Computed tomographic features of canine intracranial and jugular foraminal masses involving the combined glossopharyngeal, vagus, and accessory nerve roots.

A chronic cough, gag, or retch is a common presenting clinical complaint in dogs. Those refractory to conservative management frequently undergo further diagnostic tests to investigate the cause, including CT examination of their head, neck, and thorax for detailed morphological assessment of their respiratory and upper gastrointestinal tract. This case series describes five patients with CT characteristics consistent with an intracranial and jugular foraminal mass of the combined glossopharyngeal (IX), vagus (X), and accessory (XI) cranial nerves and secondary features consistent with their paresis. The consistent primary CT characteristics included an intracranial, extra-axial, cerebellomedullary angle, and jugular foraminal soft tissue attenuating, strongly enhancing mass (5/5). Secondary characteristics included smooth widening of the bony jugular foramen (5/5), mild hyperostosis of the petrous temporal bone (3/5), isolated severe atrophy of the ipsilateral sternocephalic, cleidocephalic, and trapezius muscles (5/5), atrophy of the ipsilateral thyroarytenoideus and cricoarytenoideus muscles of the vocal fold (5/5), and an ipsilateral "dropped" shoulder (4/5). Positional variation of the patient in CT under general anesthesia made the "dropped" shoulder of equivocal significance. The reported clinical signs and secondary CT features reflect a unilateral paresis of the combined cranial nerves (IX, X, and XI) and are consistent with jugular foramen syndrome/Vernet's syndrome reported in humans. The authors believe this condition is likely chronically underdiagnosed without CT examination, and this case series should enable earlier CT diagnosis in future cases.

The vagus nerve cross-sectional area on ultrasound in patients with type 2 diabetes.

Diabetic neuropathy, including autonomic neuropathy is a serious complication related to type 2 diabetes mellitus (T2D). The vagus nerve (VN) is the longest nerve in the autonomic nervous system, and since diabetic neuropathy manifests first in longer nerves, the VN is commonly affected in early diabetic autonomic neuropathy. The use of high-resolution ultrasound for peripheral and cranial nerve imaging has significantly increased over the past 2 decades. The aim of the study is to compare the cross-sectional area of the VN in patients with T2D to that of a control cohort without T2D. A total of 52 VN cross-sectional areas were recorded from patients with T2D. A total of 56 VN cross-sectional areas were also recorded from asymptomatic subjects without T2D. In each subject, high-resolution ultrasound imaging of the bilateral VNs was performed in the short-axis between the common carotid artery and the internal jugular vein. The VN cross-sectional areas were recorded and compared. In the patients with T2D, HbA1c and fasting blood glucose levels were obtained as well as the duration of T2D in years and correlated with the cross-sectional areas. The bilateral VN cross-sectional areas were similar in both cohorts. Additionally, no correlation was seen between the VN cross-sectional areas, demographics, or clinical data of T2D. Our study demonstrated normal VN cross-sectional areas in patients with T2D without any significant relation with the patients' demographic or clinical data.

Vagus nerve cross-sectional area decreases in Parkinson's disease.

INTRODUCTION: Morphological alterations of the vagus nerve (VN) in Parkinson's disease (PD) are discussed controversially. Several studies reported no difference in VN cross-sectional area (CSA) in PD patients in nerve ultrasound, others found a reduced CSA interpreted as atrophy of the VN and involvement of the dorsal nucleus of VN. METHODS: In a prospective comparative cross-sectional study, CSA of the VN bilaterally and the right ulnar nerve, clinical PD scales, non-motor symptoms and autonomic tests were compared between 49 PD patients and 24 healthy controls. Nerve ultrasound was performed by two independent investigators, patients and controls were compared at Bonferroni corrected p < 0.025 using results of both investigators and averaged results. Blinding included CSA measurements and PD scores, but not PD diagnosis. RESULTS: Bilateral averaged VN CSA was significantly lower in PD patients than in controls (Right VN PD mean 2.70 mm2 SD 0.69, controls 3.30 mm2 SD 0.49, p < 0.001. Left VN PD mean 2.45 mm2 SD 0.57, controls 2.77 mm2 SD 0.46, p = 0.012). No difference was found in the ulnar nerve. There was a weak negative correlation between the right VN CSA and the Unified Parkinson Disease Rating Scale (-0.08 mm2 per 10 points). The area under the receiver operating characteristic curve for the right VN was 0.78 (p < 0.001). CONCLUSION: The present results support the hypothesis of atrophy of the VN in PD. Reduction of VN CSA is a weak marker of disease progression. Nerve ultrasound of the VN might represent a supplementary method in diagnosis of PD.

Ultrasound morphometry of the cervical vagus nerve for daily clinical practice: Reference values for cross sectional area and fascicle count.

INTRODUCTION: High resolution ultrasound (US) of the cervical vagus nerve (CVN) is clinically relevant in the diagnostic workup and during neurostimulation therapy of several neurologic diseases. This prospective study aims to provide reference data of the cross-sectional area (CSA) and fascicle count of the normal CVN and to investigate their possible association with anthropometric data in a large cohort of patients. METHODS: A total of 657 CVNs in 330 individuals without history of neurological disease were examined using US (7-15Mhz). The CVN fascicle count and CSA inside the hyperechoic epineurium at the level of the thyroid lobes were measured. Three CSA measurements were performed to calculate the mean value. Anthropometric data were recorded. RESULTS: The mean fascicle count was 2.4 ± 1.1 (right) and 2 ± 1 (left) (paired t- test, p < 0.001). Two CVN patterns were identified: A single hypoechoic fascicular structure (26.2 % right, 36.3 % left) and a honeycomb structure of 2-6 discrete fascicles (72.3 % right, 63.7 % left). Right CVN mean CSA was larger compared to left (2.3 ± 1 mm2 and 1.8 ± 0.8 mm2 respectively, t-test, p-0.000). There was no difference in the CSA values between sex and no correlation to age or height. A positive correlation between the CSA and weight and BMI was found (Pearson's correlation, p = 0.01 right and p = 0.05 left). CONCLUSION: The right CVN has larger CSA and contains more fascicles than the left. CVN is usually mono- or oligo-fascicular with a honeycomb appearance. The CSA increased with increasing BMI but no age and sex specific differences were noted.

Ultrasound of the normal vagus nerve cross-sectional area in the carotid sheath.

The aim of this article is to utilize ultrasound to evaluate the normal cross-sectional area (CSA)of the vagus nerve (VN) in the carotid sheath. This study included 86 VNs in 43 healthy subjects (15 men, 28 women); mean age 42.1 years and mean body mass index 26.2 kg/m2. For each subject, the bilateral VNs were identified by US at the anterolateral neck within the common carotid sheaths. One radiologist obtained 3 separate CSA measurements for each of the bilateral VNs with complete transducer removal between each measurement. Additionally, for each participant, demographic information of age and gender as well as body mass index, weight, and height were documented. The mean CSA of the right VN in the carotid sheath was 2.1 and 1.9 mm2 for the left VN. The right VN CSA was significantly larger than the left VN (P < .012). No statistically significant correlation was noted in relation to height, weight, and age. We believe that the reference values for the normal CSA of the VN obtained in our study, could help in the sonographic evaluation of VN enlargement, as it relates to the diagnosis of various diseases affecting the VN.

Ultrasound evaluation of vagus nerve cross-sectional area in a community-dwelling elderly Japanese cohort.

OBJECTIVES: Although the vagus nerve (VN) is easily observed by ultrasonography, few studies have evaluated the cross-sectional area (CSA) of the VN in healthy older individuals from East Asia. In this study, we aimed to report reference values for the CSA of the VN in community-dwelling elderly Japanese individuals and to identify any associated medical history and/or lifestyle factors. METHODS: The present study included 336 participants aged ≥ 70 years from a prospective cohort study conducted in Yahaba, Japan from October 2021 to February 2022. The CSA of the VN was measured bilaterally at the level of the thyroid gland by ultrasonography. Simple linear regression analysis and generalized estimating equation were conducted to identify the associations between clinical and background factors and the CSA of the VN. RESULTS: In our cohort, the median CSA of the VN was 1.3 mm2 (interquartile range [IQR] 1.1-1.6) on the right side and 1.2 mm2 (IQR 1.0-1.4) on the left side. Generalized estimating equation showed that history of head injury (ß = 0.19, p < .01), current smoking habit (ß = -0.09, p = .03), and BMI (ß = 0.02, p < .01) were independently associated with the CSA of the VN. CONCLUSION: We have reported reference VN CSA values for community-dwelling elderly Japanese individuals. In addition, we showed that the CSA of the VN was positively associated with a history of head injury and BMI and inversely associated with current smoking habit.

Sonographic vagus nerve atrophy in Parkinson's disease: Myth or fact? A systematic review and meta-analysis of recent evidence answers.

BACKGROUND: Parkinson's disease (PD) is a major cause of disability. We aimed to assess the benefit of ultrasonography of the vagus nerve (VN) to compare between PD and healthy controls as well as to deliver reference values of nerve cross sectional area (CSA). MATERIALS AND METHODS: We performed a systematic search on Medline (PubMed), Scopus, Embase, and Web of Science, up till July 25, 2022. After article selection and screening, we performed a quality assessment using the Newcastle-Ottawa Scale. Furthermore, a statistical analysis and subgroup analysis was performed. RESULTS: Eleven studies were included with a total of 809 participants (409 PD patients and 400 controls). A statistically significant difference in the CSA of the right and left VN between PD patients and healthy controls was observed, indicating the atrophy of VN in PD patients (p < 0.00001). The subgroup meta-analysis for average measurements of VN CSA showed insignificant heterogeneity for age (I2 = 48.67%, p = 0.058), level of measurements (I2 = 57.91%, p = 0.05), and disease duration (I2 = 27.1%, p = 0.241). CONCLUSION: Our meta-analysis showed a sonographically detectable degree of neuronal damage in PD, which correlates with VN atrophy with high confidence. Therefore, we believe this is a potential marker for vagus neuronal lesions. Future studies are required to assess the potential clinical correlation.

Sonographic Reference Values of Vagus Nerve: A Systematic Review and Meta-analysis.

PURPOSE: To establish the first comprehensive and standardized set of vagus nerve (VN) sonographic reference values across all the published studies that can be used to standardize and guide clinical practice and research. METHODS: This systematic review includes all possible available data from a total of 27 studies and 21 of them were included in the meta-analysis having a total of 864 participants. RESULTS: The overall mean cross-sectional area ranged from 2.29 to 2.76 mm2 for the right VN and from 1.83 to 2.23 mm2 for the left VN with 95% confidence interval. Sonographic reference values of VN at common carotid artery bifurcation, thyroid gland, and cartilage as well as other anatomic landmarks were provided. CONCLUSIONS: The mean cross-sectional area of the right VN of 2.53 mm2 and the left one of 2.03 mm2 can be considered as sonographic reference values in healthy adults. This review provides these reference values to be considered in the further sonographic evaluation of VNs.

The first experience of ultrasound-guided percutaneous microwave ablation for extracranial schwannoma of the cervical vagus nerve in carotid space and treatment response evaluation with contrast-enhanced imaging: A case report.

Schwannoma is a benign tumor that originates from Schwann cells in the nerve sheathing of cranial, other peripheral, or autonomic nerves. Patients often present with painless mass as the chief complaint. The main symptoms of this tumor are related to its size and specific nerve origin. At present, the pretreatment diagnosis is mainly made by ultrasound, CT, MR, or biopsy, and the main treatment is surgical resection. We reported a new treatment method for cervical schwannoma in a 65-year-old woman with a history of non-small cell lung cancer (NSCLC). When the patient's neck mass was initially found with hoarseness and severe cough, it was considered as cervical lymph node metastasis of lung cancer due to her medical history. And she was diagnosed with schwannoma by core-needle biopsy after chemotherapy failed and the tumor shrank after the radiotherapy with no improvement of the clinical symptoms. After considering the physical condition, the patients were treated in our department for minimal invasiveness treatment. The patient was definitively diagnosed with cervical vagus schwannoma and was treated with ultrasound-guided microwave ablation of schwannoma under general anesthesia with systematic evaluation and improved preoperative examination. Her condition was stable, and the symptoms of severe cough disappeared after anesthesia resuscitation and the ablation. The tumor continued to shrink after the operation with no recurrence of cough symptoms. Ultrasound-guided percutaneous microwave ablation (MWA) for cervical vagus schwannomas might be a minimally invasive, effective, and relatively safe alternative to conventional treatment for those patients with severe symptoms.

Evaluation of Carotid Space Schwannoma Using Ultrasonography: Characteristics and Role in Defining the Nerve of Origin.

OBJECTIVES: We aimed to evaluate the ultrasonography (US) characteristics of carotid space schwannoma and their role in identifying the nerve of origin. METHODS: This prospective study enrolled patients with cervical carotid space schwannoma accessible by US. The US characteristics of vagus nerve schwannomas (VNSs) and sympathetic nerve schwannomas (SNSs) were assessed; a carotid space schwannoma was defined as a VNS if the tumor originated in the mid-vagal region and an SNS if it arose posterior to the intact vagus nerve, displacing the vagus nerve anteriorly. RESULTS: Twenty patients with carotid space schwannoma were enrolled. The vagus and sympathetic nerves were identified as the nerve of origin in 12 and 8 patients, respectively. VNSs were centered at levels II, III, and IV in 5, 3, and 4 patients, respectively, while SNSs were centered at levels II (7 patients) and IV (1 patient) (P = .105). The maximal diameters were 3.2 and 4.8 cm for VNSs and SNSs, respectively (P = .011). Internal vascularity was absent and low in 9 and 3 VNSs, respectively, and low and intermediate in 4 SNSs each (P = .002). Twelve patients with VNSs underwent active surveillance without immediate surgery; no adverse events occurred during the 55.2-month follow-up period. Eight patients with potential SNSs underwent surgery, confirming the sympathetic nerve as the nerve of origin. CONCLUSIONS: US facilitates identification of the nerve of origin in cervical carotid space schwannoma. VNSs are more frequent in infrahyoid locations and tend to be smaller in size with lower vascularity compared with SNSs on US.

Effect of aging on vagus somatosensory evoked potentials and ultrasonographic parameters of the vagus nerve.

Vagus somatosensory evoked potentials (VSEP) and ultrasonography can be used to detect functional and structural changes of the vagus nerve (VN) that are hypothesized to be associated with neurodegenerative diseases. However, it has not yet been established whether age-related changes in the VN occur in the healthy population. In this pilot study we included healthy volunteers in the 26-30 and 51-55 age range who comprised the younger (n = 20) and older (n = 20) groups, respectively. VSEP were recorded separately for stimulation of the auricular branch of the left and right VN. The VN CSA was measured in the transverse plane proximal to the carotid bifurcation, at the level of the distal end of the common carotid artery. No differences were found between the younger and older groups when comparing the average VN CSA (2.01 ± 0.20 vs 2.05 ± 0.20, mm2; p = 0.570) or the CSA of the right (2.08 ± 0.19 vs 2.17 ± 0.24, mm2; p = 0.233) or left VN (1.94 ± 0.26 vs 1.93 ± 0.24, mm2; p = 0.911). The right VN was larger than the left in 95% (n = 19) of older participants and in 65% (n = 13) of younger participants (p = 0.055). In comparison with the younger group, older participants showed significantly longer VSEP latencies of all wave components for electrodes C4-F4 and Fz-F3, of P1 for electrodes C3-F3 and of N1 and P2 for electrodes Fz-F4. The results of this study indicate that older age is associated with longer VSEP latencies but not with changes in VN CSA.

Vagus nerve ultrasonography in Parkinson's disease: A systematic review and meta-analysis.

OBJECTIVES: Vagus nerve (VN) has been suggested as one of the major routes of Parkinson's disease (PD) progression from enteric nervous system to brain. Therefore, the recent studies have investigated the VN structurally, with a focus on the changes in its size in PD patients using high-frequency ultrasonography. This systematic review and meta-analysis aims to evaluate VN size via ultrasound in PD compared to controls. METHODS: Totally, five studies were included with a total of 238 participants (128 PD patients and 111 controls). RESULTS: The estimate mean difference in four studies showed that the VN CSA was smaller in PD patients with 0.29 mm2 (95% CI, -0.52 to -0.06) and 0.23 mm2 (95% CI, -0.42 to -0.05) for right and left VNs respectively. The test for overall effect was significant for both measurements (p = 0.01). CONCLUSIONS: This review reveals that there is a degree of vagus nerve atrophy in PD which could be detected sonographically with high confidence, thus can be used as a marker for vagus neuronal lesion or neuropathy. Further studies are needed to examine its clinical correlation thoroughly.

A CASE OF VAGUS NERVE SCHWANNOMA DIFFICULT TO DISTINGUISH FROM LYMPH NODAL METASTASIS OF ESOPHAGEAL CANCER.

In this report, we describe a rare case of vagus nerve schwannoma associated with esophageal cancer. A 70-year-old man visited our hospital complaining of worsening dysphagia. His upper gastrointenstinal endoscopy revealed a mass in the esophagus. A contrast-enhanced chest computed tomography also detected a 15 mm nodule attached to the tracheal membrane. This nodule was diagnosed as a metastatic lymph node. Although the primary tumor reduced after neoadjuvant chemotherapy, the nodule remained intact ; it showed fluorodeoxyglucose accumulation on positron emission tomography. We had a clinical diagnosis of stage III after neoadjuvant chemotherapy and underwent surgery. Intraoperatively, the nodule could not be detached from the right vagus nerve ; therefore, we excised the nodule along with the adjacent vagus nerve. The nodule was pathologically diagnosed as a vagus schwannoma. The nodule was not a regional lymph node metastasis of esophageal cancer. His postoperative course was uneventful, and he is currently undergoing outpatient follow-up without recurrence. J. Med. Invest. 68 : 205-208, February, 2021.

High-resolution ultrasound changes of the vagus nerve in idiopathic Parkinson's disease (IPD): a possible additional index of disease.

BACKGROUND AND RATIONALE: Histopathological studies revealed degeneration of the dorsal motor nucleus of the vagus nerve (VN) early in the course of idiopathic Parkinson's disease (IPD). Degeneration of VN axons should be detectable by high-resolution ultrasound (HRUS) as a thinning of the nerve trunk. In order to establish if the VN exhibits sonographic signs of atrophy in IPD, we examined patients with IPD compared with age-matched controls. MATERIAL AND METHODS: We measured the caliber (cross-sectional area, CSA) and perimeter of the VN in 20 outpatients with IPD (8 females and 12 males; mean age 73.0 + 8.6 years) and in age-matched controls using HRUS. Evaluation was performed by blinded raters using an Esaote MyLab Gamma device in conventional B-Mode with an 8-19 MHz probe. RESULTS: In both sides, the VN CSA was significantly smaller in IPD outpatients than in controls (right 2.37 + 0.91, left 1.87 + 1.35 mm2 versus 6.0 + 1.33, 5.6 + 1.26 mm2; p <0.001), as well as the perimeter (right 5.06 + 0.85, left 4.78 + 1.74 mm versus 8.87 + 0.86, 8.58 + 0.97 mm; p <0.001). There were no significant correlations between VN CSA and age, the Hoehn and Yahr scale, L-dopa therapy, and disease duration. CONCLUSION: Our findings provide evidence of atrophy of the VNs in IPD patients by HRUS. Moreover, HRUS of the VN represent a non-invasive easy imaging modality of screening in IPD patients independent of disease stage and duration and an interesting possible additional index of disease.

Mini Review: Central Organization of Airway Afferent Nerve Circuits.

Airway afferents monitor the local chemical and physical micro-environments in the airway wall and lungs and send this information centrally to regulate neural circuits involved in setting autonomic tone, evoking reflex and volitional respiratory motor outflows, encoding perceivable sensations and contributing to higher order cognitive processing. In this mini-review we present a current overview of the central wiring of airway afferent circuits in the brainstem and brain, highlighting recent discoveries that augment our understanding of airway sensory processing. We additionally explore how advances in describing the molecular diversity of airway afferents may influence future research efforts aimed at defining central mesoscale connectivity of airway afferent pathways. A refined understanding of how functionally distinct airway afferent pathways are organized in the brain will provide deeper insight into the physiology of airway afferent-evoked responses and may foster opportunities for targeted modulation of specific pathways involved in disease.

Transcutaneous Sonography for Detection of the Cervical Vagus Nerve.

Cervical vagus nerve is not identified by computed tomography or magnetic resonance imaging. Transcutaneous sonography may be the best imaging study to evaluate the cervical vagus nerve. A 7 to 18 MHz linear array transducer was placed transversely on the lateral neck focusing on the carotid sheath from the clavicle level upward to the digastric muscle level bilaterally. The gray-scale technique was used, with the scan setting for the thyroid gland. Between January 2015 and March 2016, 314 patients with 628 cervical vagus nerves were enrolled, including 104 men and 210 women. Their ages ranged from 14 to 84 years. Transcutaneous sonography identified the entire trunk of bilateral cervical vagus nerves in 254 (80.9%) patients and did not identify 1 or both cervical vagus nerves in the other 60 (19.1%) patients. Among 628 cervical vagus nerves, transcutaneous sonography identified 626 (99.6%) lower cervical vagus nerves and 551 (87.7%) upper cervical vagus nerves. Among 551 visible upper cervical vagus nerves, 495 (89.8%) nerves were located laterally, 17 (3%) nerves were located medially, 9 (1.6%) nerves were located anteriorly, and 30 (5.4%) nerves were located posterior to the internal carotid artery. Man and left-side nerve were the factors associated with the anatomical variation in the upper cervical vagus nerve. Transcutaneous sonography can be the best imaging study to show the cervical vagus nerve and may be helpful to evaluate the nerve before neck operation.

Neurosarcoidosis Directly Involving the Cervical Vagus Nerve.

OBJECTIVES: To present a novel location in which neurosarcoidomatous inflammation is identified and its accompanying presentation. METHODS: The authors present a case of bilateral vocal fold paresis associated with non-caseating granulomatous inflammation of the cervical and intra-axial portions of the vagus nerve masquerading as a cranial nerve tumor. RESULTS: Examination revealed bilateral vocal fold paresis and asymmetric palate elevation. MRI demonstrated enhancing bilateral jugular foramen masses, and neck ultrasound demonstrated bilateral thickened appearance of the vagus nerves. Vagus nerve biopsy demonstrated non-caseating granulomas. CONCLUSIONS: Neurosarcoidosis may contribute to variable cranial neuropathies. Vocal fold paresis is usually thought to arise from mediastinal compression of the left recurrent laryngeal nerve. Rarely, though, lesions may arise in other parts of the vagus nerve. Failure of response to steroids does not rule out the diagnosis, making tissue diagnosis important in some cases.

Ultrasound visualization of the vagus nerve for intraoperative neuromonitoring in thyroid surgery.

OBJECTIVE: Localization of the vagus nerve is required during intraoperative neuromonitoring (IONM) for thyroid surgery in order to electromyographically verify the functional integrity of inferior laryngeal nerve and aim to reduce the risk of postoperative vocal fold paralysis. Classically, the vagus nerve courses within the carotid sheath between the common carotid artery and internal jugular vein, but anatomic variations have been described. Our aim was to compare preoperative ultrasound (US) and intraoperative localization of vagus nerve and to document anatomic variations. PATIENTS AND METHODS: Retrospective study of patients undergoing thyroidectomy. The vagus nerve was identified 2 cm below the inferior border of the cricoid cartilage, on US performed 6 weeks prior to surgery; then, vagus nerve was identified surgically. RESULTS: For 82 patients, on preoperative US, the right vagus nerve was in between, superficial, or deep to the vessels in 94%, 2.4%, and 3.6%, and on the left in 72%, 24.4%, and 3.6%. Intraoperatively, the right vagus was in between, superficial, or deep in 90%, 4%, and 6%, and on the left in 67%, 27%, and 6%. US correlated with surgery on the right in 79/82 (96%) and on the left in 78/82 (95%). CONCLUSIONS: To our knowledge, this is the first study directly comparing US and intraoperative findings. The US and surgical findings were identical in 95% on the left and 96% on the right The vagus nerve was superficial in 27% of cases on the left and 4% on the right. Identifying this anatomic variation preoperatively may facilitate IONM. KEY POINTS: • Localization of the vagus nerve is necessary during thyroid surgery when using neuromonitoring for electromyographic testing of the inferior laryngeal nerve to reduce the risk of postoperative vocal fold paralysis. • The vagus nerve in the neck can be routinely visualized using ultrasound, and is generally in between the common carotid artery and the internal jugular vein. Its location on ultrasound corresponds very closely to that observed in vivo during surgery (95%). • At the level of the thyroid lobe, there is an anatomic variant with the vagus nerve superficial to the common carotid artery which is seen more often on the left than on the right.