
==== Front
Medicine (Baltimore)
Medicine (Baltimore)
MD
Medicine
0025-7974
1536-5964
Lippincott Williams & Wilkins Hagerstown, MD

MD-D-24-05459
00038
10.1097/MD.0000000000039388
3
5300
Research Article
Clinical Case Report
Transcutaneous electrical stimulation of the stellate ganglion: A case report on its application in treating carotid sinus syndrome
Hou Taifu MD houtaifu6384y@21cn.com
a
Xu Mengya MM xu76384t45@21cn.com
b
https://orcid.org/0009-0003-2320-1972
Zhang Zhiguo MD a*
a Wushu College of Henan University, Kaifeng, China
b Department of Neurological Rehabilitation, The Second Affiliated Hospital of Zhengzhou University, Zhengzhou, China.
* Correspondence: Zhiguo Zhang, Wushu College of Henan University, No. 85 Minglun Street, Shunhe Hui District, Kaifeng 475001, China (e-mail: zhiguozhang_zzg@126.com).
06 9 2024
06 9 2024
103 36 e3938819 5 2024
01 8 2024
Copyright © 2024 the Author(s). Published by Wolters Kluwer Health, Inc.
2024
https://creativecommons.org/licenses/by/4.0/ This is an open access article distributed under the Creative Commons Attribution License 4.0 (CCBY), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Rationale:

Syncope is a common condition in emergency departments, posing a diagnostic challenge due to its multifactorial nature. Among the potential causes, carotid sinus hypersensitivity leading to carotid sinus syndrome (CSS) is a significant consideration that can severely impact patient quality of life. Despite its importance, establishing effective treatment methods for CSS has been difficult.

Patient concerns:

A 43-year-old male presented with recurrent episodes of syncope, which significantly affected his daily life and well-being.

Diagnoses:

After a thorough evaluation, the patient was diagnosed with CSS, a condition that can be difficult to pinpoint and requires specialized diagnostic procedures to confirm.

Interventions:

The patient was treated with stellate ganglion block therapy, a targeted intervention aimed at addressing the underlying cause of CSS. This treatment was administered over a 12-day period.

Outcomes:

Following the treatment, the patient’s symptoms showed gradual improvement, and he was discharged after meeting the clinical cure criteria. During a 7-month follow-up, he remained symptom-free.

Lessons:

The case highlights the effectiveness of transcutaneous stellate ganglion block therapy in treating CSS. It suggests that further research and clinical trials are needed to validate this treatment’s efficacy, potentially offering a new therapeutic option for patients suffering from CSS.

carotid sinus hypersensitivity
carotid sinus syndrome
stellate ganglion
syncope
transcutaneous electrical nerve stimulation
OPEN-ACCESSTRUE
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pmc1. Introduction

Syncope, marked by sudden loss of consciousness and global cerebral hypoperfusion that results in an inability to maintain posture and muscle tone, frequently prompts emergency department visits.[1] It presents a complex and pervasive challenge in healthcare, with symptoms that vary widely. Despite thorough and costly investigations, the causes and underlying mechanisms often remain elusive.[2] The carotid sinus, a neurovascular structure containing baroreceptors, is situated at the point where the internal and external carotid arteries merge into the common carotid artery. This structure, which experiences a dilation at the bifurcation of the carotid arteries, can exhibit carotid sinus hypersensitivity (CSH) when its receptors become overly reactive to stimulation.[3] This hypersensitivity often leads to syncope and primarily affects older adults and those with cardiovascular, cerebrovascular, and neurodegenerative conditions.[3] Although CSH is not a standalone clinical diagnosis, it can manifest as carotid sinus syndrome (CSS) in some individuals. CSS, a poorly understood autonomic nervous system disorder, causes recurrent unexplained syncope and frequent falls.[4] The origins of CSS are mostly unknown, and epidemiological data remain scarce,[5] significantly impairing patients’ quality of life and causing substantial physical and psychological distress. In this particular case, the patient with CSS received transcutaneous electrical nerve stimulation (TENS) at the stellate ganglion, which will be detailed in subsequent reports.

2. Clinical data

The patient, a 43-year-old male, presented at the rehabilitation clinic on July 10, 2022, reporting “recurrent unexplained dizziness and even syncope over the past 2 years, worsening in the last 6 months.” Fifteen years earlier, he had undergone microsurgical replantation of the distal joint of his right index finger following trauma in Shenzhen, though the specific hospital and details of the surgery are not known. The surgery successfully restored full functionality to his hand. He reported no history of blood transfusions or donations and confirmed adherence to local vaccination protocols. He also denied any history of allergies.

Blood pressure was measured at 125/82 mm Hg and heart rate at 85 beats/min. During a specialized examination, the patient’s cervical curvature was normal; there were no significant changes in local skin color or temperature, and no palpable nodules, rashes, or indurations were present. There was no tenderness when palpating over the C4/C5/C6/C7 spinous processes or adjacent paravertebral muscles. Pain on forward neck flexion and tenderness at the exits of the greater occipital nerves bilaterally were noted. Nevertheless, neck mobility was functional, exhibiting normal flexion, extension, lateral flexion, and rotation. Sensory tests confirmed intact skin perception, and muscle strength was symmetrical with no signs of atrophy in all limbs; tendon reflexes were normal, with negative results for Hoffman sign, positional vertigo, head compression test, Spurling test, cervical torsion test, and neck extension test.

Imaging examination: a chest X-ray and electrocardiogram (dated June 29th) showed no abnormalities. A computed tomography scan of the cervical spine, also conducted on June 29th, displayed normal cervical lordosis without any other significant findings. A color Doppler ultrasound of the bilateral neck vessels revealed no noticeable abnormalities in the carotid arteries (venous) on either side. Routine laboratory biochemical tests were within normal limits.

The patient shared additional historical details, noting episodes of dizziness, chest tightness, and a feeling of suffocation when a barber bib was placed around his neck. These symptoms would subside upon removal of the bib. Additionally, the patient reported a 2-year history of avoiding high-collared clothing due to the onset of similar symptoms, including dizziness, tinnitus, chest tightness, and a sensation of suffocation. Similar symptoms occurred when a quilt was wrapped around his neck at night, alleviating upon loosening his collar or pulling down the covers.

Differential diagnosis included assessing psychogenic factors, where the Somatic Symptom Scale yielded a score of 16, the Generalized Anxiety Disorder 7-item scale registered a score of 3, and the 9-item Patient Health Questionnaire also scored 3, effectively ruling out psychological causes. A Head-Up Tilt Test was administered with initial blood pressure readings at 125/82 mm Hg. During ECG-monitored carotid sinus massage, the patient experienced symptoms of dizziness, chest tightness, and syncope, with blood pressure dropping to 70/42 mm Hg and ECG showing a ventricular arrest lasting 3.9 s (≥3 s), as depicted in Figure 1. The systolic blood pressure decreased by 55 mm Hg (>50 mm Hg), leading to syncope and generalized weakness. These symptoms aligned with a diagnosis of CSS.[2]

Figure 1. ECG recorded during the initial carotid sinus stimulation test.

To treat the patient’s condition, we employed physical factor therapy using TENS, specifically targeting the stellate ganglion with a WOND2000F2 Multifunctional Neurological Rehabilitation Diagnosis and Treatment System (Guangzhou Sanjia Medical Equipment Co., LTD). We set the stimulation parameters to a frequency of 100 Hz and a pulse width of 100 μs, adjusting the current intensity to the patient’s comfort level, measured in milliamps (mA). We followed standard disinfection procedures using 75% alcohol to ensure cleanliness and reduce biological impedance. Two disposable ECG electrodes were placed on the patient’s body: one on the body surface projection at the midline of the C4/C5 vertebrae on the patient’s back, and the other on the left anterolateral surface projection of the stellate ganglion, which previous studies suggested is more effective than the right side.[2] The electrodes were aligned parallel to the C7 vertebra throughout the treatment, as shown in Figure 2. The treatment sessions were conducted twice daily, in the morning and afternoon with a 6-hour interval, each lasting 20 minutes, over a 12-day period.

Figure 2. Diagram illustrating the application site of transcutaneous electrical nerve stimulation (TENS).

2.1. Treatment results

Three days into the treatment, the patient experienced only mild dizziness when touching his neck. By the 6th day, he could wear high-necked clothing without suffering from dizziness, tinnitus, chest tightness, a sense of asphyxia, or fatigue. On the 7th day, after resting, he was able to slightly tighten his high-necked clothing and pull the covers closer to his neck during sleep without any discomfort. By the 10th day, he could gently grasp his neck with his hand without any discomfort. On the 12th day of treatment, his blood pressure was recorded at 127/83 mm Hg, remaining stable at 122/81 mm Hg after a carotid sinus stimulation test, with the ECG indicating a ventricular arrest of approximately 0.78 seconds (see Fig. 3). Following 2 additional days of consolidation treatment, the patient fulfilled the clinical cure criteria and was discharged. During monthly follow-ups over the next 7 months, the patient did not experience any recurrence of syncope in his daily activities.

Figure 3. ECG recording during the second carotid sinus stimulation test.

3. Discussion

After more than 50 years of studying the physiology and pathology of the carotid sinuses, researchers have established that: (1) the carotid sinus functions as a baroreceptor sensitive to the stretching of the arterial wall. When external stretching stimuli exceed a certain threshold, it triggers increased activity in the vagus nerve and decreased activity in the sympathetic nerve. In contrast, a drop in arterial blood pressure leads to decreased blood flow and vessel wall stretching, which in turn reduces the baroreceptors’ firing rate and lowers vagus nerve excitation. The afferent pathway of this baroreceptor-mediated reflex involves the glossopharyngeal and vagus nerves, which transmit impulses from the carotid sinus to the brainstem, ending in the solitary tract nucleus in the medulla oblongata. The reflex’s efferent signals are then relayed to the heart and blood vessels through the sympathetic and parasympathetic nerves (vagus nerves), regulating heart rate and vasomotor tone. This impulse transmission via the vagus nerve is crucial in the development of CSS.[6]

Stellate ganglion block involves administering a local anesthetic near the stellate ganglion to disrupt the conduction of sympathetic nerve impulses. This therapeutic approach aims to correct dysfunction in the autonomic nervous system and promote stability in the body’s internal environment.[7] Research indicates that noninvasive stellate ganglion block can be achieved through physical therapy techniques,[8] which have been shown to effectively reduce cardiovascular sympathetic activity, stress responses, and vascular tone, ultimately improving vascular function in the limbs.[9]

TENS is a therapeutic approach that delivers pulsed alternating current to a specific treatment area via electrodes placed on the skin.[10] Studies have indicated that positive membrane potentials occur in fibers N1 and N3 at depths ranging from approximately 21 mm to 23 mm, which coincides with the typical needle depth for stellate ganglion nerve block (2.0–2.5 cm).[11] The mechanism of action is rooted in the gate control theory, which suggests that activating large nerve fibers (A-β fibers) and exciting glial cells (Stellate Ganglion Cells) in the spinal dorsal horn can inhibit the transmission of nociceptive information through extraganglionic analgesic mechanisms.[12]

In this case, the chosen stimulation parameters were a high frequency of 100 Hz and a pulse width of 100 μs. Peripheral blockade induced by TENS within thick fibers can create a “busy line effect,” causing collisions between nerve impulses in A-δ fibers and nociceptive impulses from injured tissues. This phenomenon primarily involves segmental mechanisms, potentially leading to segmental inhibition of nociceptive information transmission in the spinal dorsal horn, thereby reducing afferent impulses from the periphery and lowering nerve sensitivity to achieve therapeutic effects for CSH.[13] Pfyffer et al found that high-frequency TENS could stimulate A-β fibers and activate Stellate Ganglion cells to release inhibitory neurotransmitters, thereby suppressing damaging sensory signals generated by the excitatory action of projective neurons on the same segmental sensory fine fibers in the spinal cord dorsal horn.[10] Additionally, TENS can produce thermal effects that decrease the excitability of sensory nerves, further contributing to treatment efficacy.[14] Recent studies have suggested that TENS can influence sensory nerve thresholds, as evidenced by current perception threshold measurements conducted below the threshold level. It was observed that A-β fibers may exhibit lower current perception threshold values with subthreshold TENS, indicating that this type of stimulation may selectively enhance A-β fiber function.[15] By reducing neural sensitization and decreasing sensory fiber excitability, TENS can effectively address CSS. Moreover, TENS increases Golgi organ tension and reduces resistance caused by the viscoelastic properties of nerves and muscles.[16–18] This significantly improves muscle flexibility, autoinhibitory reflexes, strength, balance, and proprioception, while effectively alleviating muscle fatigue, which is considered a crucial factor affecting voluntary muscle control, posture, and balance.[17]

In this instance, the pre- and post-treatment data from carotid sinus stimulation illustrated the efficacy of percutaneous stellate ganglion stimulation in managing CSS, as outlined in Table 1.

Table 1 Changes in data observed during the carotid sinus stimulation test before and after treatment.

Before treatment	12 days after treatment	
BP before test	Systolic blood pressure
(SBP)	Diastolic blood pressure
(DBP)	Ventricular arrest	BP before test	Systolic blood pressure
(SBP)	Diastolic blood pressure
(DBP)	Ventricular arrest	
125/82 mm Hg	70 mm Hg	42 mm Hg	3.9 s	127/83 mm Hg	122 mm Hg	81 mm Hg	0.04 s	

The benefits of this therapy encompass its affordability, non-invasiveness, safety profile, minimal occurrence of serious adverse events, and reversibility of mild adverse effects. Nevertheless, factors influencing its effectiveness, such as precise electrode placement and optimal stimulation intensity, should be taken into account. Enhanced accuracy in electrode positioning and higher current intensity typically yield superior outcomes.[10] However, despite these potential advantages, there is currently limited high-quality clinical evidence supporting this treatment. Further clinical research is warranted to validate its efficacy.

4. Conclusion

TENS stands out as an affordable and noninvasive therapy, showing promising potential in treating CSS, as evidenced by this case study. However, while the results are encouraging, further clinical evidence is necessary to substantiate its effectiveness conclusively. Future research endeavors will likely concentrate on refining and tailoring treatment approaches for CSS and related conditions. With ongoing advancements in medical technology and a deeper understanding of neuromodulation mechanisms, we anticipate witnessing significant breakthroughs in clinical interventions based on neuromodulation. This holds promise for improving the management of syncope and related disorders, offering renewed optimism for patients in need of effective treatments.

Acknowledgments

We are particularly grateful to all the people who have given us help on our article.

Author contributions

Conceptualization: Taifu Hou, Zhiguo Zhang.

Data curation: Taifu Hou, Zhiguo Zhang.

Formal analysis: Taifu Hou.

Investigation: Mengya Xu.

Supervision: Mengya Xu, Zhiguo Zhang.

Visualization: Mengya Xu.

Writing – original draft: Taifu Hou, Zhiguo Zhang.

Writing – review & editing: Taifu Hou, Mengya Xu, Zhiguo Zhang.

Abbreviations:

CSH carotid sinus hypersensitivity

CSS carotid sinus syndrome

TENS transcutaneous electrical nerve stimulation

The written, informed consent was obtained from the participant for the publication of this case report (including all data and images).

The study was conducted in accordance with the Declaration of Helsinki (as was revised in 2013). The study was approved by Ethics Committee of the Wushu college of Henan university (No. 202207102).

The authors have no funding and conflicts of interest to disclose.

The datasets generated during and/or analyzed during the current study are available from the corresponding author on reasonable request.

How to cite this article: Hou T, Xu M, Zhang Z. Transcutaneous electrical stimulation of the stellate ganglion: A case report on its application in treating carotid sinus syndrome. Medicine 2024;103:36(e39388).
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References

[1] du Fay de Lavallaz J Zimmermann T Badertscher P . Performance of the American Heart Association/American College of Cardiology/Heart Rhythm Society versus European Society of Cardiology guideline criteria for hospital admission of patients with syncope. Heart Rhythm. 2022;19 :1712–22.35644354
[2] Goldberger ZD Petek BJ Brignole M . ACC/AHA/HRS Versus ESC Guidelines for the diagnosis and management of syncope: JACC guideline comparison. J Am Coll Cardiol. 2019;74 :2410–23.31699282
[3] Kharsa A Wadhwa R . Carotid Sinus Hypersensitivity. In: StatPearls. Treasure Island (FL): StatPearls Publishing; October 17, 2022.
[4] Liu WL . Interpretation of Chinese expert consensus on diagnosis and treatment of syncope (2018). Chin J Pract Intern Med. 2019;39 :949–55.
[5] Mulvaney SW Lynch JH Curtis KE Ibrahim TS . The successful use of left-sided stellate ganglion block in patients that fail to respond to right-sided stellate ganglion block for the treatment of post-traumatic stress disorder symptoms: a retrospective analysis of 205 patients. Mil Med. 2022;187 :e826–9.33580677
[6] Zhang B Li L Jiang RH . Observation on the treatment of cardioinhibitory carotid sinus syndrome with cardiac ganglion plexus ablation. Chin J Cardiac Pacing Electrophysiol. 2022;36 :199–203.
[7] Liu YW Meng AX Yu RJ Cao S Fan BF . Clinical observation on the treatment of sympathetic cervical spondylosis with stellate ganglion block combined with duloxetine. Chin J Pain Med. 2022;28 :834–8.
[8] Liao CD Tsauo JY Liou TH Chen HC Rau CL . Efficacy of noninvasive stellate ganglion blockade performed using physical agent modalities in patients with sympathetic hyperactivity-associated disorders: a systematic review and meta-analysis. PLoS One. 2016;11 :e0167476.27911934
[9] Feigin G Velasco Figueroa S Englesakis MF D’Souza R Hoydonckx Y Bhatia A . Stellate ganglion block for non-pain indications: a scoping review. Pain Med. 2023;24 :775–81.36727500
[10] Vance CGT Dailey DL Chimenti RL Van Gorp BJ Crofford LJ Sluka KA . Using TENS for pain control: update on the state of the evidence. Medicina (Kaunas). 2022;58 :1332.36295493
[11] Araiza Illan G Stüber H Friedl KE Summers IR Peer A . A simulation environment for studying transcutaneous electrotactile stimulation. PLoS One. 2019;14 :e0212479.30794630
[12] Hou TF Yin HB Xu MY . Efficacy of low-intensity pulsed ultrasound combined with percutaneous electrical nerve stimulation in the treatment of knee osteoarthritis. Chin J Phys Med Rehabil. 2023;45 :251–4.
[13] Mokhtari T Ren Q Li N Wang F Bi Y Hu L . Transcutaneous electrical nerve stimulation in relieving neuropathic pain: basic mechanisms and clinical applications. Curr Pain Headache Rep. 2020;24 :14.32072323
[14] Yang Y Tang Y Qin H Xu J . Efficacy of transcutaneous electrical nerve stimulation in people with pain after spinal cord injury: a meta-analysis. Spinal Cord. 2022;60 :375–81.35277650
[15] Shimo K Fukui H Ueta H . Decrease in current perception thresholds of A-beta fibers by subthreshold noise stimulation using transcutaneous electrical nerve stimulation. Neuroreport. 2023;34 :287–9.36881753
[16] Caetano A Pereira P Pereira M de Carvalho M . Modulation of sensory nerve fiber excitability by transcutaneous cathodal direct current stimulation. Neurophysiol Clin. 2019;49 :385–90.31735493
[17] Alahmari KA Silvian P Ahmad I . Effectiveness of low-frequency stimulation in proprioceptive neuromuscular facilitation techniques for post ankle sprain balance and proprioception in adults: a randomized controlled trial. Biomed Res Int. 2020;2020 :9012930.33029528
[18] Artuç SE Uçkun AC Sivas FA Yurdakul FG Bodur H . Comparison of the effects of transcutaneous electrical nerve stimulation and interferential current therapies in central sensitization in patients with knee osteoarthritis. Korean J Pain. 2023;36 :392–403.37394276
