Swallowing safety in Parkinson's disease after zona incerta deep brain stimulation

[Dysphagia in Parkinsonian Syndromes]

Dysphagia is a clinically relevant problem in Parkinson's disease as well as in atypical Parkinsonian syndromes, such as multiple system atrophy and diseases from the spectrum of 4‑repeat tauopathies, which affect most patients to a varying degree in the course of their disease. This results in relevant restrictions in daily life due to impaired intake of food, fluids, and medication with a subsequent reduction in quality of life. This article not only gives an overview of the pathophysiological causes of dysphagia in the various Parkinson syndromes, but also presents screening, diagnostic and treatment procedures that have been investigated for the different diseases.

Chemogenetic and optogenetic stimulation of zona incerta GABAergic neurons ameliorates motor impairment in Parkinson's disease

Parkinson's disease (PD) is characterized by the degeneration of dopaminergic neurons in the substantia nigra and leads to progressive motor dysfunction. While studies have focused on the basal ganglia network, recent evidence suggests neuronal systems outside the basal ganglia are also related to PD pathogenesis. The zona incerta (ZI) is a predominantly inhibitory subthalamic region for global behavioral modulation. This study investigates the role of GABAergic neurons in the ZI in a mouse model of 6-hydroxydopamine (6-OHDA)-induced PD. First, we found a decrease in GABA-positive neurons in the ZI, and then the mice used chemogenetic/optogenetic stimulation to activate or inhibit GABAergic neurons. The motor performance of PD mice was significantly improved by chemogenetic/optogenetic activation of GABAergic neurons, and repeated chemogenetic activation of ZI GABAergic neurons increased the dopamine content in the striatum. Our work identifies the role of ZI GABAergic neurons in regulating motor behaviors in 6-OHDA-lesioned PD model mice.

Effectiveness of Interventions for Dysphagia in Parkinson Disease: A Systematic Review

PURPOSE

Dysphagia is a common sequela of Parkinson disease (PD) and is associated with malnutrition, aspiration pneumonia, and mortality. This review article synthesized evidence regarding the effectiveness of interventions for dysphagia in PD.

METHOD

Electronic searches were conducted in Ovid MEDLINE, Embase, Cochrane Central Register of Controlled Trials, CINAHL, and speechBITE. Of the 2,015 articles identified, 26 met eligibility criteria: interventional or observational studies with at least five or more participants evaluating dysphagia interventions in adults with PD-related dysphagia, with outcomes measured using videofluoroscopic swallowing study (VFSS), fiberoptic endoscopic evaluation of swallowing (FEES), or electromyography (EMG). Risk of bias (RoB) was evaluated using the Evidence Project tool and predetermined criteria regarding the rigor of swallowing outcome measures.

RESULTS

Interventions were classified as follows: pharmacological (n = 11), neurostimulation (n = 8), and behavioral (n = 7). Primary outcome measures varied across studies, including swallowing timing, safety, and efficiency, and were measured using VFSS (n = 17), FEES (n = 6), and EMG (n = 4). Critical appraisal of study findings for RoB, methodological rigor, and transparency showed the majority of studies failed to adequately describe contrast media used, signal acquisition settings, and rater blinding to time point. Low certainty evidence generally suggested improved swallow timing with exercises with biofeedback and deep brain stimulation (DBS), improved safety with DBS and expiratory muscle strength training, and improved efficiency with the Lee Silverman Voice Treatment and levodopa.

CONCLUSIONS

Studies with lower RoB and greater experimental rigor showed potential benefit in improving swallowing efficiency but not safety. Further research investigating discrete changes in swallowing pathophysiology post-intervention is warranted to guide dysphagia management in PD.

SUPPLEMENTAL MATERIAL

https://doi.org/10.23641/asha.17132162.

Dysphagia in Parkinson's disease patients prior to deep brain stimulation: Is screening accurate?

BACKGROUND

Swallowing problems are common in Parkinson's Disease (PD) and aspiration pneumonia is the leading cause of death. Deep brain stimulation (DBS) surgery can successfully manage the motor symptoms of PD when pharmacological management begins to fail. Before DBS it is important to identify baseline dysfunction, but no consensus regarding swallowing screening exists.

OBJECTIVES

This study was undertaken to: 1) identify the prevalence of dysphagia prior to DBS; and 2) determine if screening measures or other characteristics were predictive for reduced airway protection.

METHODS

A standardized protocol was performed for 137 consecutive patients with idiopathic PD and no confounding medical conditions, including those referred for work-up of dysphagia (n = 57) and those prior to DBS (n = 80). Three validated screening measures were completed before videofluoroscopic evaluation.

RESULTS

On videofluoroscopy, there were significant differences in reduced airway protection by group (dysphagia group: 44 %; pre-DBS group: 21 %). Aspiration also differed by group (dysphagia group: 18 %; pre-DBS group: 8 %) although not significantly. Although there were significant between-group differences, none of the screening measures was predictive of reduced airway protection or aspiration in the sample overall. Male gender, previous videofluoroscopic evaluation, history of pneumonia, and previous DBS surgery were associated with increased aspiration-risk. Age also showed a modest correlation.

CONCLUSIONS

Dysphagia is not uncommon prior to DBS. No screening measure accurately predicted reduced airway protection on videofluoroscopy. Abnormal findings on clinical assessment prior to DBS, particularly in patients that are older, male, or have a history of pneumonia, may identify individuals requiring an objective dysphagia evaluation.

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.

Swallowing safety in Parkinson's disease after zona incerta deep brain stimulation

OBJECTIVES

The objective of this study was to examine swallowing function in patients with Parkinson's disease before and after caudal zona incerta deep brain (cZI DBS) surgery. The aims were to examine the effect of cZI DBS on swallowing safety regarding liquid and solid food, as well as to identify the effect of cZI DBS on body mass index (BMI) and specific items from part II of the Unified Parkinson's Disease Rating Scale (UPDRS).

MATERIALS AND METHODS

The median age of the 14 patients was 57 years (range 46-71), with a median disease duration of 6 years (range 2-13). The present sample is an extension of a previous report, into which six additional patients have been added. Fiber endoscopic examinations of swallowing function, measures of BMI, and evaluation of UPDRS part II items were made before and 12 months after surgery, with and without activated DBS.

RESULTS

There were no significant changes due to cZI DBS regarding penetration/aspiration, pharyngeal residue or premature spillage (p > .05). Median BMI increased by +1.1 kg/m² 12 months after surgery (p = .01, r = .50). All reported specific symptoms from the UPDRS part II were slight or mild. A significant improvement regarding handling of utensils was seen 12 months postoperatively (p = .03, r = -.42).

CONCLUSIONS

Caudal zona incerta DBS was found not to have a negative impact on swallowing safety. A significant increase in postoperative weight was observed, and speech seemed to be slightly negatively affected, whereas handling of utensils was improved with cZI DBS.