The effect of subthalamic deep brain stimulation on gastric motility in Parkinson's disease

Associations between gut microbiota characteristics and non-motor symptoms following pharmacological and surgical treatments in Parkinson's disease patients

BACKGROUND

The gut microbiota has been implicated in Parkinson's disease (PD), with alterations observed in microbial composition and reduced microbial species richness, which may influence gastrointestinal symptoms in PD patients. It remains to be determined whether the severity of gastrointestinal symptoms correlates with microbiota variations in PD patients treated pharmacologically or with subthalamic nucleus deep brain stimulation (STN-DBS) therapy. This study aims to explore how these treatments affect gut microbiota and gastrointestinal symptoms in PD, identifying specific microbial differences associated with each treatment modality.

METHODS

A total of 42 individuals diagnosed with PD, along with 38 age-matched household control participants, contributed stool samples for microbiota characterization. Differences in the gut microbiota across various groups of PD patients and their households were identified through comprehensive sequencing of the 16S rRNA gene amplicon sequencing.

KEY RESULTS

Differences in microbial communities were observed between PD patients and controls, as well as between PD patients receiving pharmacological treatment and those with STN-DBS. Pharmacologically treated advanced PD patients have higher gastrointestinal dysfunctions. Gut microbiota profile linked to STN-DBS and reduced levodopa consumption, characterized by its anti-inflammatory properties, might play a role in diminishing gastrointestinal dysfunction relative to only pharmacological treatments.

CONCLUSIONS & INFERENCES

Advanced PD patients on medication exhibit more gastrointestinal issues, despite relatively stable microbial diversity, indicating a complex interaction between gut microbiota, PD progression, and treatment effects. An imbalanced gut-brain axis, particularly due to reduced butyrate production, may lead to constipation by affecting the enteric nervous system, which emphasizes the need to incorporate gut microbiome insights into treatment strategies.

Development of a Gastrointestinal-Myoelectrical-Activity-Based Nomogram Model for Predicting the Risk of Mild Cognitive Impairment

Mild cognitive impairment (MCI) is the prodromal stage and an important risk factor of Alzheimer's disease (AD). Interventions at the MCI stage are significant in reducing the occurrence of AD. However, there are still many obstacles to the screening of MCI, resulting in a large number of patients going undetected. Given the strong correlation between gastrointestinal function and neuropsychiatric disorders, the aim of this study is to develop a risk prediction model for MCI based on gastrointestinal myoelectrical activity. The Mini-Mental State Examination and electrogastroenterography were applied to 886 participants in western China. All participants were randomly assigned to the training and validation sets in a ratio of 7:3. In the training set, risk variables were screened using LASSO regression and logistic regression, and risk prediction models were built based on nomogram and decision curve analysis, then validation was performed. Eight predictors were selected in the training set, including four electrogastroenterography parameters (rhythm disturbance, dominant frequency and dominant power ratio of gastric channel after meal, and time difference of intestinal channel after meal). The area under the ROC curve for the prediction model was 0.74 in the training set and 0.75 in the validation set, both of which exhibited great prediction ability. Furthermore, decision curve analysis displayed that the net benefit was more desirable when the risk thresholds ranged from 15% to 35%, indicating that the nomogram was clinically usable. The model based on gastrointestinal myoelectrical activity has great significance in predicting the risk of MCI and is expected to be an alternative to scales assessment.

Effects of subthalamic deep brain stimulation on non-motor symptoms of Parkinson's disease: A meta-analysis

Deep brain stimulation (DBS) is a well-defined treatment for motor symptoms in advanced PD. Although several studies have investigated the DBS effect on non-motor symptoms (NMS), controversial results exist regarding this matter. The aim of this meta-analysis and systematic review was to assess the bilateral subthalamic nucleus (STN) DBS effect on NMS of PD. We conducted a systematic search on the literature of Web of Science (WOS), PubMed/MEDLINE, Scopus, Cochrane, and Embase. An additional hand search was also done. Finally, a meta-analysis was conducted on 10 studies containing pre- and post-bilateral STN-DBS data regarding NMS acquired using Non-Motor Symptoms Scale for Parkinson's Disease (NMSS) or Non-Motor Symptoms Questionnaire (NMSQ). A random-effects model was used to determine weighted mean differences, and the heterogeneity index was evaluated using Cochrane's Q test. Our study results indicated that bilateral STN-DBS significantly reduced total NMSS and NMSQ score (WMD -17.73; 95% confidence interval [CI] -20.28 to -15.18, WMD -2.19; 95% CI -2.98 to -1.40), respectively, and no publication bias was found. Regarding each of the NMSS domains, DBS significantly reduced the scores of following domains: sleep (WMD -5.98; 95% CI -6.82 to -5.15), miscellaneous (WMD -4.19; 95% CI -4.96 to -3.43), urinary (WMD -2.99; 95% CI -3.78 to -2.19), sexual (WMD -0.65; 95% CI -1.16 to -0.14), and attention/memory (WMD -0.59; 95% CI -1.15 to -0.03). This meta-analysis demonstrated that bilateral STN-DBS has beneficial effects on NMS of PD.

Subthalamic nucleus-deep brain stimulation improves autonomic dysfunctions in Parkinson's disease

Background

To study the effects of subthalamic nucleus-deep brain stimulation (STN-DBS) on autonomic dysfunctions in Parkinson’s disease (PD) patients.

Methods

A total of 57 PD patients who underwent bilateral STN-DBS from March to December 2018, were retrospectively analyzed. Preplanned assessments at baseline and postoperatively at 1, 3, and 6 months also included the Scales for Outcomes in Parkinson’s Disease-Autonomic questionnaire (SCOPA-Aut), the Unified Parkinson’s Disease Rating Scale (UPDRS) III score, levodopa equivalent day dose (LEDD), Parkinson’s Disease Quality of Life Scale (PDQ-39), the Hamilton Anxiety Rating Scale (HAMA), and the Hamilton Depression Rating Scale (HAMD).

Results

The SCOPA-Aut scores improved significantly [14.59% (18.32%), 24.00% (27.05%), 22.16% (27.07%), all P < 0.001] at 1 month, 3 months, and 6 months of STN-DBS, respectively. Analysis of the SCOPA-Aut sub-items showed significant improvements only in urine and thermoregulation sub-items at 6 months after surgery (P < 0.001). There was no significant correlation between improvements of SCOPA-Aut scores and improvements of PDQ-39 scores (P > 0.05) at 6 months after surgery. SCOPA-Aut scores were positively correlated with age (r = 0.428, P = 0.001); the improvements of SCCOPA-Aut scores were positively correlated with improvements of HAMA and HAMD scores (HAMA: r = 0.325, P = 0.015; HAMD: r = 0.265, P = 0.049) at 6 months after surgery.

Conclusion

STN-DBS improved autonomic dysfunction symptoms of PD patients, and urinary and thermoregulatory sub-items of autonomic dysfunction were improved in the short-term after surgery. There was a close relationship between improved autonomic symptoms and improved anxiety and depression 6 months after surgery. We should therefore direct more attention to autonomic dysfunctions in PD involving detailed preoperative evaluations and postoperative follow-ups, to improve the quality of life of patients.

Gastric Emptying Is Not Delayed and Does Not Correlate With Attenuated Postprandial Blood Flow Increase in Medicated Patients With Early Parkinson's Disease

Background

We have recently used phase-contrast magnetic resonance imaging (PC-MRI) to demonstrate an attenuated postprandial blood flow response in the superior mesenteric artery (SMA) in 23 medicated patients with Parkinson's disease (PD) compared to 23 age- and sex-matched healthy controls.

Objective

To investigate in a sub-sample of the original cohort whether the observed blood flow response in SMA after oral food intake is related to a delay in gastric emptying.

Methods

We studied 15 patients with PD in an “ON-medication” state with a mean disease duration of 3.9 ± 2.2 years and 15 healthy age- and sex-matched individuals. Participants underwent dynamic gastric scintigraphy 0, 30, 60, 120, 180 and 240 minutes after the intake of a standardized radiolabeled test meal. Gastric emptying was compared between groups. 14 of the 15 PD patients and 12 of the 15 healthy control subjects had previously undergone serial postprandial PC-MRI measurements. In these individuals, we tested for a relationship between gastric emptying and postprandial blood flow response in the SMA.

Results

The dynamics of gastric emptying did not differ between groups (p = 0.68). There was substantial inter-subject variability of gastric emptying in PD patients and healthy participants. Only a single PD patient had delayed gastric emptying. In those participants who had undergone PC-MRI, postprandial increase in SMA blood flow was attenuated in PD compared to healthy controls as reported previously (p = 0.006). Gastric emptying did not correlate with the timing and amplitude of postprandial blood flow increase in SMA.

Conclusion

Our preliminary results, obtained in a small group of early-stage PD patients who continued their usual dopamine replacement therapy, suggest that variations in gastric emptying after solid meal intake is within the normal range in the majority of cases. There is also no evidence for a tight relationship between the attenuated postprandial blood flow response in the SMA and normal variations in gastric emptying.

Constipation Management in Parkinson Disease

ABSTRACT

BACKGROUND: Constipation is the most frequently reported nonmotor gastrointestinal symptom of Parkinson disease and can precede motor symptoms by up to 20 years. The causes of constipation can be multifactorial, but the implications can lead to life-threatening complications. Early recognition of constipation can lead to better health outcomes and quality of life. MANAGEMENT CONSIDERATIONS: The combination of nonpharmacological management through screening tools, nursing assessment, and patient education as well as pharmacological management is considered best practice. IMPLICATIONS FOR PRACTICE: Nurses who are knowledgeable on the current treatment options for constipation in Parkinson disease will be better equipped as active multidisciplinary team players to provide optimal care to their patients and achieve the best health outcomes.

Consensus on the treatment of dysphagia in Parkinson's disease

BACKGROUND

Dysphagia is common in Parkinson's disease (PD). The effects of antiparkinsonian drugs on dysphagia are controversial. Several treatments for dysphagia are available but there is no consensus on their efficacy in PD.

OBJECTIVE

To conduct a systematic review of the literature and to define consensus statements on the treatment of dysphagia in PD and related nutritional management.

METHODS

A multinational group of experts in the field of neurogenic dysphagia and/or Parkinson's disease conducted a systematic evaluation of the literature and reported the results according to PRISMA guidelines. The evidence from the retrieved studies was analyzed and discussed in a consensus conference organized in Pavia, Italy, and the consensus statements were drafted. The final version of statements was subsequently achieved by e-mail consensus.

RESULTS

The literature review retrieved 64 papers on treatment and nutrition of patients with PD and dysphagia, mainly of Class IV quality. Based on the literature and expert opinion in cases where the evidence was limited or lacking, 26 statements were developed.

CONCLUSIONS

The statements developed by the Consensus panel provide a guidance for a multi-disciplinary treatment of dysphagia in patients with PD, involving neurologists, otorhinolaryngologists, gastroenterologists, phoniatricians, speech-language pathologists, dieticians, and clinical nutritionists.

Bilateral Subthalamic Nucleus Deep Brain Stimulation Improves Gastric Emptying Time in Parkinson Disease

BACKGROUND

It is well-established that deep brain stimulation (DBS) can improve motor function in those with Parkinson disease (PD); however, its effects on gastrointestinal disorders remain unclear.

METHODS

From January 2019 to December 2020, 26 patients with PD who had undergone subthalamic nucleus (STN) DBS were included in our study. The evaluated items included the pre- and postoperative dose of levodopa, Unified Parkinson's Disease Rating Scale, part III, scores with and without medication and stimulation, and gastric emptying time (expressed as the peak time of carbon-¹³C dioxide excretion in the ¹³C-acetate breath test). Sex-, age-, and body weight-matched controls were recruited to test the gastric emptying time in healthy individuals.

RESULTS

All the patients benefited from DBS. The Unified Parkinson's Disease Rating Scale, part III, scores had decreased from 48.5 ± 13.77 to 25.23 ± 8.59 without medication and 31.23 ± 11.4 to 13.92 ± 5.27 with medication. The levodopa equivalent dose had decreased from 1009.8 ± 291 mg to 707.65 ± 193.79 mg. The gastric emptying time was significantly prolonged in the patients with PD before DBS compared with the healthy control group (29.23 ± 6.58 minutes) and had improved to 35.19 ± 10.14 minutes with medication and 38.07 ± 11.17 minutes without medication after 3 months of STN stimulation. At 6 months postoperatively, the gastric emptying time was 32.3 ± 10.02 minutes without medication and 33.84 ± 10.79 minutes with medication.

CONCLUSIONS

A delayed gastric emptying time is associated with greater PD severity. Antiparkinsonian medications did not affect gastric emptying in patients with PD. STN DBS can improve both movement function and gastrointestinal motility in patients with PD in the long term. The exact mechanism by which DBS improves gastric emptying requires further exploration.

A prospective pilot study of the effects of deep brain stimulation on olfaction and constipation in Parkinson's disease

BACKGROUND

Previous studies suggest deep brain stimulation of the subthalamic nucleus (STN-DBS) may improve olfaction and constipation in PD, using subjective measures.

OBJECTIVE

To utilize objective measures to assess olfaction and constipation in PD following STN-DBS.

METHODS

In this prospective pilot study, olfaction (University of Pennsylvania Smell Identification Test [UPSIT]), bowel symptoms (ROME III questionnaires, daily bowel diaries, 100 mm visual analog scales for satisfaction with treatment and bowel habits), and motor manifestations of PD were evaluated before and after STN-DBS. Levodopa equivalent daily dose (LEDD) was calculated.

RESULTS

Ten patients (8 men, mean age 67.4 ± 6.0 years) with mean PD duration of 7.5 ± 3.7 years underwent bilateral STN-DBS, with mean follow-up of 3 months for all measures, except 7 months follow-up for bowel diaries. There was improvement in the Unified Parkinson's Disease Rating Scale motor "off" scores (33.7 ± 6.7 before and 16.1 ± 10.8 after, P = 0.001). Mean UPSIT scores (20.0 ± 6.6 versus 17.5 ± 5.7, P = 0.03) worsened from severe to total hyposmia. Seven patients had baseline constipation and completed bowel diaries. There was improvement in number of complete spontaneous bowel motions (CBSM) per week (2.2 ± 1.9 before versus 4.7 ± 2.4 after, P = 0.04), satisfaction with treatment of constipation (44 ± 27 before versus 64 ± 25 after, P = 0.02), and with bowel motions (33 ± 22 before and 48 ± 20 after, P = 0.2). However, laxative use (P = 0.15) and LEDD (P = 0.15) were unchanged.

CONCLUSION

Olfaction worsened while symptoms of constipation improved but did not resolve after STN-DBS.

Gastroparesis in Parkinson Disease: Pathophysiology, and Clinical Management

Patients with Parkinson disease (PD) experience a range of non-motor symptoms, including gastrointestinal symptoms. These symptoms can be present in the prodromal phase of the disease. Recent advances in pathophysiology reveal that α-synuclein aggregates that form Lewy bodies and neurites, the hallmark of PD, are present in the enteric nervous system and may precede motor symptoms. Gastroparesis is one of the gastrointestinal involvements of PD and is characterized by delayed gastric emptying of solid food in the absence of mechanical obstruction. Gastroparesis has been reported in nearly 45% of PD. The cardinal symptoms include early satiety, postprandial fullness, nausea, and vomiting. The diagnosis requires an appropriate test to confirm delayed gastric emptying, such as gastric scintigraphy, or breath test. Gastroparesis can lead to malnutrition and impairment of quality of life. Moreover, it might interfere with the absorption of antiparkinsonian drugs. The treatment includes dietary modifications, and pharmacologic agents both to accelerate gastric emptying and relieve symptoms. Alternative treatments have been recently developed in the management of gastroparesis, and their use in patients with PD will be reported in this review.

The impact of device-assisted therapies on the gut microbiome in Parkinson's disease

BACKGROUND

Microbiome feedbacks are proposed to influence Parkinson's disease (PD) pathophysiology. A number of studies have evaluated the impact of oral medication on the gut microbiome (GM) in PD. However, the influence of PD device-assisted therapies (DATs) on the GM remains to be investigated.

OBJECTIVES

To profile acute gut microbial community alterations in response to PD DAT initiation.

METHODS

Clinical data and stool samples were collected from 21 PD patients initiating either deep brain stimulation (DBS) or levodopa-carbidopa intestinal gel (LCIG) and ten spousal healthy control (HC) subjects. 16S amplicon sequencing of stool DNA enabled comparison of temporal GM stability between groups and with clinical measures, including disease alterations relative to therapy initiation.

RESULTS

We assessed GM response to therapy in the PD group by comparing pre-therapy (- 2 and 0 weeks) with post-therapy initiation timepoints (+ 2 and + 4 weeks) and HCs at baseline (0 weeks). Altered GM compositions were noted between the PD and HC groups at various taxonomic levels, including specific differences for DBS (overrepresentation of Clostridium_XlVa, Bilophila, Parabacteroides, Pseudoflavonifractor and underrepresentation of Dorea) and LCIG therapy (overrepresentation of Pseudoflavonifractor, Escherichia/Shigella, and underrepresentation of Gemmiger). Beta diversity changes were also found over the 4 week post-treatment initiation period.

CONCLUSIONS

We report on initial short-term GM changes in response to the initiation of PD DATs. Prior to the introduction of the DAT, a PD-associated GM was observed. Following initiation of DAT, several DAT-specific changes in GM composition were identified, suggesting DATs can influence the GM in PD.

Gastrointestinal dysfunction in movement disorders

PURPOSE OF REVIEW

This article provides an overview of the clinical presentation, investigations, and treatment options for gastrointestinal tract (GIT) dysfunction in patients with Parkinson's disease (PD) and other movement disorders.

RECENT FINDINGS

GIT dysfunction commonly appears as constipation and fecal incontinence (mostly overflow, accompanied with sphincter failure in multiple system atrophy [MSA]). Bowel dysfunction (underactive) occurs irrespectively from the site of the neurologic lesion, which is in contrast to site-dependent bladder dysfunction (brain, overactive; periphery, underactive). GI emergencies may arise, including intestinal pseudo-obstruction, intussusception, volvulus, and stercoral ulcer (ulcer of the colon due to pressure and irritation resulting from severe, prolonged constipation). Bowel function tests in neurologic patients often show a combination of slow transit and anorectal dysfunction. Management for slow transit constipation includes bulking agents, softening agents, yogurt/probiotics, and prokinetic agents. Suppositories, botulinum toxin injections, and transanal irrigation are options for managing anorectal constipation.

CONCLUSIONS

Function of the bowel is commonly affected in PD and other movement disorders. Neurologists play an important role in assessing bowel symptoms in their patients and planning treatment strategies, often in collaboration with specialist teams.

Electroceuticals in the Gastrointestinal Tract

The field of electroceuticals has attracted considerable attention over the past few decades as a novel therapeutic modality. The gastrointestinal (GI) tract (GIT) holds significant potential as a target for electroceuticals as the intersection of neural, endocrine, and immune systems. We review recent developments in electrical stimulation of various portions of the GIT (including esophagus, stomach, and small and large intestine) and nerves projecting to the GIT and supportive organs. This has been tested with varying degrees of success for several dysmotility, inflammatory, hormonal, and neurologic disorders. We outline a vision for the future of GI electroceuticals, building on advances in mechanistic understanding of GI physiology coupled with novel ingestible technologies. The next wave of electroceutical therapies will be minimally invasive and more targeted than current approaches, making them an indispensable tool in the clinical armamentarium.

Detection of gastric slow oscillatory contraction using parasagittal cine MR images: Comparison with simultaneously measured electrogastrogram

PURPOSE

To determine if parasagittal gastric cine magnetic resonance imaging (MRI) is able to measure gastric oscillatory contractions around 0.05 Hz and to determine its relationship with electrical activity as measured by electrogastrography (EGG).

METHODS

Assessment of the gastric motility is important for the research of the enteric nervous system and for the diagnosis of functional gastric disorders. Electrogastrography is a non-invasive method that can measure gastric oscillatory electrical activity around 0.05 Hz (slow wave) using electrodes on the abdominal skin, but its sensitivity and specificity of the slow wave detection is limited. We used parasagittal gastric cine MRI around the angular incisure to measure gastric oscillatory contraction around 0.05 Hz in 24 healthy volunteers. Cine MRI was acquired with time resolution of 1 s for 10 min while freely breathing participants were lying on the bed. The gastric area of the cross section was measured for each MR image and assessed its change over time. The results were compared with those for simultaneously recorded EGG.

RESULTS

The main frequency of the gastric area change for each participant ranged from 0.041 to 0.059 Hz (mean ± S.D. = 0.049 ± 0.004), which corresponds to the gastric slow wave frequency (mean ± S.D. = 0.049 ± 0.004) as measured by EGG (p = 7.9585 × 10 ^-8, Kendall 's tau test). Cross correlation analysis showed that 22 of 24 participants' gastric area changes were significantly (p < 0.05) related to the EGG waveforms. Displacement of the stomach due to respiration did not affect gastric area measurements.

CONCLUSIONS

Parasagittal cine MRI is correlated with EGG recordings and able to detect and quantifying gastric motility abnormalities.

Effect of Deep Brain Stimulation on Swallowing Function: A Systematic Review

The effect of deep brain stimulation (DBS) on swallowing function in movement disorders is unclear. Here, we systematically reviewed this topic by searching keywords following PICOS strategy of problem (swallowing or swallow or dysphagia or aspiration) and intervention (deep brain stimulation, or DBS) in the PubMed and Web of Science in English in April 2020, with comparators [subthalamic nucleus (STN), globus pallidus interna (GPi), ventralis intermedius, (ViM), post-subthalamic area, or caudal zona incerta (PSA/cZi); ON/OFF DBS state/settings, ON/OFF medication state, Parkinson's disease (PD), dystonia, tremor], outcomes (swallowing function measures, subjective/objective) and study types (good quality original studies) in mind. We found that STN DBS at usual high-frequency stimulation could have beneficial effect (more so on subjective measures and/or OFF medication), no effect, or detrimental effect (more so on objective measures and/or ON medication) on swallowing function in patients with PD, while low-frequency stimulation (LFS) could have beneficial effect on swallowing function in patients with freezing of gait. GPi DBS could have a beneficial effect (regardless of medication state and outcome measures) or no effect, but no detrimental effect, on swallowing function in PD. GPi DBS also has beneficial effects on swallowing function in majority of the studies on Meige syndrome but not in other diseases with dystonia. PSA/cZi DBS rarely has detrimental effect on swallowing functions in patients with PD or tremor. There is limited information on ViM to assess. Information on swallowing function by DBS remains limited. Well-designed studies and direct comparison of targets are further needed.

Assessments of plasma acyl-ghrelin levels in Parkinson's disease patients treated with deep brain stimulation

Gastrointestinal dysfunction is the most common non-motor symptom in Parkinson's disease (PD) with rates rising as the disease progresses. Deep brain stimulation of subthalamic nucleus (STN DBS) improves motor functions in advanced PD. However, the effect of STN DBS on ghrelin concentration and consequently on motility disturbances as well as body weight is unclear. The objective of this study was to assess acyl-ghrelin levels in comparison to weight in advanced PD patients treated with STN DBS. Plasma concentrations of acyl-ghrelin was measured in 29 PD patients in the fasting state and at 30, 60, 120, and 180 min after a standard meal preoperatively and 3 months after surgery. The level of acyl-ghrelin in PD patients were compared with 30 age and sex-matched healthy controls. We reported that mean plasma acyl-ghrelin levels were decreased in PD patients before STN DBS in fasting (p = 0.0003) and in 30 min postprandial phase (p = 0.04) compared with healthy controls. The plasma acyl-ghrelin levels after STN DBS increased in pre-prandial and postprandial phase in PD patients at the investigated time points. Body weight gained on average 2.33 kg during the first 3 months after surgery. There was no correlation between the acyl-ghrelin plasma levels and BMI. After STN DBS in fasting and postprandial phase plasma acyl-ghrelin levels were increased. The results showed that STN DBS therapy elicited a modification of ghrelin levels, increasing its concentration in pre- and postprandial state. In addition, body weight was increased during 3 months after surgery.

Clinical Impact of Deep Brain Stimulation on the Autonomic System in Patients with Parkinson's Disease

Background

The role of deep brain stimulation (DBS) in the management of motor symptoms in patients with Parkinson's disease is well defined. However, it is becoming increasingly clear that DBS can either improve or worsen a number of non-motor phenomena.

Objectives

We examined the published literature to better understand the effects on autonomic symptoms following DBS of the subthalamic nucleus and the globus pallidus interna.

Methods

We conducted a PubMed search of studies regarding the effects of DBS on the autonomic system published from January 2001. We searched for the following terms and their combinations: Parkinson's disease, deep brain stimulation, subthalamic nucleus, globus pallidus interna, autonomic dysfunction.

Results

Most studies reported in the literature focus on DBS targeting the subthalamic nucleus, with particular emphasis on favorable outcomes regarding gastrointestinal function and bladder control. However, the emergence or worsening of autonomic symptoms in subgroups of patients has also been documented. More controversial is the effect of stimulation on the cardiovascular, pulmonary, and thermo-regulatory systems as well as sexual functioning. Data regarding the influence of DBS on the autonomic system when the target is the globus pallidus interna is less forthcoming, with target selection varying according to centre and clinical indication.

Conclusions

DBS appears to affect the autonomic nervous system, with varying degrees of influence, which may or may not be clinically beneficial for the patient. A better understanding of these effects could help personalize stimulation for individual patients with autonomic disorders and/or avoid autonomic symptoms in susceptible patients.

Autonomic dysfunction in Parkinson's disease: Implications for pathophysiology, diagnosis, and treatment

Parkinson's disease (PD) is a neurodegenerative disease with a 200 year-long research history. Our understanding about its clinical phenotype and pathogenesis remains limited, although dopaminergic replacement therapy has significantly improved patient outcomes. Autonomic dysfunction is an essential category of non-motor phenotypes that has recently become a cutting edge field that directs frontier research in PD. In this review, we initially describe the epidemiology of dysautonomic symptoms in PD. Then, we perform a meticulous analysis of the pathophysiology of autonomic dysfunction in PD and propose that the peripheral autonomic nervous system may be a key route for α-synuclein pathology propagation from the periphery to the central nervous system. In addition, we recommend that constipation, orthostatic hypotension, urinary dysfunction, erectile dysfunction, and pure autonomic failure should be viewed as prodromal dysautonomic markers in PD prediction and diagnosis. Finally, we summarize the strategies currently available for the treatment of autonomic dysfunction in PD and suggest that high-quality, better-designed, randomized clinical trials should be conducted in the future.

The Use of Neuromodulation for Symptom Management

Pain and other symptoms of autonomic dysregulation such as hypertension, dyspnoea and bladder instability can lead to intractable suffering. Incorporation of neuromodulation into symptom management, including palliative care treatment protocols, is becoming a viable option scientifically, ethically, and economically in order to relieve suffering. It provides further opportunity for symptom control that cannot otherwise be provided by pharmacology and other conventional methods.

Activities of Daily Living and Their Relationship to Health-Related Quality of Life in Patients with Parkinson Disease After Subthalamic Nucleus Deep Brain Stimulation

BACKGROUND

Deep brain stimulation (DBS) of the subthalamic nucleus (STN) can reduce motor symptoms in patients with Parkinson disease (PD) and improve their health-related quality of life (HRQoL). The effect of STN DBS on activities of daily living (ADL), an important component of quality of life, is poorly understood. We aimed to investigate effects of STN DBS on HRQoL and ADL in patients with PD.

METHODS

HRQoL and ADL were assessed using the following disease-specific and generic questionnaires at baseline and 3, 6, and 12 months after surgery: the Parkinson's Disease Questionnaire 39 (PDQ-39), the Short-Form 36 health survey questionnaire, the World Health Organization Quality of Life Scale-Brief version, the Unified Parkinson's Disease Rating Scale part II, the ADL scale, and the Instrumental Activities of Daily Living scale.

RESULTS

We reported significant early improvements (3 months) in the HRQoL and ADL, and these benefits increased over time (6 months); however, further improvement between 6 and 12 months was nonsignificant. Two PDQ-39 subdomains (social support and communications) and a Short-Form 36 health survey questionnaire subdomain (social functioning) showed declines after surgery. Changes in the Instrumental Activities of Daily Living scale were significantly correlated with changes in the PDQ-39 summary index and other PDQ-39 subdomains, including mobility, emotional well-being, social support, and cognition, at all follow-up points.

CONCLUSIONS

STN DBS caused a marked improvement in HRQoL at 3 and 6 months; however, HRQoL remained stable at the 12-month postoperative follow-up. Moreover, we have shown a significant correlation between ADL performance and HRQoL after STN DBS.

Management of constipation in patients with Parkinson's disease

A considerable body of research has recently emerged around nonmotor symptoms in Parkinson's disease (PD) and their substantial impact on patients' well-being. A prominent example is constipation which occurs in up to two thirds of all PD-patients thereby effecting psychological and social distress and consequently reducing quality of life. Despite the significant clinical relevance of constipation, unfortunately little knowledge exists on effective treatments. Therefore this systematic review aims at providing a synopsis on clinical effects and safety of available treatment options for constipation in PD. For this purpose, three electronic databases (MEDLINE, EMBASE, PsycINFO) were searched for experimental and quasi-experimental studies investigating the efficacy/effectiveness of interventions in the management of PD-associated constipation. Besides, adverse events were analyzed as secondary outcome. In total, 18 publications were identified involving 15 different interventions, of which none can be attributed sufficient evidence to derive strong recommendations. Nevertheless, some evidence indicates that dietetic interventions with probiotics and prebiotics may reduce symptom burden while providing a very favorable side-effects profile. Furthermore, the use of lubiprostone, macrogol and in the specific case of isolated or prominent outlet obstruction constipation injections of botulinum neurotoxin A into the puborectal muscles may as well be moderately supported. In summary, too little attention has been paid to treatment options for constipation in PD leaving abundant room for further research addressing this topic.

Weight Loss and Malnutrition in Patients with Parkinson's Disease: Current Knowledge and Future Prospects

Parkinson's Disease (PD) is currently considered a systemic neurodegenerative disease manifested with not only motor but also non-motor symptoms. In particular, weight loss and malnutrition, a set of frequently neglected non-motor symptoms, are indeed negatively associated with the life quality of PD patients. Moreover, comorbidity of weight loss and malnutrition may impact disease progression, giving rise to dyskinesia, cognitive decline and orthostatic hypotension, and even resulting in disability and mortality. Nevertheless, the underlying mechanism of weight loss and malnutrition in PD remains obscure and possibly involving multitudinous, exogenous or endogenous, factors. What is more, there still does not exist any weight loss and malnutrition appraision standards and management strategies. Given this, here in this review, we elaborate the weight loss and malnutrition study status in PD and summarize potential determinants and mechanisms as well. In conclusion, we present current knowledge and future prospects of weight loss and malnutrition in the context of PD, aiming to appeal clinicians and researchers to pay a closer attention to this phenomena and enable better management and therapeutic strategies in future clinical practice.

Neurotransmitters: The Critical Modulators Regulating Gut-Brain Axis

Neurotransmitters, including catecholamines and serotonin, play a crucial role in maintaining homeostasis in the human body. Studies on these neurotransmitters mainly revolved around their role in the "fight or flight" response, transmitting signals across a chemical synapse and modulating blood flow throughout the body. However, recent research has demonstrated that neurotransmitters can play a significant role in the gastrointestinal (GI) physiology. Norepinephrine (NE), epinephrine (E), dopamine (DA), and serotonin have recently been a topic of interest because of their roles in the gut physiology and their potential roles in GI and central nervous system pathophysiology. These neurotransmitters are able to regulate and control not only blood flow, but also affect gut motility, nutrient absorption, GI innate immune system, and the microbiome. Furthermore, in pathological states, such as inflammatory bowel disease (IBD) and Parkinson's disease, the levels of these neurotransmitters are dysregulated, therefore causing a variety of GI symptoms. Research in this field has shown that exogenous manipulation of catecholamine serum concentrations can help in decreasing symptomology and/or disease progression. In this review article, we discuss the current state-of-the-art research and literature regarding the role of neurotransmitters in regulation of normal GI physiology, their impact on several disease processes, and novel work focused on the use of exogenous hormones and/or psychotropic medications to improve disease symptomology. J. Cell. Physiol. 232: 2359-2372, 2017. © 2016 Wiley Periodicals, Inc.

Effects of Deep Brain Stimulation on Autonomic Function

Over the course of the development of deep brain stimulation (DBS) into a well-established therapy for Parkinson's disease, essential tremor, and dystonia, its utility as a potential treatment for autonomic dysfunction has emerged. Dysfunction of autonomic processes is common in neurological diseases. Depending on the specific target in the brain, DBS has been shown to raise or lower blood pressure, normalize the baroreflex, to alter the caliber of bronchioles, and eliminate hyperhidrosis, all through modulation of the sympathetic nervous system. It has also been shown to improve cortical control of the bladder, directly induce or inhibit the micturition reflex, and to improve deglutition and gastric emptying. In this review, we will attempt to summarize the relevant available studies describing these effects of DBS on autonomic function, which vary greatly in character and magnitude with respect to stimulation target.