Impact of simultaneous subthalamic and nigral stimulation on dysphagia in Parkinson's disease

Effect of subthalamic and nigral deep brain stimulation on speech and voice in Parkinson's patients

Deep brain stimulation can influence the speech and voice quality in Parkinson´s disease (PD). This controlled, randomized, double-blind, cross-over clinical trial was conducted in 15 PD patients with bilateral subthalamic deep brain stimulation (DBS) to compare the effects of STN-DBS with combined subthalamic and nigral stimulation (STN + SNr-DBS) and DBS OFF on speech and voice parameters in PD patients. Speech and voice were analyzed subjectively using questionnaires (voice/pronunciation quality VAS, VHI, SHI) and objectively using audio analysis (maximum phonation time, AVQI, mean F0, intonation, syllable rate, reading time). Both stimulation conditions, STN + SNr-DBS and STN-DBS, revealed heterogeneous effects on speech and voice production with a slight beneficial effect on the voice quality of individual patients compared to DBS OFF, but not in the whole group. Small, but not significant effects were seen only in subjective voice quality on the VAS and intonation (both stimulation conditions compared to DBS OFF). No significant changes of the objective speech parameters during the audio analysis could be observed (both stimulation conditions compared to DBS OFF). There were no significant differences between STN + SNr-DBS and STN-DBS in any speech and voice domain. The beneficial effects on speech and voice production are minor in most patients compared to the motor improvements by DBS. Both STN-DBS and STN + SNr-DBS were safe, with comparable effects between both DBS modes, and represent no contraindications from the perspective of the voice specialist.

The Effects of Non-Pharmacological Therapies for Dysphagia in Parkinson's Disease: A Systematic Review

BACKGROUND

Parkinson's disease (PD) is currently the second most common degenerative neurological disorder globally, with aspiration pneumonia caused by difficulty swallowing being the deadliest complication. The patient's subjective experience and the safety of swallowing have been the main focus of previous evaluations and treatment plans. The effectiveness of treatment may be attributed to the brain's ability to adapt and compensate. However, there is a need for more accurate assessment methods for dysphagia and further research on how treatment protocols work.

OBJECTIVE

This systematic review was designed to assess the effectiveness and long-term impact of published treatment options for swallowing disorders in patients with PD.

METHODS

In adherence to the Preferred Reporting Items for Reviews and Meta-analysis (PRISMA) guidelines, we conducted a systematic review where we thoroughly searched multiple databases (PubMed, Web of Science, Elsevier, and Wiley) for clinical studies published in various languages until December, 2023. Two reviewers evaluated the studies against strict inclusion/exclusion criteria.

RESULTS

This systematic review included a total of 15 studies, including 523 participants, involving six treatment approaches, including breath training, deep brain stimulation, reduction of upper esophageal sphincter (UES) pressure, transcranial magnetic stimulation, postural compensation, and video-assisted swallowing therapy. Primary outcomes included video fluoroscopic swallowing study (VFSS), fiberoptic endoscopic evaluation of swallowing (FEES), high-resolution pharyngeal impedance manometry (HPRIM), and functional magnetic resonance imaging (fMRI).

CONCLUSION

Treatments that reduce UES resistance may be an effective way to treat dysphagia in PD patients. HRPIM can quantify pressure changes during the pharyngeal period to identify patients with reduced swallowing function earlier. However, due to the limited number of randomized controlled trials (RCTs) included and the high risk of bias in some studies, large-scale RCTs are needed in the future, and objective indicators such as HRPIM should be used to determine the effectiveness and long-term impact of different therapies on dysphagia in PD patients.

Oral Transport, Penetration, and Aspiration in PD: Insights from a RCT on STN + SNr Stimulation

Dysphagia is frequent and detrimental in advanced Parkinson's disease (PD) and does not respond to standard treatments. Experimental models suggested that pathological overactivity of the substantia nigra pars reticulata (SNr) may hinder oral contributions to swallowing. Here, we hypothesized that the combined stimulation of subthalamic nucleus (STN) and SNr improves measures of dysphagia after eight weeks of active treatment. We enrolled 20 PD patients with dysphagia and deep brain stimulation (DBS). Patients were assessed in 'medication on' and 'STN' stimulation at baseline (V1) and then were randomized 1:1 to 'STN' or 'STN + SNr' stimulation. In addition, patients of both groups received swallowing therapy as a standard of care. The primary endpoint was the change in Penetration-Aspiration Scale (PAS) at eight-week follow-up (V2) with respect to the baseline (V1) under the hypothesis, that 'STN + SNr' was superior to 'STN'. We obtained further secondary endpoints on oral preparation, transport, pharyngeal phase, penetration, and aspiration. PAS change from V1 to V2 was not significantly different between groups (p = 0.221). When considering all patients for secondary analyses, we found that the entire study cohort showed better PAS scores at V2 compared to V1 irrespective from DBS treatment allocation (p = 0.0156). Both STN and STN + SNr treatments were safe. 'STN + SNr' stimulation was not superior compared to standard 'STN' stimulation both on PAS and the secondary endpoints. We found that the entire study cohort improved dysphagia after eight weeks, which presumably mirrors the effect of continued swallowing therapy and the increased patient attention on swallowing.

Deep brain stimulation of the subthalamic nucleus increases the risk of sialorrhea in patients with advanced Parkinson's disease

INTRODUCTION

Sialorrhea is a common neurological manifestation of Parkinson's disease (PD). No specifically designed prospective study has tested the effects of deep brain stimulation of the subthalamic nucleus (STN-DBS) on sialorrhea in patients with advanced PD. We focused on the effect of STN-DBS on the incidence of sialorrhea in patients with PD.

METHODS

This multicenter, prospective, non-randomized concurrent clinical trial analyzed the incidence of sialorrhea during long-term follow-up in 170 patients with advanced PD (84 patients with STN-DBS and 86 patients with medication therapy).

RESULTS

After STN-DBS, 58.1% of patients presented with sialorrhea (Drooling Rating Scale (DRS) > 5) compared with 39.3% of patients with medication therapy (P < 0.001). STN-DBS stimulation demonstrated a significant increase in DRS and Drooling Severity and Frequency Scale (DSFS) compared with the patients with medication therapy (P < 0.001). At follow-up, the onabotulinumtoxin-A (BTX-A) injection ratio was significantly higher in the STN-DBS group (29.8% vs. 11.9%, P = 0.0057) compared with the patients with medication therapy.

CONCLUSIONS

STN-DBS increased the risk of sialorrhea in patients with advanced PD.

TRIAL REGISTRATION

clinicaltrials. gov (NCT06090929).

Pathways from the Superior Colliculus to the Basal Ganglia

The present work aims to review the structural organization of the mammalian superior colliculus (SC), the putative pathways connecting the SC and the basal ganglia, and their role in organizing complex behavioral output. First, we review how the complex intrinsic connections between the SC's laminae projections allow for the construction of spatially aligned, visual-multisensory maps of the surrounding environment. Moreover, we present a summary of the sensory-motor inputs of the SC, including a description of the integration of multi-sensory inputs relevant to behavioral control. We further examine the major descending outputs toward the brainstem and spinal cord. As the central piece of this review, we provide a thorough analysis covering the putative interactions between the SC and the basal ganglia. To this end, we explore the diverse thalamic routes by which information from the SC may reach the striatum, including the pathways through the lateral posterior, parafascicular, and rostral intralaminar thalamic nuclei. We also examine the interactions between the SC and subthalamic nucleus, representing an additional pathway for the tectal modulation of the basal ganglia. Moreover, we discuss how information from the SC might also be relayed to the basal ganglia through midbrain tectonigral and tectotegmental projections directed at the substantia nigra compacta and ventrotegmental area, respectively, influencing the dopaminergic outflow to the dorsal and ventral striatum. We highlight the vast interplay between the SC and the basal ganglia and raise several missing points that warrant being addressed in future studies.

Evaluation of Post-Swallow Residue with Visual Analysis of Swallowing Efficiency and Safety in Patients with Idiopathic Parkinson's Disease

Objectives: Dysphagia is common in idiopathic Parkinson's disease (IPD) and is associated with impairments in both swallowing safety and swallowing efficiency. The goals of this study were to define post-swallow residue patterns in people with IPD and describe pathophysiological endoscopic findings affecting residue accumulation. Methods: This was a prospective single-blinded cross-sectional cohort study of patients with the diagnosis of IPD recruited from a Movement Disorder Clinic. Clinical variables included patient age, cognitive function, and measures of disease severity, and laryngoscopic examinations with a flexible endoscopic evaluation of swallowing (FEES) were completed for each patient. Visual Analysis of Swallowing Efficiency and Safety (VASES) was used to analyze FEES. Post-swallow residue outcomes and non-residue endoscopic outcomes including the Bowing index, Penetration Aspiration Scale (PAS) score, premature leakage, and build-up phenomenon were evaluated. Multiple regression models were used to evaluate factors affecting the residue at different anatomic levels. Results: Overall 53 patients completed the study. The multiple regression analyses showed a relation between (1) the presence of residue at the level of oropharynx and epiglottis with premature leakage, (2) the presence of residue at the level of the laryngeal vestibule and vocal folds with build-up phenomenon, and (3) the presence of residue at the level of the hypopharynx, laryngeal vestibule, and subglottis with airway invasion. Conclusion: Residue pattern during FEES is associated with specific swallow dysfunctions in IPD. Using residue localization and quantification may be a helpful tool in assessing the impact of targeted swallowing interventions in patients with IPD and dysphagia.

Dysphagia treatments in Parkinson's disease: A systematic review and meta-analysis

BACKGROUND

The majority of patients with Parkinson's disease (PD) develop oropharyngeal dysphagia during the course of their disease. However, the efficacy of dysphagia treatments for these patients remains controversial. Therefore, we conducted this systematic review and meta-analysis to evaluate treatment efficacy based on the evidence from randomized controlled trials (RCTs).

METHODS

Five electronic databases were systematically searched from inception date to April 2022. Two reviewers independently extracted and analyzed the data. The outcome measures were changes in swallowing-related characteristics based on instrumental swallowing assessments.

KEY RESULTS

An initial search identified 187 RCT studies of relevance. After screening, nine studies with a total sample size of 286 were included in the meta-analysis. The pooled effect size for all dysphagia treatments compared with control comparators was significant and medium (SMD [95% CI] = 0.58 [0.22, 0.94], p = 0.001; I2  = 50%). Subgroup analysis revealed a significant and medium pooled effect size for stimulation treatments (brain stimulation, peripheral neurostimulation and acupuncture) (SMD [95% CI] = 0.54 [0.15, 0.92]; p = 0.006; I2  = 22%). Specifically, the effect sizes for the single RCTs on neuromuscular stimulation (SMD [95% CI] = 1.58 [0.49, 2.86]; p = 0.005) and acupuncture (SMD [95% CI] = 0.82 [0.27, 1.37]; p = 0.003) were significant and large.

CONCLUSIONS AND INFERENCES

Our results showed that overall, dysphagia treatments, particularly stimulation treatments, can potentially benefit PD patients. However, given the limited number of small RCTs for each type of treatment, the evidence remains weak and uncertain. Further large-scale, multicenter RCTs are warranted to fully explore their clinical efficacy in the PD population.

Dysphagia in Parkinson Disease: Part II-Current Treatment Options and Insights from Animal Research

Purpose of Review

Dysphagia is highly prevalent in Parkinson disease (PD) but is not typically identified nor treated until later in the disease process. This review summarizes current pharmacological, surgical, and behavioral treatments for PD-associated dysphagia and contributions from translational animal research.

Recent Findings

Swallowing is a complex physiologic process controlled by multiple brain regions and neurotransmitter systems. As such, interventions that target nigrostriatal dopamine dysfunction have limited or detrimental effects on swallowing outcomes. Behavioral interventions can help target PD-associated dysphagia in mid-to-late stages. Animal research is necessary to refine treatments and useful in studying prodromal dysphagia.

Summary

Dysphagia is an early, common, and debilitating sign of PD. Current pharmacological and surgical interventions are not effective in ameliorating swallowing dysfunction; behavioral intervention remains the most effective approach for dysphagia treatment. Animal research has advanced our understanding of mechanisms underlying PD and PD-associated dysphagia, and continues to show translational promise for the study of dysphagia treatment options.

Combined Stimulation of the Substantia Nigra and the Subthalamic Nucleus for the Treatment of Refractory Gait Disturbances in Parkinson's Disease: A Preliminary Study

Deep brain stimulation of the subthalamic nucleus is efficient for the treatment of motor symptoms (i.e., tremors) in patients with Parkinson's disease. Gait disorders usually appear during advanced stages of idiopathic Parkinson's disease in up to 80% of patients and have an important impact on their quality of life. The effects of deep brain stimulation of the subthalamic nucleus on gait and balance are still controversial. For this reason, alternative targets have been considered, such as stimulation of the pedunculopontine nucleus and the pars reticulata of substantia nigra, involved in the integration of the functional connections for gait. Due to the proximity of the subthalamic nucleus to the substantia nigra, their combined stimulation is feasible and may lead to better outcomes, improving axial symptoms. Our objective was to prospectively compare simultaneous stimulation of both structures versus conventional subthalamic stimulation in improving gait disorders. In ten patients with advanced Parkinson's disease, deep brain stimulation leads (eight linear contacts) were implanted, and gait analysis was performed 6 months after surgery in off-stimulation and after 4 weeks of dual or single subthalamic stimulation. An improvement in gait parameters was confirmed with both stimulation conditions, with better results with combined substantia nigra and subthalamic stimulation compared with conventional subthalamic stimulation. Further studies are needed to determine if this effect remains after long-term dual-target stimulation.

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.

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.

The Effect of Deep Brain Stimulation on Swallowing Function in Parkinson's Disease: A Narrative Review

Unlike appendicular motor symptoms, such as bradykinesia and rigidity, in Parkinson's disease (PD), which have already been reported to respond well to deep brain stimulation (DBS), there is limited literature on the effects of DBS on swallowing function in patients with PD. The field lacks consensus as there are conflicting reports among existing studies regarding whether swallowing function improves or declines following DBS implantation. This narrative review aims to summarize and analyze the studies published on the effect of DBS on swallowing function in patients with PD. We collated studies published up to February 2020 using a comprehensive electronic database search of PubMed, SCOPUS, EMBASE, and the Cochrane Library. Two reviewers independently assessed the studies using strict inclusion and exclusion criteria. The primary literature search yielded 529 relevant papers. After reading their titles and abstracts and assessing their eligibility based on the full-text, we finally included and reviewed 14 publications. Nine of these studies reported positive effects of DBS on swallowing function and four studies showed no significant positive results. The remaining study showed decreased swallowing function after unilateral subthalamic nucleus-DBS surgery. In conclusion, we found that DBS has the potential to improve swallowing function in patients with PD. However, high-quality evidence is lacking. To clearly elucidate the effect of DBS on swallowing function in patients with PD, high-quality randomized controlled trials should be conducted in the future.

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.