Evaluation of cerebral autoregulation by multimodality monitoring during tilt table test and Valsalva maneuver in Parkinson's disease

Objective To analyze clinical characteristic of static and dynamic cerebral autoregulation(CA)in patients with Parkinson disease(PD),mean cerebral blood flow velocities (MCBFV)in both middle cerebral artery(MCA),mean arterial blood pressure(MABP),end tidal CO_2 (EtCO_2)and some other index are measured simultaneously and continuously during the Valsalva maneuver (VM)and tilt table testing(TTT).Methods Seventeen patients with PD and eight age-matched control subjects were measured continuously and simultaneously of heart rate(HR),CBFV in both MCA by transeranial Doppler,MABP,MABP adjusted to brain level(MABP_(brain))by Finapress 2300 Ohmeda and end-tidal CO_2(EtCO_2).TTT was performed firstly during graded tilt(in the rest supine position as baseline,10°,30°,70°head-up tilt,and supine recovery).Secondly,VM was carried out.Goshng' s pulsatility index of MABP_(brain).and both MCA(PI_(BP),PIMCBFV_L,PIMCBFV_R),ratio of PIMCBFV_L/PI_(BP), PIMCBFV_R/PIB_p(PI_L/PI_(BP),PI_R/PI_(BP))were calculated for all phases.Cerebrovascular resistance (CVR)and static CA(sCA)were also calculated.The autoregulatory indices,as authoregulatory slope indice(ASI),A Ⅰ-Ⅱ and A Ⅰ-Ⅳ,side-to-side differences of indices(SSD),were also calculated during VM.Results The results in TTT showed that MABP_(brain)was decreased significantly in control and patients with Head-up tilt,but there was a significant decrease from baseline only at 70°head-up position (77.1±12.3,59.9±10.2,P=0.03;79.2±11.8,61.8±15.1,P=0.02),but it was not significant between patients and controls at any tilt level(P0.05).MCBFV in MCA in the patients was significantly lower than that in the controls((34.1±7.5)-(44.1±13.8),(61.4±15.9)-(65.4±19.2),P 0.05),and CVR in the patients were significantly higher than that in the controls at all test positions ((2.0±1.1)-(2.3±1.0),(1.0±0.2)-(1.2±0.4),P0.05).sCA_(MCAL)and sCA_(MCAR)were significantly decreased in the patient group(by 15.0%,6.8%)than those in the control group(by 73.4%,75.7%)(P0.01).During VM,MCBFV was significantly lower in the patients than in the controls in all phases((35.7±12.7)-(54.2±16.1),(47.1±11.3)-(80.2±25.5),P0.05). MCBFV in the patients was not different between phase Ⅱ a and Ⅱb(P=0.33).PI_(BP)in the controls was markedly lower in phase Ⅱb than on the baseline(P0.05),and PI_L/PI_(Bp)was markedly higher in phase Ⅱ a,Ⅲb than on the baseline(P0.05).PI_(BP)in patients was markedly decreased in phase Ⅰ,Ⅱ a, Ⅱb,Ⅲ than on the baseline((0.6±0.1)-(0.5±0.2),0.7±0.1,P0.05)respectively,but PI_L/PI_(BP) and PI_R/PI_(BP)rose significantly in phase Ⅱ a to Ⅲ((2.1±1.0)-(2.9±1.5),1.5±0.5,P0.05). Conclusions Patients with PD are in a baseline condition of higher CVR,lower MCBFV.The results in TTT showed that the patients with PD presented a special type of dysfunction of sCA resulting from dysfunction of dilatation of the downstream resistance vessels.Dynamic CA during VM shows characteristic phase-delayed changes in healthy controls.The clinical threshold of CA markedly rises and the intensity of CA.Decreases in PD,which makes CA further delayed to phase Ⅲ.PI_L/PI_(BP)and PI_R/PI_(BP)were better parameters for testing dynamic CA in PD.