Route of Feeding as a Proxy for Dysphagia After Stroke and the Effect of Transdermal Glyceryl Trinitrate: Data from the Efficacy of Nitric Oxide in Stroke Randomised Controlled Trial

New and Evolving Treatments for Neurologic Dysphagia

Despite swallowing being a frequently performed daily function, it is highly complex. For a safe swallow to occur, muscles within the head, neck, and thorax need to contract in a concerted pattern, controlled by several swallowing centers at multiple levels of the central nervous system, including the midbrain, cerebral cortex, and cerebellum in addition to five cranial nerves. Dysphagia, or difficulty swallowing, is caused by a long list of pathologic processes and diseases, which can interfere with various stages along the swallowing sensorimotor pathway. When present, dysphagia leads to increased mortality, morbidity, hospital length of stay, and reduced quality of life. Current dysphagia management approaches, such as altering the texture and consistency of foods and fluids and teaching patients rehabilitative exercises, have been broadly unchanged for many years and, in the case of texture modification, are of uncertain effectiveness. However, evidence is emerging in support of new medication-based and neuromodulatory treatment approaches. Regarding medication-based therapies, most research has focused on capsaicinoids, which studies have shown are able to improve swallowing in patients with post-stroke dysphagia. Separately, albeit convergently, in the field of neuromodulation, there is a growing and positive evidential base behind three non-invasive brain stimulation techniques: repetitive transcranial magnetic stimulation (rTMS), transcranial direct current stimulation (TDCS), and pharyngeal electrical stimulation (PES). Should some or all of these emerging therapies fulfill their promise, dysphagia-related patient outcomes may be improved. This paper describes the current state of our understanding regarding new medication and neuromodulation-based neurogenic oropharyngeal dysphagia treatments.

Research trends and hotspots of post-stroke dysphagia rehabilitation: a bibliometric study and visualization analysis

Background

Post-stroke dysphagia (PSD) is one of the most prevalent stroke sequelae, affecting stroke patients' prognosis, rehabilitation results, and quality of life while posing a significant cost burden. Although studies have been undertaken to characterize the pathophysiology, epidemiology, and risk factors of post-stroke dysphagia, there is still a paucity of research trends and hotspots on this subject. The purpose of this study was to create a visual knowledge map based on bibliometric analysis that identifies research hotspots and predicts future research trends.

Methods

We searched the Web of Science Core Collection for material on PSD rehabilitation research from its inception until July 27, 2023. We used CiteSpace, VOSviewer, and Bibliometrix R software packages to evaluate the annual number of publications, nations, institutions, journals, authors, references, and keywords to describe present research hotspots and prospective research orientations.

Results

This analysis comprised 1,097 articles from 3,706 institutions, 374 journals, and 239 countries or regions. The United States had the most publications (215 articles), and it is the most influential country on the subject. "Dysphagia" was the most published journal (100 articles) and the most referenced journal (4,606 citations). Highly cited references focused on the pathophysiology and neuroplasticity mechanisms of PSD, therapeutic modalities, rehabilitation tactics, and complications prevention. There was a strong correlation between the terms "validity" and "noninvasive," which were the strongest terms in PSD rehabilitation research. The most significant words in PSD rehabilitation research were "validity" and "noninvasive brain stimulation," which are considered two of the most relevant hotspots in the field.

Conclusion

We reviewed the research in the field of PSD rehabilitation using bibliometrics to identify research hotspots and cutting-edge trends in the field, primarily including the pathogenesis and neurological plasticity mechanisms of PSD, complications, swallowing screening and assessment methods, and swallowing rehabilitation modalities, and this paper can provide in the follow-up research in the field of PSD rehabilitation. The results of this study can provide insightful data for subsequent studies in the field of PSD rehabilitation.

Effects of pharmacological agents for neurogenic oropharyngeal dysphagia: A systematic review and meta-analysis

BACKGROUND

This systematic review and meta-analysis aimed to evaluate the effects of pharmacological agents for neurogenic oropharyngeal dysphagia based on evidence from randomized controlled trials (RCTs).

METHODS

Electronic databases were systematically searched between January 1970 and March 2021. Two reviewers independently extracted and synthesized the data. The outcome measure was changed in (any) relevant clinical swallowing-related characteristics.

KEY RESULTS

Data from 2186 dysphagic patients were collected from 14 RCT studies across a range of pharmacotherapies. The pooled effect size of transient receptor potential (TRP) channel agonists was large compared to placebo interventions (SMD[95%CI] =1.27[0.74,1.80], p < 0.001; I²  = 79%). Data were limited for other pharmacological agents and the overall pooled effect size of these agents was non-significant (SMD [95% CI] =0.25 [-0.24, 0.73]; p = 0.31; I²  = 85%). When analyzed separately, large effect sizes were observed with Nifedipine (SMD[95%CI] =1.13[0.09,2.18]; p = 0.03) and Metoclopramide (SMD[95%CI] =1.68[1.08,2.27]; p < 0.001). By contrast, the effects of angiotensin-converting enzyme (ACE) inhibitors (SMD[95%CI] = -0.67[-2.32,0.99]; p = 0.43; I²  = 61%), Physostigmine (SMD[95%CI] = -0.05[-1.03,0.93]; p = 0.92) and Glyceryl Trinitrate (GTN) (SMD [95% CI] = -0.01 [-0.11, 0.08]; p = 0.78) were non-significant. Within stroke patients, subgroup analysis showed that TRP channel agonists had a moderate pooled effect size (SMD[95%CI] =0.74[0.10,1.39]; p = 0.02; I²  = 82%) whereas the effects of other agents were non-significant (SMD[95%CI] =0.40[-0.04,0.84]; p = 0.07; I²  = 87%).

CONCLUSIONS & INFERENCES

Our results showed that TRP channel agonists, Nifedipine and Metoclopromide may be beneficial for neurogenic dysphagic patients. Large scale, multicenter clinical trials are warranted to fully explore their therapeutic effects on swallowing.

Predictive Model of Dysphagia and Brain Lesion-Symptom Mapping in Acute Ischemic Stroke

Background and purpose: Early recognition and management of post-stroke dysphagia (PSD) based on MRI may reduce the incidence of complications. Combining clinical symptoms with applications of MRI, we aimed to identify the risk factors of PSD, develop a prediction scale with high accuracy and map key dysphagia brain areas.

Methods: A total of 275 acute ischemic stroke patients were enrolled in this study, and 113 (41.1%) patients were diagnosed with PSD. All patients underwent the water-swallowing test (WST) and volume-viscosity swallow test (V-VST) within first 24 h following admission to assess swallowing. Vascular factors were evaluated and MRI brain scans were obtained within 3 days after symptom onset for each participant admitted to the hospital. T-test, chi-squared test and Fisher’s exact test were used to investigate the associations of various patient characteristics with dysphagia, and multivariable logistic regression models were used to construct a prediction scale. Scale accuracy was assessed using receiver operating characteristic (ROC) analysis. We extracted white matter hyperintensities for each patient as potential brain lesions. Voxel-based lesion-symptom mapping (VLSM) was used to identify key brain areas for dysphagia.

Results: Risk factors related with PSD were older age, history of atrial fibrillation, higher fasting blood glucose, NIH stroke scale, TOAST classification, progressive stroke, middle cerebral artery lesion and anterior cerebral artery lesion. Three variables with most significant associations, including NIH stroke scale, TOAST classification and progressive stroke, combined with age and gender, were used to construct a dysphagia prediction scale with high accuracy (AUC = 0.86). VLSM identified left inferior parietal gyrus as a key brain region for PSD.

Conclusion: Risk factors of PSD were identified and a predictive model of dysphagia was constructed intelligently and automatically. The left inferior parietal gyrus was identified as a key brain area for dysphagia, which provides a new symptom-based treatment target for early rehabilitation in the future.

Pharyngeal electrical stimulation for neurogenic dysphagia following stroke, traumatic brain injury or other causes: Main results from the PHADER cohort study

BACKGROUND

Neurogenic dysphagia is common and has no definitive treatment. We assessed whether pharyngeal electrical stimulation (PES) is associated with reduced dysphagia.

METHODS

The PHAryngeal electrical stimulation for treatment of neurogenic Dysphagia European Registry (PHADER) was a prospective single-arm observational cohort study. Participants were recruited with neurogenic dysphagia (comprising five groups - stroke not needing ventilation; stroke needing ventilation; ventilation acquired; traumatic brain injury; other neurological causes). PES was administered once daily for three days. The primary outcome was the validated dysphagia severity rating scale (DSRS, score best-worst 0-12) at 3 months.

FINDINGS

Of 255 enrolled patients from 14 centres in Austria, Germany and UK, 10 failed screening. At baseline, mean (standard deviation) or median [interquartile range]: age 68 (14) years, male 71%, DSRS 11·4 (1·7), time from onset to treatment 32 [44] days; age, time and DSRS differed between diagnostic groups. Insertion of PES catheters was successfully inserted in 239/245 (98%) participants, and was typically easy taking 11·8 min. 9 participants withdrew before the end of treatment. DSRS improved significantly in all dysphagia groups, difference in means (95% confidence intervals, CI) from 0 to 3 months: stroke (n = 79) -6·7 (-7·8, -5·5), ventilated stroke (n = 98) -6·5 (-7·6, -5·5); ventilation acquired (n = 35) -6·6 (-8·4, -4·8); traumatic brain injury (n = 24) -4·5 (-6·6, -2·4). The results for DSRS were mirrored for instrumentally assessed penetration aspiration scale scores. DSRS improved in both supratentorial and infratentorial stroke, with no difference between them (p = 0·32). In previously ventilated participants with tracheotomy, DSRS improved more in participants who could be decannulated (n = 66) -7·5 (-8·6, -6·5) versus not decannulated (n = 33) -2·1 (-3·2, -1·0) (p<0·001). 74 serious adverse events (SAE) occurred in 60 participants with pneumonia (9·2%) the most frequent SAE.

INTERPRETATION

In patients with neurogenic dysphagia, PES was safe and associated with reduced measures of dysphagia and penetration/aspiration.

FUNDING

Phagenesis Ltd.

PRECIOUS: PREvention of Complications to Improve OUtcome in elderly patients with acute Stroke-statistical analysis plan of a randomised, open, phase III, clinical trial with blinded outcome assessment

Rationale

Aspiration, infections, and fever are common in the first days after stroke, especially in older patients. The occurrence of these complications has been associated with an increased risk of death or dependency.

Aims and design

PREvention of Complications to Improve OUtcome in elderly patients with acute Stroke (PRECIOUS) is an international, multi-centre, 3 × 2 factorial, randomised, controlled, open-label clinical trial with blinded outcome assessment, which will assess whether prevention of aspiration, infections, or fever with metoclopramide, ceftriaxone, paracetamol, respectively, or any combination of these in the first 4 days after stroke onset improves functional outcome at 90 days in elderly patients with acute stroke.

Discussion

This statistical analysis plan provides a technical description of the statistical methodology and unpopulated tables and figures. The paper is written prior to data lock and unblinding of treatment allocation.

Trial registration

ISRCTN registry ISRCTN82217627. Registered on 22 September 2015. The trial was prospectively registered.

Pharyngeal electrical stimulation for early decannulation in tracheotomised patients with neurogenic dysphagia after stroke (PHAST-TRAC): a prospective, single-blinded, randomised trial

BACKGROUND

Dysphagia after stroke is common, especially in severely affected patients who have had a tracheotomy. In a pilot trial, pharyngeal electrical stimulation (PES) improved swallowing function in this group of patients. We aimed to replicate and extend this single-centre experience.

METHODS

We did a prospective, single-blind, randomised controlled trial across nine sites (seven acute care hospitals, two rehabilitation facilities) in Germany, Austria, and Italy. Patients with recent stroke who required tracheotomy were randomly assigned to receive 3 days of either PES or sham treatment (1:1). All patients had the stimulation catheter inserted; sham treatment was applied by connecting the PES base station to a simulator box instead of the catheter. Randomisation was done via a computerised interactive system (stratified by site) in blocks of four patients per site. Patients and investigators applying PES were not masked. The primary endpoint was assessed by a separate investigator at each site who was masked to treatment assignment. The primary outcome was readiness for decannulation 24-72 h after treatment, assessed using fibreoptic endoscopic evaluation of swallowing and based on a standardised protocol, including absence of massive pooling of saliva, presence of one or more spontaneous swallows, and presence of at least minimum laryngeal sensation. We planned a sequential statistical analysis of superiority for the primary endpoint. Interim analyses were to be done after primary outcome data were available for 50 patients (futility), 70 patients, and every additional ten patients thereafter, up to 140 patients. Analysis was by intention to treat. This trial is registered with the ISRCTN registry, number ISRCTN18137204.

FINDINGS

From May 29, 2015, to July 5, 2017, of 81 patients assessed, 69 patients from nine sites were randomly assigned to receive PES (n=35) or sham (n=34) treatment. Median onset to randomisation time was 28 days (IQR 19-41; PES 28 [20-49]; sham 28 [18-40]). The Independent Data and Safety Monitoring Board recommended that the trial was stopped early for efficacy after 70 patients had been recruited and primary endpoint data for 69 patients were available. This decision was approved by the steering committee. More patients were ready for decannulation in the PES group (17 [49%] of 35 patients) than in the sham group (three [9%] of 34 patients; odds ratio [OR] 7·00 [95% CI 2·41-19·88]; p=0·0008). Adverse events were reported in 24 (69%) patients in the PES group and 24 (71%) patients in the sham group. The number of patients with at least one serious adverse event did not differ between the groups (ten [29%] patients in the PES group vs eight [23%] patients in the sham group; OR 1·30 [0·44-3·83]; p=0·7851). Seven (20%) patients in the PES group and three (9%) patients in the sham group died during the study period (OR 2·58 [0·61-10·97]; p=0·3059). None of the deaths or serious adverse events were judged to be related to PES.

INTERPRETATION

In patients with stroke and subsequent tracheotomy, PES increased the proportion of patients who were ready for decannulation in this study population, many of whom received PES within a month of their stroke. Future trials should confirm whether PES is beneficial in tracheotomised patients who receive stimulation similarly early after stroke and explore its effects in other cohorts.

FUNDING

Phagenesis Ltd.