Injection techniques for auricular nerve blocks in the rabbit cadaver.

OBJECTIVE: To describe the landmarks for localization and to determine the methodology and volume of methylene blue dye to adequately stain the auricular nerves in rabbit cadavers. STUDY DESIGN: Prospective, randomized, cadaveric study. ANIMALS: A total of 26 rabbit cadavers (Dutch-Belted and New Zealand White breeds). METHODS: Part I: anatomical dissections were performed to identify the sensory auricular nerves and to establish the ideal injection approach and volume of dye required for nerve staining. Part II: a single injection technique using 0.1 mL kg-1 dye was evaluated for staining the greater auricular nerve and two techniques (perpendicular and angled needle approaches) using 0.075 mL kg-1 dye were evaluated for the auriculotemporal nerve. Dye spread was evaluated through cadaveric dissections and nerve staining graded using a 0-2 point scale. Injections were considered successful if the nerve was stained circumferentially. Cadavers were assessed for staining of the mandibular nerve owing to the close proximity to the auriculotemporal nerve. Fisher's exact test and mixed effects logistic regression model were used for statistical analysis. RESULTS: The greater auricular nerve was stained in 24/27 (88.9%) injections. The auriculotemporal nerve was stained in 7/12 injections (58.3%) with the perpendicular needle approach; staining success increased to 80% (12/15 injections) with the angled needle approach; however, this difference was not statistically significant (p = 0.228). Mandibular nerve staining occurred on seven auriculotemporal injections with no statistically significant difference in the incidence of nerve staining between techniques. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that the auricular nerves in rabbit cadavers can be successfully located and stained using anatomic landmarks and the described injection techniques.

Long-term quality of life and sensory impact of great auricular nerve preservation in parotid surgery as measured with the Parotidectomy Outcome Inventory-8.

OBJECTIVES: This study aimed to evaluate sensory dysfunction resulting from great auricular nerve (GAN) sacrifice versus preservation in parotid surgery for benign lesions and its imact on long-term health-related quality of life (QOL). DESIGN: Retrospective. SETTING/MAIN OUTCOME MEASURES: Participants were divided into two groups (GAN and non-GAN), and both short-term (two postoperative weeks) and long-term (at least 5 years) QOL were assessed. The second item of the Parotidectomy Outcome Inventory-8 (POI-8) was used to analyse postoperative sensory loss. All items of the POI-8 questionnaire were used to determine health-related QOL.We used t test for dependent samples and Mann-Whitney U-test to compare patient groups PARTICIPANTS: A total of 137 patients (65 male and 72 female) enrolled in this study. Average age at the time of surgery was 53 years (±12.8). RESULTS: The GAN preservation group had significantly better sensation than the GAN sacrifice in short term (2.8 vs 2.1; P = 0.017). Both groups experienced improved sensation in the long term, and there was a trend towards better QOL in the GAN-preservation group. However, the difference in sensation was not statistically significant (1.7 vs 1.3; P = 0.145). Health-related QOL also increased in the long term (compared to short term) for both groups (7.6 ± 6.2 to 12 ± 7.6; P < 0.0001) postoperatively. GAN preservation did not significantly improve sensation in long term, nor did it increase health-related QOL postoperatively. CONCLUSION: Although GAN preservation was easily feasible, it only improved sensation in short term. We report a negative result: GAN preservation did not significantly improve sensation in long-term, nor did it increase health-related QOL postoperatively when compared to GAN sacrifice.

Modulation of Muscle Tone and Sympathovagal Balance in Cervical Dystonia Using Percutaneous Stimulation of the Auricular Vagus Nerve.

Primary cervical dystonia is characterized by abnormal, involuntary, and sustained contractions of cervical muscles. Current ways of treatment focus on alleviating symptomatic muscle activity. Besides pharmacological treatment, in severe cases patients may receive neuromodulative intervention such as deep brain stimulation. However, these (highly invasive) methods have some major drawbacks. For the first time, percutaneous auricular vagus nerve stimulation (pVNS) was applied in a single case of primary cervical dystonia. Auricular vagus nerve stimulation was already shown to modulate the (autonomous) sympathovagal balance of the body and proved to be an effective treatment in acute and chronic pain, epilepsy, as well as major depression. pVNS effects on cervical dystonia may be hypothesized to rely upon: (i) the alteration of sensory input to the brain, which affects structures involved in the genesis of motoric and nonmotoric dystonic symptoms; and (ii) the alteration of the sympathovagal balance with a sustained impact on involuntary movement control, pain, quality of sleep, and general well-being. The presented data provide experimental evidence that pVNS may be a new alternative and minimally invasive treatment in primary cervical dystonia. One female patient (age 50 years) suffering from therapy refractory cervical dystonia was treated with pVNS over 20 months. Significant improvement in muscle pain, dystonic symptoms, and autonomic regulation as well as a subjective improvement in motility, sleep, and mood were achieved. A subjective improvement in pain recorded by visual analog scale ratings (0-10) was observed from 5.42 to 3.92 (medians). Muscle tone of the mainly affected left and right trapezius muscle in supine position was favorably reduced by about 96%. Significant reduction of muscle tone was also achieved in sitting and standing positions of the patient. Habituation to stimulation leading to reduced stimulation efficiency was observed and counteracted by varying stimulation patterns. Experimental evidence is provided for significantly varied sympathovagal modulation in response to pVNS during sleep, assessed via heart rate variability (HRV). Time domain measures like the root mean square of successive normal to normal heart beat intervals, representing parasympathetic (vagal) activity, increased from 37.8 to 67.6 ms (medians). Spectral domain measures of HRV also show a shift to a more pronounced parasympathetic activity.

Great auricular nerve preservation during parotidectomy for benign tumors.

The great auricular nerve, the largest sensory branch of the cervical plexus, arises from the third cervical nerve (C3) with irregular contribution from the C2. The first part of its course is deep to the sternocleidomastoid muscle. In few years, many experiences by different authors concerning the issue of great auricular nerve integrity during parotidectomy were published in the literature. The aims of our article were to report our experience with 78 consecutive patients who underwent standard superficial, subtotal, or total parotidectomy for benign tumors and to illustrate postsurgical findings regarding the sensibility of the pinna and mandibular angle as subjectively reported in the early postsurgical period and after 3, 6, and 12 months from surgery.

A failsafe method to avoid injury to the great auricular nerve.

BACKGROUND: The great auricular nerve (GAN) is the most commonly injured nerve during facelift surgery. Although rare, injury can result in long-term sequelae. OBJECTIVES: Previous reports have described the nerve's location at the midbelly of the sternocleidomastoid muscle (SCM) or at its emergence from underneath the SCM. The purpose of our study was to identify the superior course of the great auricular nerve as it applies to facelift. METHODS: Thirteen fresh cadavers were dissected. A vertical line through the midlobule was drawn perpendicular to the Frankfort's horizontal, acting as a reference to the course of the GAN. Transparent paper overlay tracings were then done to record each nerve's location. The distance from the bony external auditory canal (EAC) to the nerve was measured at the anterior muscle border, at the midbelly of the SCM, and as the nerve emerged from under the SCM. Branching patterns of the nerve and its relation to the external jugular vein were identified. RESULTS: In 100% of the dissections, the superior course of the GAN fell within a 30-degree angle constructed using the vertical limb perpendicular to the Frankfurt horizontal and a second limb drawn posteriorly from the midlobule. The distance from the EAC to the nerve was 4.9 ± 1.1 cm at the anterior muscle border, 7.3 ± 1.0 cm at the midbelly of the SCM, and 9.8 ± 1.2 cm at the GAN's emergence from under the SCM. Four types of branching patterns were identified. CONCLUSIONS: The 30-degree angle described above rapidly and accurately identifies the nerve's location.

Mandibular reconstruction using iliac bone and great auricular nerve grafts and oral rehabilitation using osseointegrated implants in a patient with a large ossifying fibroma: a 10-year follow-up study.

Ossifying fibromas are bone-related benign neoplasms that are characterized by well-demarcated lesions composed of fibrocellular tissue and mineralized material with varying appearances. Although small lesions are asymptomatic, they may cause enlargement of the affected jaw and rarely require reconstructive or restorative treatments for aesthetic and functional problems. In this study, we report a 35-year-old woman who underwent multidisciplinary treatment for a large ossifying fibroma of the mandible. A segmental mandibular resection was performed, and immediate reconstruction was performed using iliac bone and great auricular nerve grafts. After consolidation of the grafted bone, oral rehabilitation was fulfilled using osseointegrated implants and a fixed prosthesis. There was no evidence of recurrence ten years after the resection of the tumor. The range of mouth opening and motion of the temporomandibular joint provided a functional mandible. The neurosensory examination revealed the recovery of sensibility of the mental region and pulpal sensitivity of the teeth. The prosthesis was stable, and no clinical or radiographic signs of implant failure were observed. Our results demonstrate that the proper combination of reconstructive and restorative treatments could result in appropriate aesthetic and functional outcomes for a period of ten years.

Anatomical landmarks to avoid injury to the great auricular nerve during rhytidectomy.

BACKGROUND: An estimated 116 086 facelifts were performed in 2011. Regardless of the technique employed, facial flap elevation carries with it anatomical pitfalls of which any surgeon performing these procedures should be aware. Injury to the great auricular nerve (GAN) is the most common of these injuries, occurring at a rate of 6% to 7%. OBJECTIVES: We report our findings on the location of the GAN on the basis of anatomical landmarks to aid surgeons with planning their surgical approach for safe elevation of rhytidectomy skin flaps in the lateral neck region. METHODS: Sixteen fresh cadaveric heads were dissected under loupe magnification. All specimens were dissected in a 45-degree (facelift) position in which a mid-sternocleidomastoid (SCM) incision was used for exposure. Measurements from the bony mastoid process, bony external auditory canal, external jugular vein, and anterior border of the SCM to the GAN were taken in each cadaver. RESULTS: The GAN follows a consistent course over the mid-body of the SCM before bifurcating into anterior and posterior branches and terminal arborization. Regardless of the length of the SCM, the GAN at its most superficial location was found to be consistently at a ratio of one-third the distance from either the mastoid process or the external auditory canal to the clavicular origin of the SCM. CONCLUSIONS: Knowledge of the anatomy, course, and location of the GAN along the surface of SCM muscle based on anatomic landmarks and distance ratios can facilitate a safer dissection in the lateral neck during rhytidectomy procedures.

Sensation recovery of auricle following chronic ear surgery by retroauricular incision.

The aim of this prospective analysis was to objectify and quantify the sensory loss in the auricular area that occurs following surgery for chronic otitis media or cholesteatoma, and to assess the exact recovery time of the auricular sensation. Till now, no study has yet been conducted on the sensory loss that is developed after retroauricular incision is performed for chronic ear surgery. Forty-eight patients underwent surgery via retroauricular incision for chronic otitis media or for chronic otitis media or cholesteatoma between March 2009 and January 2010. The skin around the auricle was divided into six areas. The sensation of each area was assessed before the surgery and 3 days, 7 days, 1 month, 3 months, and 6 months after the surgery, using the Semmes-Weinstein monofilaments. The patients were also asked to record the sensation that they felt using the visual analog scale (VAS). In the objective sensory assessment, only area 5, which corresponds to the retroauricular area, showed significant sensory loss. Three months after the surgery, the sensation was recovered to a level comparable to that before the surgery in most of the patients. The mean subjective VAS score was 10 prior to the surgery, 8.56 (± 1.08) 3 months after the surgery, and 9.32 (± 0.74) 6 months after the surgery, respectively. In conclusion, following chronic ear surgery, the sensation of the auricle was recovered to the previous level within 3 months. Therefore, patients who are to undergo retroauricular incision should be informed that they will experience temporary sensory loss for approximately 3 months after the surgery.

Characteristics of calcium currents in rat geniculate ganglion neurons.

Geniculate ganglion (GG) cell bodies of chorda tympani (CT), greater superficial petrosal (GSP), and posterior auricular (PA) nerves transmit orofacial sensory information to the rostral nucleus of the solitary tract (rNST). We used whole cell recording to study the characteristics of the Ca(2+) channels in isolated Fluorogold-labeled GG neurons that innervate different peripheral receptive fields. PA neurons were significantly larger than CT and GSP neurons, and CT neurons could be further subdivided based on soma diameter. Although all GG neurons possess both low voltage-activated (LVA) "T-type" and high voltage-activated (HVA) Ca(2+) currents, CT, GSP, and PA neurons have distinctly different Ca(2+) current expression patterns. Of GG neurons that express T-type currents, the CT and GSP neurons had moderate and PA neurons had larger amplitude T-type currents. HVA Ca(2+) currents in the GG neurons were separated into several groups using specific Ca(2+) channel blockers. Sequential applications of L, N, and P/Q-type channel antagonists inhibited portions of Ca(2+) current in all CT, GSP, and PA neurons to a different extent in each neuron group. No difference was observed in the percentage of L- and N-type Ca(2+) currents reduced by the antagonists in CT, GSP, and PA neurons. Action potentials in GG neurons are followed by a Ca(2+) current initiated after depolarization (ADP) that may influence intrinsic firing patterns. These results show that based on Ca(2+) channel expression the GG contains a heterogeneous population of sensory neurons possibly related to the type of sensory information they relay to the rNST.

Ameliorating effects and mechanisms of transcutaneous auricular vagal nerve stimulation on abdominal pain and constipation.

BackgroundAbdominal pain and constipation are 2 main symptoms in patients with constipation-predominant irritable bowel syndrome (IBS-C). This study aimed to investigate the effects and possible mechanisms of transcutaneous auricular vagal nerve stimulation (taVNS) in patients with IBS-C.MethodsForty-two patients with IBS-C were randomized into a 4-week sham-taVNS or taVNS treatment. The primary outcomes were complete spontaneous bowel movements per week (CSBMs/week) and visual analog scale (VAS) for abdominal pain. High-resolution anorectal manometry (HRAM) was performed to evaluate anorectal motor and sensory function. Cytokines and brain gut peptides were analyzed in blood samples. ECG was recorded for the assessment of autonomic function.ResultsCompared with sham-taVNS, (a) taVNS increased CSBMs/week (P = 0.001) and decreased VAS pain score (P = 0.001); (b) improved quality of life (P = 0.020) and decreased IBS symptom score (P = 0.001); (c) improved rectoanal inhibitory reflex (P = 0.014) and improved rectal sensation (P < 0.04); (d) decreased a number of proinflammatory cytokines and serotonin in circulation; and (e) enhanced vagal activity (P = 0.040). The vagal activity was weakly correlated with the CSBMs/week (r = 0.391; P = 0.010) and the VAS pain score (r = -0.347; P = 0.025).ConclusionsNoninvasive taVNS improves both constipation and abdominal pain in patients with IBS-C. The improvement in IBS-C symptoms might be attributed to the integrative effects of taVNS on intestinal functions mediated via the autoimmune mechanisms.Trial registrationwww.chictr.org.cn, no. ChiCTR2000029644.FundingNational Natural Science Foundation of China (grant no. 81970538 for FL).

Great auricular nerve blockade using high resolution ultrasound: a volunteer study.

This prospective, observational volunteer study aimed to describe the appearance of the great auricular nerve using ultrasound and its blockade under ultrasound guidance. An in-plane needle guidance technique was used for blockade of the great auricular nerve with 0.1 ml mepivacaine 1%. Sensory block was evaluated by pinprick testing in comparison with the contralateral area propriae. The great auricular nerve was successfully seen in all volunteers and the tail of the helix, antitragus, lobula and mandibular angle were blocked in all cases whereas the antihelix and concha were never blocked. Ultrasound imaging of the great auricular nerve can be reliably achieved and successful blockade with minimal volumes of local anaesthetic is another example of the benefits of ultrasound-guided peripheral nerve blocks.

Long-term outcomes of composite auricle as a neurosensorial facial subunit allotransplant.

A total of 22 composite auricle transplantations were performed in allogeneic experimental (group I, n = 10), allogeneic control (group IIa, n = 5), and isogeneic control (group IIb, n = 7) groups. Allotransplantations were carried out across major histocompatibility complex barrier from Lewis Brown Norway rats to Lewis rats. Isotransplantations were performed between Lewis rats. Group II group received no treatment. Allotransplant recipients in group I were immunosupressed by tapered dose of cyclosporine A for 100 days. Then the treatment was discontinued and immunologic, histopathologic, and clinic assessments including neurosensory recovery were carried out. Group IIa rejected their allografts within 7 to 9 days. All 10 animals from group I and 6 animals from group IIb survived for 100 days without infection, illness, signs of rejection, and graft versus host disease. Satisfactory sensory recovery was attained. Suppressed mixed lymphocyte reaction reactivity under CsA treatment was increased 10 days after cessation of the treatment. CD4-positive/RT1 and CD8-positive/RT1 chimeric cell rates were detected as 0.9% and 1.2% respectively at day 100.

No modulation of pupil size and event-related pupil response by transcutaneous auricular vagus nerve stimulation (taVNS).

Transcutaneous auricular vagus nerve stimulation (taVNS) bears therapeutic potential for a wide range of medical conditions. However, previous studies have found substantial interindividual variability in responsiveness to taVNS, and no reliable predictive biomarker for stimulation success has been developed so far. In this study, we investigate pupil size and event-related pupil response as candidate biomarkers. Both measures have a direct physiological link to the activity of the locus coeruleus (LC), a brainstem structure and the main source of norepinephrine in the brain. LC activation is considered one of the key mechanisms of action of taVNS, therefore, we expected a clear increase of the pupillary measures under taVNS compared to sham (placebo) stimulation, such that it could serve as a prospective predictor for individual clinical and physiological taVNS effects in future studies. We studied resting pupil size and pupillary responses to target stimuli in an auditory oddball task in 33 healthy young volunteers. We observed stronger pupil responses to target than to standard stimuli. However, and contrary to our hypothesis, neither pupil size nor the event-related pupil response nor behavioral performance were modulated by taVNS. We discuss potential explanations for this negative finding and its implications for future clinical investigation and development of taVNS.

Relationship of the lobular branch of the great auricular nerve to the tympanoparotid fascia: Spatial anatomy for salvage during face and neck lift.

To enable selection of a safer suspension site to use in face and neck lifting procedures, the spatial relationship between the tympanoparotid fascia and the great auricular nerve should be clarified. In this study, we aimed to elucidate the position of the tympanoparotid fascia and the pathway of the lobular branch of the great auricular nerve traversing the tympanoparotid fascia. Twenty hemifaces from non-preserved bequeathed Korean cadavers (5 males, 7 females; mean age, 77.0 years) were dissected to determine the great auricular nerve distribution close to the tympanoparotid fascia of clinical significance for face and neck lift procedures. We observed the tympanoparotid fascia in all specimens (20 hemifaces). The tympanoparotid fascia was located anteriorly between the tragus and intertragic notch. Regarding the spatial relationship between the tympanoparotid fascia and the great auricular nerve, we found the sensory nerve entering the tympanoparotid fascia in all specimens (100%), and the depth from the skin was approximately 4.5 mm; in 65% of the specimens, the lobular branch was found to run close to the tympanoparotid fascia before going into the earlobe. Provided with relatively safer surface mapping to access the tympanoparotid fascia free of the lobular branch of the great auricular nerve, surgeons may better protect the lobular branch by anchoring the SMAS-platysma flap and thread to the deeper superior and anterior portions of the expected tympanoparotid fascia.

Electrical Stimulation of the Greater Auricular Nerve to Reduce Postoperative Atrial Fibrillation.

BACKGROUND: Postoperative atrial fibrillation (POAF) occurs in up to 40% of patients undergoing cardiac surgery. Invasive stimulation of the vagal nerve previously demonstrated a reduced risk of POAF. Therefore, we examined the antiarrhythmic and anti-inflammatory effects of noninvasive low-level transcutaneous electrical stimulation (LLTS) of the greater auricular nerve in a pilot trial including patients undergoing cardiac surgery. METHODS: Patients were randomized into a sham (n=20) or a treatment group (n=20) for LLTS. After cardiac surgery, electrodes were applied in the triangular fossa of the ear. Stimulation (amplitude 1 mA, frequency 1 Hz for 40 minutes, followed by a 20 minutes break) was performed for up to 2 weeks after cardiac surgery. Heart rhythm was recorded continuously using an ECG during the observation period. CRP (C-reactive protein) and IL (interleukin)-6 plasma concentrations were measured immediately after surgery as well as on day 2 and 7 postsurgery. RESULTS: Patients receiving LLTS had a significantly reduced occurrence of POAF (4 of 20) when compared with controls (11 of 20, P=0.022) during a similar mean Holter recording period. The median duration of POAF was comparable between the treatment and the control group (878 [249; 1660] minutes versus 489 [148; 1775] minutes; P=0.661). No effect of LLTS on CRP or IL-6 levels was detectable. CONCLUSIONS: LLTS of the greater auricular nerve may be a potential therapy for POAF. We demonstrated the feasibility to conduct a randomized trial of neurostimulation as an outlay for a multisite clinical trial.

Modulatory effects of somatosensory electrical stimulation on neural activity of the dorsal cochlear nucleus of hamsters.

The effects of somatosensory electrical stimulation on the dorsal cochlear nucleus (DCN) activity of control and tone-exposed hamsters were investigated. One to three weeks after sound exposure and control treatment, multiunit activity was recorded at the surface of the left DCN before, during, and after electrical stimulation of the basal part of the left pinna. The results demonstrated that sound exposure induced hyperactivity in the DCN. In response to electrical stimulation, neural activity in the DCN of both control and exposed animals manifested four response types: S-S, suppression occurring during and after stimulation; E-S, excitation occurring during stimulation and suppression after; S-E, suppression occurring during stimulation and excitation after; and E-E, excitation occurring during and after stimulation. The results showed that there was a higher incidence of suppressive (up to 70%) than of excitatory responses during and after stimulation in both groups. In addition, there was a significantly higher degree of suppression after, rather than during stimulation. At high levels of electrical current, the degree of the induced suppression was generally higher during and after stimulation in exposed animals than in controls. The similarity of our results to those of previous clinical studies further supports the view that DCN hyperactivity is a direct neural correlate of tinnitus and that somatosensory electrical stimulation can be used to modulate DCN hyperactivity. Optimization of stimulation strategy through activating only certain neural pathways and applying appropriate stimulation parameters may allow somatosensory electrical stimulation to be used as an effective tool for tinnitus suppression.

Investigation of specificity of auricular acupuncture points in regulation of autonomic function in anesthetized rats.

Auricular acupuncture has been used for various autonomic disorders in clinical practice. It has been theorized that different auricular areas have distinct influence on autonomic functions. The present study aims to examine the effects of acupuncture stimulation at different auricular areas on cardiovascular and gastric responses. In male Sprague-Dawley rats anesthetized with pentobarbital sodium, five auricular areas, which were located at the apex of the helix (A(1)), the middle of the helix (A(2)), the tail of the helix (A(3)), the inferior concha (A(4)) and the middle of the antihelix (A(5)), had been selected for stimulation with manual acupuncture (MA) and different parameters of electroacupuncture (EA). A mild depressor response (6%-12% decrease from baseline) was evoked from A(1), A(3) and A(4) by MA and from all five areas by EA (100 Hz-1 mA). The biggest depressor response (-18.4+/-3.1 mmHg, p<0.001) was evoked from A(4). A small bradycardia was evoked by MA from A(4) and by EA at A(3), A(4) and A(5.) Increase in intragastric pressure (8-14 mmH(2)O) was evoked by MA from A(1), A(3) and A(4) and by EA at A(2.) These results show that similar patterns of cardiovascular and gastric responses could be evoked by stimulation of different areas of the auricle. The present results do not support the theory of a highly specific functional map in the ear. Rather, there is a similar pattern of autonomic changes in response to auricular acupuncture, with variable intensity depending on the area of stimulation.

Transcutaneous auricular vagus nerve stimulation in treating major depressive disorder: A systematic review and meta-analysis.

BACKGROUND: Transcutaneous auricular vagus nerve stimulation (taVNS), as a noninvasive intervention, has beneficial effects on major depressive disorder based on clinical observations. However, the potential benefits and clinical role of taVNS in the treatment of major depressive disorder are still uncertain and have not been systematically evaluated. Therefore, we performed a systematic review and meta-analysis to evaluate the effectiveness and safety of taVNS in treating major depressive disorder. METHODS: Four electronic databases, namely, Embase, MEDLINE, the Cochrane Library and PsycINFO, were searched for all related trials published through May 1, 2018. We extracted the basic information and data of the included studies and evaluated the methodological quality with the Cochrane risk of bias tool and the nonrandomized studies-of interventions (ROBINS-I) tool. A meta-analysis of the comparative effects was conducted using the Review Manager 5.3 software. RESULTS: A total of 423 citations from the databases were searched, and 4 studies with 222 individuals were included in the meta-analysis. The taVNS technique could decrease 24-item HAMD scores more than the sham intervention (MD: -4.23, 95% CI: -7.15, -1.31; P = .005) and was also more effective in decreasing Self-Rating Depression Scale scores ((MD: -10.34, 95% CI: -13.48, -7.20; P < .00001), Beck Depression Inventory scores (MD: -10.3, 95% CI: -18.1, -2.5; P = .01) and Self-Rating Anxiety Scale scores (MD: -6.57, 95% CI: -9.30, -3.84; P < .00001). However, there was no significant difference in the Hamilton Anxiety Rating Scale scores between the taVNS and sham taVNS groups (MD: -1.12, 95% CI: -2.56, 0.32; P = .13). No obvious adverse effects of taVNS treatment were reported in the included studies. CONCLUSION: The results of the analysis preliminarily demonstrated that taVNS therapy can effectively ameliorate the symptoms of major depressive disorder, providing an alternative technique for addressing depression. However, more well-designed RCTs with larger sample sizes and follow-ups are needed in future studies to confirm our findings.

Transauricular vagus nerve stimulation at auricular acupoints Kindey (CO10), Yidan (CO11), Liver (CO12) and Shenmen (TF4) can induce auditory and limbic cortices activation measured by fMRI.

The purpose of this study was to explore the central mechanism of transauricular vagus nerve stimulation (taVNS) to human by fMRI and to find a suitable taVNS site for potential tinnitus treatment. 24 healthy subjects aged between 28 and 38 years were enrolled in the experiment. 8 subjects were stimulated in the auricular acupoints Kindey (CO10), Yidan (CO11), Liver (CO12) and Shenmen (TF4) in the left ear, 8 subjects were stimulated at the anterior wall of the auditory canal and left lower limb as an anterior stimulation group; 8 persons who were arranged in a sham group received taVNS at the left ear lobe and tail of the helix. Functional magnetic resonance imaging (fMRI) data from the cortices was collected and an Alphasim analysis was performed. We found that taVNS at auricular acupoints CO10-12, TF4 can instantly and effectively generate blood oxygenation level dependent (BOLD) signal changes in the prefrontal, auditory and limbic cortices of healthy subjects by fMRI. When comparing the acupoints group and the sham group in the left brain, the signals from the prefrontal cortex, the auditory ascending pathway including superior temporal gyrus, middle temporal gyrus, thalamus and limbic system regions such as putamen, caudate, posterior cingulate cortex, amygdala and parahippocampal gyrus were increased under our stimulation. The difference of the BOLD signal in the left brain between acupoints group and anterior group was in the superior temporal gyrus. We could also find signal differences in several regions of right brain among the groups. In conclusion, taVNS at acupoints CO10-12, TF4 could activate the prefrontal, auditory and limbic cortices of healthy brain and this scheme could be a promising tool for tinnitus treatment.