Electroacupuncture-Based Cerebral Electric Field Therapy for Unilateral Vocal Cord Paralysis with Secondary Dysphagia Post Upper Respiratory Infection

Summary

This manuscript presents a treatment protocol using electroacupuncture-based cerebral electric field therapy for post-infectious unilateral vocal fold paralysis with dysphagia, aiming to improve vocal and swallowing function through neuroanatomically targeted acupuncture interventions.

Abstract

Unilateral vocal fold paralysis secondary to peripheral nerve injury presents limited treatment options and inconsistent outcomes. This protocol describes an electroacupuncture-based cerebral electric field therapy designed to target neuroanatomically relevant pathways through combined scalp, posterior cervical, and anterior neck electroacupuncture. The procedure includes standardized point selection, stimulation parameters, and treatment sequencing, followed by objective functional assessment using laryngoscopy and videofluoroscopic swallowing study. In a representative case, the application of this protocol was associated with observable improvements in voice quality and swallowing function. Patients with unilateral vocal fold paralysis frequently experience hoarseness, dysphagia, aspiration, and reduced laryngeal sensation, leading to substantial functional limitations and decreased quality of life. This protocol demonstrates the feasibility of electroacupuncture-based cerebral electric field therapy as a structured intervention for unilateral vocal fold paralysis and provides a reproducible framework for future clinical exploration. Additional investigation may help clarify its potential role as a supportive therapeutic option. Future controlled studies may further evaluate its clinical effectiveness and applicability.

Introduction

Unilateral vocal fold paralysis (UVFP) is caused by injury to the recurrent laryngeal nerve (RLN), resulting in partial or complete impairment of vocal fold mobility¹. Due to the longer anatomical course of the left RLN around the aortic arch, left-sided paralysis is more frequently observed.². Patients commonly present with hoarseness, vocal fatigue, dysphagia, aspiration, and reduced laryngeal sensation, all of which substantially affect quality of life. The most prevalent etiologies of UVFP include iatrogenic nerve injury during surgery, tumor compression, and external trauma^2,3. In contrast, UVFP secondary to viral or post-inflammatory processes, such as upper respiratory tract infections (URTI), is relatively uncommon and remains underrecognized, with its true incidence not well established in the literature.

Current management strategies for UVFP include voice therapy, swallowing rehabilitation, and surgical interventions such as injection laryngoplasty or medialization thyroplasty⁴. Although spontaneous recovery of vocal fold mobility has been reported to occur within approximately 4–6 months in some patients, outcomes with conservative management are variable, and surgical approaches are associated with procedural risks and timing considerations^5,6. During this waiting period, persistent dysphonia and dysphagia may significantly impair daily functioning, underscoring the need for additional therapeutic approaches that are safe, accessible, and potentially supportive of functional recovery. Electroacupuncture (EA) has been increasingly investigated for its neuromodulatory effects and its potential to promote neuroplasticity and neuromuscular coordination, particularly in central neurological disorders. However, standardized protocols applying EA-based cerebral electric field therapy to UVFP resulting from peripheral nerve injury have rarely been described. The absence of clearly defined procedural guidance limits reproducibility and broader clinical application.

The overall goal of the present protocol is to demonstrate a structured electroacupuncture-based cerebral electric field therapy approach for a patient with presumed post-infectious UVFP, accompanied by dysphagia⁷. In this study, the term “electroacupuncture-based cerebral electric field therapy” is used to describe a scalp-centered electroacupuncture strategy combined with predefined central–peripheral electrode configurations, intended to engage distributed cortico–brainstem–peripheral functional networks. This protocol is intended for patients in the acute to subacute stage of UVFP in whom peripheral nerve injury is suspected and spontaneous recovery remains uncertain. While conclusions regarding efficacy cannot be generalized from a single case, this protocol provides detailed procedural steps and objective assessment methods to support future clinical exploration and replication.

Case Presentation:
On January 3, 2025, a 56-year-old man developed headache, rhinorrhea, sneezing, and mild pharyngeal discomfort. He initially considered these symptoms a common cold and did not seek medical care. He had no history of recent surgery, trauma, or malignancy, and his past medical, family, and social histories were unremarkable. Over the following days, his symptoms progressed to include increasing throat discomfort, hoarseness, and vocal fatigue. On January 13, he was admitted to a local hospital for further evaluation.

Initial laboratory tests revealed a low lymphocyte ratio (15.9%) and an elevated absolute monocyte count (0.7 × 10⁹/L). Cranial magnetic resonance imaging (MRI) demonstrated multiple lacunar infarctions, but no acute lesions. Laryngoscopy showed left vocal fold hypomobility with incomplete glottic closure, consistent with left-sided UVFP (Figure 1, Figure 1A). Serum tests for respiratory pathogens, including influenza A/B, parainfluenza virus, Mycoplasma pneumoniae, and Chlamydia pneumoniae IgM, were negative, supporting a diagnosis based on exclusion. Despite negative results, the temporal correlation with flu-like symptoms and the lack of other causative findings supported a presumptive post-viral etiology.

Despite the lack of positive pathogen findings, the patient exhibited typical prodromal symptoms of URTI, and no alternative causes such as recent surgery, trauma, or neoplasm were identified. Based on the clinical course and exclusion of common etiologies, a diagnosis of post-infectious UVFP following URTI was established, a rare but recognized clinical entity. Symptomatic treatment, including anti-inflammatory, antiviral, expectorant, and nebulized therapies, was administered, but the patient’s hoarseness persisted, and new symptoms of choking while drinking and dysphagia emerged. Although definitive pathogen testing was inconclusive, the patient’s symptom trajectory, laboratory findings, and exclusion of other causes support a clinically reasonable diagnosis of post-infectious UVFP. We acknowledged that the absence of pathogen confirmation represents a limitation, but such exclusion-based diagnostic approaches were frequently used in real-world clinical settings.

On January 25, he was discharged without significant improvement and remained untreated at home. His symptoms persisted. On February 4, he visited the acupuncture outpatient clinic at the Second Affiliated Hospital of Heilongjiang University of Chinese Medicine, where a comprehensive assessment was conducted.

Diagnosis, Assessment, and Plan:
Imaging studies: Cranial diffusion-weighted imaging (DWI) showed no new ischemic lesions. The thyroid ultrasound and chest CT were unremarkable.

Video fluoroscopic swallowing study (VFSS): In the lateral view, swallow initiation was normal, but there was substantial residue of 60% barium contrast in the epiglottic valleculae and pyriform sinuses, which was not cleared despite multiple swallows. Frontal view revealed bilateral pyriform sinus residue, more prominent on the left, with most contrast entering the esophagus via the left pharyngeal tract. The upper esophageal sphincter opened normally, and no aspiration was observed (Figure 1B–C). Pharyngeal residue was evaluated using the Yale pharyngeal residue severity rating scale (YPRSRS), which rates residue in the valleculae and pyriform sinuses separately on a 0–4 scale. The scores reflect the estimated percentage of space filled with residue, with 0 indicating none and 4 indicating severe residue (>50%). In this case, the YPRSRS score was 4 for the valleculae and 3 for the pyriform sinuses, indicating significant residue in both regions.

Neurological and clinical assessment: The laryngeal prominence was slightly deviated to the left, with mildly reduced elevation of the soft palate. The left pharyngeal and gag reflexes were diminished. Other neurological findings were unremarkable, and no pathological reflexes were observed.

Voice assessment: Voice function was evaluated using the voice handicap index-30 (VHI-30), a validated questionnaire assessing the physical, emotional, and functional impacts of voice disorders (score range: 0–120). The patient’s total score at baseline was 99, indicating a severe voice handicap.

Swallowing assessment: Water swallow test (WST) was grade 4, and the functional oral intake scale (FOIS) was level 4. Based on the findings, the patient was diagnosed with left-sided UVFP with dysphagia. The patient subsequently initiated outpatient EA treatment.

Protocol

This study reports a single retrospective clinical case conducted as part of routine clinical practice at the second affiliated hospital of Heilongjiang University of Chinese Medicine. According to institutional policies, formal ethical approval was not required for single case reports. After thorough communication and informed consent, EA was performed by an experienced senior acupuncturist with more than five decades of clinical practice. All materials used in this procedure are listed in the Table of Materials.

1. Practitioner qualification and patient preparation

1. Practitioner qualification: All procedures were performed by a licensed senior acupuncturist with more than 50 years of clinical experience in the treatment of neurological disorders with acupuncture.
2. Pre-treatment communication and consent: Prior to treatment, the procedure, expected benefits, and potential risks-including fainting, needle retention, local hematoma, electrical injury, and infection-were explained to the patient. Emergency management procedures were also described. Written informed consent was obtained.
3. Patient positioning: The patient was placed in a comfortable seated position with the head and neck supported and exposed to ensure stability throughout the procedure.
4. Skin preparation: All acupoint areas were disinfected using standard medical 75% alcohol-based antiseptic solution prior to needle insertion.

2. Acupoint selection (Table 1)

1. Scalp acupuncture points: According to the World Health Organization (WHO) international standard for scalp acupuncture, three parallel needles were inserted bilaterally into the lower two-fifths of the anterior oblique line of the vertex-temporal (MS6, Motor-Sensory aera line 6) extending from Qianshencong (1 cun anterior to Baihui) to Xuanli (GB6, Gallbladder meridian 6)(Figure 2A).
2. Posterior neck points
   Bilateral posterior neck points included Fengchi (GB20, Gallbladder meridian 20), Gongxue, Tunyan 2, Tiyan, and Juanshe (Figure 2A).
3. Anterior neck points
   Anterior neck points included Zhiqiang, Tunyan 1, Fayin, and Zhifanliu (Figure 2B). Due to unilateral left-sided vocal fold paralysis, only the affected (left) side was treated.

3. Scalp and posterior neck electroacupuncture procedure

1. Needle specifications and insertion technique: Disposable sterile stainless-steel needles (0.35 mm × 40 mm; Andi Medical, China) were inserted into the scalp at an angle of approximately 30°. The needle was advanced until resistance decreased, indicating entry into the subgaleal layer beneath the aponeurosis, and then inserted to a depth of approximately 1 cm. Mild twirling was applied until the patient reported a “Deqi” sensation (soreness, numbness, or distention).
2. Device connection and electrode configuration: Inserted scalp and posterior neck needles were connected to a pulse electroacupuncture device (KWD-808Ⅰmodel; Great Wall Medical Device Co., China). Electrodes were paired in parallel as follows:
   1. Scalp points with Tunyan 2 and Tiyan
   2. Fengchi (GB20) with Gongxue. A total of six electrode pairs were formed. Leads were arranged in parallel without crossing.
3. Electrical stimulation parameters: Continuous-wave stimulation was applied at 50 Hz, with the current intensity gradually increased from 0 mA to a patient-tolerated level of 2–4 mA. Stimulation was maintained for 30 min.
4. Monitoring during stimulation: The patient was continuously observed for discomfort or adverse reactions throughout the session.

4. Anterior neck acupuncture procedure

1. Needle specifications and insertion: Following completion of electroacupuncture stimulation, all electrical leads and scalp needles were removed. Disposable sterile needles (0.35 mm × 60 mm) were then used for anterior neck acupuncture.
2. Manipulation technique: Due to laryngeal movement during swallowing, needles at the anterior neck points were not retained. Each needle was rapidly inserted to a depth of approximately 15–20 mm, manually twirled for 10–15 s, and then immediately withdrawn.
3. Stimulation intensity: Strong manual stimulation was applied at Fayin and Zhifanliu. Other anterior neck points received standard manual stimulation.

5. Post-treatment procedures and waste disposal

1. Completion of session: After treatment, all needles were removed, and the insertion sites were inspected for bleeding or adverse reactions.
2. Sharps and biohazard disposal: All used needles were immediately disposed of in approved sharps containers in accordance with standard clinical biohazard waste management protocols.
3. Session documentation: Each treatment session was documented, including stimulation parameters, duration, patient tolerance, and any adverse events.

6. Treatment schedule and safety monitoring

1. Treatment frequency: Treatment was administered once daily, five sessions per week.
2. Adverse event monitoring: No adverse events or complications were observed during any treatment sessions.
3. Combination therapy: During the treatment period, the patient did not receive concurrent voice therapy, swallowing rehabilitation, pharmacological neurotrophic agents, or other neuromodulatory interventions.

Results

Swallowing and voice function were objectively evaluated using the VHI, YPRSRS (vallecula and pyriform sinus), WST, and FOIS. These standardized tools demonstrated progressive improvements during the treatment and follow-up periods, as detailed in Table 2.

After one week of EA treatment, the patient reported no significant improvement. By the second week (after 8 sessions), pharyngeal discomfort and a foreign-body sensation were alleviated. Swallowing became easier without obv...

Discussion

This patient initially presented with prominent symptoms of URTI, including sore throat and pharyngeal discomfort, followed by the gradual onset of hoarseness and dysphagia. This temporal sequence suggested a potential post-infectious mechanism underlying the development of UVFP. Viral or bacterial pathogens can induce acute inflammatory changes in the laryngopharyngeal mucosa, leading to mucosal congestion and edema. Persistent inflammation may result in submucosal thickening due to fibrous proliferation and hyaline deg...

Materials

List of materials used in this article

Name	Company	Catalog Number	Comments
75% Ethanol(commercially available)	Widely available	N/A
Pulse Electrotherapy Device	Great Wall®, Changzhou,China	KWD-808I (https://www.vedeng.com/zhucezheng/gc/40971.html)
Sterile acupuncture needles (0.30 × 40 mm; 0.30 × 60 mm)	Andi®, Guizhou, China	Product link-https://www.qxw18.com/info/show-25306.html