Cardiovascular autonomic nervous system evaluation in Parkinson disease and multiple system atrophy

Abnormal brain-heart electrophysiology in mild and severe orthostatic hypotension

INTRODUCTION

This study investigated the changes in cardiocerebral electrophysiology in patients with mild orthostatic hypotension (MOH) and severe orthostatic hypotension (SOH) and their relationship with the severity of orthostatic hypotension, psychiatric symptoms, and cognitive dysfunction.

METHODS

This study included 72 nonorthostatic hypotension (NOH), 17 with MOH, and 11 with SOH. Seated resting-state heart rate variability (HRV) and quantitative electroencephalogram parameters were synchronized and recorded. HRV measures in the time and frequency domains were analyzed, along with the peak frequency and power of the brain waves.

RESULTS

Abnormal neuronal activity was found in FP1 in patients with MOH, whereas it was more widespread in FP1, FP2, and O2 in patients with SOH (P < 0.05). Cardiac and cerebral electrophysiological abnormalities were significantly associated with orthostatic hypotension severity, psychiatric symptoms, and cognitive dysfunction.

CONCLUSION

Abnormal EEG activity in patients are mainly manifested in the prefrontal and occipital lobes, especially in patients with SOH. These results may help patients to better understand the mechanisms underlying orthostatic hypotension severity and psychiatric and cognitive impairment in orthostatic hypotension.

Monitoring autonomic responses in Parkinson's disease individuals: non-linear and chaotic global metrics of heart rate variability

AIM

To examine and compare the autonomic responses, as assessed through the non-linear and chaotic global metrics of heart rate variability in two groups: the Parkinson's Disease Group (PDG) and the Control Group (CG), both at rest and during an active tilt test.

METHODS

The study encompassed 46 participants (PDG: n = 23; 73.73 ± 7.28 years old; CG: n = 23; 70.17 ± 8.20 years old). Initial data collection involved the acquisition of participant's characteristics. The autonomic modulation was estimated both at rest and during the active tilt test. For this assessment, we computed non-linear indices derived from five entropies (Approximate, Sample, Shannon, Renyi, Tsallis), Detrended Fluctuation Analysis and the seven chaotic global metrics (hsCFP1-hsCFP7).

RESULTS

At rest, the PDG exhibited lower values of hsCFP3 (0.818 ± 0.116 vs. 0.904 ± 0.065; p < 0.05) and Sample Entropy (0.720 ± 0.149 vs. 0.799 ± 0.171; p < 0.05). During the test, the PDG demonstrated lower values of ApEn, while the CG presented lower values of SampEn, hsCFP1, hsCFP3, hsCFP7, and higher values of hsCFP5. An interaction was observed, indicating that hsCFP1 and hsCFP3 exhibit differential behavior for the CG and PDG in response to the test.

CONCLUSION

subjects with PD exhibited reduced complexity of the RR interval series at rest, and a diminished autonomic response to the active tilt test when compared with the CG. The test, together with non-linear indices, may serve for assessing the Autonomic Nervous System in individuals with PD in a clinical setting. The interpretation of these data should be approached with caution, given the possible influences of pharmacotherapies and the inclusion of diabetic participants.

Synchronous monitoring of brain-heart electrophysiology using heart rate variability coupled with rapid quantitative electroencephalography in orthostatic hypotension patients with α-synucleinopathies: Rapid prediction of orthostatic hypotension and preliminary exploration of brain stimulation therapy

BACKGROUND

In α-synucleinopathies, the dysfunction of the autonomic nervous system which typically manifests as orthostatic hypotension (OH) often leads to severe consequences and poses therapeutic challenges. This study aims to discover the brain-cardiac electrophysiological changes in OH patients with α-synucleinopathies using the rapid quantitative electroencephalography (qEEG) coupled with heart rate variability (HRV) technique to identify rapid, noninvasive biomarkers for early warning and diagnosis, as well as shed new light on complementary treatment approaches such as brain stimulation targets.

METHODS

In this study, 26 subjects of α-synucleinopathies with OH (α-OH group), 21 subjects of α-synucleinopathies without OH (α-NOH group), and 34 healthy controls (control group) were included from September 2021 to August 2023 (NCT05527067). The heart rate-blood pressure variations in supine and standing positions were monitored, and synchronization parameters of seated resting-state HRV coupled with qEEG were collected. Time-domain and frequency-domain of HRV measures as well as peak frequency and power of the brainwaves were extracted. Differences between these three groups were compared, and correlations between brain-heart parameters were analyzed.

RESULTS

The research results showed that the time-domain parameters such as MxDMn, pNN50, RMSSD, and SDSD of seated resting-state HRV exhibited a significant decrease only in the α-OH group compared to the healthy control group (p < 0.05), while there was no significant difference between the α-NOH group and the healthy control group. Several time-domain and frequency-domain parameters of seated resting-state HRV were found to be correlated with the blood pressure changes within the first 5 min of transitioning from supine to standing position (p < 0.05). Differences were observed in the power of beta1 waves (F4 and Fp2) and beta2 waves (Fp2 and F4) in the seated resting-state qEEG between the α-OH and α-NOH groups (p < 0.05). The peak frequency of theta waves in the Cz region also showed a difference (p < 0.05). The power of beta2 waves in the Fp2 and F4 brain regions correlated with frequency-domain parameters of HRV (p < 0.05). Additionally, abnormal electrical activity in the alpha, theta, and beta1 waves was associated with changes in heart rate and blood pressure within the first 5 min of transitioning from supine to standing position (p < 0.05).

CONCLUSION

Rapid resting-state HRV with certain time-domain parameters below normal levels may serve as a predictive indicator for the occurrence of orthostatic hypotension (OH) in patients with α-synucleinopathies. Additionally, the deterioration of HRV parameters correlates with synchronous abnormal qEEG patterns, which can provide insights into the brain stimulation target areas for OH in α-synucleinopathy patients.

Heart rate variability during sleep in synucleinopathies: a review

Synucleinopathies are a group of neurodegenerative diseases characterized by abnormal accumulations of insoluble alpha-synuclein in neurons or glial cells. These consist of Parkinson's disease (PD), dementia with Lewy bodies (DLB), and multiple system atrophy (MSA). Moreover, idiopathic REM sleep behavior disorder (iRBD) is often the first manifestation of synucleinopathies, demonstrating a pathophysiological continuum. While these disorders vary in prevalence, symptom patterns, and severity, they can all include autonomic nervous system (ANS) dysfunction, which significantly reduces quality of life and worsens prognosis. Consequently, identifying abnormalities of the ANS can provide opportunities for improving quality of life through symptomatic treatments that are tailored to the individual's symptoms. An exciting development is using heart rate variability (HRV) as a non-invasive research tool for analyzing how the ANS regulates physiological processes. HRV during sleep, however, may provide a more accurate and reliable measure of ANS activity than during wakefulness, as during awake time, ANS activity is influenced by a variety of factors, including physical activity, stress, and emotions, which may mask or confound the underlying patterns of ANS activity. This review aims to provide an overview of the current knowledge regarding sleep-related HRV in synucleinopathies and to discuss contributing mechanisms. Evidence suggests that iRBD, PD, and MSA are associated with nocturnal ANS dysfunction. Further, comparative studies indicate that the presence of RBD could exacerbate this abnormality. In contrast, no studies have been conducted in patients with DLB. Overall, this review provides new insight into the complex interplay between the ANS and synucleinopathies and underscores the need for further research in this area to develop effective therapies to improve sleep and overall quality of life in patients with synucleinopathies.

Autonomic and cardiorespiratory responses to the active tilt test in individuals with Parkinson disease: cross-sectional study

BACKGROUND

The Parkinson disease (PD) is frequently associated with autonomic dysfunctions. However, data regarding the influence of PD on the autonomic responses to postural changes is limited.

OBJECTIVE

To analyze and compare the autonomic responses, evaluated through linear and non-linear methods of heart rate variability, and cardiorespiratory parameters in two groups: Parkinson disease (PDG) and control (CG), at rest and during the active tilt test.

METHODS

A total of 48 participants were analyzed (PDG: n = 25;73.40 ± 7.01 years / CG: n = 23;70.17 ± 8.20 years). The autonomic modulation and cardiorespiratory parameters were evaluated at rest and during the active tilt test. To assess the autonomic modulation the linear indices, at the time (rMSSD, SDNN) and frequency (LF, HF, LF/HF) domains, and the non-linear indices, obtained through the Poincaré plot (SD1, SD2, SD1/SD2), were calculated. The cardiorespiratory parameters evaluated were heart rate (HR), systolic (SBP), and diastolic blood pressure (DBP), peripheral oxygen saturation (SpO₂), and respiratory rate.

RESULTS

At rest, the PDG presented significantly lower values of rMSSD, SDNN, LF, HF, SD1, SD2, and DBP, and higher values of SpO₂. During test, in the PD group, modifications were observed in HR, and SBP, besides a reduced parasympathetic response, and an increased global modulation. The qualitative analysis of the Poincaré plot showed that the PDG has a lower dispersion of the RR intervals during rest and the active tilt test.

CONCLUSION

Individuals with PD present reduced global variability and parasympathetic modulation at rest, and reduced parasympathetic response and damage in HR regulation when performing the active tilt test, compared with controls.

Does length of time since diagnosis in Parkinson's disease influence heart rate variability? A cross-sectional study

BACKGROUND

Intrinsic changes in Parkinson's disease (PD) affect the autonomic nervous system, and the disease course can aggravate the initial condition. Although the impact of time since disease onset on autonomic modulation has already been studied in other populations, this has not yet been investigated in PD.

OBJECTIVE

To investigate the impact of the length of time since diagnosis on the cardiac autonomic modulation of individuals with PD and compare with healthy individuals.

METHODS

Fifty participants were divided into three groups: a control group (CG; n = 24) and two groups with PD, divided according to the median length of time since diagnosis (median = 5.5 years): below the median (PG1; n = 13) and above the median (PG2; n = 13). To evaluate cardiac autonomic modulation, heart rate was obtained beat-to-beat in the supine position over a 30-min period, and heart rate variability (HRV) indices were calculated using linear methods in the time and frequency domains.

RESULTS

There were no significant differences in HRV indices between the PG groups, or between the three groups regarding Mean RR, LFun, HFun and LF/HF ratio. Significant reductions in the RMSSD, SDNN, pNN50, LFms2 and HFms2 indices were observed in PG1 and PG2, compared with CG.

CONCLUSIONS

The cardiac autonomic modulation of individuals with PD was not influenced by the time since diagnosis. However, reduced parasympathetic and global modulation were observed in these individuals, compared with controls. These results emphasize the importance of aerobic exercise for improving autonomic modulation among individuals with PD.

Analysis of Cardiovascular Hemodynamic and Autonomic Variables in Individuals with Systemic Arterial Hypertension, Type 2 Diabetes Mellitus, and Parkinson's Disease: A Comparative Study

BACKGROUND

Systemic arterial hypertension (SAH), type 2 diabetes mellitus (T2DM), and Parkinson's disease (PD) are highly prevalent chronic diseases that can significantly impact the cardiovascular system.

AIM

The aim of this study was to compare hemodynamic and autonomic variables at rest in individuals with SAH, T2DM, or PD.

METHODS

Fifty sedentary or insufficiently active individuals (22 men) with SAH (age = 66 ± 5.0 yr), T2DM (age = 52 ± 10 yr) or PD (age = 68 ± 8.0 yr) had their resting blood pressure (BP), arterial stiffness, endothelial function, and heart rate variability (HRV) assessed and compared.

RESULTS

Systolic and diastolic BP were higher in SAH (130 ± 10 / 80 ± 10 mmHg) than T2DM (110 ± 14 / 75 ± 11 mmHg) and PD, and (123 ± 20 / 70 ± 11 mmHg) respectively. T2DM individuals showed lower arterial stiffness (8.4 ± 1.1 m/s), when compared to SAH (10.3 ± 2.3 m/s) and PD (10.6 ± 3.0 m/s). T2DM had greater resting tachycardia showed by the mean RR (759 ± 79 ms), than SAH (962 ± 169 ms) and PD (976 ± 134 ms), which was accompanied by higher sympathetic modulation (low frequency [LF]: 62 ± 19 nu) and lower parasympathetic modulation (high frequency [HF]: 32 ± 16 nu) when compared to SAH (LF: 40 ± 16 nu; HF: 61 ± 33 nu). No differences among groups were found on non-linear HRV markers and endothelial reactivity indexes.

CONCLUSIONS

Individuals with T2DM showed impaired levels of cardiac autonomic markers when compared to individuals with SAH and PD, despite of having lower levels of BP and arterial stiffness.

The importance of heart rate variability in predicting cardiac autonomic dysfunction in patients with amyotrophic lateral sclerosis

AIM

Amyotrophic lateral sclerosis (ALS) is a progressive disease characterized by degeneration in the upper and lower motor neurons of the corticospinal tract, brain stem, and spinal cord. Recent studies have revealed that the disease does not present solely with motor neuron involvement. Accordingly, the aim of this study is to investigate the presence of cardiac autonomic impairment in patients diagnosed with ALS.

MATERIAL AND METHOD

A total of 61 patients, who were diagnosed with ALS according to the Revised El Escorial Criteria (R-EEC), were included in this prospective study, in addition to the 29 healthy individuals, who were included in the study as controls. In order to assess the cardiac autonomic involvement, the presence of orthostatic hypotension was investigated, and transthoracic echocardiography and 24-hour electrocardiogram (ECG) using a Holter monitor were performed.

RESULTS

Orthostatic hypotension was detected in 14 (22.2%) patients. Holter electrocardiogram results of the patient group revealed statistically significantly lower heart rate variability (HRV) indicators in the time domain (SDNN, SDANN, SDNN index, rMSSD, and pNN50) and in the frequency domain (high frequency [HF], low frequency [LF], and very low frequency [VLF]) than those of the control group (P < .05).

CONCLUSION

Contrary to the popular opinion, cardiac autonomic dysfunction in patients with ALS can occur at any stage of the disease. Therefore, it is recommended that the patients are evaluated via periodic examinations during the follow-up period for cardiac autonomic involvement.

Early recognition and diagnosis of multiple system atrophy: best practice and emerging concepts

Introduction: Multiple system atrophy (MSA) is a progressive degenerative disorder of the central and autonomic nervous systems characterized by parkinsonism, cerebellar ataxia, dysautonomia, and pyramidal signs. The confirmatory diagnosis is pathological, but clinical-diagnostic criteria have been developed to help clinicians. To date, the early diagnosis of MSA is challenging due to the lack of reliable diagnostic biomarkers.Areas covered: The authors reappraised the main clinical, neurophysiological, imaging, genetic, and laboratory evidence to help in the early diagnosis of MSA in the clinical and in the research settings. They also addressed the practical clinical issues in the differential diagnosis between MSA and other parkinsonian and cerebellar syndromes. Finally, the authors summarized the unmet needs in the early diagnosis of MSA and proposed the next steps for future research efforts in this field.Expert opinion: In the last decade, many advances have been achieved to help the correct MSA diagnosis since early stages. In the next future, the early diagnosis and correct classification of MSA, together with a better knowledge of the causative mechanisms of the disease, will hopefully allow the identification of suitable candidates to enroll in clinical trials and select the most appropriate disease-modifying strategies to slow down disease progression.

Heart Rate Variability Analyses in Parkinson's Disease: A Systematic Review and Meta-Analysis

Recent evidence suggests that the vagus nerve and autonomic dysfunction play an important role in the pathogenesis of Parkinson's disease. Using heart rate variability analysis, the autonomic modulation of cardiac activity can be investigated. This meta-analysis aims to assess if analysis of heart rate variability may indicate decreased parasympathetic tone in patients with Parkinson's disease. The MEDLINE, EMBASE and Cochrane Central databases were searched on 31 December 2020. Studies were included if they: (1) were published in English, (2) analyzed idiopathic Parkinson's disease and healthy adult controls, and (3) reported at least one frequency- or time-domain heart rate variability analysis parameter, which represents parasympathetic regulation. We included 47 studies with 2772 subjects. Random-effects meta-analyses revealed significantly decreased effect sizes in Parkinson patients for the high-frequency spectral component (HFms²) and the short-term measurement of the root mean square of successive normal-to-normal interval differences (RMSSD). However, heterogeneity was high, and there was evidence for publication bias regarding HFms². There is some evidence that a more advanced disease leads to an impaired parasympathetic regulation. In conclusion, short-term measurement of RMSSD is a reliable parameter to assess parasympathetically impaired cardiac modulation in Parkinson patients. The measurement should be performed with a predefined respiratory rate.

Parkinson's disease effect on autonomic modulation: an analysis using geometric indices

BACKGROUND

Parkinson's disease (PD) produces autonomic changes, indicating lower parasympathetic modulation and global variability, but these changes need further studying regarding geometric methods.

OBJECTIVE

To investigate the autonomic modulation in individuals with PD using heart rate variability (HRV) indices obtained through geometric methods.

METHODS

This is a cross-sectional study that assessed 50 individuals, split into two groups: PD group (PDG; n=26; 75.36±5.21 years) and control group (CG; n=24; 75.36±5.21 years). We evaluated the autonomic modulation by measuring the heart rate beat-to-beat for 30 min with the individual in supine rest using a heart rate monitor and assessed geometric indices (RRtri, TINN, SD1, SD2, SD1/SD2 ratio, and qualitative analysis of the Poincaré plot).

RESULTS

Significant reductions were found in RRtri, TINN, SD1, and SD2 indices among PDG compared to CG. Regarding the SD1/SD2 ratio, no significant changes were detected between the groups. The Poincaré plot demonstrated that individuals with PD had lower beat-to-beat dispersion in RR intervals, in addition to greater long-term dispersion of RR intervals compared to CG.

CONCLUSIONS

The results suggest a reduction in the parasympathetic autonomic modulation and global variability in individuals with PD compared to controls, regardless of sex, age, and body mass index.

Cardiovascular autonomic function testing in multiple system atrophy and Parkinson's disease: an expert-based blinded evaluation

PURPOSE

Multiple system atrophy (MSA) and Parkinson's disease (PD) are sporadic neurodegenerative diseases characterized by an accumulation of misfolded α-synuclein. Cardiovascular autonomic failure develops in both MSA and PD, although studies indicate different sites of autonomic nervous system lesion. However, it is unclear whether this could potentially aid the differential diagnosis of these diseases. Here we determined whether cardiovascular autonomic function testing (CAFT) can discriminate between the parkinsonian variant of MSA (MSA-P) and PD based on either an expert-based blinded evaluation or a systematic comparison of cardiovascular autonomic function indices.

METHODS

We included 22 patients aged 55-80 with neurogenic orthostatic hypotension (nOH) who had been diagnosed with either clinically probable MSA-P (n = 11) according to current consensus criteria or clinically definite PD (n = 11) according to the Queen Square criteria. Three physicians with expertise in CAFT were blinded to the neurological diagnosis and were asked to identify the correct neurological diagnosis by applying a self-created evaluation scheme to the CAFT recordings. Afterwards, a systematic comparison of clinical-demographic characteristics and CAFT parameters was carried out.

RESULTS

Neither the raters (overall diagnostic accuracy: 58.46%) nor the evaluation scheme created post hoc (72.73%) showed reliable discriminatory capacity. The inter-rater reliability was slight (κ = 0.01). We observed no statistically significant differences in cardiovascular autonomic indices between PD and MSA-P patients.

CONCLUSION

CAFT is the gold standard for assessing the presence and severity of cardiovascular autonomic failure, but the results of our pilot study suggest that CAFT might be of limited value in the differential diagnosis between MSA-P and PD once nOH is present.

Role of circular RNAs in brain development and CNS diseases

In mammals, many classes of noncoding RNAs (ncRNAs) are expressed at a much higher level in the brain than in other organs. Recent studies have identified a new class of ncRNAs called circular RNAs (circRNAs), which are produced by back-splicing and fusion of either exons, introns, or both exon-intron into covalently closed loops. The circRNAs are also highly enriched in the brain and increase continuously from the embryonic to the adult stage. Although the functional significance and mechanism of action of circRNAs are still being actively explored, they are thought to regulate the transcription of their host genes and sequestration of miRNAs and RNA binding proteins. Some circRNAs are also shown to have translation potential to form peptides. The expression and abundance of circRNAs seem to be spatiotemporally maintained in a normal brain. Altered expression of circRNAs is also thought to mediate several disorders, including brain-tumor growth, and acute and chronic neurodegenerative disorders by affecting mechanisms such as angiogenesis, neuronal plasticity, autophagy, apoptosis, and inflammation. This review discusses the involvement of various circRNAs in brain development and CNS diseases. A better understanding of the circRNA function will help to develop novel therapeutic strategies to treat CNS complications.

Central modulation of parasympathetic outflow is impaired in de novo Parkinson's disease patients

Task- and stimulus-based neuroimaging studies have begun to unveil the central autonomic network which modulates autonomic nervous system activity. In the present study, we aimed to evaluate the central autonomic network without the bias constituted by the use of a task. Additionally, we assessed whether this circuitry presents signs of dysregulation in the early stages of Parkinson’s disease (PD), a condition which may be associated with dysautonomia. We combined heart-rate-variability based methods for time-varying assessments of the autonomic nervous system outflow with resting-state fMRI in 14 healthy controls and 14 de novo PD patients, evaluating the correlations between fMRI time-series and the instantaneous high-frequency component of the heart-rate-variability power spectrum, a marker of parasympathetic outflow. In control subjects, the high-frequency component of the heart-rate-variability power spectrum was significantly anti-correlated with fMRI time-series in several cortical, subcortical and brainstem regions. This complex central network was not detectable in PD patients. In between-group analysis, we found that in healthy controls the brain activation related to the high-frequency component of the heart-rate-variability power spectrum was significantly less than in PD patients in the mid and anterior cingulum, sensorimotor cortex and supplementary motor area, insula and temporal lobe, prefrontal cortex, hippocampus and in a region encompassing posterior cingulum, precuneus and parieto-occipital cortex. Our results indicate that the complex central network which modulates parasympathetic outflow in the resting state is impaired in the early clinical stages of PD.

Reverse blood pressure dipping as marker of dysautonomia in Parkinson disease

INTRODUCTION

We sought to evaluate if the presence of abnormal circadian loss of nocturnal blood pressure dipping (reverse dipping) is associated with cardiovascular dysautonomia, a major source of morbidity in Parkinson disease.

METHODS

Consecutive Parkinson disease patients were enrolled in this cross-sectional study between January 2015 and June 2017. All subjects underwent same-day autonomic testing and 24-h ambulatory blood pressure monitoring. Cardiovascular dysautonomia was defined by the presence of at least one moderate or severe cardiovagal and adrenergic test abnormality.

RESULTS

We recruited 114 PD patients (79 males; mean age 64 ± 10 years; disease duration 6 ± 4 years). Cardiovascular dysautonomia was present in 32% (36/114). The blood pressure patterns were normal dipping in 28.9% (n = 33), extreme dipping in 6.1% (n = 7), reduced dipping in 32.5% (n = 37), and reverse dipping in 32.5% (n = 37). Reverse dipping was disproportionately prevalent in subjects with cardiovascular dysautonomia (69% vs 15%, p < 0.001). The diagnostic accuracy of reverse dipping in discriminating cardiovascular dysautonomia (AUC 0.791, specificity 84%, sensitivity 69%) was higher than that of bedside blood pressure ascertainment of neurogenic orthostatic hypotension (0.681, 66%, 69%) and supine hypertension (0.641, 78%, 50%).

CONCLUSIONS

Reverse nocturnal blood pressure dipping is a marker of cardiovascular dysautonomia in Parkinson disease, which can be screened for with ease and affordability using ambulatory blood pressure monitoring.

Early differentiation of dementia with Lewy bodies and Alzheimer's disease: Heart rate variability at mild cognitive impairment stage

OBJECTIVE

Our study aimed to investigate whether heart rate variability (HRV) could be a useful diagnostic screening tool at MCI (mild cognitive impairment) stage of Dementia with Lewy bodies (DLB) from Alzheimer's disease (AD).

METHODS

This retrospective study used a selected sample from Ajou neurological registry. We identified MCI patients who underwent HRV testing at baseline, and who developed probable DLB (MCI-DLB: n = 23) or AD (MCI-AD: n = 32).

RESULTS

The MCI-DLB group exhibited significantly lower levels of almost all HRV parameters compared with the MCI-AD group. Fronto-executive function and visuospatial abilities were poorer in the MCI-DLB group, whereas the extent of verbal memory impairment was greater in the MCI-AD. Verbal memory score was negatively correlated with overall HRV parameters, and visuospatial function was positively correlated with the frequency domain of HRV. Receiver operating curve area under the curve (AUC) analysis revealed that the low frequency component was the best potential diagnostic marker (AUC = 0.88).

CONCLUSION

MCI-DLB patients exhibited greater cardiac autonomic dysfunction (as measured by HRV) and greater fronto-executive and visuospatial deficit compared with MCI-AD patients.

SIGNIFICANCE

HRV may be useful method to differentiate DLB from AD in patients with MCI; this would facilitate early disease-specific intervention.

Evaluation of autonomic functions of patients with multiple system atrophy and Parkinson's disease by head-up tilt test

The aim of this study was to evaluate the autonomic neural function in Parkinson's disease (PD) and multiple system atrophy (MSA) with head-up tilt test and spectral analysis of cardiovascular parameters. This study included 15 patients with MSA, 15 patients with PD, and 29 healthy control (HC) subjects. High frequency power of the RR interval (RR-HF), the ratio of low frequency power of RR interval to RR-HF (RR-LF/HF) and LF power of systolic BP were used to evaluate parasympathetic, cardiac sympathetic and vasomotor sympathetic functions, respectively. Both patients with PD and MSA showed orthostatic hypotension and lower parasympathetic function (RR-HF) at tilt position as compared to HC subjects. Cardiac sympathetic function (RR-LF/HF) was significantly high in patients with PD than MSA at supine position. RR-LF/HF tended to increase in MSA and HC, but decreased in PD by tilting. Consequently, the change of the ratio due to tilting (ΔRR-LF/HF) was significantly lower in patients with PD than in HC subjects. Further analysis showed that compared to mild stage of PD, RR-LF/HF at the supine position was significantly higher in advanced stage. By tilting, it was increased in mild stage and decreased in the advanced stage of PD, causing ΔRR-LF/HF to decrease significantly in the advanced stage. Thus, we demonstrated that spectral analysis of cardiovascular parameters is useful to identify sympathetic and parasympathetic disorders in MSA and PD. High cardiac sympathetic function at the supine position, and its reduction by tilting might be a characteristic feature of PD, especially in the advanced stage.

Nonmotor Features in Atypical Parkinsonism

Atypical parkinsonism (AP) comprises mainly multiple system atrophy (MSA), progressive supranuclear palsy (PSP), and corticobasal degeneration (CBD), which are distinct pathological entities, presenting with a wide phenotypic spectrum. The classic syndromes are now called MSA-parkinsonism (MSA-P), MSA-cerebellar type (MSA-C), Richardson's syndrome, and corticobasal syndrome. Nonmotor features in AP have been recognized almost since the initial description of these disorders; however, research has been limited. Autonomic dysfunction is the most prominent nonmotor feature of MSA, but also gastrointestinal symptoms, sleep dysfunction, and pain, can be a feature. In PSP and CBD, the most prominent nonmotor symptoms comprise those deriving from the cognitive/neuropsychiatric domain. Apart from assisting the clinician in the differential diagnosis with Parkinson's disease, nonmotor features in AP have a big impact on quality of life and prognosis of AP and their treatment poses a major challenge for clinicians.

Sympathetic skin response and heart rate variability in predicting autonomic disorders in patients with Parkinson disease

The purpose of this study was to evaluate sympathetic skin response (SSR) and heart rate variability (HRV) in determining autonomic nervous system (ANS) involvement in patients with Parkinson disease (PD). Forty-eight idiopathic PD patients and 30 healthy controls participated in this study. SSR, HRV, Unified Parkinson's Disease Rating Scale (UPDRS) III, the Scales for outcomes in Parkinson's Disease-Autonomic (SCOPA-AUT), Hoehn and Yahr (H&Y) scale were evaluated. Absent lower limb SSR was determined unilaterally in 2, bilaterally in 1 of 3 advanced PD patients; there was significant difference between PD and control groups in terms of the SSR (P < 0.01), significant prolonged SSR latencies and decreased SSR amplitudes from bilateral hands and feet. Significant difference was noted in HRV between PD and control groups except for root mean square of successive differences (rMSSD) and high-frequency (HF) power (P < 0.05). There was a significant different correlation between the parameters of SSR and the SCOPA-AUT, and between the parameters (except HF power) of HRV and the SCOPA-AUT. Some parameters of SSR were relevantly associated with HRV. The right hand SSR amplitude correlated positively with the (SD) of all R-R interval, total spectral power, very low frequency. The right foot amplitude correlated positively with total spectral power. Both SSR and HRV parameters are sensitive in determining ANS dysfunction not only in late but also in the early stage of PD, which can be used for early detection of autonomic dysfunction in patients with PD and have the potential to serve as electrophysiological markers of dysautonomia of PD.

Heart rate variability to differentiate essential tremor from early-stage tremor-dominant Parkinson's disease

BACKGROUND

Essential tremor (ET) and Parkinson's disease (PD) are the most common movement disorders in the elderly, but it is difficult to differentiate ET from early-stage tremor-dominant Parkinson's disease (TDPD).

METHODS

We investigated heart rate variability (HRV) in 23 patients with ET, 27 patients with TDPD, and 23 healthy controls. HRV was determined using the RR intervals of a 5-min electrocardiogram recording. Measurements of beat-to-beat RR variability, including time domains [(standard deviation of the normal-to-normal RR interval (SDNN), and the root mean square difference of successive RR intervals (RMSSD)] and frequency domains [low-frequency (LF) and high-frequency (HF) components and total spectral power (TP)], were assessed retrospectively.x

RESULTS

In the TDPD group, SDNN, LF, HF, and TP were significantly lower than those in the ET group. In a receiver operating characteristic area under the curve (AUC) analysis, LF was the best potential diagnostic marker (AUC=0.87).

CONCLUSION

Non-invasive and routine electrocardiography may be helpful in differentiating ET from TDPD during the early disease stage.

Lesion of medullary catecholaminergic neurons is associated with cardiovascular dysfunction in rotenone-induced Parkinson's disease rats

In recent years, non-motor symptoms have been recognised as of vital importance in Parkinson's disease (PD); among these, cardiovascular dysfunctions are commonly seen in PD patients before their motor signs. The role of cardiovascular dysfunction in the progression of PD pathology, and its underlying mechanisms, are largely unknown. In the present study, in rotenone-induced PD rats, there was a gradual reduction in the number of nigral tyrosine hydroxylase-immunoreactive (TH-ir) neurons after 7, 14 and 21 days treatment. With the 56% reduction in striatal dopamine content and 52% loss of TH-ir neurons on the 14th day, the rats showed motor dysfunctions. However, from ECG power spectra, reductions in normalised low-frequency power and in the low-frequency power : high-frequency power ratio, as well as in mean blood pressure, were observed as early as the 3rd day. Plasma norepinephrine (NE) and epinephrine (E) levels were decreased by 39% and 26% respectively at the same time. Pearson's correlation analysis showed that both plasma NE and plasma E levels were positively correlated with MBP. Our results also showed that the loss of catecholaminergic neurons in the rostral ventrolateral medulla (RVLM), but not in the caudal ventrolateral medulla or the nucleus tractus solitarii, emerged earlier than the loss of nigral dopaminergic neurons. This suggests that dysfunction of catecholaminergic neurons in the RVLM might account for the reduced sympathetic activity, MBP and plasma catecholamine levels in the early stages of PD.

Atypical parkinsonism: diagnosis and treatment

Atypical parkinsonism comprises typically progressive supranuclear palsy, corticobasal degeneration, and mutilple system atrophy, which are distinct pathologic entities; despite ongoing research, their cause and pathophysiology are still unknown, and there are no biomarkers or effective treatments available. The expanding phenotypic spectrum of these disorders as well as the expanding pathologic spectrum of their classic phenotypes makes the early differential diagnosis challenging for the clinician. Here, clinical features and investigations that may help to diagnose these conditions and the existing limited treatment options are discussed.

Cardiovascular neural regulation is impaired in amyotrophic lateral sclerosis patients. A study by spectral and complexity analysis of cardiovascular oscillations

Although the clinical hallmark of amyotrophic lateral sclerosis (ALS) is a progressive motor weakness, different combinations of autonomic nervous system (ANS) dysfunction have been described. No clear correlation between ANS abnormalities and ALS clinical characteristics has been found so far. We investigated the cardiovascular neural regulation in ALS with a non-invasive methodology, using spectral and complexity analysis of heart rate variability (HRV) and systolic arterial pressure (SAP) variability. In all patients, we found low RR variance and an altered response to orthostasis, witnessed by the indices derived from both spectral and complexity analysis of HRV and SAP variability. Besides, we identified two groups with distinct autonomic profiles at rest, those with higher, and those with lower cardiac sympathetic activity. In both groups the cardiovascular response to tilting was impaired. Our study outlined that ANS is invariably impaired in ALS, and patients can present with different baseline patterns. Our findings suggest important pathophysiological, clinical and prognostic insights. The presence of different autonomic profiles at rest supports the new concept of ALS as a multisystem disorder with phenotypic heterogeneity. Our results are also relevant in clinical practice. They can help to improve patients' management, and to identify prognostic factors.

Cardiovascular autonomic testing performed with a new integrated instrumental approach is useful in differentiating MSA-P from PD at an early stage

OBJECTIVE

To evaluate whether a battery of cardiovascular autonomic tests (Ewing's battery, EB) performed with a new integrated instrumental approach is useful in differentiating multiple system atrophy with predominant parkinsonism (MSA-P) from Parkinson's disease (PD) at an early stage.

METHODS

We retrospectively analyzed EB tests of all the patients (n = 99) with a parkinsonian syndrome referred to our clinic who performed EB during the first diagnostic workup and were subsequently evaluated at least once a year until a final diagnosis of MSA-P (n = 34) or PD (n = 65). Thirty-eight controls matched for age and sex were included. EB consisted of head-up tilt test (HUTT), Valsalva manoeuvre (VM), deep breathing, and sustained handgrip whose correct execution and results were checked and obtained automatically. Results were compared between groups. Discriminant analysis was performed to identify MSA-P or PD patients.

RESULTS

Orthostatic hypotension was found in 22 MSA-P and 3 PD patients. Cardiovascular reflexes indices were significantly more affected in MSA-P compared to PD and controls. EB presented a 91% sensitivity and 94% specificity in the differentiation of MSA-P and PD. HUTT + VM presented a 91% sensitivity and 92% specificity.

CONCLUSIONS

Our results suggest that EB or HUTT + VM performed with an integrated instrumental approach and analyzed with the discriminant procedure may distinguish MSA-P from PD at an early stage and might improve the accuracy of current diagnostic criteria. However, a validation in separate samples and prospective studies is needed.

Time- and frequency-domain parameters of heart rate variability and sympathetic skin response in Parkinson's disease

The autonomic nervous system (ANS) is regularly affected in Parkinson's disease (PD). Information on autonomic dysfunction can be derived from e.g. altered heart rate variability (HRV) and sympathetic skin response (SSR). Such parameters can be quantified easily and measured repeatedly which might be helpful for evaluating disease progression and therapeutic outcome. In this 2-center study, HRV and SSR of 45 PD patients and 26 controls were recorded. HRV was measured during supine metronomic breathing and analyzed in time- and frequency-domains. SSR was evoked by repetitive auditory stimulation. Various ANS parameters were compared (1) between patients and healthy controls, (2) to clinical scales (Unified Parkinson's disease rating scale, Mini-Mental State Examination, Becks Depression Inventory), and (3) to disease duration. Root mean square of successive differences (RMSSD) and low frequency/high frequency (LF/HF) ratio differed significantly between PD and controls. Both, HRV and SSR parameters showed low or no association with clinical scores. Time-domain parameters tended to be affected already at early PD stages but did not consistently change with longer disease duration. In contrast, frequency-domain parameters were not altered in early PD phases but tended to be lower (LF, LF/HF ratio), respectively higher (HF) with increasing disease duration. This report confirms previous results of altered ANS parameters in PD. In addition, it suggests that (1) these ANS parameters are not relevantly associated with motor, behavioral, and cognitive changes in PD, (2) time-domain parameters are useful for the assessment of early PD, and (3) frequency-domain parameters are more closely associated with disease duration.