Tilt-table test during transcranial Doppler monitoring in Parkinson's disease

Cerebrovascular responses to somatomotor stimulation in Parkinson's disease: A multivariate analysis

Parkinson's disease (PD) is a common neurodegenerative disorder, yet little is known about cerebral haemodynamics in this patient population. Previous studies assessing dynamic cerebral autoregulation (dCA), neurovascular coupling (NVC) and vasomotor reactivity (VMR) have yielded conflicting findings. By using multi-variate modelling, we aimed to determine whether cerebral blood flow (CBF) regulation is impaired in PD patients.55 healthy controls (HC) and 49 PD patients were recruited. PD subjects underwent a second recording following a period of abstinence from their anti-Parkinsonian medication. Continuous bilateral transcranial Doppler in the middle cerebral arteries, beat-to-beat mean arterial blood pressure (MAP; Finapres), heart rate (HR; electrocardiogram), and end-tidal CO₂ (EtCO₂; capnography) were measured. After a 5-min baseline period, a passive motor paradigm comprising 60 s of elbow flexion was performed. Multi-variate modelling quantified the contributions of MAP, ETCO₂ and neural stimulation to changes in CBF velocity (CBFV). dCA, VMR and NVC were quantified to assess the integrity of CBF regulation.Neural stimulation was the dominant input. dCA, NVC and VMR were all found to be impaired in the PD population relative to HC (p < 0.01, p = 0.04, p < 0.01, respectively). Our data suggest PD may be associated with depressed CBF regulation. This warrants further assessment using different neural stimuli.

The effect of subthalamic nucleus - Deep brain stimulation and different stimulation frequencies on cerebral hemodynamics in Parkinson's disease: A transcranial doppler study

OBJECTIVES

To investigate the effect of deep brain stimulation of the subthalamic nucleus (STN-DBS) and to compare low-frequency versus high-frequency STN-DBS on hemodynamic parameters of the middle cerebral artery between patients with advanced Parkinson's disease and age-sex matched healthy controls.

PATIENTS AND METHODS

Eighteen patients with advanced Parkinson's disease (PD) with bilateral STN-DBS and 18 control subjects underwent Transcranial Doppler Ultrasound (TCDU) were included in the study. The hemodynamic parameters including blood flow velocity (FV), pulsatility index (PI) and, resistance index (RI) of the right middle cerebral artery (MCA) were measured and compared during the phases using TCDU. The first DBS-off, the second low-frequency DBS of 60 Hz, and the third high-frequency DBS of 130 Hz were compared.

RESULTS

PD patients had significantly higher MCA-PI values compared with controls (0.99 ± 0.27 vs. 0.82 ± 0.14) (p = 0.031). Also, the MCA-PI values were higher in the low-frequency DBS (0.94 ± 0.14) and high-frequency DBS (0.93 ± 0.16) than in the controls (0.82 ± 0.14) (p = 0.022 and p = 0.041, respectively). There were no significant differences of FV and RI values among the DBS-on, DBS-off and, controls. The RI values were higher in the PD patients than in the controls, although these were not statistically significant. Also, PI values of the MCA decrease in different frequencies (60 Hz or 130 Hz).

CONCLUSION

The results of this study showed that MCA-PI values are higher in advanced PD compared with controls. These indices indicate that MCA resistances and impedances are increased in advanced PD. Low- or high-frequency DBS treatment have beneficial effect to reduce high PI in advanced PD patients.

Transcranial Doppler in autonomic testing: standards and clinical applications

When cerebral blood flow falls below a critical limit, syncope occurs and, if prolonged, ischemia leads to neuronal death. The cerebral circulation has its own complex finely tuned autoregulatory mechanisms to ensure blood supply to the brain can meet the high metabolic demands of the underlying neuronal tissue. This involves the interplay between myogenic and metabolic mechanisms, input from noradrenergic and cholinergic neurons, and the release of vasoactive substrates, including adenosine from astrocytes and nitric oxide from the endothelium. Transcranial Doppler (TCD) is a non-invasive technique that provides real-time measurements of cerebral blood flow velocity. TCD can be very useful in the work-up of a patient with recurrent syncope. Cerebral autoregulatory mechanisms help defend the brain against hypoperfusion when perfusion pressure falls on standing. Syncope occurs when hypotension is severe, and susceptibility increases with hyperventilation, hypocapnia, and cerebral vasoconstriction. Here we review clinical standards for the acquisition and analysis of TCD signals in the autonomic laboratory and the multiple methods available to assess cerebral autoregulation. We also describe the control of cerebral blood flow in autonomic disorders and functional syndromes.

Orthostatic dizziness in Parkinson's disease is attributed to cerebral hypoperfusion: A transcranial doppler study

OBJECTIVES

Orthostatic hypotension (OH) is controversially regarded as the cause of orthostatic dizziness in Parkinson's disease (PD). We sought to evaluate whether cerebral autoregulation is an alternative cause for orthostatic dizziness in PD patients, using transcranial Doppler monitoring during head-up tilting.

METHODS

Forty-five PD patients with dizziness, 13 PD patients without dizziness, and 10 age-matched healthy controls were enrolled. Participants were divided into the following four groups: patients with dizziness and OH (group 1, n = 22), patients with dizziness but no OH (n = 23, group 2), patients without dizziness (n = 11, group 3), and age-matched healthy controls (n = 10, group 4). All participants underwent transcranial Doppler and blood pressure monitoring for 10 minutes during the head-up tilt test. Changes in the cerebral blood flow velocity (CBFV) in the middle cerebral artery and the mean blood pressure (mBP) within 3 minutes after head-up tilting were compared between groups.

RESULTS

Group 1 showed a significantly higher change in mBP (-16.3 ± 10.8 mmHg) than groups 2 (-2.6 ± 4.9), 3 (-2.2 ± 3.6), or 4 (1.8 ± 6.0) (p < 0.001). However, groups 3 (4.6 ± 3.0 cm/s) and 4 (-4.2 ± 2.5) showed a significantly smaller change in CBFV than groups 1 (-9.0 ± 4.2) and 2 (-8.1 ± 5.1) (p < 0.01).

CONCLUSIONS

Our results suggest that cerebral hypoperfusion contributes to dizziness in PD patients despite a lack of OH. Transcranial Doppler monitoring during head-up tilting may be a useful tool for evaluating dizziness in PD patients with or without OH. © 2016 Wiley Periodicals, Inc. J Clin Ultrasound 45:337-342, 2017.

Orthostatic Hypotension in Parkinson's Disease: The Relation of Blood Pressure Tests and Symptoms in Daily Life

Background

Orthostatic hypotension (OH) is common in Parkinson's disease (PD), but the relation between the results of orthostatic blood pressure tests and orthostatic symptoms in daily life is not clear.

Methods

We performed a cross-sectional study in an incident nontertiary care cohort of PD patients with additional recruitment of PD patients from our own outpatient clinic. We recruited sex- and age-matched controls. All participants underwent orthostatic blood pressure tests using continuous blood pressure measurements. Orthostatic symptoms experienced in daily life were assessed using autonomic symptom questionnaires (SCOPA-AUT and COMPASS-31).

Results

A total of 83 PD patients and 35 controls were included. Mean patient age was 69.2 years (standard deviation [SD]: 10.0). Mean disease duration was 6.6 years (SD, 0.8). The estimated prevalence of OH in PD was 24.1% (95% confidence interval: 16.2-34.3). There was no significant difference between PD patients with and without OH regarding reported daily orthostatic symptoms. Alternative OH criteria did not substantially improve this.

Conclusions

Perceived orthostatic symptoms in daily life have no clear association with the results of a single orthostatic blood pressure test. Better diagnostic strategies are needed.

Cerebral autoregulation and white matter lesions in Parkinson's disease and multiple system atrophy

Cerebral autoregulation is a complex homeostatic process which ensures constant brain blood supply, despite continuous blood pressure fluctuations. Recent evidence suggests that in Parkinson's disease (PD) and multiple system atrophy (MSA) this process is maintained in a broadened range of blood pressure values, consistent with an adaptive mechanism to increase tolerance to orthostatic hypotension. In PD and MSA orthostatic hypotension may be accompanied by supine hypertension which has been recently linked with cerebral white matter lesions in these conditions. We hypothesize that cerebral autoregulation adaptation to chronic orthostatic hypotension may be directly related with an increase susceptibility to hypertensive peaks. Evaluation of cerebral autoregulatory behavior may thus represent a novel approach to simultaneously target orthostatic symptoms and silent end-organ damage in alpha-synucleinopathies, with a beneficial impact on cerebrovascular and cognitive outcome.

Abnormal Cerebrovascular Reactivity in Patients with Parkinson's Disease

Background. Orthostatic hypotension (OH) is an important nonmotor manifestation of Parkinson's disease (PD). Changes in cerebrovascular reactivity may contribute to this manifestation and can be monitored using transcranial Doppler. Objective. To identify possible changes in cerebrovascular reactivity in patients with OH. Methods. Twenty-two individuals were selected and divided into three groups: with and without OH and controls. Transcranial Doppler was used to assess basal mean blood flow velocity, postapnea mean blood flow velocity, percentage increase in mean blood flow velocity, and cerebrovascular reactivity as measured by the breath-holding index. Results. PD patients had lower values of basal velocity (p = 0.019), postapnea velocity (p = 0.0015), percentage increase in velocity (p = 0.039), and breath-holding index (p = 0.04) than the controls. Patients with OH had higher values of basal velocity (p = 0.09) and postapnea velocity (p = 0.19) but lower values of percentage increase in velocity (p = 0.22) and breath-holding index (p = 0.32) than patients without OH. Conclusions. PD patients present with abnormalities in a compensatory mechanism that regulates cerebral blood flow. OH could be an indicator of these abnormalities.

Orthostatic hypotension in patients with Parkinson's disease and atypical parkinsonism

Orthostatic hypotension (OH) is one of the commonly occurring nonmotor symptoms in patients with idiopathic Parkinson's disease (IPD) and atypical parkinsonism (AP). We aimed to review current evidences on epidemiology, diagnosis, treatment, and prognosis of OH in patients with IPD and AP. Major electronic medical databases were assessed including PubMed/MEDLINE and Embase up to February 2013. English-written original or review articles with keywords such as "Parkinson's disease," "atypical parkinsonism," and "orthostatic hypotension" were searched for relevant evidences. We addressed different issues such as OH definition, epidemiologic characteristics, pathophysiology, testing and diagnosis, risk factors for symptomatic OH, OH as an early sign of IPD, prognosis, and treatment options of OH in parkinsonian syndromes. Symptomatic OH is present in up to 30% of IPD, 80% of multiple system atrophy (MSA), and 27% of other AP patients. OH may herald the onset of PD before cardinal motor symptoms and our review emphasises the importance of its timely diagnosis (even as one preclinical marker) and multifactorial treatment, starting with patient education and lifestyle approach. Advancing age, male sex, disease severity, and duration and subtype of motor symptoms are predisposing factors. OH increases the risk of falls, which affects the quality of life in PD patients.

Orthostatic hypotension in Parkinson’s disease

SUMMARY Orthostatic hypotension (OH) is a frequent non-motor symptom in Parkinson’s disease (PD), affecting between 22.9 and 38.4% of patients. In PD, OH is related to an increased risk of falls, and possibly to cognitive dysfunction and increased mortality. These data emphasize the importance of its prompt recognition and treatment. OH is related to pre- and post-ganglionic adrenergic denervation, but other factors, such as drugs, heat, meals or alcohol intake, might also induce or aggravate it. Evidence about the efficacy and safety of pharmacological or nonpharmacological strategies for OH treatment in PD is weak. Nonpharmacological measures include liberal addition of salt to the diet, exercise, compression stockings or physical maneuvers. Severe cases may be treated with midodrine or fludrocortisone. Some results suggest that droxidopa and fipamezole may be effective treatments. We finish this review article by discussing the most important unanswered questions about PD-related OH, which may be the focus of future research.

The dysarthria impact profile: a preliminary French experience with Parkinson's disease

This preliminary study aimed to adapt the Dysarthria Impact Profile (DIP) in French and to confirm its relevance for the assessment of the psychosocial impact of dysarthria in Parkinson's disease (PD). The DIP scale was administered to 10 people with PD and 10 age-matched control subjects. The DIP psychometric properties were calculated (discriminant validity, internal consistency, and concurrent validity), notably by using the Voice Handicap Index (VHI) for interscale comparisons. The French version of the DIP discriminated people with PD from control subjects (χ² test, P < 0.05). Good internal consistency was observed in both populations (Cronbach's α = 0.93 for PD people and α = 0.76 for control subjects). The DIP was highly correlated with the VHI (Spearman's ρ = −0.70, P < 0.01), confirming the external validity of the scale. There was no direct relationship between PD speech and quality of life as assessed by the Parkinson's Disease Questionnaire-39 (PDQ-39). Our preliminary data suggest that the French version of the DIP has the potential to make a useful contribution for the assessment and outcome management in acquired dysarthria for both clinicians and researchers.

Subthalamic stimulation improves the cerebral hemodynamic response to the cold pressure test in patients with Parkinson's disease

PURPOSE

Disturbances of the autonomic nervous system are common in patients with Parkinson's disease (PD) but the effect of deep brain stimulation of the subthalamic nucleus on cerebrovascular reactivity is not entirely known.

METHODS

Seven patients in an advanced stage of the disease and seven healthy age-matched controls participated in the study, which took place after one night of drug withdrawal. Cerebral blood flow velocity was continuously monitored on both sides with transcranial Doppler ultrasound, and cerebrovascular reactivity (CR) was evaluated with the cold pressure test. The measurements were repeated and compared during the stimulation-on and -off phases.

RESULTS

The PD patients had significantly higher CR values in the stimulation-on than -off conditions (15.1% ± 6.9 versus 9.4% ± 6.2; p = 0.03). CR values were higher in controls than in patients in the stimulation-off condition (20.4% ± 12.5 versus 9.4% ± 6.2; p = 0.007) without a significant difference with the stimulation-on phase.

CONCLUSIONS

CR, evaluated by the response to the cold pressure test, is impaired in patients with advanced PD and improved by subthalamic nucleus.

Evaluation of cerebral vasomotor reactivity in Parkinson's disease: is there any association with orthostatic hypotension?

OBJECTIVE

Our aim was to look for a probable relationship between cerebral vasomotor reactivity (VMR) and orthostatic hypotension (OH) in Parkinson's disease (PD).

MATERIALS AND METHODS

This study was conducted on 44 patients with PD. Assessment of cerebral VMR was performed by means of transcranial Doppler (TCD) of middle cerebral artery (MCA) before and after a vasodilatory stimulus, carbon dioxide test. Moreover, orthostatic hypotension was evaluated.

RESULTS

OH was presented in 12 (27.3%) Parkinson's patients. The average resting blood flow velocity (BFV) in the MCA was 30.20 (SD=9.58)cms(-1) which significantly increased to 46.25 (SD=16.23)cms(-1) after carbon dioxide test (P<0.001). Impaired VMR was observed in 15 (34.1%) of the subjects, while it was not associated with the presence of OH (P=0.770).

CONCLUSION

Evaluation of VMR in patients affected by PD, could assist in early diagnosis of cerebral autonomic dysfunction and prevent its serious consequences prior and more valid to OH.

Transcranial Doppler monitoring in Parkinson's disease: cerebrovascular compensation of orthostatic hypotension

Despite of precipitous blood pressure falls in Parkinson's Disease (PD) patients, they may not experience syncope or postural complaints. Can cerebral blood flow regulation explain why orthostatic hypotension (OH) has often no accompanying symptoms? In patients with PD and OH (18 asymptomatic; 8 symptomatic), arterial blood pressure (ABP) as well as Doppler-detected cerebral blood flow velocity (CBFV) in middle and posterior cerebral arteries (MCA and PCA) were monitored during head-up tilt and compared with 25 controls and eight non-PD-OH patients. Analysis included the transfer function between slow spontaneous pressure and flow-oscillations. ABP and CBFV were maintained at significantly higher levels in asymptomatic than symptomatic PD-OH (ABP: 85.7 ± 10.5 vs. 66.9 ± 12.5%; MCA-FV: 83.3 ± 9.3 vs. 66.1 ± 6.8%; PCA-FV: 84.4 ± 12.2 vs. 65.9 ± 9.3% of supine). When orthostatic complaints occurred, CBFV depended directly on ABP changes (MCA r(2) = 0.64; PCA r(2) = 0.62; both p < 0.05). Despite of a tilt-induced blood pressure instability in PD-OH, the transfer function parameters did not differ from normal [phase: MCA: 46.6 ± 20.5°; PCA 39.2 ± 28.8°, gain: MCA 2.0 ± 0.7; PCA 2.9 ± 1.6)]. Results showed a normal autoregulatory response to downward blood pressure shifts in PD. Moreover, orthostatic blood pressure instability is compensated equally sufficient in anterior and posterior parts of cerebral circulation. Whether in PD patients, OH becomes symptomatic rather seems to depend on blood pressure falling below the autoregulated range.

Blood pressure and heart rate in parkinsonian patients with and without wearing-off

Our study aimed to investigate the cardiovascular autonomic regulation related to the wearing-off phenomenon in Parkinson's disease (PD). We measured blood pressure (BP) and heart rate (HR) at rest and during orthostatic test in 16 patients with PD with wearing-off and in 15 patients with PD without wearing-off both before (baseline) and repetitively at 1-h intervals for up to 4 h after the morning PD medication dose. The patients with wearing-off had fluctuation of BP during the observation period, BP increasing when the motor performance worsened and vice versa. The mean supine BP was at its highest at the baseline measurement (patients with wearing-off, 145 +/- 18 mmHg; patients without wearing-off, 138 +/- 17 mmHg), fell during the first hour (patients with wearing-off, 119 +/- 17 mmHg; patients without wearing-off, 126 +/- 18 mmHg), and then rose again toward the end of the observation period (patients with wearing-off, 136 +/- 15 mmHg; patients without wearing-off, 138 +/- 18 mmHg). This BP change was statistically significant only in PD patients with wearing-off (P < 0.001). In conclusion, BP seems to fluctuate with motor impairment in PD patients with wearing-off. This fluctuation may represent autonomic dysfunction caused by the PD process itself, the effect of PD medication, or both.

Transcranial Doppler ultrasonographic evaluation of cerebral circulation during passive tilting in patients with Parkinson's disease

PURPOSE

To assess the effects of the tilt test on cerebral blood flow velocity (CBFV), blood pressure, and heart rate in patients with Parkinson's disease (PD) without symptomatic orthostatic dysautonomia.

METHODS

Thirty patients with idiopathic PD and 15 healthy controls were included. Mean middle cerebral artery blood flow velocity (CBFV) was recorded with transcranial Doppler sonography, while systolic (SBP), diastolic (DBP), and mean (MBP) blood pressure and heart rate were measured in the supine position and after passive tilting.

RESULTS

There was no difference in resting SBP, DBP, or MBP between patients and controls. CBFV was lower at rest in patients than in controls and dropped significantly and similarly after tilting in both groups. SBP decreased in patients during the first 5 minutes of tilting (p < 0.05), whereas it increased progressively after the first minute in controls. In patients, DBP decreased slightly and MBP dropped during the first 2 minutes, then increased. Baseline heart rate was higher in patients than in controls (p < 0.05) and increased in both groups during tilting.

CONCLUSION

Our results suggest that cardiovascular responses to tilting are delayed in PD patients and that subclinical autonomic dysfunction may be present even in the absence of symptomatic orthostatic dysautonomia.

Is cerebral autoregulation impaired in Parkinson's disease? A transcranial Doppler study

Orthostatic hypotension (OH) is one of the many autonomic disturbances observed in Parkinson's disease (PD). It has been debated whether an additional impairment of cerebral autoregulation (CA) in PD patients may exacerbate the consequences of OH upon brain perfusion. We assessed CA in PD patients and the potential influence of dopaminergic agents. CA was determined by means of transcranial Doppler (TCD) monitoring of the middle cerebral artery (MCA) at rest and during a thigh cuff release test inducing a systemic blood pressure (BP) drop. Fourteen patients were investigated when taking their usual dopaminergic medication and after drug discontinuation for 12 h. A control group was composed of 11 age-matched subjects (CS). In comparison with PD patients, CS presented a significantly higher increase of the mean cerebral blood flow velocities in the MCA after the BP drop. Mean velocities were increased above the initial values in all CS, whereas a flattened curve was observed in PD patients. No significant differences could be further observed between the PD patients regarding the BP, the cerebrovascular resistance, the heart rate and the pulsatility index. These results provide evidence of an impaired cerebral autoregulation in PD patients which appears independent of dopaminergic treatment.

Cerebral vasomotor reactivity in Parkinson's disease, multiple system atrophy and pure autonomic failure

Parkinson's disease (PD), multiple system atrophy (MSA) and pure autonomic failure (PAF) are neurodegenerative disorders frequently associated with orthostatic hypotension and syncope, though with different underlying mechanisms. Cerebral hemodynamic responses in these three neurodegenerative diseases are still incompletely studied and it is possible that they would be differentially affected. We measured blood flow velocity (BFV) in the middle cerebral artery (MCA) and vertebral artery (VA) in patients with these disorders and investigated whether cerebral vasomotor reactivity (VMR) differs in these three disorders. Twenty-four patients (9 with PD, 10 with MSA and 5 with PAF) were studied. VMR was assessed in the MCA and VA, using transcranial Doppler (TCD) and Diamox test (injection of 1 g acetazolamide i.v.) with the patients in a recumbent position. The percent difference between BFV before and after acetazolamide injection was defined as VMR% and the results were compared by ANOVA. The mean MCA and VA blood flow velocities were similar in the three disorders and within normal limits for our laboratory. The mean MCA VMR values were 37.5+/-24.0%, 27.9+/-28.0% and 38.0+/-33.9% in PD, MSA and PAF, respectively. The VA VMR values were 22.9+/-23.6%, 32.4+/-38.0% and 18.9+/-18.3%, respectively, with no significant differences between the groups. We conclude that BFV is normal in PD, MSA and PAF and that the VMR, as investigated by TCD and the Diamox test, did not disclose differences in cerebral vasomotor responses between these conditions.