The Development and Validation of the SWADOC: A Study Protocol for a Multicenter Prospective Cohort Study

Swallowing function management in patients with disorders of consciousness: a scoping review

Objective

Patients with disorders of consciousness often have concurrent swallowing difficulties, although the assessment methods, interventions, and their effectiveness have not been systematically described. This study aims to conduct a comprehensive review of assessment methods and rehabilitation interventions for swallowing function in patients with disorders of consciousness.

Methods

This scoping review was performed and reported according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses extension for Scoping Reviews (PRISMA-ScR) guideline. Studies that describe a screening method to examine swallowing function or assess a kind of swallowing management intervention among individuals with disorders of consciousness (DoC) were included. Following Arksey and O'Malley's five-stage framework, databases including CNKI, WangFan, VIP, SinoMed, PubMed, Web of Science, Embase, ClinicalTrials.gov, Cochrane, Scopus, and Medline were systematically searched, from the inception of each database to June 2024. Relevant studies were extracted and analyzed. The main review question is "What has been studied about swallowing function management in patients with DoC?".

Results

Assessment methods for swallowing function in patients with disorders of consciousness primarily included clinical swallowing assessments, scale-based evaluations, and instrument-based assessments. Rehabilitation interventions for swallowing function encompassed sensory stimulation, K-point stimulation, functional oral intake therapy, oral intermittent tube feeding, neuromuscular electrical stimulation, and acupuncture therapy. Most of the included studies did not explicitly specify the timing of swallowing assessment and intervention.

Conclusion

A standardized approach for evaluating and intervening in swallowing function among patients with disorders of consciousness is notably lacking. Selecting appropriate swallowing assessment tools and devising evidence-based management plans tailored to assessment results could improve the swallowing function and patient outcomes. More high-quality designing research that compares the assessment accuracy of different evaluation methods, as well as develops personalized interventions are imperative.

Systematic review registration

https://doi.org/10.17605/OSF.IO/SURBY.

Non-pharmacologic interventions in disorders of consciousness

Severely brain-injured patients with disorders of consciousness pose significant challenges in terms of management, particularly due to the limited therapeutic options available. Despite the potential for some patients to benefit from interventions even years after the injury, clinicians often lack clear and reliable treatment strategies to promote patient recovery. In response to this clinical need, the field of neuromodulation has emerged as a promising alternative to traditional pharmacologic therapies. Both invasive and noninvasive brain stimulation techniques offer diverse possibilities for restoring physiologic neural activity and enhancing functional network integrity in these complex neurological disorders. This chapter offers a comprehensive overview of current neuromodulation techniques, exploring their potential applications and analyzing the existing evidence for their efficacy. Specifically, we describe transcranial electrical stimulation, transcranial magnetic stimulation, deep brain stimulation, low-intensity focused ultrasound, vagal nerve stimulation (including transcutaneous methods), spinal cord stimulation, and median nerve stimulation. While certain approaches show promise for patients with disorders of consciousness, there remains a pressing need for large-scale interventional clinical trials that will play an essential role for elucidating the underlying mechanisms of recovery and for refining stimulation parameters. This, together with the development of tailored individual interventions will move the field forward and optimize therapeutic outcomes.

Common Data Elements for Disorders of Consciousness: Recommendations from the Working Group on Outcomes and Endpoints

BACKGROUND

Clinical management of persons with disorders of consciousness (DoC) is dedicated largely to optimizing recovery. However, selecting a measure to evaluate the extent of recovery is challenging because few measures are designed to precisely assess the full range of potential outcomes, from prolonged DoC to return of preinjury functioning. Measures that are designed specifically to assess persons with DoC are often performance-based and only validated for in-person use. Moreover, there are no published recommendations addressing which outcome measures should be used to evaluate DoC recovery. The resulting inconsistency in the measures selected by individual investigators to assess outcome prevents comparison of results across DoC studies. The National Institute of Neurological Disorders and Stroke (NINDS) common data elements (CDEs) is an amalgamation of standardized variables and tools that are recommended for use in studies of neurologic diseases and injuries. The Neurocritical Care Society Curing Coma Campaign launched an initiative to develop CDEs specifically for DoC and invited our group to recommend CDE outcomes and endpoints for persons with DoCs.

METHODS

The Curing Coma Campaign Outcomes and Endpoints CDE Workgroup, consisting of experts in adult and pediatric neurocritical care, neurology, and neuroscience, used a previously established five-step process to identify and select candidate CDEs: (1) review of existing NINDS CDEs, (2) nomination and systematic vetting of new CDEs, (3) CDE classification, (4) iterative review and approval of panel recommendations, and (5) development of case report forms.

RESULTS

Among hundreds of existing NINDS outcome and endpoint CDE measures, we identified 20 for adults and 18 for children that can be used to assess the full range of recovery from coma. We also proposed 14 new outcome and endpoint CDE measures for adults and 5 for children.

CONCLUSIONS

The DoC outcome and endpoint CDEs are a starting point in the broader effort to standardize outcome evaluation of persons with DoC. The ultimate goal is to harmonize DoC studies and allow for more precise assessment of outcomes after severe brain injury or illness. An iterative approach is required to modify and adjust these outcome and endpoint CDEs as new evidence emerges.

Swallowing Assessment in Post-Comatose Patients: A Feasibility Study on the SWADOC Tool

Background: After a severe brain injury and a coma, patients may develop disorders of consciousness (DoC), frequently accompanied by severe dysphagia. The evaluation and therapy of swallowing are therefore essential aspects of their management. Objectives: This study aims to evaluate the SWallowing Assessment in Disorders of Consciousness (SWADOC) tool in the assessment of swallowing in post-comatose patients. Here, we validate its quantitative items, describe preliminary results and identify limitations. Methods: Fourteen post-comatose patients were repeatedly evaluated with the Simplified Evaluation of CONsciousness Disorders (SECONDs) and with the SWADOC. Results: The internal consistency of the oral and pharyngeal subscales of the SWADOC was good. The test-retest reliability showed that all items, all subscores and the total score were stable except for two items (endo-buccal secretions and bronchial congestion). A comparison to the Facial Oral Tract Therapy Swallowing Assessment of Saliva (F.O.T.T-SAS) confirmed that scoring with the SWADOC offers a greater potential for quantitative observations in assessing swallowing abilities among patients with DoC. The SECONDs scores and SWADOC total scores showed a significant positive correlation (τ = 0.78, p < 0.001). Conclusions: This study provides preliminary but encouraging results on the psychometric properties of the SWADOC tool. It shows that this tool is relevant and feasible as a bedside assessment of dysphagia in patients with DoC.

Swallowing dysfunctions in patients with disorders of consciousness: Evidence from neuroimaging data, assessment, and management

Following severe brain injuries, a subset of patients may remain in an altered state of consciousness; most of these patients require artificial feeding. Currently, a functional oral phase and the presence of exclusive oral feeding may constitute signs of consciousness. Additionally, the presence of pharyngo-laryngeal secretions, saliva aspiration, cough reflex and tracheostomy are related to the level of consciousness. However, the link between swallowing and consciousness is yet to be fully understood. The primary aim of this review is to establish a comprehensive overview of the relationship between an individual's conscious behaviour and swallowing (reflexive and voluntary). Previous studies of brain activation during volitional and non-volitional swallowing tasks in healthy subjects are also reviewed. We demonstrate that the areas activated by voluntary swallowing tasks (primary sensorimotor, cingulate, insula, premotor, supplementary motor, cerebellum, and operculum) are not specific to deglutitive function but are shared with other motor tasks and brain networks involved in consciousness. This review also outlines suitable assessment and treatment methods for dysphagic patients with disorders of consciousness. Finally, we propose that markers of swallowing could contribute to the development of novel diagnostic guidelines for patients with disorders of consciousness.

Feeding modality evolution in traumatic brain injury patients with severe alteration of consciousness: A observational study

The aim of this study was to compare feeding modalities and the level of consciousness in patients with a severe brain injury during reeducation and rehabilitation. The clinical data of vegetative state or minimal conscious state due to severe traumatic brain injury hospitalized in a coma arousal unit were collected from 2012 to 2019. Feeding modalities were evaluated clinically and with functional endoscopy evaluation of swallowing or video fluoroscopy and functional oral intake scale. Evolution of consciousness was evaluated using Wessex Head Injury Matrix scale (WHIM). Comparison between WHIM score and feeding modalities were performed at admission and at discharge of the arousal unit. Of the 93 patients considered, 33 were included corresponding to inclusion criteria (traumatic brain injury, disorder of consciousness and age > 18 years). The mean age was 44.8 ± 16.8 years, and there were 6 females for 27 males. At admission, all patients were fed by gastrostomy (n = 25) or by nasogastric tube (n = 8) and 27 had a tracheostomy. At discharge, 10 patients keep an exclusive alimentation by gastrostomy (Group 1, G1) as 23 had exclusive oral feeding (Group 2, G2). The score of the WHIM at admission was identical in both groups (21.7 ± 10.9 (G1) vs. 21.0 ± 15.33 (G2) (ns)). At discharge, WHIM increased to 38.3 ± 15.4 in G1 and to 49.8 ± 9.7 in G2 (P < .05). WHIM score was significantly higher in G2 than in G1 (P < .05). There was a positive correlation between functional oral intake scale and WHIM at discharge. Our results demonstrated that recovery of oral feeding in patients with a severe traumatic brain injury appeared in those who had the better improvement of consciousness level.

Links Between Swallowing and Consciousness: A Narrative Review

This literature review explores a wide range of themes addressing the links between swallowing and consciousness. Signs of consciousness are historically based on the principle of differentiating reflexive from volitional behaviors. We show that the sequencing of the components of swallowing falls on a continuum of voluntary to reflex behaviors and we describe several types of volitional and non-volitional swallowing tasks. The frequency, speed of initiation of the swallowing reflex, efficacy of the pharyngeal phase of swallowing and coordination between respiration and swallowing are influenced by the level of consciousness during non-pathological modifications of consciousness such as sleep and general anesthesia. In patients with severe brain injury, the level of consciousness is associated with several components related to swallowing, such as the possibility of extubation, risk of pneumonia, type of feeding or components directly related to swallowing such as oral or pharyngeal abnormalities. Based on our theoretical and empirical analysis, the efficacy of the oral phase and the ability to receive exclusive oral feeding seem to be the most robust signs of consciousness related to swallowing in patients with disorders of consciousness. Components of the pharyngeal phase (in terms of abilities of saliva management) and evoked cough may be influenced by consciousness, but further studies are necessary to determine if they constitute signs of consciousness as such or only cortically mediated behaviors. This review also highlights the critical lack of tools and techniques to assess and treat dysphagia in patients with disorders of consciousness.

Behavioral Assessment of Patients with Disorders of Consciousness

Severe brain injury is associated with a period of impaired level of consciousness that can last from days to months and results in chronic impairment. Systematic assessment of level of function in patients with disorders of consciousness (DoC) is critical for diagnosis, prognostication, and evaluation of treatment efficacy. Approximately 40% of patients who are thought to be unconscious based on clinical bedside behavioral assessment demonstrate some signs of consciousness on standardized behavioral assessment. This finding, in addition to a growing body of literature demonstrating the advantages of standardized behavioral assessment of DoC, has led multiple professional societies and clinical guidelines to recommend standardized assessment over routine clinical evaluation of consciousness. Nevertheless, even standardized assessment is susceptible to biases and misdiagnosis, and examiners should consider factors, such as fluctuating arousal and aphasia, that may confound evaluation. We review approaches to behavioral assessment of consciousness, recent clinical guideline recommendations for use of specific measures to evaluate patients with DoC, and strategies for mitigating common biases that may confound the examination.

The Importance of Material Used in Speech Therapy: Two Case Studies in Minimally Conscious State Patients

Speech therapy can be part of the care pathway for patients recovering from comas and presenting a disorder of consciousness (DOC). Although there are no official recommendations for speech therapy follow-up, neuroscientific studies suggest that relevant stimuli may have beneficial effects on the behavioral assessment of patients with a DOC. In two case studies, we longitudinally measured (from 4 to 6 weeks) the behavior (observed in a speech therapy session or using items from the Coma Recovery Scale—Revised) of two patients in a minimally conscious state (MCS) when presenting music and/or autobiographical materials. The results highlight the importance of using relevant material during a speech therapy session and suggest that a musical context with a fast tempo could improve behavior evaluation compared to noise. This work supports the importance of adapted speech therapy for MCS patients and encourages larger studies to confirm these initial observations.

Neurogenic Dysphagia and Nutrition in Disorder of Consciousness: An Overview with Practical Advices on an "Old" but Still Actual Clinical Problem

Neurogenic dysphagia is a difficulty in swallowing food caused by disease or impairment of the nervous system, including stroke and traumatic brain injury. The most clinically apparent complication of neurogenic dysphagia is pulmonary aspiration, which may manifest itself acutely as choking or coughing, respiratory distress, wheezing, gasping or gurgling, and tachycardia. However, chronic symptoms, including weight loss, production of excessive oral secretions and aspiration pneumonia, may be also present, especially in patients with a disorder of consciousness (DOC). Usually, patients with dysphagia after the acute phase need to be treated with enteral nutrition using a feeding tube. This avoids patient malnutrition and supports the rehabilitation program. This narrative review aims to investigate dysphagia and its complications and management in patients with DOC. Clinical indications and practical advice on how to assess and treat this complex problem are also provided.