Pharyngeal electrical stimulation for the treatment of dysphagia in Wallenberg syndrome: A FEES-based case analysis

Abstract

Swallowing is regulated by cortical networks and the caudal brainstem. Damage to central pattern generators, commonly seen after stroke, can result in severe dysphagia with limited treatment options. Pharyngeal electrical stimulation (PES) presents a promising therapy as it may enhance sensory input to impaired brainstem networks by targeting pharyngeal sensory afferents, the primary site of dysfunction in brainstem infarction.

This single-case study reports on a 78-year-old woman with a confirmed left-sided infarction in the dorsolateral medulla oblongata, resulting in severe dysphagia. PES was delivered 2 days after the onset of symptoms using the Phagenyx® system via a nasogastric catheter. The stimulation was applied at 5 Hz for 10 min daily over 4 days.

The initial fiberoptic endoscopic evaluation of swallowing (FEES) showed severe dysphagia with saliva aspiration. Assessment revealed a Penetration-Aspiration-Scale (PAS) score of 8 for half a tablespoon of ice chips, alongside a score of 3 on Murray's Secretion Scale (MSS) and 7 on the New Zealand Secretion Scale (NZSS). No other consistencies were tested. After 4 consecutive days of stimulation followed by a 48-h period without stimulation, follow-up FEES revealed normal swallowing frequency and adequate saliva control, with a score of 0 on MSS. The patient safely swallowed all tested consistencies, scoring 1 on the PAS. On the NZSS, both fluids and solids scored 0. With pudding, residue in the pyriform fossae resulted in a score of 1.

PES appears to be a targeted and effective approach for the treatment of severe dysphagia after brainstem stroke.

Highlights

• •Rapid recovery of swallowing function was observed after Wallenberg syndrome.
• •Pharyngeal electrical stimulation (PES) may improve severe post-stroke dysphagia.
• •Early initiation of treatment could be crucial to the effectiveness of PES.
• •This case supports PES as a potential treatment for dysphagia after brainstem stroke.

1. Introduction

Swallowing requires a coordinated interaction of cortical regions and the brainstem swallowing centre. Lesions in the area of the swallowing central pattern generators, as seen in Wallenberg syndrome may result in profound swallowing impairment with dysfunction in the pharyngeal phase. Conventional treatment options for severe dysphagia remain limited, especially when the pharyngeal phase is affected. Large cohort studies such as those conducted by Bath et al. [1] show that pharyngeal electrical stimulation (PES) presents a safe, targeted therapy that may enhance pharyngeal and laryngeal sensitivity and restore swallowing reflexes. A subgroup analysis of stroke patients showed that PES was equally effective for supratentorial and infratentorial infarcts [1]. However, the evidence and mechanism for neuroplasticity in infratentorial infarcts have not yet been fully clarified.

This study focuses on patients with infratentorial stroke, a subgroup, for whom evidence on PES remains limited.

2. Case presentation

The case report aims to identify a specific clinical pattern that may benefit from PES and to explore prognostic factors influencing therapeutic outcome.

2.1. Report of the case

This single-case study involved a 78-year-old woman presented to our clinic with acute left facial paresis, severe dysarthrophonia with hypophonia, dysphagia, and vertigo. The dysphagia manifested as saliva drooling and absence of spontaneous swallowing. Lung auscultation revealed abnormal breathing sounds, which could indicate saliva aspiration. She reported that the symptoms had been present for 1 day prior to presentation at our clinic. An MRI revealed a left dorsolateral medullary infarct, corresponding to the symptoms identified during the initial neurological examination. A follow-up cranial MRI conducted a few days later revealed an additional infarction in the left basal ganglia, which had evidently developed between the initial examination and the follow-up scan.

Examination of the swallowing-related cranial nerves by the speech and language therapist revealed left-sided facial paresis (cranial nerve VII), reduced mandibular mobility (cranial nerve V), absence of cough and swallow reflexes, indicating impairment of cranial nerves IX and X, dysarthric voice quality, and restricted tongue movements in all directions (cranial nerve XII).

Two days post-onset, a fiberoptic endoscopic evaluation of swallowing (FEES) by two trained speech and language therapists was performed. To assess the swallowing function, the Dynamic Imaging Grade of Swallowing Toxicity applied to flexible endoscopic evaluation of swallowing (DIGEST-FEES) [2], which includes the Penetration-Aspiration Scale (PAS) by Rosenbek, the secretion severity rating scale by Murray (MSS) [3] and the New Zealand Secretion Scale (NZSS) [4] were used. The DIGEST-FEES was utilised to permit a more detailed assessment of swallowing safety and swallowing efficiency. For reasons of clarity, only the PAS is presented in the figure, while the safety and efficiency grades are described in the main text. The consistencies used in the examinations were described according to the International Dysphagia Diet Standardisation Initiative (IDDSI) [5].

The examination showed extensive saliva pooling and aspiration without protective responses interpreted as 7 on the NZSS, which was also observed when a teaspoon of frozen IDDSI 0 (Ice chips) was given, rated as PAS 8. Persistent secretion within the aditus was rated as grade 3 on the MSS. The safety and efficiency grades of the DIGEST-FEES were each rated as 4. Throughout the FEES, there was no swallowing reflex elicitable.

Consistent with the left-sided dorsolateral medullary infarct, reduced mobility of the left vocal fold was suspected. The endoscopic findings also suggested left vocal fold hypotonia, although visualization was limited by saliva pooling.

The supplementary video: "Baseline FEES findings"presents a part of the pre-intervention FEES. It shows saliva in the hypopharynx and aspiration during inspiration.

2.2. Treatment

In this study, PES treatment was delivered using the CE-marked Phagenyx® system (Phagenesis Ltd. Manchester, UK) via a nasogastric treatment catheter with built-in electrodes and which functions as a nasogastric feeding tube [1]. Stimulation was applied at a frequency of 5 Hz for 10 min daily over four consecutive sessions.

Immediately following the FEES examination, the stimulation catheter was placed by the speech therapy team and the first PES treatment session delivered. The stimulation intensity was determined individually each day by identifying the patient's sensory threshold and maximum tolerance level, and set at 75% of the tolerable limit above sensory threshold as previously reported [1]. Stimulation began at 42 mA on day one, followed by 27 mA on the second day, 22 mA on the third day, and 20 mA on the final day of treatment. After the 4 days of stimulation, a 48-h rest period was observed.

No further speech and language therapy, such as functional dysphagia therapy, was provided during the PES interval. Saliva-reducing medication was administered during treatment and discontinued before the 48-h stimulation pause.

2.3. Outcome

A post-PES-treatment FEES was performed after the 48-h stimulation pause and showed physiological swallowing frequency, effective saliva management a secretion score of 0, and safe swallowing of all tested consistencies without penetration or aspiration. The consistencies tested, IDDSI 0 (Water given in teaspoon-sized boluses and by consecutive cup drinking), 4, and 7(Easy to chew), were all rated as 1 on the PAS. On the NZSS, IDDSI 0 and 7 (Easy to chew) both scored 0. However, with IDDSI 4 (viscous porridge), residue was observed in the pyriform fossae, resulting in a score of 1 on the NZSS. For these observations, an efficiency grade of 1 was assigned on the DIGEST-FEES, while the safety grade was rated as 0.

Fig. 1 presents the pre- and post-intervention FEES results measured by the rating scales used to evaluate swallowing function.

Fig. 1.

Overview of pre- and post-intervention assessment data.

Residual findings included mild dysphagia with occasional initiation difficulties of swallowing and slight residues, vocal cord paresis, and persistent facial paresis. The dysarthrophonia had subjectively slightly improved in the assessment of spontaneous speech by two speech and language therapists.

The supplementary video: "Post-Intervention FEES findings" presents a part of the post-treatment FEES. It reveals the patient managing blue-dyed water with intact swallowing safety and minimal deficits in swallowing efficiency.

3. Discussion

This case demonstrates rapid recovery of swallowing following early PES in Wallenberg syndrome. Within 4 days of consecutive stimulation, pharyngeal and laryngeal sensitivity, reflex triggering, and saliva control improved substantially. The early timing of intervention (2 days after stroke onset) likely contributed to its effectiveness and is consistent with findings by Cheng et al. [6], who identified early initiation as a predictor of treatment success in stroke patients with dysphagia.

While research has largely focused on cortical reorganization as demonstrated by Hamdy et al. [7], this case highlights the potential for neuroplasticity within the brainstem itself. The PHADER study demonstrated beneficial effects of PES on swallowing recovery in both supratentorial and infratentorial stroke [1]. PES may activate impaired neural pathways and promote functional recovery [8]. However, this mechanism remains hypothetical, as findings on cortical neuroplasticity cannot be directly translated to the brainstem. Although adaptive reorganization of brainstem networks may contribute to recovery, it remains unclear whether this reflects reorganization within affected structures, recruitment of contralesional networks, or increased involvement of supratentorial pathways. Cheng et al. [8] suggested that beneficial effects following brainstem stroke may be mediated through activation of preserved swallowing-related pathways and recruitment of residual neural networks, particularly in cases involving damage to the central pattern generator (CPG). Further research is needed to clarify the mechanisms of infratentorial neuroplasticity following brainstem infarction.

As described by Yang et al. [9], brainstem lesions are commonly associated with severe dysphagia, particularly affecting the pharyngeal phase of swallowing. PES targets pharyngeal sensorimotor pathways bilaterally, aligning with the typical pattern of impairment observed in patients with brainstem lesions. This anatomical and functional integration suggests that PES may be an effective treatment for brainstem-related dysphagia, as it directly engages affected neural circuits.

Moreover, PES requires minimal patient cooperation while precisely targeting impaired pharyngeal structures, making it especially suitable for patients with brainstem stroke, who often experience profound neurological deficits and limited treatment options [10].

A key limitation is that spontaneous recovery cannot be excluded. Without a control group, the contribution of PES to the observed improvement cannot be determined with certainty. In addition to PES, the patient received saliva-reducing medication, which was discontinued at the end of treatment.

The patient showed marked improvement exclusively in swallowing. Other symptoms, including facial paresis, dysarthria, and vertigo, did not demonstrate comparable subjective improvement. This finding may indicate a specific impact of PES on swallowing mechanisms.

Another limitation is that assessments were not blinded and were conducted by the same therapists who administered treatment, introducing potential observer bias.

Although evidence from a single case study is limited, the findings are consistent with those of the PHADER study [1], indicating that both infratentorial and supratentorial strokes can benefit from PES.

4. Conclusion

This case study demonstrates marked improvement in swallowing function and airway protection following early PES application in a patient with severe dysphagia after brainstem infarction. Recovery, particularly in the pharyngeal phase, supports PES as a targeted intervention at the primary site of impairment. Although spontaneous recovery cannot be excluded and the study design has limitations, selective swallowing improvement despite persistent neurological deficits suggests a specific effect of PES on swallowing mechanisms. These findings highlight the potential therapeutic role of PES in swallowing recovery after brainstem stroke and neurogenic dysphagia.

The following are the supplementary data related to this article.

CRediT authorship contribution statement

Franziska Hinkelmann: Writing – review & editing, Writing – original draft, Visualization. Marcel Kaspari: Writing – original draft. Lars Wojtecki: Writing – review & editing.

Declaration of generative AI and AI-assisted technologies in the writing process

During the preparation of this work the authors used ChatGPT for language optimization. After using this tool, the authors reviewed and edited the content as needed and take full responsibility for the content of the publication.

Funding

This report received funding from Phagenesis Ltd. for payment of publication fees.

Declaration of competing interest

LW has previously received funding grants and institutional support from the German Research Foundation, Hilde-Ulrichs-Stiftung für Parkinsonforschung, and the ParkinsonFonds Germany, BMBF/ERA-NETNEURON, DFG Forschergruppe (FOR1328), Deutsche Parkinson Vereinigung (DPV), Forschungskommission, Medizinische Fakultät, HHU Düsseldorf, UCB; Medtronic, UCB, Teva, Allergan, Merz, Abbvie, Roche, Bial, Merck, Novartis, Desitin, Spectrum. LW owned stock in company BioNTech SE. He is consultant to the following companies or received travel honarium from: TEVA, UCB Schwarz, Desitin, Medtronic, Abbott/Abbvie, MEDA, Boehringer I, Storz Medical, Kyowa Kirin, Guidepoint, Merck, Merz, Synergia, BIAL, Zambon, Sapio Life, STADA, Inomed, Vertanical.

FH, MK and LW received funding fees from Phagenesis Ltd.

Data availability

The data supporting the findings of this study are available from the corresponding author upon request.