1.Low-frequency auricular vagus nerve stimulation facilitates cerebrospinal fluid influx by promoting vasomotion
Seunghwan CHOI ; In Seon BAEK ; Kyungjoon LEE ; Sun Kwang KIM
The Korean Journal of Physiology and Pharmacology 2025;29(1):109-116
Auricular vagus nerve stimulation (aVNS) is one of the promising neuromodulation techniques due to its non-invasiveness, convenience, and effectiveness. aVNS has been suggested as a potential treatment for neurodegenerative diseases showing impaired cerebrospinal fluid (CSF) dynamics. Improving CSF flow has been proposed as a key mechanism of the therapeutic effect on neurodegenerative diseases. However, aVNS parameters have been set empirically and the effective parameter that maximize the effect remains elusive. Here we show that 30 minutes of low-frequency aVNS increased arterial vasomotion events and enhanced cortical CSF influx along the branches of middle cerebral arteries. By using in vivo two photon imaging or widefield fluorescence microscopy with plasma and CSF tracers for visualizing blood vessels and perivascular spaces, arterial vasomotion and cortical CSF influx dynamics were acquired. The low-frequency (2 Hz) aVNS, but not middleand high-frequency (40 and 100 Hz) aVNS, significantly increased the number of vasomotion events compared to the sham group. Accordingly, in the CSF imaging, 2 Hz of aVNS markedly enhanced the CSF influx. Our findings demonstrate that lowfrequency aVNS is the effective parameter in respect to modulating vasomotion and CSF influx, resulting in brain clearance effect.
2.Low-frequency auricular vagus nerve stimulation facilitates cerebrospinal fluid influx by promoting vasomotion
Seunghwan CHOI ; In Seon BAEK ; Kyungjoon LEE ; Sun Kwang KIM
The Korean Journal of Physiology and Pharmacology 2025;29(1):109-116
Auricular vagus nerve stimulation (aVNS) is one of the promising neuromodulation techniques due to its non-invasiveness, convenience, and effectiveness. aVNS has been suggested as a potential treatment for neurodegenerative diseases showing impaired cerebrospinal fluid (CSF) dynamics. Improving CSF flow has been proposed as a key mechanism of the therapeutic effect on neurodegenerative diseases. However, aVNS parameters have been set empirically and the effective parameter that maximize the effect remains elusive. Here we show that 30 minutes of low-frequency aVNS increased arterial vasomotion events and enhanced cortical CSF influx along the branches of middle cerebral arteries. By using in vivo two photon imaging or widefield fluorescence microscopy with plasma and CSF tracers for visualizing blood vessels and perivascular spaces, arterial vasomotion and cortical CSF influx dynamics were acquired. The low-frequency (2 Hz) aVNS, but not middleand high-frequency (40 and 100 Hz) aVNS, significantly increased the number of vasomotion events compared to the sham group. Accordingly, in the CSF imaging, 2 Hz of aVNS markedly enhanced the CSF influx. Our findings demonstrate that lowfrequency aVNS is the effective parameter in respect to modulating vasomotion and CSF influx, resulting in brain clearance effect.
3.Low-frequency auricular vagus nerve stimulation facilitates cerebrospinal fluid influx by promoting vasomotion
Seunghwan CHOI ; In Seon BAEK ; Kyungjoon LEE ; Sun Kwang KIM
The Korean Journal of Physiology and Pharmacology 2025;29(1):109-116
Auricular vagus nerve stimulation (aVNS) is one of the promising neuromodulation techniques due to its non-invasiveness, convenience, and effectiveness. aVNS has been suggested as a potential treatment for neurodegenerative diseases showing impaired cerebrospinal fluid (CSF) dynamics. Improving CSF flow has been proposed as a key mechanism of the therapeutic effect on neurodegenerative diseases. However, aVNS parameters have been set empirically and the effective parameter that maximize the effect remains elusive. Here we show that 30 minutes of low-frequency aVNS increased arterial vasomotion events and enhanced cortical CSF influx along the branches of middle cerebral arteries. By using in vivo two photon imaging or widefield fluorescence microscopy with plasma and CSF tracers for visualizing blood vessels and perivascular spaces, arterial vasomotion and cortical CSF influx dynamics were acquired. The low-frequency (2 Hz) aVNS, but not middleand high-frequency (40 and 100 Hz) aVNS, significantly increased the number of vasomotion events compared to the sham group. Accordingly, in the CSF imaging, 2 Hz of aVNS markedly enhanced the CSF influx. Our findings demonstrate that lowfrequency aVNS is the effective parameter in respect to modulating vasomotion and CSF influx, resulting in brain clearance effect.
4.Low-frequency auricular vagus nerve stimulation facilitates cerebrospinal fluid influx by promoting vasomotion
Seunghwan CHOI ; In Seon BAEK ; Kyungjoon LEE ; Sun Kwang KIM
The Korean Journal of Physiology and Pharmacology 2025;29(1):109-116
Auricular vagus nerve stimulation (aVNS) is one of the promising neuromodulation techniques due to its non-invasiveness, convenience, and effectiveness. aVNS has been suggested as a potential treatment for neurodegenerative diseases showing impaired cerebrospinal fluid (CSF) dynamics. Improving CSF flow has been proposed as a key mechanism of the therapeutic effect on neurodegenerative diseases. However, aVNS parameters have been set empirically and the effective parameter that maximize the effect remains elusive. Here we show that 30 minutes of low-frequency aVNS increased arterial vasomotion events and enhanced cortical CSF influx along the branches of middle cerebral arteries. By using in vivo two photon imaging or widefield fluorescence microscopy with plasma and CSF tracers for visualizing blood vessels and perivascular spaces, arterial vasomotion and cortical CSF influx dynamics were acquired. The low-frequency (2 Hz) aVNS, but not middleand high-frequency (40 and 100 Hz) aVNS, significantly increased the number of vasomotion events compared to the sham group. Accordingly, in the CSF imaging, 2 Hz of aVNS markedly enhanced the CSF influx. Our findings demonstrate that lowfrequency aVNS is the effective parameter in respect to modulating vasomotion and CSF influx, resulting in brain clearance effect.
5.Low-frequency auricular vagus nerve stimulation facilitates cerebrospinal fluid influx by promoting vasomotion
Seunghwan CHOI ; In Seon BAEK ; Kyungjoon LEE ; Sun Kwang KIM
The Korean Journal of Physiology and Pharmacology 2025;29(1):109-116
Auricular vagus nerve stimulation (aVNS) is one of the promising neuromodulation techniques due to its non-invasiveness, convenience, and effectiveness. aVNS has been suggested as a potential treatment for neurodegenerative diseases showing impaired cerebrospinal fluid (CSF) dynamics. Improving CSF flow has been proposed as a key mechanism of the therapeutic effect on neurodegenerative diseases. However, aVNS parameters have been set empirically and the effective parameter that maximize the effect remains elusive. Here we show that 30 minutes of low-frequency aVNS increased arterial vasomotion events and enhanced cortical CSF influx along the branches of middle cerebral arteries. By using in vivo two photon imaging or widefield fluorescence microscopy with plasma and CSF tracers for visualizing blood vessels and perivascular spaces, arterial vasomotion and cortical CSF influx dynamics were acquired. The low-frequency (2 Hz) aVNS, but not middleand high-frequency (40 and 100 Hz) aVNS, significantly increased the number of vasomotion events compared to the sham group. Accordingly, in the CSF imaging, 2 Hz of aVNS markedly enhanced the CSF influx. Our findings demonstrate that lowfrequency aVNS is the effective parameter in respect to modulating vasomotion and CSF influx, resulting in brain clearance effect.
6.The potential of 222-nm wavelength ultraviolet light for medical applications: a review
Yeon Soo KIM ; A Jeong YOU ; Sunho LEE ; Kwang Yoon JUNG ; Seung-Kuk BAEK
Medical Lasers 2024;13(1):12-18
In recent years, there has been a growing interest in the use of 222-nm wavelength ultraviolet (UV) light for medical applications due to its potent germicidal properties and reduced risk of harm to human tissue. This review explores the current state of research surrounding the utilization of 222 nm UVC light in various medical settings. We discuss its efficacy in disinfection, potential applications in wound healing, and dermatology, and its role in combating airborne pathogens. Furthermore, we address safety considerations and future directions for research and development in this promising field.
7.The role of CO2 laser surgery in the management of severe laryngomalacia: efficacy, safety, and future directions
Yeon Soo KIM ; Kwang Yoon JUNG ; Seung-Kuk BAEK
Medical Lasers 2024;13(3):123-127
Laryngomalacia is the most common cause of stridor in infants and often resolves spontaneously by 18-24 months of age. However, severe cases necessitate medical intervention due to significant respiratory distress and feeding difficulties. Laser surgery, using carbon dioxide (CO2 ) lasers, has emerged as a pivotal therapeutic approach for severe laryngomalacia. This review examines the efficacy, safety, and long-term outcomes of CO2 laser surgery for laryngomalacia. CO2 lasers offer precise tissue vaporization, minimizing collateral damage and enhancing recovery. Numerous studies have reported high success rates, with significant symptomatic improvement and a reduction in the need for more invasive procedures like tracheostomy. Complications such as intraoperative bleeding and postoperative edema may occur. However, they are generally manageable. Long-term outcomes indicate normal growth and development with minimal impact on voice quality and swallowing function. Advancements in laser technology and ongoing research are expected to further improve the efficacy and safety of laser surgery for laryngomalacia.
8.Laser phonomicrosurgery of vocal fold polyps using CO2 and 532-nm lasers in Republic of Korea: a retrospective studies
Yeon Soo KIM ; Dabin LEE ; Jaehyung PARK ; Kwang-Yoon JUNG ; Seung-Kuk BAEK
Medical Lasers 2024;13(3):150-154
Background:
Laser laryngeal microsurgery is a common treatment of vocal fold polyps (VFP), a leading causeof dysphonia. The CO2 laser is predominantly used for its precision in excising delicate tissues while minimizingdamage to the surrounding healthy tissue. The 532-nm diode laser can also be employed for the cauterization of the microvasculature within the vocal folds. This study aims to evaluate the efficacy of the 532-nm diode laser in the treatment of VFP.
Methods:
Forty-four patients diagnosed with VFP were enrolled and underwent laser laryngeal microsurgery using a CO2 laser. The patients were divided into two groups: one receiving additional treatment with the 532-nm diode laser. Voice status was assessed and compared preoperatively and postoperatively using acoustic analysis, aerodynamic analysis, voice range profile, the GRBAS scale, and the voice handicap index (VHI).
Results:
The mean flow rate and maximal pitch showed significant improvements from preoperative to postoperative measurements in additional 532-nm diode laser treatment group. All objective indicators demonstrated normalization and enhancement following surgery. Subjective perceptual assessments also indicated significant improvement postoperatively, and the VHI showed improvement across all domains.However, there was no significant difference in the test results between the two groups, regardless of the additional use of the 532-nm diode laser.
Conclusion
Laser phonomicrosurgery using both CO2 and 532-nm diode lasers is an effective in treating VFP. Although the additional benefit of the diode laser was not conclusively demonstrated, its potential for photocoagulating the vocal fold microvasculature suggests further research is warranted.
9.Outcomes of Ulnar Shortening Osteotomy with an Intramedullary Bone Graft for Idiopathic Ulnar Impaction Syndrome
Kyung Wook KIM ; Ji Hyeung KIM ; Hyung Ryul LIM ; Kee Jeong BAE ; Yo Han LEE ; Young Kwang SHIN ; Goo Hyun BAEK
Clinics in Orthopedic Surgery 2024;16(2):313-321
Background:
Although several techniques for the treatment of ulnar impaction syndrome (UIS) have been introduced, there have still been reports on various complications such as delayed union, nonunion, refracture, wrist pain, plate irritation, and chronic regional pain syndrome. This study aimed to compare the differences in radiological and clinical outcomes of patients in which intramedullary bone grafting was performed in addition to plate stabilization with those without additional bone grafting during ulnar shortening osteotomies (USOs).
Methods:
Between November 2014 and June 2021, 53 wrists of 50 patients with idiopathic UIS were retrospectively reviewed. Patients were divided into 2 groups according to whether intramedullary bone grafting was performed. Among the 53 wrists, USO with an intramedullary bone graft was performed in 21 wrists and USO without an intramedullary bone graft was performed in 32 wrists. Demographic data and factors potentially associated with bone union time were analyzed.
Results:
There was no significant difference between the 2 groups when comparing postoperative radioulnar distance, postoperative ulnar variance, amount of ulnar shortening, and postoperative Disabilities of the Arm, Shoulder and Hand score. Compared to the without-intramedullary bone graft group, bone union time of the osteotomy site was significantly shortened, from 8.8 ± 3.0 weeks to 6.7 ± 1.3 weeks in the with-intramedullary bone graft group. Moreover, there were no cases of nonunion or plate-induced symptoms. Both in univariable and multivariable analyses, intramedullary bone grafting was associated with shorter bone union time.
Conclusions
USO with an intramedullary bone graft for idiopathic UIS has favorable radiological and clinical outcomes. The advantage of this technique is the significant shortening of bone union time.
10.Analgesic Effect of Auricular Vagus Nerve Stimulation on Oxaliplatin-induced Peripheral Neuropathic Pain in a Rodent Model
In Seon BAEK ; Seunghwan CHOI ; Heera YOON ; Geehoon CHUNG ; Sun Kwang KIM
Experimental Neurobiology 2024;33(3):129-139
Cancer chemotherapy often triggers peripheral neuropathy in patients, leading to neuropathic pain in the extremities. While previous research has explored various nerve stimulation to alleviate chemotherapy-induced peripheral neuropathy (CIPN), evidence on the effectiveness of noninvasive auricular vagus nerve stimulation (aVNS) remains uncertain. This study aimed to investigate the efficacy of non-invasive aVNS in relieving CIPN pain. To induce CIPN in experimental animals, oxaliplatin was intraperitoneally administered to rats (6 mg/kg). Mechanical and cold allodynia, the representative symptoms of neuropathic pain, were evaluated using the von Frey test and acetone test, respectively. The CIPN animals were randomly assigned to groups and treated with aVNS (5 V, square wave) at different frequencies (2, 20, or 100 Hz) for 20 minutes. Results revealed that 20 Hz aVNS exhibited the most pronounced analgesic effect, while 2 or 100 Hz aVNS exhibited weak effects. Immunohistochemistry analysis demonstrated increased c-Fos expression in the locus coeruleus (LC) in the brain of CIPN rats treated with aVNS compared to sham treatment. To elucidate the analgesic mechanisms involving the adrenergic descending pathway, α 1 -, α 2 -, or β-adrenergic receptor antagonists were administered to the spinal cord before 20 Hz aVNS. Only the β-adrenergic receptor antagonist, propranolol, blocked the analgesic effect of aVNS.These findings suggest that 20 Hz aVNS may effectively alleviate CIPN pain through β-adrenergic receptor activation.

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