypercapnia in the early stage of PD patients and the potential influence of levodopa medication (LD). Material and Methods: De novo PD patients with unilateral motor symptoms (Hoehn and Yahr stage: 1.0) were recruited from our outpatient clinic. Transcranial Doppler (TCD) was used to measure cerebral blood flow velocity (MFV) in both middle cerebral arteries at baseline and after 30 s of apnea. Bilateral MFV, pulsatility index (PI) and breath‐holding index (BHI) were recorded. Patients were studied in basal condition and after administration of 100/25 mg of Levodopa/carbidopa (LD/CD). Results: Thirty‐one de novo never treated PD patients were investigated (mean age 57; range 44–69 years). The affected hemispheric‐side (HS) presented slightly higher BHI (mean 1.31 ± 0.51 vs 1.10 ± 0.40), similar value of PI (mean 0.99 ± 0.21 vs 1.03 ± 0.17) and MFV (mean 47.1 ± 11.7 vs 46.7 ± 10.1) respect the unaffected HS. The LD/CD administration induced a significant increase in BHI only in the unaffected HS (P = 0.004). Conclusions: These results provide evidence of normal CVR to hypercapnia in the early phase of PD. Higher BHI values and the response to LD/CD administration in the affected hemisphere could represent the results of nitric‐oxide dependent mechanisms upregulation.