Ultrasound-guided greater auricular nerve block for surgical anesthesia of the external ear.

The Greater Auricular Nerve (GAN), a branch of the cervical plexus, is used to provide anesthesia or pain relief in the ear and neck region. This case report details the use of a GAN block in a 71-year-old male patient with basal cell carcinoma on his right auricular helix. Due to multiple comorbidities (myocardial infarction resulting in a cardiac stent, hypertension), regional anesthesia was preferred. We aim to share our experience with the GAN block for ear surgery.

The effects of low-and high-frequency non-invasive transcutaneous auricular vagal nerve stimulation (taVNS) on gastric slow waves evaluated using in vivo high-resolution mapping in porcine.

BACKGROUNDS: Gastric motility is regulated by an electrophysiological activity called slow-wave and neuronal innervations by the vagus nerve. Transcutaneous auricular vagal nerve stimulation (taVNS) has been demonstrated to have therapeutic potential for a wide range of medical conditions, including the management of gastric dysfunctions. The main objective of this study was to gain a better understanding of how non-invasive neuromodulation influences gastric slow wave under in vivo conditions. METHODS: TaVNS protocols were applied in conjunction with 192-channel gastric bioelectrical mapping in porcine subjects under general anesthesia. The spatiotemporal profiles of gastric slow wave were assessed under two different taVNS protocols at 10 and 80 Hz. KEY RESULTS: The taVNS protocols effectively altered the interval and amplitude of gastric slow waves, but not the velocity or the percentage of spatial dysrhythmias. In the subjects that responded to the protocols, the 10 Hz protocol was shown to normalize slow-wave propagation pattern in 90% of the subjects, whereas the 80 Hz protocol was shown to inhibit slow waves in 60% of the subjects. CONCLUSIONS AND INFERENCES: Chronic responses of gastric motility and slow waves in response to taVNS should be investigated using non-invasive means in conscious subjects in future.

Development of the interscutularis model as an outcome measure for facial nerve surgery.

INTRODUCTION: Animal models for the study of facial paralysis have been well developed, but concern has arisen regarding the accuracy of eye closure and whisker movement as outcome measures due to new data regarding interconnectivity between facial nerve branches and autonomic innervation. The posterior auricular nerve (PAN) is an isolated branch of the facial nerve which has been confirmed as the sole motor innervat or of the interscutularis muscle. This study was designed to develop a model for facial nerve palsy utilizing the PAN and interscutularis muscle. METHODS: A custom-made automated video capture system was built into a poly methyl methacrylate cage using a high definition monochrome digital camera and image sensor to record the animal as it drank from a water feeder. A copper floor pad and copper collar around the water feeder were connected to an electrical circuit for automatic saving of the video recording 10 s prior to and 30 s following the drinking event. A pre-operative baseline recording of ear movement during drinking was captured. Female YFP-16 mice at 6 weeks were assigned to sham (Sh, n = 5), nerve excision (Ex, n = 10), or nerve crush (Cr, n = 10) groups with all interventions performed on the right PAN. Sh mice were irrigated with 10 ml normal saline as were the Ex and Cr mice following operative intervention. In Ex mice, a 3 mm section of the PAN was sharply excised and nerve gap was confirmed with fluorescent microscopy. In Cr mice, the PAN was crushed 3 mm from the origin of the facial nerve trunk with size 5 jeweler's forceps for two periods of 20 s. Post-operative video recordings were collected on post-operative days (POD) 1, 10, 20, and 30. To determine the change in ear movement, the right ear was graphically compared to the left control side. RESULTS: Sh animals exhibited a statistically significant reduction in ear movement at POD01 compared to other POD recordings (p < 0.05), but no significant change in right ear movement following POD05. Ex animals had a significant reduction in right ear movement at all PODs in comparison to the left ear (p < 0.05) with no significant change in right ear movement during the study period (p = 0.94). Cr animals showed a significant reduction in right ear movement compared to the left at POD01, POD10, and POD20 (p < 0.05). At POD30, there was no significant difference between ear movement on either side (p = 0.35). There was a significant change in right ear movement during the data collection period (p < 0.05). CONCLUSION: The results show that significant differences were demonstrated between the experimental groups and that significant changes within the crush group were identifiable making this an acceptable model to develop as an accurate outcome measure following rodent facial nerve surgery.

Innervation of the Human Cavum Conchae and Auditory Canal: Anatomical Basis for Transcutaneous Auricular Nerve Stimulation.

The innocuous transcutaneous stimulation of nerves supplying the outer ear has been demonstrated to be as effective as the invasive direct stimulation of the vagus nerve for the treatment of some neurological and nonneurological disturbances. Thus, the precise knowledge of external ear innervation is of maximal interest for the design of transcutaneous auricular nerve stimulation devices. We analyzed eleven outer ears, and the innervation was assessed by Masson's trichrome staining, immunohistochemistry, or immunofluorescence (neurofilaments, S100 protein, and myelin-basic protein). In both the cavum conchae and the auditory canal, nerve profiles were identified between the cartilage and the skin and out of the cartilage. The density of nerves and of myelinated nerve fibers was higher out of the cartilage and in the auditory canal with respect to the cavum conchae. Moreover, the nerves were more numerous in the superior and posterior-inferior than in the anterior-inferior segments of the auditory canal. The present study established a precise nerve map of the human cavum conchae and the cartilaginous segment of the auditory canal demonstrating regional differences in the pattern of innervation of the human outer ear. These results may provide additional neuroanatomical basis for the accurate design of auricular transcutaneous nerve stimulation devices.

Sensation loss after superficial parotidectomy: A prospective controlled multicenter trial.

BACKGROUND: The purpose of this study was to evaluate the occurrence of hypoesthesia after superficial parotidectomy depending on preservation of posterior branch of the great auricular nerve (GAN). METHODS: This prospective, controlled, double blind, multicenter trial included 130 patients. The posterior branch was preserved in 93 patients (GAN group), and ligated in 33 patients (non-GAN group). In 4 patients, GAN status was unknown. Included patients underwent sensory testing (TouchTest) and subjective evaluation at 6, 12, and 24 months after surgery. RESULTS: Better improvement of sensation was present in the GAN group. After 12 months, 59% of the patients in the GAN-group showed positive test results in the lobule, versus 24% of the non-GAN group (p = .013). Additionally, after 24 months, 71% of the patients in the GAN-group showed a positive test in the antitragus, versus 31% in the non-GAN group (p = .045). Hypoesthesia equally limited quality of life in both groups (all p > .05). CONCLUSION: Preservation of the posterior branch of the GAN led to significantly better improvement of sensation in the lobule and antitragus, and should be recommended during parotidectomy. © 2017 Wiley Periodicals, Inc. Head Neck 39: 520-526, 2017.

Ultrasound-guided Greater Auricular Nerve Block for Emergency Department Ear Laceration and Ear Abscess Drainage.

BACKGROUND: Adequate emergency department (ED) anesthesia for painful ear conditions, such as ear lacerations or ear abscesses, can be challenging. Much of the sensory innervation of the ear is supplied from the anterior and posterior branches of the greater auricular nerve (GAN). The GAN is a branch of the superficial cervical plexus, which arises from the C2/C3 spinal roots. The GAN innervation includes most of the helix, antihelix, the lobule, and the skin over the mastoid process and parotid gland. Anesthesia of the GAN is commonly performed in emergency medicine as part of a landmark-based ear "ring" block. Recently, a selective ultrasound-guided GAN block has been described. CASE REPORT: We report the first cases of ultrasound-guided greater auricular nerve block (UGANB) successfully performed in the ED as the sole procedural anesthesia for both an ear laceration and abscess drainage. In addition, we review the relevant anatomy and technical details of the procedure. WHY SHOULD AN EMERGENCY PHYSICIAN BE AWARE OF THIS?: Our cases suggest that UGANB is a potentially effective nerve block for ED management of acute ear pain related to procedures involving the tail of the helix and the lobule, such as ear lacerations or ear abscess incision and drainage. Advantages include real-time visualization of the GAN that may increase block success and the decreased volume of local anesthetic required for a block.

[The study of preserving the great auricular nerve in the parotidectomy].

OBJECTIVE: To assess the effect for local sensory to preserve great auricular nerve in the parotidectomy. METHOD: It was a prospective study. Eighy-one patients who underwent parotidectomy were randomly divided into 2 groups, preserving the great auricular nerve group and no preserving the great auricular nerve group. They were tested with the subjective and objective sensory function testing in 3, 6, 9, 12 months after operation. We assessed the result. RESULT: In the subjective sensory function testing, the result of the preserving the great auricular nerve group was better than no preserving the great auricular nerve group. In the objective sensory function testing, the result of the preserving the great auricular nerve group was obviously better than no preserving the great auricular nerve group. There was significant difference between the 2 groups (P<0.05). CONCLUSION: It was effective for recovering the sensory function that we preserved the great auricular nerve in the parotidectomy.

Sensory dysfunction and quality of life after great auricular nerve sacrifice during parotidectomy: our experience.

OBJECTIVE: This study aimed to investigate the impact on patients' quality of life of great auricular nerve sacrifice during parotidectomy. METHODS: A retrospective review was conducted of 191 consecutive patients who underwent parotidectomy with great auricular nerve sacrifice between 2006 and 2011. Residual sensory dysfunction and its impact on quality of life was analysed using an eight-item quality of life survey. RESULTS: In all, 139 out of 191 patients (72.8 per cent) experienced one or more abnormal sensations in the ear or neck region after surgery. There was a moderate inverse correlation between the number of abnormal sensations and time elapsed since surgery. Moreover, the degree of discomfort correlated significantly with the frequency of symptom occurrence (p < 0.001), duration of the abnormal sensation (p < 0.001) and size of the affected area (p < 0.001). CONCLUSION: Sacrifice of the great auricular nerve has only a small impact on patient quality of life; their daily activities are not significantly affected.

Parotidectomy combined with identification and preservation procedures of the great auricular nerve.

CONCLUSIONS: We found that the great auricular nerve (GAN) passes at the median (m) point between the tips of the mandibular angle and mastoid process. We also established the GAN definitive line using this point for rapid identification of the trunk of the GAN and systematic parotidectomy combined with procedures for identification of the GAN, elevation of the skin flap, and exposure of the parotid capsule, which showed a high rate of preservation of the nerve and the lobular branch. OBJECTIVE: The aim of this study was to improve parotidectomy and the rate of preservation of the GAN. METHODS: This study comprised 74 consecutive patients who were scheduled to have parotidectomy for benign tumors at our department between November 2011 and April 2014. We examined whether our GAN definitive line including the m point was useful to identify the trunk of the GAN and whether anterograde dissection of the nerve could be performed simultaneously with skin flap elevation and exposure of the parotid capsule and contributed to preservation of the trunk to the lobular branch. RESULTS: The trunk was identified under the GAN definitive line drawn preoperatively in 97.3% of cases (72/74). Combined surgery was successfully performed with a 95.9% (71/74) preservation rate of the GAN including the lobular branch.

Non-invasive Access to the Vagus Nerve Central Projections via Electrical Stimulation of the External Ear: fMRI Evidence in Humans.

BACKGROUND: Tract-tracing studies in cats and rats demonstrated that the auricular branch of the vagus nerve (ABVN) projects to the nucleus tractus solitarii (NTS); it has remained unclear as to whether or not the ABVN projects to the NTS in humans. OBJECTIVE: To ascertain whether non-invasive electrical stimulation of the cymba conchae, a region of the external ear exclusively innervated by the ABVN, activates the NTS and the "classical" central vagal projections in humans. METHODS: Twelve healthy adults underwent two fMRI scans in the same session. Electrical stimulation (continuous 0.25ms pulses, 25Hz) was applied to the earlobe (control, scan #1) and left cymba conchae (scan #2). Statistical analyses were performed with FSL. Two region-of-interest analyses were performed to test the effects of cymba conchae stimulation (compared to baseline and control, earlobe, stimulation) on the central vagal projections (corrected; brainstem P < 0.01, forebrain P < 0.05), followed by a whole-brain analysis (corrected, P < 0.05). RESULTS: Cymba conchae stimulation, compared to earlobe (control) stimulation, produced significant activation of the "classical" central vagal projections, e.g., widespread activity in the ipsilateral NTS, bilateral spinal trigeminal nucleus, dorsal raphe, locus coeruleus, and contralateral parabrachial area, amygdala, and nucleus accumbens. Bilateral activation of the paracentral lobule was also observed. Deactivations were observed bilaterally in the hippocampus and hypothalamus. CONCLUSION: These findings provide evidence in humans that the central projections of the ABVN are consistent with the "classical" central vagal projections and can be accessed non-invasively via the external ear.

Anatomic and histological study of great auricular nerve and its clinical implication.

BACKGROUND: The great auricular nerve (GAN) is often sacrificed during parotidectomy, rhytidectomy, and platysma flap operation. Transection of the nerve results in a wooden numbness of preauricular region, pain, and neuroma. The aim of this study was to describe the branching patterns and distribution area of the GAN. METHODS: Twenty-five embalmed, adult hemifacial Korean cadavers (16 males, nine females; mean age 62.5 years) were used in this study. The branching of the GAN was determined through careful dissection. The histological structure of the GAN was also examined by harvesting and sectioning specimens, and then viewing them with the aid of a light microscope. RESULTS: The branching pattern of the anterior, posterior, deep, and superficial branches of the GAN could be classified into five types: type I (20%), where the deep branches arose from the anterior branch; type II (24%), where all branches originated at the same point; type III (28%), where the deep branch arose from the posterior branch; type IV (8%), where the superficial branches arose from the posterior branch; and type V (20%), where the anterior and posterior branches ran independently. A connection between the GAN and the facial nerve trunk was observed in all specimens, and a connection with the auriculotemporal nerve was observed in a few specimens. The total fascicular area of both regions decreased from proximal (1.42 mm2) to distal (0.60 mm2). There were 2.5 and 5 fascicles in the proximal and distal regions, respectively. CONCLUSION: The results reported herein will help toward preservation of the GAN during surgery in the region of the parotid gland. Furthermore, the histologic findings suggest that the GAN would be a good donor site for nerve grafting.

Electrical stimulation of the vagus nerve dermatome in the external ear is protective in rat cerebral ischemia.

BACKGROUND: Although cervical vagus nerve stimulation is effective for reducing infarct volume in rats, it is not feasible for acute human stroke as it requires surgical incision of the neck. We hypothesized that stimulation of the dermatome in the external ear innervated by the vagus nerve (auricular vagus nerve stimulation; aVNS) reduces infarct volume after transient focal ischemia in rats. METHODS: Animals were randomized to active aVNS or sham stimulation. For aVNS, electrical stimulation of the left cavum concha (1 h duration) using percutaneous needles was initiated 30 min after induction of ischemia. Behavioral and tissue outcome were measured 24 h after induction of ischemia. In a separate experimental dataset, c-Fos immunohistochemistry was performed to identify the brain regions activated after the stimulation. RESULTS: Stimulation of the left cavum concha resulted in bilateral c-Fos staining in the nuclei tractus solitarii and the loci coerulei in all animals. There was no c-Fos staining in any part of the brainstem in sham control animals. The mean infarct volume (SD) as calculated by indirect method was 44.20 ± 7.58% in controls and 31.65 ± 9.67% in treated animals (P < 0.0001). The effect of aVNS on tissue outcome was associated with better neurological scores at 24 h after ischemia (P < 0.0001). CONCLUSIONS: Electric stimulation of the vagus nerve dermatome in the external ear activates brainstem afferent vagal nuclei and reduces infarct volume in rats. This finding has potential to facilitate the development of treatments that leverage the brain's endogenous neuroprotective pathways at the setting of acute ischemic stroke.

[Aural Stimulation with Capsaicin Ointment Improved the Swallowing Function in Patients with Dysphagia: Evaluation by the SMRC Scale].

Cough and swallowing reflexes are important airway-protective mechanisms against aspiration. Angiotensin-converting enzyme (ACE) inhibitors, one of the side effects of which is cough, have been reported to reduce the incidence of aspiration pneumonia in hypertensive patients with stroke. ACE inhibitors have also been reported to improve the swallowing function in post-stroke patients. On the other hand, stimulation of the Arnold nerve, the auricular branch of the vagus, triggers the cough reflex (Arnold's ear-cough reflex). Capsaicin, an agonist of Transient Receptor Potential Vanilloid 1 (TRPV1), has been shown to activate the peripheral sensory C-fibers. Stimulation of the sensory branches of the vagus in the laryngotracheal mucosa with capsaicin induces the cough reflex and has been reported to improve the swallowing function in patients with dysphagia. In our previous study, we showed that aural stimulation of the Arnold nerve with 0.025% capsaicin ointment improved the swallowing function, as evaluated by the endoscopic swallowing score, in 26 patients with dysphagia. In the present study, the video images of swallowing recorded in the previous study were re-evaluated using the SMRC scale by an independent otolaryngologist who was blinded to the information about the patients and the endoscopic swallowing score. The SMRC scale is used to evaluate four aspects of the swallowing function: 1) Sensory: the initiation of the swallowing reflex as assessed by the white-out timing; 2) Motion: the ability to hold blue-dyed water in the oral cavity and induce laryngeal elevation; 3) Reflex: glottal closure and the cough reflex induced by touching the epiglottis or arytenoid with the endoscope; 4) Clearance: pharyngeal clearance of the blue-dyed water after swallowing. Accordingly, we demonstrated that a single application of capsaicin ointment to the external auditory canal of patients with dysphagia significantly improved the R, but not the S, M or C scores, and this effect lasted for 60 min. After repeated aural stimulation with the ointment for 7 days, the R score improved significantly in patients with severe dysphagia. The present findings suggest that stimulation of the Arnold's branch of the vagus in the external auditory canal with capsaicin improves the glottal closure and cough reflex in patients with dysphagia. Thus, aural stimulation with capsaicin represents a novel treatment for dysphagia. It is also suggested that repeated alternative aural stimulation with capsaicin for a week, rather than a single application, is needed to improve the swallowing function in patients with severe dysphagia. By the same mechanism as that underlying the effect of ACE inhibitors, aural stimulation with capsaicin may reduce the incidence of aspiration pneumonia in patients with dysphagia.

[Replantation of amputated ear with anastomosis of vessel].

OBJECTIVE: To investigate the application of microsurgical technique in the replantation of amputated ear. METHODS: 7 cases of amputated ears were analyzed from June 2009 to April 2015 in our department. We used microsurgical technique to anastomose about five vessels and nerves. The blood supply of auricle was restored within three to six hours. All subjects underwent treatments including anti-freezing, anti-spasm and anti-infection treatment after the emergency surgery. RESULTS: 7 amputated ears were all survived after replantation. The patients were followed up for one month to six months ( average for 28 months). The appearances of survived ears body were fully recovered without any significant atrophy or pigmentation. The sensory function of ears recovered to normal after 1 year. CONCLUSIONS: The application of microsurgical technique in the replantation of amputated ear can expect the high success rate of ear replantation. However, skilled and high-quality anastomosis technique of small vascular are required.

High-Resolution Ultrasound for Diagnostic Assessment of the Great Auricular Nerve--Normal and First Pathologic Findings.

PURPOSE: The great auricular nerve (GAN) is a sensory branch of the superficial cervical plexus. While its blockade is an established procedure, little is known about the ultrasound appearance of pathologic conditions of the GAN itself. We, therefore, aimed to evaluate the possibility of the visualization and diagnostic assessment of the GAN along its entire course by means of high-resolution ultrasound (HRUS). MATERIALS AND METHODS: To assess the feasibility of visualization, we performed HRUS with an 18 MHz probe, HRUS-guided, fine-needle ink markings and consecutive dissection in six anatomical specimens. Then, we measured the diameter of the GAN in healthy volunteers and finally performed a retrospective review of patients referred for HRUS examinations because of pain within GAN territory between August 1, 2012 and August 1, 2013. RESULTS: The GAN was clearly visible with HRUS from its formation to the final branches, and was marked successfully on both sides in all anatomical specimens (n = 12). The mean average in-vivo was 0.14 cm ± 0.03 (range 0.08-0.2). Seven cases of patients with GAN pathologies of various origins (idiopathic, traumatic, tumorous and iatrogenic) were identified, of which 6 were visible on HRUS and all of which could be confirmed by complete resolution of symptoms after selective HRUS-guided GAN block. CONCLUSION: This study confirms the reliable ability to visualize the GAN with HRUS throughout its course, both in anatomical specimens and in vivo. The provided cases show that pathologies of the GAN seem to have a variety of causes and may not be rare. We, therefore, encourage the use of HRUS in patients with unclear pain in the auricular, periauricular and posterior-lateral head.

Accommodating to new ears: the effects of sensory and sensory-motor feedback.

Changing the shape of the outer ear using small in-ear molds degrades sound localization performance consistent with the distortion of monaural spectral cues to location. It has been shown recently that adult listeners re-calibrate to these new spectral cues for locations both inside and outside the visual field. This raises the question as to the teacher signal for this remarkable functional plasticity. Furthermore, large individual differences in the extent and rate of accommodation suggests a number of factors may be driving this process. A training paradigm exploiting multi-modal and sensory-motor feedback during accommodation was examined to determine whether it might accelerate this process. So as to standardize the modification of the spectral cues, molds filling 40% of the volume of each outer ear were custom made for each subject. Daily training sessions for about an hour, involving repetitive auditory stimuli and exploratory behavior by the subject, significantly improved the extent of accommodation measured by both front-back confusions and polar angle localization errors, with some improvement in the rate of accommodation demonstrated by front-back confusion errors. This work has implications for both the process by which a coherent representation of auditory space is maintained and for accommodative training for hearing aid wearers.

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.