Orthostatic hypotension in patients with Parkinson's disease: pathophysiology and management

Parkinson's disease updates: Addressing the pathophysiology, risk factors, genetics, diagnosis, along with the medical and surgical treatment

After only Alzheimer's disease (AD), Parkinson's disease (PD) is the second most prevalent neurodegenerative disease. The incidence of this disease increases with age, especially for those above 70 years old. There are many risk factors that are well-established in the contribution to the development of PD, such as age, gender, ethnicity, rapid eye movement sleep disorder, high consumption of dairy products, traumatic brain injury, genetics, and pesticides/herbicides. Interestingly, smoking, consumption of caffeine, and physical activities are the protective factors of PD. A deficiency of dopamine in the substantia nigra of the brainstem is the main pathology. This, subsequently, alters the neurotransmitter, causing an imbalance between excitatory and inhibitory signals. In addition, genetics is also involved in the pathogenesis of the disease. As a result, patients exhibit characteristic motor symptoms such as tremors, stiffness, bradykinesia, and postural instability, along with non-motor symptoms, including dementia, urinary incontinence, sleeping disturbances, and orthostatic hypotension. PD may resemble other diseases; therefore, it is important to pay attention to the diagnosis criteria. Parkinson's disease dementia can share common features with AD; this can include behavioral as well as psychiatric symptoms, in addition to the pathology being protein aggregate accumulation in the brain. For PD management, the administration of pharmacological treatment depends on the motor symptoms experienced by the patients. Non-pharmacological treatment plays a role as adjuvant therapy, while surgical management is indicated in chronic cases. This paper aims to review the etiology, risk factors, protective factors, pathophysiology, signs and symptoms, associated conditions, and management of PD.

Detecting and treating the protean manifestations of diabetic autonomic neuropathy

The manifestations of diabetic autonomic neuropathy (DAN) are protean and clinically involve multiple systems, including the cardiovascular system, the gastrointestinal system, the genitourinary system as well as the sweat glands (sudomotor dysfunction) and the gallbladder. In addition, cardiac autonomic neuropathy (CAN) is associated with a correctible inability to appreciate and correct hypoglycaemia. While not a clinical problem, pupillary involvement should be the clue and the catalyst to investigate for other manifestations of DAN. This review outlines a practical approach to detecting and investigating the manifestations of DAN. Of particular importance is early detection of cardiovascular involvement where prompt therapy through glycaemic control can decrease the severity of CAN and decelerate the frequency and severity of retinopathy and nephropathy in addition to decreasing cardiovascular events and mortality. CAN also plays a role in accelerating other diabetic complications such as acute ischaemic stroke, heart failure, medial artery calcinosis, foot ulcers, peripheral artery disease and Charcot joints. Many therapies of DAN are available, which should not only decrease morbidity and mortality from DAN, but also improve the patient's quality of life. However, the therapies available are largely symptomatic.

Abnormal circadian blood pressure regulation and cognitive impairment in α-synucleinopathies

Circadian blood pressure (BP) rhythm is important for the maintenance of healthy daily life, and its disruption is associated with poor outcomes. Cardiovascular autonomic failure is often observed in older populations but has a greater impact on neurodegenerative disorders such as α-synucleinopathies. These BP abnormalities include orthostatic hypotension (OH), supine hypertension (SH), and a loss of nocturnal BP fall. OH not only causes falls or syncope but is also related to cognitive impairment in α-synucleinopathies. For example, OH doubles or triples the risk for the development of cognitive impairment in Parkinson's disease (PD). The diffuse central and peripheral neuropathology of α-synuclein may contribute to both OH and cognitive impairment. Moreover, repeated cerebral hypoperfusion in OH is thought to be related to cerebrovascular and neuronal damage, which may cause cognitive impairment. SH, which often coexists with OH, is also associated with cognitive impairment through cerebrovascular damage, such as white matter lesions and cerebral microbleeds. The reverse-dipping (riser) pattern on ambulatory BP monitoring is commonly observed in PD (∼56%), regardless of disease duration and severity. It is also related to cognitive impairment and more pronounced when coexisting with OH. These abnormal circadian BP profiles may be synergistically associated with cognitive impairment and poor outcomes in α-synucleinopathies. Although evidence for aggressive control of BP dysregulation improving cognitive impairment and outcomes is limited, regular BP monitoring appears to be important for total management of α-synucleinopathies.

Vestibular syncope: clinical characteristics and mechanism

Background and Objectives

Vestibular syncope is a condition in which vertigo‐induced hemodynamic changes cause syncope. This study investigated the clinical and laboratory findings of vestibular syncope and tried to refine our knowledge of the mechanism underlying this newly recognized entity.

Methods

This study retrospectively analyzed 53 patients (33 women, median age = 63 years [interquartile range = 54–71 years]) with vestibular syncope from January 2017 to December 2021. To explain the mechanism of vestibular syncope, we incorporated a velocity‐storage model into the dual reflex pathways comprising the vestibulo‐sympathetic reflex and baroreflex and predicted the cardiovascular responses.

Results

Twenty (37.7%) patients had multiple episodes of vestibular syncope, and seven (13.2%) had potentially life‐threatening injuries. Meniere's disease (20.8%) and benign paroxysmal positional vertigo (9.4%) were the most common underlying vestibular disorders. Abnormal vestibular function tests included impaired cervical vestibular‐evoked myogenic potentials (57.5%) and positive head impulse tests (31.0%). Orthostatic hypotension was found in 19.5% of patients. Dyslipidemia (30.2%) and hypertension (28.3%) were common medical comorbidities. The dual reflex pathways incorporating the function of the velocity‐storage circuit in the brainstem and cerebellum suggest that vestibular syncope is a neurally mediated reflex syncope associated with a sudden hemodynamic change during vertigo. This change can be arterial hypertension triggered by a false downward inertial cue, as suggested previously, or hypotension driven by a false upward inertial cue.

Conclusions

Vestibular syncope is associated with various vestibular disorders and requires careful evaluation and intervention to prevent recurrent falls and significant injuries.

Istradefylline for OFF Episodes in Parkinson’s Disease: A US Perspective of Common Clinical Scenarios

The effective management of OFF episodes remains an important unmet need for patients with Parkinson’s disease (PD) who develop motor complications with long-term levodopa therapy. Istradefylline is a selective adenosine A_2A receptor antagonist for the treatment of patients with PD experiencing OFF episodes while on levodopa/decarboxylase inhibitor. Originally approved in Japan, istradefylline was recently approved in the USA. In this article, we provide a specific review of the four clinical studies that the FDA included in the approval of istradefylline in the USA, and discuss common clinical scenarios, based on our experience, where treatment with istradefylline may benefit patients experiencing motor fluctuations.

The role of basket trials in drug development for neurodegenerative disorders

Background

Drug development for neurodegenerative disorders (NDDs) is a long, complex, and expensive enterprise. Methods to optimize drug development for NDDs are needed. Basket trials have been widely used in oncology and have been promoted by the Food and Drug Administration as a means of enhancing the efficiency of drug development.

Discussion

We reviewed clinical trials for NDDs registered on clinicaltrials.gov in the past 10 years. We identified 59 basket trials assessing the impact of treatment on more than one NDD in the trial. Forty-one of the trials were for 25 agents addressing symptoms of NDD such as motor impairment, hypotension, or psychosis. Eighteen of the trials assessed 14 disease-modifying therapies; the principal targets were mitochondrial function, tau biology, or alpha-synuclein aggregation. Basket trials are most common in phase 2 but have been conducted in phase 1, phase 3, and phase 4. The duration and size of the basket trials are highly variable depending on their developmental phase and the intent of the trial. Parkinson’s disease was the most common disorder included in basket trials of symptomatic agents, and Alzheimer’s disease was the most common disorder included in basket trials of disease-modifying therapies. Most of the basket trials of symptomatic agents were sponsored by pharmaceutical companies (29 of 41 trials); similarly, most of the basket trials investigating DMTs in basket trials were sponsored by the biopharmaceutical industry (11/17 trials).

Conclusions

Basket trials may increase drug development efficiency by reducing redundancy in trial implementation, enhancing recruitment, sharing placebo groups, and using biomarkers relevant to the mechanism of action of the treatment across NDDs. There have been relatively few basket trials including multiple NDDs in the same trial conducted over the past 10 years. The use of the basket trial strategy may represent an opportunity to increase the efficiency of development programs for agents to treat NDDs.

Cardiac Changes in Parkinson's Disease: Lessons from Clinical and Experimental Evidence

Dysautonomia is a common non-motor symptom in Parkinson's disease (PD). Most dysautonomic symptoms appear due to alterations in the peripheral nerves of the autonomic nervous system, including both the sympathetic and parasympathetic nervous systems. The degeneration of sympathetic nerve fibers and neurons leads to cardiovascular dysfunction, which is highly prevalent in PD patients. Cardiac alterations such as orthostatic hypotension, heart rate variability, modifications in cardiogram parameters and baroreflex dysfunction can appear in both the early and late stages of PD, worsening as the disease progresses. In PD patients it is generally found that parasympathetic activity is decreased, while sympathetic activity is increased. This situation gives rise to an imbalance of both tonicities which might, in turn, promote a higher risk of cardiac damage through tachycardia and vasoconstriction. Cardiovascular abnormalities can also appear as a side effect of PD treatment: L-DOPA can decrease blood pressure and aggravate orthostatic hypotension as a result of a negative inotropic effect on the heart. This unwanted side effect limits the therapeutic use of L-DOPA in geriatric patients with PD and can contribute to the number of hospital admissions. Therefore, it is essential to define the cardiac features related to PD for the monitorization of the heart condition in parkinsonian individuals. This information can allow the application of intervention strategies to improve the course of the disease and the proposition of new alternatives for its treatment to eliminate or reverse the motor and non-motor symptoms, especially in geriatric patients.

The Pathogenesis and Treatment of Cardiovascular Autonomic Dysfunction in Parkinson's Disease: What We Know and Where to Go

Cardiovascular autonomic dysfunctions (CAD) are prevalent in Parkinson’s disease (PD). It contributes to the development of cognitive dysfunction, falls and even mortality. Significant progress has been achieved in the last decade. However, the underlying mechanisms and effective treatments for CAD have not been established yet. This review aims to help clinicians to better understand the pathogenesis and therapeutic strategies. The literatures about CAD in patients with PD were reviewed. References for this review were identified by searches of PubMed between 1972 and March 2021, with the search term “cardiovascular autonomic dysfunctions, postural hypotension, orthostatic hypotension (OH), supine hypertension (SH), postprandial hypotension, and nondipping”. The pathogenesis, including the neurogenic and non-neurogenic mechanisms, and the current pharmaceutical and non-pharmaceutical treatment for CAD, were analyzed. CAD mainly includes four aspects, which are OH, SH, postprandial hypotension and nondipping, among them, OH is the main component. Both non-neurogenic and neurogenic mechanisms are involved in CAD. Failure of the baroreflex circulate, which includes the lesions at the afferent, efferent or central components, is an important pathogenesis of CAD. Both non-pharmacological and pharmacological treatment alleviate CAD-related symptoms by acting on the baroreflex reflex circulate. However, pharmacological strategy has the limitation of failing to enhance baroreflex sensitivity and life quality. Novel OH treatment drugs, such as pyridostigmine and atomoxetine, can effectively improve OH-related symptoms via enhancing residual sympathetic tone, without adverse reactions of supine hypertension. Baroreflex impairment is a crucial pathological mechanism associated with CAD in PD. Currently, non-pharmacological strategy was the preferred option for its advantage of enhancing baroreflex sensitivity. Pharmacological treatment is a second-line option. Therefore, to find drugs that can enhance baroreflex sensitivity, especially via acting on its central components, is urgently needed in the scientific research and clinical practice.

Fatigability and Cardiorespiratory Impairments in Parkinson's Disease: Potential Non-Motor Barriers to Activity Performance

Parkinson's disease (PD) is the second most common neurodegenerative condition after Alzheimer's disease, affecting an estimated 160 per 100,000 people 65 years of age or older. Fatigue is a debilitating non-motor symptom frequently reported in PD, often manifesting prior to disease diagnosis, persisting over time, and negatively affecting quality of life. Fatigability, on the other hand, is distinct from fatigue and describes the magnitude or rate of change over time in the performance of activity (i.e., performance fatigability) and sensations regulating the integrity of the performer (i.e., perceived fatigability). While fatigability has been relatively understudied in PD as compared to fatigue, it has been hypothesized that the presence of elevated levels of fatigability in PD results from the interactions of homeostatic, psychological, and central factors. Evidence from exercise studies supports the premise that greater disturbances in metabolic homeostasis may underly elevated levels of fatigability in people with PD when engaging in physical activity. Cardiorespiratory impairments constraining oxygen delivery and utilization may contribute to the metabolic alterations and excessive fatigability experienced in individuals with PD. Cardiorespiratory fitness is often reduced in people with PD, likely due to the combined effects of biological aging and impairments specific to the disease. Decreases in oxygen delivery (e.g., reduced cardiac output and impaired blood pressure responses) and oxygen utilization (e.g., reduced skeletal muscle oxidative capacity) compromise skeletal muscle respiration, forcing increased reliance on anaerobic metabolism. Thus, the assessment of fatigability in people with PD may provide valuable information regarding the functional status of people with PD not obtained with measures of fatigue. Moreover, interventions that target cardiorespiratory fitness may improve fatigability, movement performance, and health outcomes in this patient population.

Managing autonomic dysfunction in Parkinson's disease: a review of emerging drugs

Introduction: Autonomic dysfunction is an integral part of Parkinson disease (PD) complex and can be seen both in early and advanced stages. There is a paucity of medicines available to manage autonomic dysfunction in PD and this adds to the considerable morbidity associated with the illness.Areas covered: The pathophysiology and the available therapeutic options of autonomic dysfunction seen in PD are discussed in detail. The potential targets for novel regimens are reviewed and the available literature on the drugs emerging in management of autonomic dysfunction in PD is highlighted.Expert opinion: In the current scenario, there are several drugs that can be tried for constipation viz stool laxatives, prucalopride, prokinetic agents and a high fiber diet. Bladder dysfunction has been treated with β-agonists and with mirabegron, a selective β-3 agonist, the anticholinergic side effects are minimized, and the drug has been found to be effective. Orthostatic hypotension is managed with midodrine while droxidopa is a new drug with promising efficacy. Botulinum toxin works best for management of sialorrhea, but repeated injections are needed.

Ganglioside Metabolism and Parkinson's Disease

Here we advance the hypothesis that Parkinson's disease (PD) is fundamentally a failure of trophic support for specific classes of neurons, primarily catecholaminergic. Evidence from our laboratory provides a framework into which a broad array of findings from many quarters can be integrated into a general theory that offers testable hypotheses to new and established investigators. Mice deficient in the ability to synthesize series-a gangliosides, specifically GM1 ganglioside, develop parkinsonism. We found that this seems to be due to a failure in signaling efficiency by the important catecholaminergic growth factor, GDNF. Interestingly, these mice accumulate alpha-synuclein in nigral neurons. Striatal over-expression of GDNF eliminates these aggregates and also restores normal motor function. These findings bring into question common beliefs about alpha-synuclein pathology and may help us to reinterpret other experimental findings in a new light. The purpose of this article is to provoke new thinking about PD and hopefully encourage younger scientists to explore some of the ideas presented below.

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.

Cerebral vasomotor reactivity in neurodegenerative diseases

Small-caliber cerebral vessels change their diameters in response to alterations of key metabolite concentrations such as carbon dioxide or oxygen. This phenomenon, termed the cerebral vasomotor reactivity (CVMR), is the basis for blood flow regulation in the brain in accordance with its metabolic status. Typically, CVMR is determined as the amount of change in cerebral blood flow in response to a vasodilating stimulus, which can be measured by various neuroimaging methods or by transcranial Doppler. It has been shown that CVMR is impaired in cerebrovascular diseases, but there is also evidence of a similar dysfunction in neurodegenerative disorders. Here, we review studies that have investigated CVMR in the common neurodegenerative diseases such as Alzheimer's disease, Parkinson's disease and multiple sclerosis. Moreover, we discuss potential neurodegenerative mechanisms responsible for the impairment of CVMR.

The recommendations of Chinese Parkinson's disease and movement disorder society consensus on therapeutic management of Parkinson's disease

BACKGROUND

Parkinson's disease (PD) is a chronic, progressive and debilitating disease, which affects over 2.5 million people in China. PD is characterized clinically by resting tremor, muscular rigidity, bradykinesia and postural instability. As the disease progresses, additional complications can arise such as non-motor and neurobehavioral symptoms. Pharmacological treatment and surgical intervention for PD have been implemented in China. Until 10 years ago, there was lack of standardization for the management of PD in different regions and among different physicians, leading to different treatment levels in different regions and different physicians. Since then, the Chinese Parkinson's Disease and Movement Disorder Society have published three versions of guidelines for the management of PD in China, in 2006, 2009 and 2014, respectively. Correspondingly, the overall level of treatment for PD in China improved.

OBJECTIVES

To update the treatment guidelines based on current foreign and domestic practice guidelines and clinical evidence, and to improve the treatment options available to physicians in the management of PD.

SUMMARY

A variety of treatment recommendations in the treatment guidelines have been proposed, including physical activity and disease-modifying medication, which should be initiated at the early-stage of the disease. The principles of dosage titration should be followed to avoid acute adverse reactions to the drugs, to achieve a satisfactory clinical effect with a low dose and to reduce the incidence of long-term motor complications. Moreover, different treatment strategies should be considered at different stages of the disease. Importantly, treatment guidelines and personalized treatments should be valued equally. A set of treatment recommendations has been developed to assist physicians to improve and optimize clinical outcomes for patients with PD in China.

New insights into orthostatic hypotension in multiple system atrophy: a European multicentre cohort study

OBJECTIVES

Orthostatic hypotension (OH) is a key feature of multiple system atrophy (MSA), a fatal progressive neurodegenerative disorder associated with autonomic failure, parkinsonism and ataxia. This study aims (1) to determine the clinical spectrum of OH in a large European cohort of patients with MSA and (2) to investigate whether a prolonged postural challenge increases the sensitivity to detect OH in MSA.

METHODS

Assessment of OH during a 10 min orthostatic test in 349 patients with MSA from seven centres of the European MSA-Study Group (age: 63.6 ± 8.8 years; disease duration: 4.2 ± 2.6 years). Assessment of a possible relationship between OH and MSA subtype (P with predominant parkinsonism or C with predominant cerebellar ataxia), Unified MSA Rating Scale (UMSARS) scores and drug intake.

RESULTS

187 patients (54%) had moderate (> 20 mm Hg (systolic blood pressure (SBP)) and/or > 10 mm Hg (diastolic blood pressure (DBP)) or severe OH (> 30 mm Hg (SBP) and/or > 15 mm Hg (DBP)) within 3 min and 250 patients (72%) within 10 min. OH magnitude was significantly associated with disease severity (UMSARS I, II and IV), orthostatic symptoms (UMSARS I) and supine hypertension. OH severity was not associated with MSA subtype. Drug intake did not differ according to OH magnitude except for antihypertensive drugs being less frequently, and antihypotensive drugs more frequently, prescribed in severe OH.

CONCLUSIONS

This is the largest study of OH in patients with MSA. Our data suggest that the sensitivity to pick up OH increases substantially by a prolonged 10 min orthostatic challenge. These results will help to improve OH management and the design of future clinical trials.

The choroid and lamina cribrosa is affected in patients with Parkinson's disease: enhanced depth imaging optical coherence tomography study

PURPOSE

To compare lamina cribrosa (LC) and choroidal thicknesses using enhanced depth imaging optical coherence tomography (EDI-OCT) in patients with Parkinson's disease (PD) and healthy controls.

METHODS

A total number of 44 eyes of 22 patients with PD and 50 eyes of 25 healthy subjects were utilized in this institutional cross-sectional study. After a complete ophthalmic examination, all eyes were imaged with OCT (RTVue-100 version 5.1 Fourier-domain optical coherence tomography; Optovue Inc., Fremont, CA, USA); LC and choroidal thickness were assessed.

RESULTS

The mean LC thicknesses were 209.4 ± 40.2 μm in patients with PD and 292.5 ± 33.7 μm in control subjects. There was a significant difference in the mean LC thickness between the groups (p < 0.0001). The choroidal thickness measurements of the PD group at the subfoveal region and 1.5 mm temporal and 1.5 mm nasal to the fovea were 228.1 ± 44.3, 193.2 ± 41.4 and 188.4 ± 49.0 μm, respectively, whereas measurements for the controls were, respectively, 246.5 ± 38.2, 227.3 ± 34.7 and 216.7 ± 51.4 μm. The choroid was significantly thinner in eyes of the PD group compared to that of the controls (p = 0.001, p < 0.001, and p = 0.006). There was no significant correlation between the disease severity and OCT parameters. The duration of the disease showed a statistically significant negative correlation with LC (rs[94] = -0.700, p < 0.001), and average subfoveal and temporal and nasal choroid thicknesses (rs[94] = -0.282, p = 0.006; rs[94] = -0.324, p = 0.001, rs[94] = -0.240, and p = 0.020, respectively).

CONCLUSIONS

Regardless of the disease severity, PD may cause atrophy and volume loss in the lamina cribrosa, and choroid. An enhanced depth imaging technique may be used as an additional modality in the diagnosis and follow-up of patients with PD.

Evaluation of Cardiac Autonomic Functions in Older Parkinson's Disease Patients: a Cross-Sectional Study

In Parkinson's disease (PD), non-motor symptoms may occur such as autonomic dysfunction. We aimed to evaluate both parasympathetic and sympathetic cardiovascular autonomic dysfunction in older PD cases. 84 PD cases and 58 controls, for a total of 142, participated in the study. Parasympathetic tests were performed using electrocardiography. Sympathetic tests were assessed by blood pressure measurement and 24-hour ambulatory blood pressure measurement. The prevalence of orthostatic hypotension in PD patients was 40.5% in PD patients and 24.1% in the control group (p> 0.05). The prevalence of postprandial hypotension was 47.9% in the PD group and 27.5% in the controls (p <0.05). The prevalence of impairment in heart rate response to deep breathing was 26.2% in the PD group and 6.9% in the control group (p <0.05). The prevalence of postprandial hypotension in PD with orthostatic hypotension was 94% and 16% in PD patients without orthostatic hypotension (p <0.05). The prevalence of impairment in heart rate response to deep breathing was 52.9% in PD patients with orthostatic hypotension and 8% in PD cases without orthostatic hypotension (p<0.05). The prevalence of impairment in heart rate response to postural change was 41% in PD cases with orthostatic hypotension and 12% in PD cases without orthostatic hypotension (p <0.05).Although there are tests for assessing cardiovascular autonomic function that are more reliable, they are more complicated, and evaluation of orthostatic hypotension by blood pressure measurement and cardiac autonomic tests by electrocardiography are recommended since these tests are cheap and easy.

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.

Dysautonomia in Parkinson disease

Dysautonomias are conditions in which altered function of one or more components of the autonomic nervous system (ANS) adversely affects health. This review updates knowledge about dysautonomia in Parkinson disease (PD). Most PD patients have symptoms or signs of dysautonomia; occasionally, the abnormalities dominate the clinical picture. Components of the ANS include the sympathetic noradrenergic system (SNS), the parasympathetic nervous system (PNS), the sympathetic cholinergic system (SCS), the sympathetic adrenomedullary system (SAS), and the enteric nervous system (ENS). Dysfunction of each component system produces characteristic manifestations. In PD, it is cardiovascular dysautonomia that is best understood scientifically, mainly because of the variety of clinical laboratory tools available to assess functions of catecholamine systems. Most of this review focuses on this aspect of autonomic involvement in PD. PD features cardiac sympathetic denervation, which can precede the movement disorder. Loss of cardiac SNS innervation occurs independently of the loss of striatal dopaminergic innervation underlying the motor signs of PD and is associated with other nonmotor manifestations, including anosmia, REM behavior disorder, orthostatic hypotension (OH), and dementia. Autonomic dysfunction in PD is important not only in clinical management and in providing potential biomarkers but also for understanding disease mechanisms (e.g., autotoxicity exerted by catecholamine metabolites). Since Lewy bodies and Lewy neurites containing alpha-synuclein constitute neuropathologic hallmarks of the disease, and catecholamine depletion in the striatum and heart are characteristic neurochemical features, a key goal of future research is to understand better the link between alpha-synucleinopathy and loss of catecholamine neurons in PD.

Safety overview of FDA-approved medications for the treatment of the motor symptoms of Parkinson's disease

INTRODUCTION

Parkinson's disease (PD) is among the most common of the neurodegenerative disorders. Treatment is primarily focused on correcting neurotransmitter imbalances. Several classes of medication are available for this purpose.

AREAS COVERED

A Medline search was performed to gather information about the safety of the medications approved for the treatment of the motor symptoms of PD. This was supplemented with additional articles obtained from online sources and information provided by the FDA and the manufacturers. The focus of this review is the side-effect and safety profiles of carbidopa/levodopa, dopamine agonists, selective monoamine oxidase inhibitors, catechol-o-methyltransferase inhibitors, anticholinergics and amantadine.

EXPERT OPINION

Though serious side-effects may occur, as a group, the medications used for the treatment of PD motor symptoms tend to produce side-effects that are mild to moderate in nature, and that primarily reflect the focus on dopaminergic therapies. Care plans for Parkinson's patients should be approached based on the needs of the individual as disease presentation, lifestyle, level of disability, concurrent disease states and the presence of non-motor symptoms make each case unique. Patients and caregivers must have realistic expectations about the use of PD medications.

Factors predicting incremental administration of antihypertensive boluses during deep brain stimulator placement for Parkinson's disease

Hypertension is common in deep brain stimulator (DBS) placement predisposing to intracranial hemorrhage. This retrospective review evaluates factors predicting incremental antihypertensive use intraoperatively. Medical records of Parkinson's disease (PD) patients undergoing DBS procedure between 2008-2011 were reviewed after Institutional Review Board approval. Anesthesia medication, preoperative levodopa dose, age, preoperative use of antihypertensive medications, diabetes mellitus, anxiety, motor part of the Unified Parkinson's Disease Rating Scale score and PD duration were collected. Univariate and multivariate analysis was done between each patient characteristic and the number of antihypertensive boluses. From the 136 patients included 60 were hypertensive, of whom 32 were on angiotensin converting enzyme inhibitors (ACEI) or angiotensin receptor blockers (ARB), told to hold on the morning of surgery. Antihypertensive medications were given to 130 patients intraoperatively. Age (relative risk [RR] 1.01; 95% confidence interval [CI] 1.00-1.02; p=0.005), high Joint National Committee (JNC) class (p<0.0001), diabetes mellitus (RR 1.4; 95%CI 1.2-17; p<0.0001) and duration of PD >10 years (RR 1.2; 95%CI 1.1-1.3; p=0.001) were independent predictors for antihypertensive use. No difference was noted in the mean dose of levodopa (p=0.1) and levodopa equivalent dose (p=0.4) between the low (I/II) and high severity (III/IV) JNC groups. Addition of dexmedetomidine to propofol did not influence antihypertensive boluses required (p=0.38). Intraoperative hypertension during DBS surgery is associated with higher age group, hypertensive, diabetic patients and longer duration of PD. Withholding ACEI or ARB is an independent predictor of hypertension requiring more aggressive therapy. Levodopa withdrawal and choice of anesthetic agent is not associated with higher intraoperative antihypertensive medications.

Neurogenic orthostatic hypotension in Parkinson's disease: evaluation, management, and emerging role of droxidopa

Neurogenic orthostatic hypotension (nOH) is due to failure of the autonomic nervous system to regulate blood pressure in response to postural changes due to an inadequate release of norepinephrine, leading to orthostatic hypotension and supine hypertension. nOH is common in Parkinson’s disease (PD). Prevalence varies throughout the course of PD, ranging from 40% to 60%, and resulting in symptomatic nOH in approximately half. Symptomatic nOH, including lightheadedness, can limit daily activities and lead to falls. Symptomatic nOH can also limit therapeutic options for treating PD motor symptoms. Clinical evaluation should routinely include symptom assessment and blood pressure measurement of supine, sitting, and 3-minute standing; 24-hour ambulatory blood pressure monitoring can also be helpful. Non-pharmacological management of symptomatic nOH involves education, physical maneuvers, and adequate hydration. Current pharmacological treatment of symptomatic nOH includes salt supplement, fludrocortisone, midodrine, pyridostigmine, and other empiric medications. Despite these options, treatment of symptomatic nOH remains suboptimal, often limited by severe increases in supine blood pressure. Droxidopa, an oral prodrug converted by decarboxylation to norepinephrine, is a promising therapeutic option for symptomatic nOH in PD, improving symptoms of nOH, daily activities, falls, and standing systolic blood pressure in several recent trials. These trials demonstrated short-term efficacy and tolerability, with comparable increases in standing and supine blood pressures. Longer-term studies are ongoing to confirm durability of treatment effect.

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 does not increase cardiovascular risk in the elderly at a population level

BACKGROUND

The general belief that orthostatic hypotension (OH) predisposes to cardiovascular events is based on sparse and contradictory data, rarely derived from population studies.

METHODS

A total of 1,016 men and women aged ≥65 years was studied in a 12-year epidemiological population-based study. Cardiovascular events were detected in subjects with and without OH (blood pressure (BP) decrease ≥20mm Hg for systolic or ≥10mm Hg for diastolic), and Cox analysis was performed including OH as an independent variable.

RESULTS

In univariate analysis, coronary (20.2% vs. 13.1%, P = 0.05), cerebrovascular (13.1% vs. 8.4%, P = 0.05), and heart failure (HF) events (20.2% vs. 13.8%, P = 0.03) were apparently more incidental in subjects with OH than in those without OH. Nevertheless, after adjusting for age, gender, and systolic BP as confounders, OH did not act as a cardiovascular predictor (relative risk for cerebrovascular events 1.33, 95% confidence interval (CI), 0.78-2.2, for coronary events 1.25, CI 0.82-1.88, for HF 1.07, CI 0.71-1.62, for arrhythmias 0.82, CI 0.40-1.37, and for syncope 0.58, CI 0.13-2.71).

CONCLUSIONS

Although OH seems to be a predictor of coronary, cerebrovascular, and HF events, no predictive role was found in models that include biological confounders. Independent of the cause of OH, age and systolic BP, which are positively associated with OH, fully explain the greater incidence of cardiovascular events and the greater cardiovascular risk observed in subjects with OH.

Genome-wide association study of orthostatic hypotension and supine-standing blood pressure changes in two korean populations

Orthostatic hypotension (OH) is defined by a 20-mm Hg difference of systolic blood pressure (dtSBP) and/or a 10-mm Hg difference of diastolic blood pressure (dtDBP) between supine and standing, and OH is associated with a failure of the cardiovascular reflex to maintain blood pressure on standing from a supine position. To understand the underlying genetic factors for OH traits (OH, dtSBP, and dtDBP), genome-wide association studies (GWASs) using 333,651 single nucleotide polymorphisms (SNPs) were conducted separately for two population-based cohorts, Ansung (n = 3,173) and Ansan (n = 3,255). We identified 8 SNPs (5 SNPs for dtSBP and 3 SNPs for dtDBP) that were repeatedly associated in both the Ansung and Ansan cohorts and had p-values of <1 × 10^-5 in the meta-analysis. Unfortunately, the SNPs of the OH case control GWAS did not pass our p-value criteria. Four of 8 SNPs were located in the intergenic region of chromosome 2, and the nearest gene (CTNNA2) was located at 1 Mb of distance. CTNNA2 is a linker between cadherin adhesion receptors and the actin cytoskeleton and is essential for stabilizing dendritic spines in rodent hippocampal neurons. Although there is no report about the function in blood pressure regulation, hippocampal neurons interact primarily with the autonomic nervous system and might be related to OH. The remaining SNPs, rs7098785 of dtSBP trait and rs6892553, rs16887217, and rs4959677 of dtDBP trait were located in the PIK3AP1 intron, ACTBL2-3' flanking, STAR intron, and intergenic region, respectively, but there was no clear functional link to blood pressure regulation.

The Effects of Parkinson's Disease on Caregivers and People with Parkinson's Disease: A Literature Review

Parkinson's disease (PD) is a complex, slowly progressive, neurodegenerative, neurological condition characterised by a wide range of motor problems such as movement disorders, issues with gait and balance, and difficulty with swallowing and speech. In addition, sufferers also experience non-motor symptoms such as disorder of sleep, postural hypotension, mood alterations, lethargy, and cognitive dysfunction. As PD progresses to an advanced stage, people experience periods of debilitating physical and neurological problems and their caregivers face increasing complexity of care. Many people with PD require the support of a caregiver to attend to activities of daily living. This paper will review the literature on the effects of Parkinson's disease on both the patient and caregiver. Findings highlight the progressive nature of the disease affecting both functional and affective domains, and the need for caregiver support to enable the delivery of quality of care to this group throughout the disease trajectory.

The management of orthostatic hypotension in Parkinson's disease

Orthostatic hypotension (OH) is a common and disabling symptom affecting Parkinson's disease (PD) patients. We present the effect of the different therapies commonly used to manage PD on this clinical manifestation. For this purpose, we describe the relationship between OH and the current treatments employed in PD, such as L-DOPA, dopaminergic agonists, and continuous dopaminergic stimulation therapies. Additionally, we review the therapeutic measures that could be used to ameliorate OH. There are different approaches to deal with this manifestation, including pharmacological and non-pharmacological treatments, although none of them is specifically aimed for treating OH in PD.

Arterial hypertension, a tricky side of Parkinson's disease: physiopathology and therapeutic features

The role of arterial hypertension (HT) as risk factor for Parkinson's disease (PD) is still debated. Case-control and retrospective studies do not support an association between HT and PD and the risk of PD seems to be lower in hypertensive than in normotensive subjects. In addition, the use of calcium-channel blockers (CCBs) and angiotensin-converting enzyme inhibitors seems to have a protective effect on the risk of developing PD. In clinical practice, a crucial finding in subjects with PD is the high supine systolic blood pressure (SBP) coupled with orthostatic hypotension (OH). It is not clear whether this SBP load could be a risk factor for target organ damage as this load can be largely due to the drugs used to treat OH (i.e., fludrocortisone acetate, midodrine) or PD itself (i.e., monoamine oxidase inhibitors, dopamine D2-receptor antagonists). This blood pressure (BP) load is largely independent of medications as the 40 % of subjects with PD have a non-dipping pattern of BP during 24 h ambulatory monitoring (24-h ABPM). In PD, nocturnal HT is usually asymptomatic and 24-h ABPM should be used to track both supine HT and OH. Treatment of HT in PD is difficult because the reduction of supine BP could worsen OH. To avoid this, short-acting dihydropyridine CCBs, clonidine or nitrates are recommended, assuming between meals, in late afternoon or in the evening in avoiding an aggravation in the post-prandial hypotension characteristic of PD.

Nonmotor symptoms in Parkinson's disease in 2012: relevant clinical aspects

Nonmotor symptoms (NMSs) of Parkinson's disease (PD) are common, but they are often underrecognized in clinical practice, because of the lack of spontaneous complaints by the patients, and partly because of the absence of systematic questioning by the consulting physician. However, valid specific instruments for identification and assessment of these symptoms are available in 2012. The administration of the self-completed screening tool, NMSQuest, associated with questioning during the consultation, improves the diagnosis of NMSs. NMSs play a large role in degradation of quality of life. More relevant NMSs are described in this review, mood disorders, impulse control disorders, cognitive deficits, hallucinations, pain, sleep disorders, and dysautonomia.

Mechanisms of orthostatic hypotension and supine hypertension in Parkinson disease

Non-motor aspects of Parkinson disease (PD) are now recognized to be important both clinically and scientifically. Among these facets are abnormalities in blood pressure regulation. As much as 40% of PD patients have orthostatic hypotension (OH), which is usually associated with supine hypertension (SH). Symptoms of OH range from light-headedness to falls with serious trauma. SH, while typically asymptomatic, poses a significant increased risk for cardiovascular morbidity and mortality. Neuroimaging, neurochemical, and neuropharmacological studies indicate cardiac and extra-cardiac sympathetic noradrenergic denervation and baroreflex failure in virtually all PD patients with OH, and cardiac sympathetic denervation has been confirmed histopathologically. Mechanisms of SH in PD+OH remain poorly understood. The diurnal blood pressure profile shows increased variability that is correlated with decreased baroreflex gain and with increased morbidity and mortality. Treatment should be individually tailored according to the timing of OH or SH, using primarily short-acting sympathomimetic medications in the daytime for OH and short-acting antihypertensive in the nighttime for SH. Future research is needed to understand better and attenuate blood pressure fluctuations through manipulations that improve baroreflex function.

The Movement Disorders task force review of dysautonomia rating scales in Parkinson's disease with regard to symptoms of orthostatic hypotension

Orthostatic hypotension is defined as a blood pressure fall of > 20 mm Hg systolic and/or 10 mm Hg diastolic within 3 minutes of an upright position. The Movement Disorders Society commissioned a task force to assess existing clinical rating scales addressing symptoms of orthostatic hypotension in Parkinson's disease. Seven neurologists and a clinimetrician assessed each scale's previous use and critiqued its clinimetric properties. A scale was "recommended" if it had been applied to populations of patients with Parkinson's disease, with data on its use in studies beyond the group that developed the scale, and was found to be clinimetrically valid. A scale was considered "suggested" if it had been applied to Parkinson's disease, but only 1 of the other criteria was applied. A scale was "listed" if it met only 1 criterion. Symptoms of orthostatic hypotension are generally assessed in scales on wider autonomic or nonmotor symptoms. Some scales designed to detect orthostatic hypotension-related symptoms provide information on their severity: the AUTonomic SCale for Outcomes in PArkinson's Disease and the COMPosite Autonomic Symptom Scale met criteria for recommended with some limitations; the Novel Non-Motor Symptoms Scale and the Orthostatic Grading Scale were classified as suggested. The Self-completed Non-Motor Symptoms Questionnaire for Parkinson's Disease was classified as suggested as a tool for screening orthostatic symptoms. However, these and the listed scales need further validation and application before they can be recommended for clinical use in patients with Parkinson's disease.

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.

Clinical review of treatment options for select nonmotor symptoms of Parkinson's disease

BACKGROUND

Parkinson's disease (PD) is associated with a host of nonmotor symptoms, including psychosis, cognitive impairment, depression, sleep disturbance, swallowing disorders, gastrointestinal symptoms, and autonomic dysfunction. The nonmotor symptoms of PD have the potential to be more debilitating than the motor features of the disorder.

OBJECTIVE

The aim of this article was to review treatment options for the nonmotor manifestations of PD, including pharmacologic and nonpharmacologic interventions.

METHODS

The PubMed and MEDLINE databases were searched for articles published in English between January 1966 and April 2010, using the terms Parkinson's disease, nonmotor, psychosis, hallucination, antipsychotic, cognitive impairment, dementia, depression, sleep disturbance, sleepiness, REM (rapid eye movement) sleep behavior disorder, dysphagia, swallowing disorder, sialorrhea, gastrointestinal, constipation, autonomic dysfunction, orthostatic hypotension, gastroparesis, erectile dysfunction, sexual dysfunction, and urinary dysfunction. Articles were selected for review if they were randomized controlled trials (RCTs), meta-analyses, or evidence-based reviews of treatment of patients with PD, and/or expert opinion regarding the treatment of nonmotor symptoms of PD.

RESULTS

A total of 148 articles, including RCTs, meta-analyses, and evidence-based reviews, were included in this review. The treatment of hallucinations or psychosis in PD should include a stepwise reduction in medications for motor symptoms, followed by the use of quetiapine or clozapine. Dementia may be treated with acetylcholinesterase inhibitors. Evidence is lacking concerning the optimal pharmacologic treatment for depression in PD, with expert opinions indicating selective serotonin reuptake inhibitors as the antidepressants of choice. However, the largest study to date found nortriptyline therapy to be efficacious compared with placebo, whereas paroxetine controlled release was not. A variety of sleep disturbances may plague a person with PD, and treatment must be individualized to the patient's specific sleep disturbance pattern and contributing factors. Swallowing disorders may lead to aspiration and pneumonia, and patients with dysphagia should be referred to a speech therapist for further evaluation and treatment. Orthostasis may be treated with nonpharmacologic interventions as well as pharmacologic treatments (eg, fludrocortisone, midodrine, indomethacin). Other autonomic symptoms are managed in a manner similar to that in patients without PD, although careful attention must be aimed at avoiding dopamine-blocking therapies in the treatment of gastrointestinal dysfunction and gastroparesis.

CONCLUSIONS

Various pharmacologic and nonpharmacologic strategies are available for the management of the nonmotor symptoms of PD. The challenges associated with nonmotor symptoms must not be forgotten in light of the motor symptoms of PD, and treatment of nonmotor symptoms should be encouraged.

Potential influences of complementary therapy on motor and non-motor complications in Parkinson's disease

Nearly two-thirds of patients with Parkinson's disease (PD) use vitamins or nutritional supplements, and many more may use other complementary therapies, yet <50% of patients have discussed the use of these complementary therapies with a healthcare professional. Physicians should be aware of the complementary therapies their patients with PD are using, and the possible effects of these therapies on motor and non-motor symptoms. Complementary therapies, such as altered diet, dietary supplements, vitamin therapy, herbal supplements, caffeine, nicotine, exercise, physical therapy, massage therapy, melatonin, bright-light therapy and acupuncture, may all influence the symptoms of PD and/or the effectiveness of dopaminergic therapy. Preliminary evidence suggests complementary therapy also may influence non-motor symptoms of PD, such as respiratory disorders, gastrointestinal disorders, mood disorders, sleep and orthostatic hypotension. Whenever possible, clinicians should ensure that complementary therapy is used appropriately in PD patients without reducing the benefits of dopaminergic therapy.

Parkinson disease and comorbid cerebrovascular disease

Optimal management of chronic diseases not only requires tackling of the primary disease processes, but also necessitates timely recognition and treatment of comorbid conditions. In this article, we illustrate this two-pronged approach for two common age-related disorders: Parkinson disease (PD) and cerebrovascular disease (CVD). We first discuss the pathophysiological mechanisms that could provide a link between PD and CVD. Patients with PD have a series of risk factors that could promote development of CVD, but also have several protective factors. We then review the available clinical, radiological and neuropathological evidence to support an association between these two conditions. We conclude by discussing the potential implications for clinical practice, highlighting how comorbid CVD could alter the clinical presentation of PD and reviewing the possibilities for prevention and secondary prophylaxis. Additional research will be needed to fully evaluate the prevalence and clinical relevance of comorbid CVD in PD. Pending further evidence, we recommend that cerebral neuroimaging should be considered if patients with initially uncomplicated PD develop-either acutely or chronically-prominent and/or treatment-resistant gait impairment, postural instability, depression, cognitive decline, or urinary incontinence. Finding comorbid CVD in such patients could have prognostic implications, and could necessitate treatment to arrest further progression of CVD.