An update on the recognition and treatment of autonomic symptoms in Parkinson’s disease

Gastrointestinal involvement in Parkinson's disease: pathophysiology, diagnosis, and management

Growing evidence suggests an increasing significance for the extent of gastrointestinal tract (GIT) dysfunction in Parkinson's disease (PD). Most patients suffer from GIT symptoms, including dysphagia, sialorrhea, bloating, nausea, vomiting, gastroparesis, and constipation during the disease course. The underlying pathomechanisms of this α-synucleinopathy play an important role in disease development and progression, i.e., early accumulation of Lewy pathology in the enteric and central nervous systems is implicated in pharyngeal discoordination, esophageal and gastric motility/peristalsis impairment, chronic pain, altered intestinal permeability and autonomic dysfunction of the colon, with subsequent constipation. Severe complications, including malnutrition, dehydration, insufficient drug effects, aspiration pneumonia, intestinal obstruction, and megacolon, frequently result in hospitalization. Sophisticated diagnostic tools are now available that permit more detailed examination of specific GIT impairment patterns. Furthermore, novel treatment approaches have been evaluated, although high-level evidence trials are often missing. Finally, the burgeoning literature devoted to the GIT microbiome reveals its importance for neurologists. We review current knowledge about GIT pathoanatomy, pathophysiology, diagnosis, and treatment in PD and provide recommendations for management in daily practice.

Association between Cardiac Autonomic Control and Postural Control in Patients with Parkinson's Disease

Parkinson's disease (PD) is a neurodegenerative disorder that affects postural and cardiac autonomic control. However, since it is unknown whether these changes are associated, the objective of this study was to determine whether such a relationship exists. Twenty-three patients with PD participated. The RR intervals were recorded in different positions and heart rate variability (HRV) was analyzed. Postural sway was analyzed based on the center of pressure. No significant differences on HRV indices were induced by postural change. A correlation was found between these indices and postural control, high frequency (HF), and anterior-posterior (AP) root mean square (RMS-AP) (r = 0.422, p = 0.045), low frequency (LF)/HF, and AP mean velocity (r = 0.478, p = 0.021). A correlation was found between HRV induced by postural change and postural control, Δ LF/HF and RMS-AP (r = 0.448, p = 0.032), Δ LF/HF and ellipse area (r = 0.505, p = 0.014), Δ LF/HF and AP mean velocity (r = -0.531; p = 0.009), and Δ LF and AP mean velocity (r = -0.424, p = 0.044). There is an association between the autonomic and postural systems, such that PD patients with blunted cardiac autonomic function in both the supine and orthostatic positions have worse postural control.

Using Deep Brain Stimulation to Unravel the Mysteries of Cardiorespiratory Control

This article charts the history of deep brain stimulation (DBS) as applied to alleviate a number of neurological disorders, while in parallel mapping the electrophysiological circuits involved in generating and integrating neural signals driving the cardiorespiratory system during exercise. With the advent of improved neuroimaging techniques, neurosurgeons can place small electrodes into deep brain structures with a high degree accuracy to treat a number of neurological disorders, such as movement impairment associated with Parkinson's disease and neuropathic pain. As well as stimulating discrete nuclei and monitoring autonomic outflow, local field potentials can also assess how the neurocircuitry responds to exercise. This technique has provided an opportunity to validate in humans putative circuits previously identified in animal models. The central autonomic network consists of multiple sites from the spinal cord to the cortex involved in autonomic control. Important areas exist at multiple evolutionary levels, which include the anterior cingulate cortex (telencephalon), hypothalamus (diencephalon), periaqueductal grey (midbrain), parabrachial nucleus and nucleus of the tractus solitaries (brainstem), and the intermediolateral column of the spinal cord. These areas receive afferent input from all over the body and provide a site for integration, resulting in a coordinated efferent autonomic (sympathetic and parasympathetic) response. In particular, emerging evidence from DBS studies have identified the basal ganglia as a major sub-cortical cognitive integrator of both higher center and peripheral afferent feedback. These circuits in the basal ganglia appear to be central in coupling movement to the cardiorespiratory motor program. © 2020 American Physiological Society. Compr Physiol 10:1085-1104, 2020.

Nicotine Gum as a Therapeutic Approach for Low Blood Pressure in Parkinson's Disease: A Randomized Pilot Study

Introduction

One cause for low blood pressure (BP) in Parkinson's disease (PD) is denervation of the sympathetic nervous system and reduced levels of norepinephrine. Nicotine increases heart rate and BP acutely by causing sympathetic stimulation. The absorption rate of nicotine gum is relatively quick and absorbed at a constant rate. Our objective was to evaluate how nicotine gum affects acute low BP in PD.

Methods

Ten subjects (age 69.3 ± 8.8) completed this double blind, placebo controlled, cross-over design trial using nicotine gum (4 mg) and placebo gum on two separate days. The gum was administered for 30 min. BP was recorded every 10 min for 90 min.

Results

On the nicotine gum treatment day, the baseline systolic BP was 94.8 (standard deviation [SD] = 4.4), and it increased in a parabolic pattern to be 115.8 (SD = 11.2) in 20 min, 124.2 (SD = 9.3) in 40 min, and 133.2 (SD = 13.1) in 60 min reaching the highest value, and then decreased to be 121.6 (SD = 10.4) in 90 min. On the placebo day, the baseline systolic BP 95.2 (SD = 3.0) didn't show an outstanding change with the mean systolic BP values from 93.0 to 95.7 (SD from 2.1 to 3.7) at all time points.

Conclusions

Our data suggests that 4 mg of nicotine gum can increase systolic BP within 10 min of administration. It is strongly warranted that further research should pursue the use of nicotine gum as an intervention to treat acute episodes of low BP in individuals with PD.

Implications

More than 50% of Parkinson's disease (PD) patients have low blood pressure (BP) that fluctuates throughout the day and decreases quality of life. This study found an increase in systolic blood pressure within 10 min of administering nicotine gum to Parkinson's subjects with low BP. Their BP remained elevated for 90 min. Nicotine gum gets absorbed rapidly and may act as a therapeutic novel approach to individuals whose daily lives are interrupted with low BP.

Gastric emptying in Parkinson's disease - A mini-review

Patients with Parkinson's disease (PD) experience a range of non-motor symptoms, including constipation and other gastrointestinal problems. These symptoms are sometimes present in the prodromal disease phase. An improved understanding of the underlying pathophysiology is needed considering that PD has been hypothesized to originate in the gut. Delayed gastric emptying time (GET) is often listed as a prevalent gastrointestinal symptom in PD, but the true prevalence is controversial. The aim of this short review was to investigate if GET in PD is dependent on the applied measuring methodology. A systemic search of Pubmed identified 15 relevant studies, including six using gold standard method gastric scintigraphy and nine using ¹³C-octanoate breath tests. Overall, gastric scintigraphy studies showed a non-significant GET delay (standardized mean difference (SMD) 0.42) in PD patients. After exclusion of one outlier study, GET was significantly increased (SMD 0.59). In contrast, highly significant GET delay (SMD 1.70) was seen in breath test studies. A limitation of the meta-analyses was reuse of the same control group in some studies. In summary, the marked GET delay observed in breath test studies is not confirmed by gold standard gastric scintigraphy studies. This discrepancy can perhaps be explained by breath test being an indirect GET measure, depending not only on mechanic stomach emptying but also intestinal absorption and liver metabolism. Thus, multi-modality studies under standardized conditions are needed to elucidate the prevalence and severity of gastric dysmotility in PD, along with contributions from other factors including intestinal absorption and permeability.