Abstract

Objective
Orthostatic hypotension (OH) is one of the most common autonomic dysfunctions in Parkinson’s disease (PD) patients. However, many patients with OH are asymptomatic. Conversely, orthostatic dizziness (OD) is not always associated with OH. We investigated the effect of positional changes on cerebral perfusion in patients with PD and OH.
Methods
We enrolled 43 patients, of whom 31 were PD patients and 11 were healthy controls (HC). All subjects underwent the following clinical assessments: OH Questionnaire, head-up tilt test (HUTT) with transcranial Doppler (TCD), near-infrared spectroscopy, measurement of the change in oxygenated hemoglobin (Δ Hboxy) during the squat-to-stand test (SST), measurement of the time derivative of total hemoglobin (DHbtot), and time taken to reach the peak (peak time, PT) of DHbtot after re-standing.
Results
The mean flow velocity change (ΔMFV) in the TCD during the HUTT failed to differentiate between the PD-OH(+) and PD-OH(-) groups. The change in oxygenated hemoglobin Δ Hboxy was greater in the PD-OH(+) group, which persisted for 9 min until the end of the HUTT only in the left hemisphere. During SST, PT was significantly delayed in PD-OH (+) in the left hemisphere.
Conclusion
Although TCD demonstrated no significant difference in ΔMFV, the parameters measured by NIRS, such as Δ Hboxy during HUTT and PT during SST, showed significantly increased Δ Hboxy or delayed PT in the left hemisphere of PD-OH(+). Positional changes have a detrimental effect on cerebral hemodynamics in patients with PD and OH, especially in the left hemisphere.

• Keywords: Parkinson’s disease, Orthostatic hypotension, Orthostatic dizziness, Transcranial Doppler, Near-infrared spectroscopy