External Branch Research Articles

Noninvasive monitoring of the vagus nerve during thyroid surgery using cutaneous adhesive and needle electrodes: What is the optimal configuration?

Endotracheal tube (ETT) surface electrodes are used to monitor the vagus nerve (VN), recurrent laryngeal nerve (RLN), and external branch of the superior laryngeal nerve (EBSLN) during thyroid and parathyroid surgery. Alternative nerve monitoring methods are desirable when intubation under general anesthesia is not desirable or possible. In this pilot study, we compared the performance of standard ETT electrodes to four different noninvasive cutaneous recording electrode types (two adhesive electrodes and two needle electrodes) in three different orientations. The VN was stimulated directly during thyroid and parathyroid surgery using a Prass stimulator probe. Electromyographic (EMG) responses for each patient were recorded using an ETT plus one of the following four cutaneous electrode types: large-foot adhesive, small-foot adhesive, long-needle and short-needle. Each of the four electrode types was placed in three orientations: (1) bilateral, (2) ipsilateral mediolateral, and (3) ipsilateral craniocaudal. Four surgical cases were utilized for data collection with the repetitive measures obtained in each subject. Bilateral electrode orientation was superior to ipsilateral craniocaudal and ipsilateral mediolateral orientations. Regardless of electrodes type, all amplitudes in the bilateral orientation were >100 μV. When placed bilaterally, the small-foot adhesive and the long-needle electrodes obtained the highest EMG amplitudes as a percentage of ETT amplitudes. Cutaneous electrodes could potentially be used to monitor the VN during thyroid and parathyroid procedures. Different electrode types vary in their ability to record amplitudes and latencies. Bilateral orientation improves EMG responses in all electrode types. Additional validation of cutaneous electrodes as an alternative noninvasive method to monitor the VN is needed.

Varying Course of External Branch of Superior Laryngeal Nerve (EBSLN) and Recurrent Laryngeal Nerve (RLN) in Thyroidectomy-An Observational Study.

Surgical management of a diseased thyroid depends on sonological and pathological evaluation and thereby, planning of the surgery. The definite surgery has two objectives: removal of the diseased gland and preservation of the nerves, namely EBSLN(External Branch of Superior Laryngeal Nerve) and RLN (Recurrent Laryngeal Nerve) and the Parathyroid glands.The objectives of the study were:(1) To identify the course of the RLN and EBSLN of both sides, during Thyroidectomy. (2) To discern various anatomical landmarks, the relations of the two nerves with them and anatomical variations, if any. In this Prospective observational study, fifty selected goitre patients underwent various types of thyroidectomies based on sonological and cytological criteria. The course and anatomical variations of EBSLN and RLN were photo-documented and results were analysed. Most of the EBSLN were found as Cernea type 1 type (25 out of 50), followed by Cernea type 2a (comprising 36%). The least common was type 2b. It was found that 36 out of 50 (72%) of RLN passed posterior to Inferior Thyroid Artery (ITA). Moreover, before piercing cricothyroid joint, the RLN showed bifurcation in 13 out of 50 subjects (26%), 1 participant had trifurcation and the remaining 36 (72%) had a single trunk. The EBSLN shows relation to the horizontal plane passing through the upper pole of the thyroid gland and it is more prone to get damaged when it passes within less than 1cm to the plane. The RLN has various relations to the distinct anatomical landmarks thereby helping in safe dissection of the nerve. The study also noted the RLN in relation to ITA and branching before entering into the cricothyroid joint.

Possibility of thromboaspiration method in treatment of embolic migration complication during arteriovenous malformation embolization of the head and neck localization.

Aim: To analyze the embolic migration complication during arteriovenous malformations (AVMs) embolization of the head and neck localization, and to demonstrate the possibility of tromboaspiration method in treatment of such complications in cerebrovascular region. Materials and Methods: The endovascular intervention was performed in 116 patients with AVMs of the head and neck localization. We used a superselective catheterization of the external cerebral artery branches as a treatment method of AVMs embolization. During embolization of AVMs, the spherical and not spherical polyvinyl alcohol (PVA) emboli were implanted. Results: The result of treatment was technically successful in 112 (96,6 %) patients with AVMs of the head and neck localization. There were 4 (3,5 %) cerebrovascular complications during AVMs embolization of the head and neck localization. In 2 cases a cerebrovascular complication arose during the AVMs embolization of head localizations. In those 2 cases the cerebrovascular complications were successfully treated conservatively. In other 2 cases cerebrovascular complications arose during the AVMs embolization of neck localizations. One patient died as result of a massive ischemic stroke in the vertebrobasilar zone. Another patient was successful treated by tromboaspiration method. Conclusions: Any surgical intervention on the carotid arteries, including endovascular surgery, is associated with a risk to the health and life of the patient. A thorough angiographic diagnosis of the external and internal carotid and vertebral arteries is necessary before endovascular embolization. Modern endovascular technology, such as tromboaspiration, may be helpful to avoid embolic migration complication in cerebrovascular region.

Voice Changes Without Laryngeal Nerve Alterations After Thyroidectomy: The Need For Prospective Trials - A Review Study.

Thyroidectomy is a commonly performed surgical procedure that is offered for different thyroid pathologies. The most frequent complication after total thyroidectomy is transient or permanent hypoparathyroidism followed by transient or permanent recurrent laryngeal nerve palsy. Patients may experience voice impairment despite intact laryngeal nerve function. These patients are of special interest because they experience subjective symptoms which are difficult to measure and therefore to treat. The Voice Handicap Index (VHI) and VHI-10 are the most commonly used subjective questionnaires. Their results correlate with objective findings. Female sex, in particular after menopause, is a dominant factor for developing voice impairment after thyroidectomy. The extent of neck surgery and the weight and volume of the removed thyroid correlates directly with both objective and subjective voice impairment after surgery. Videolaryngostroboscopy should be considered to examine vocal cord pathologies in this patient group. Surprisingly, there are no studies showing that speech and voice therapy are beneficial for patients with voice alterations but with intact laryngeal nerves. While recurrent laryngeal nerve (RLN) paralysis can be evaluated by objective exams postoperatively, we are still left with the issue of possible partial or complete external branch of superior laryngeal nerve (EBSLN) injury. It is therefore quite difficult to segregate neural (RLN and EBSLN) and non-neural voice change populations, regardless of the method of literature evaluation. Perhaps patients' perspectives on how they experience voice functionality should play a superior role in deciding which patients should be investigated further with laryngoscopy, acoustic or perceptual analysis, and which patients should be offered treatment.

Variations in external carotid artery branches and common carotid bifurcation level: a computed tomography angiography study

BackgroundThe common carotid bifurcation level is an important surgical landmark during head and neck surgery, especially endarterectomy, that could be omitted in patients with high bifurcation levels to reduce damage to neighboring structures like the hypoglossal nerve. Additionally, having a thorough understanding of the variations in the external carotid artery branches is crucial for head and neck cancer surgeries and thyroidectomy. However, cadavers were employed in the majority of studies on these variations. In previous research, there were significant disparities in the incidence of these variations according to gender, laterality, and ethnicity. In order to identify these changes in Egyptian patients and to compare them in terms of gender and laterality, we used computed tomographic angiography.MethodsThe level of the common carotid bifurcation was assessed in a cross-sectional study utilizing computed tomographic angiography, which included 80 patients (160 carotid sides) for comparing the common carotid artery bifurcation level with the relevant vertebrae and anterior neck structures, and they were compared with regard to gender and laterality. Variations in the external carotid artery branches were also evaluated.ResultsThe most frequent location of the common carotid bifurcation level was between C3 and C4 (33.8%). It was 36.9% between the thyroid and the hyoid. 47.5% of patients had a high common carotid bifurcation (higher than the C3/4 level). The highest bifurcation was at C2, while the lowest was at D1. For external carotid artery branches variations, the superior thyroid artery emerged at and below the level of the common carotid bifurcation, respectively, at 19.4% and 23.7%. The facial artery had the largest diameter (2.38 ± 0.44 mm), while the ascending pharyngeal artery had the smallest (1.17 ± 0.11 mm). Seven types of trunks were found; the ascending pharyngeal artery-occipital artery trunk was the most common (25%) and was followed by the lingual artery-facial artery trunk (20%).ConclusionsMultiple anatomical variations in the external carotid artery branches and the common carotid bifurcation level were found by computed tomographic angiography. As a result, it can be utilized as a useful imaging technique to evaluate these variations before surgery.

Intraoperative cricothyroid muscle electromyography may contribute to the monitorization of the external branch of the superior laryngeal nerve during thyroidectomy.

In thyroid surgery, both the recurrent laryngeal nerve (RLN) and external branch of the superior laryngeal nerve (EBSLN) should be preserved for maintaining the vocal cord functions. We aimed to evaluate whether EMG of the CTM applied after the superior pole dissection provided additional informative data to the IONM via ETT or not, regarding the EBSLN function. The prospectively collected data of the patients, who have undergone thyroidectomy with the use of IONM for the exploration of both the RLN and EBSLN between October 2016 and March 2017, were evaluated retrospectively. Patients over 18 years of age with primary thyroid surgery for malignant or benign thyroid disease, and whom were applied CTM EMG with a needle electrode after the completion of thyroidectomy were included in the study. In the study, each neck side was evaluated as a separate entity considering the EBSLN at risk. The data of 41 patients (32 female, 9 male) (mean age, 46.7+9.1; range, 22-71) were evaluated. Sixty seven EBSLNs out of 26 bilateral and 15 unilateral interventions were evaluated. With EBSLN stimulation after the superior pole dissection, positive glottic EMG waveforms via ETT were obtained in 45 (67.2%) out of 67, and the mean glottic amplitude value was 261+191 μV (min-max: 116-1086 μV). Positive EMG responses via the CTM EMG were achieved from all of the 67 EBSLNs (100%) with stimulation using a monopolar probe at the most cranial portion above the area of divided superior pole vessels. The mean value of CTM amplitudes via CTM EMG obtained with EBSLN stimulation was 5268+3916 μV (min-max:1215 -19726 μV). With EBSLN stimulation, the mean CTM EMG amplitude was detected significantly higher than the mean vocal cord amplitude (p<0.0001). The CTM EMG provided more objective quantifiable data regarding the EBSLN function (100% vs 67,2%, p<0.001). In addition to the IONM via ETT, intraoperative post-dissection CTM EMG via needle electrode is a safe, simple and applicable method that may provide significant additional informative data to IONM with ETT by obtaining and recording objective quantitative data related to the EBSLN function.

Comparison of Various Thyroidectomy Approaches: A Retrospective Cross-sectional Study.

To avoid anterior neck scarring, numerous remote-access techniques to approach the thyroid gland (Remote access approach) have been described, including the transaxillary approach (TA), bilateral axillo-breast approach (BABA), and transoral robotic thyroidectomy (TORT). Popular worldwide, Remote access approachs have unique characteristics, advantages, and disadvantages. Herein, we investigated the characteristics of these distinct thyroidectomy approaches to aid surgeons in selecting the most appropriate method for patients. In total, 2351 cases of patients who underwent thyroidectomy between 2019 and 2021 were reviewed, including 1973, 281, 66, and 31 patients who underwent the conventional transcervical approach (TCA), TA, BABA, and TORT, respectively. Demographic characteristics, outcomes, and complications associated with these procedures were compared. The data were analyzed using the Student t test and the χ 2 test. Kruskal-Wallis and Mann-Whitney U tests were used if normality was not found. Central lymph nodes (LNs) were retrieved mostly in patients who underwent lobectomy through TORT (mean: 9.4, P < 0.001). Metastatic central LNs were found more frequently (mean: 1.9 in lobectomy, 3.7 in total thyroidectomy) in patients who underwent lobectomy through TCA and TORT than in those who underwent lobectomy through other approaches (mean: 1.4 and 2.4, respectively, P < 0.05). BABA group patients had significantly fewer central LNs retrieved than those in other groups in lobectomy and total thyroidectomy (mean: 4.8 and 6.2, respectively, P < 0.05). Stimulated thyroglobulin levels did not differ among the 4 groups. The incidence of transient vocal cord palsy was statistically higher in the BABA group (5 cases, 7.5%) than in the other groups; however, all patients recovered. No difference was found in permanent vocal cord palsy (0.4% in TCA) or hypoparathyroidism (1.3% to 3.1%) among the 4 groups. The tumor size was significantly larger in the BABA group than in the other groups, with 10.6% of the patients having tumors larger than 4 cm. Total thyroidectomy was performed more frequently in the BABA group (51.8%) than in the other groups ( P = 0.005). The path of the external branch of the superior laryngeal nerve was more evident in TA, and the Cernea type was confirmed and preserved in 90.6% of TA cases. Owing to the differences in working space and direction of the surgical field, TA was advantageous for preserving the external branch of the superior laryngeal nerve, whereas BABA was effective for total thyroidectomy and excision of large goiters. TORT was beneficial for central compartment neck dissection. These characteristics should be considered when choosing the best approach to improving cosmesis, function, and recurrence.

Routine use or selective use of the Intraoperative neuromonitoring during thyroidectomy

Intraoperative neuromonitoring (IONM) has become a widely utilized technique in thyroid surgery, While the routine identification of the recurrent laryngeal nerve has improved the safety of thyroidectomy, recurrent laryngeal nerve palsy remains an important complication. Some studies have shown promising results with IONM, demonstrating a lower incidence of nerve palsy compared to traditional visualization. However, the overall impact of IONM remains debated, as not all studies confirm its efficacy, especially in redo thyroid surgery. The use of IONM offers benefits in identifying and preserving the external branch of the superior laryngeal nerve, especially in cases of multinodular goiters. The decision to employ IONM should be individualized based on the surgeon's experience and the patient's clinical situation. However, its routine use is not universally supported, and its advantages may be more pronounced in specific high-risk patients and low volume surgeons.

갑상선 수술중 신경모니터링의 최근 연구

Thyroid surgery is associated with a risk of injury to the recurrent laryngeal nerve(RLN), the external branch of the superior laryngeal nerve(EBSLN), and voice changes. Intraoperative neuromonitoring(IONM) has already gained universal reliability to help in nerve identification, safe nerve dissection, and prediction of postoperative vocal cord function. IONM techniques have evolved over the past decade into intermittent IONM(I-IONM) and continuous IONM(C-IONM) modes of application. Research in the field of IONM continues, exploring new techniques and approaches to further enhance the safety and efficacy of thyroid surgery. In this article, the role of IONM and its recent studies will be reviewed.

Management of Bilateral Vocal Fold Paralysis, Injury of External Branch of Superior Laryngeal Nerve after Thyroid Surgery

Management of Bilateral Vocal Fold Paralysis, Injury of External Branch of Superior Laryngeal Nerve after Thyroid Surgery

Outcomes and predictors of complications of thyroidectomy in a scarce resource setting: Retrospective cross-sectional study

BackgroundOutcomes and predictors of complications of thyroidectomy are diverse and have been extensively studied, but data from our country and other African countries with high disease burdens are limited. ObjectiveTo evaluate the outcomes and predictors of complications of thyroidectomy among operated patients. MethodSingle institution retrospective cross-sectional study was conducted by reviewing charts from 365 patients who had undergone thyroidectomy on an elective basis between March 2018–February 2022. All patients who were admitted and underwent thyroidectomy were included in this study. Bivariate and multivariate logistic regressions were used to identify risk factors. P-value <0.05 was considered statistically significant. ResultOverall, post-thyroidectomy complications occurred in 17 % of the cases. The two most common complications were hypocalcemia and voice change; the latter being due to injury of either external branch of superior laryngeal nerve or recurrent laryngeal nerve with an incidence of 4.9 % and 2.5 % respectively. Thyroidectomy performed by surgical residents and having total thyroidectomy were significantly associated with overall complications of thyroidectomy. Total thyroidectomy was found to be a risk factor for postoperative hypocalcemia (AOR = 12.24 (95%CI: 4.53, 19.65); P = 0.02). Younger age of the patient (AOR =0.3(95%CI, 0.12,0.51)) and prolonged duration of presentation (AOR = 2.53(95%CI, 1.17,7.76)) were detected predictors of voice change due to injury of either external branch of superior laryngeal nerve or recurrent laryngeal nerve. ConclusionThe rate of thyroidectomy complications is relatively similar to other studies. In this study demographic and clinical factors associated with increased risk of complications after thyroid surgery were identified. This information will be useful for educating patients about the risks of thyroid surgery.

Management of pseudoaneurysms of the internal maxillary artery derived from orthognathic surgery based on one case.

The purpose of this article is to highlight the risk of pseudoaneurysms formation after orthognathic surgery, their clinical features and management. A case report of a 24-year-old man who suffered a pseudoaneurysm of the internal maxillary artery after sagittal osteotomy during orthognathic is reported. After three bleeding episodes, a pseudoaneurysm was diagnosed with a computed tomography angiogram (CTA) and treated with an embolization of the internal maxillary artery with polyvinyl alcohol (PVA) successfully. Pseudoaneurysms derived from the external carotid artery are an uncommon complication of orthognathic surgery, especially related to sagittal osteotomy instead of LeFort I osteotomy. Pseudoaneurysms derived from external carotid artery branches must be suspected when patients show multiple episodes of bleeding (epistaxis or through the surgical approach) within the first two weeks after orthognathic surgery. If so, vascular CT or angiography should be performed to rule out the presence of vascular injuries. In case a pseudoaneurysm is identified, vascular embolization with N-butyl-cyanoacrylate seems to be the best treatment if available. If this treatment is not available or bleeding cannot be controlled, surgical ligature of the injured vessel is a valid treatment.

Abstract 110: Autoangiogenesis Secondary to Chronic Cocaine Use Mimicking Moya‐Moya

Introduction We present the case of a young male presenting with syncope who was found to have incidental hypodensities on computed tomography (CT) of his head, with magnetic resonance imaging (MRI) concerning for Moya‐Moya related occlusion of the right internal carotid artery, but with digital subtraction angiography (DSA) showing extensive autoangiogenesis and collateralization from all other intracranial vascular territories, without Moya‐Moya related changes. This presumably developed as reactive changes to severe chronic cocaine use. Methods We present a case from a tertiary care center in the borough of Manhattan, New York City, USA. All information is deidentified and exempt from IRB approval. Results A 36‐year‐old man with history significant for asthma, active smoker status, and active cocaine use, presented for loss of consciousness. The patient reported 3 days of upper respiratory symptoms and decreased oral intake with subsequent loss of consciousness immediately preceded by lightheadedness and nausea, and without any post‐event confusion, lacerations, or incontinence. Neurologic history is significant for right upper extremity weakness from 9/2022‐12/2022 that self‐resolved and was believed to be a peripheral nerve pathology. Admission exam without focal deficits. Admission CT of his head showed multifocal confluent hypodensities in the subcortical right frontal lobe. CT Angiogram of head and neck showed severe narrowing at right Internal Carotid Artery (ICA) terminus and right M1 segment with lenticulostriate arterial collateralization, severe bilateral A1 stenosis with distal Anterior Cerebral Artery (ACA) flow suggestive of chronic collateralization, and significant right Posterior Cerebral Artery (PCA) collateralization. Given concern for Moya‐Moya disease, MRI of the brain was obtained and despite no acute infarct, MRI was significant for multifocal white matter T2/FLAIR hyperintensities with the largest in the right frontal lobe. The patient subsequently underwent digital subtraction angiography (DSA) to assess collaterals and stratify for possible need for future encephaloduroarteriosynangiosis (EDAS). DSA showed significant auto‐angiogenesis between numerous vascular territories, including recruitment of right Posterior Cerebral Artery and External Carotid Artery branches to perfuse the territory of the severe right ICA terminus steno‐occlusive disease. With minimal anterograde flow into the right Anterior Choroidal Artery and none to the right Middle Cerebral Artery (MCA), the characteristic Moya‐Moya appearance was not appreciated on DSA given minimal anigogenesis around the right ICA occlusion site. Rather, distal perfusion of the R ICA territory was dependent on collaterals from the right PCA, right ACA via the Anterior Communicating Artery, angiogenesis between the right Anterior Falcine Artery and R ACA, and angiogenesis between the right MCA and ACA/MCA cortical branches. These proliferative changes involved all cranial vascular territories, including those without steno‐occlusive disease. Conclusion Acute cocaine use is associated with increased risk of acute ischemic stroke[1], due in part to its sympathomimetic effects causing vasospasm and to its arrhythmic properties[2]. Neuroadaptation after chronic cocaine use is less well understood though rat models suggest that as cerebral ischemia develops from chronic cocaine use, the HIF‐VEGF pathway is activated to promote angiogenesis to restore local blood flow[3]. We present this case as evidence of a similar angiogenic physiologic response in humans to minimize the microvascular ischemic injury from chronic cocaine use.

Research on the mathematical model and design of a three loop controller for the oscillating scanning system of a laser line scanning galvanometer

The scanning vibration mirror system drives the scanning mirror fixed to it through the oscillation of the motor shaft, so as to control the reflected light to form a dynamic variable light path. The vibration mirror scanning system has higher controllability than the fixed optical path system and has been widely used.In this dissertation, after establishing the models of the core components of the scanning vibration mirror system, the mathematical model of the whole system is established.On this basis, simulation and theoretical analysis show that the system has some shortcomings, such as small bandwidth, low dynamic tracking accuracy, and the comprehensive dynamic performance of the system is easily affected by the input of external interference branches. A series correction controller and three closed-loop controller are designed for the above problems, respectively, and the control effects of the two controllers on the scanning vibration mirror system are studied through simulation experiments. By comparing the output response results of the system under the action of sinusoidal signals of different frequencies, it can be seen that the comprehensive effect of the three closed-loop controllers is better. Under the action of step signals, the overshoot of the three closed-loop correction controller correction system is 21.5% higher than that of the series controller correction system, the adjustment time is 82.7% less, and the steady-state error is significantly smaller. Therefore, it indicates that the three closed-loop correction system has good rapidity and steady-state accuracy.

Endovascular Treatment of Vascular Injuries in the Craniocervical Region With a Graft Stent: A Single-Center Experience.

We aimed to evaluate the efficacy and safety of graft stent implantation in the endovascular treatment of vascular injuries in the craniocervical area. This study was carried out through the retrospective screening of eight (two females and six males) patients' records. Patients who used graft stents as an endovascular method were included in the study. The mean age of the patients was 43.6 years (with a range of 15-69 years). Due to different mechanisms, the patients had vascular injuries in the craniocervical region, and graft stent implantation was performed between 2010 and 2022. We evaluated patient demographics, admission symptoms, trauma mechanisms, angiographic findings, treatment modalities and materials, patient outcomes, and follow-up periods. Due to iatrogenesis for four patients, penetrating trauma for three patients, and blunt trauma for one patient, injuries were present in the right internal carotid artery {ICA} (n=1), left ICA (n=1), left common carotid artery {CCA} (n=3), right CCA (n=1), right vertebral artery (n=1), and left vertebral artery (n=1). Angiographically, pseudoaneurysm was detected in seven patients, and vascular rupture was detected in one patient using contrast agent extravasation. All patients who underwent the endovascular method had technical success. Since bleeding from the external carotid artery branches was seen in two patients, these branches were embolized with coils. No radiologically or neurologically pathological findings were recorded during the follow-up period (with a range of one week to 12 years). Graft stent use in the endovascular treatment of craniocervical vascular injuries is an operable, safe, and promising option, especially in patients with pseudoaneurysms and active bleeding.

Distribution of External Branch Lengths in Yule Histories

The Yule branching process is a classical model for the random generation of gene tree topologies in population genetics. It generates binary ranked trees -also called histories- with a finite number $n$ of leaves. We study the lengths $\ell_1 &gt; \ell_2 &gt; \cdots &gt; \ell_k &gt; \cdots$ of the external branches of a Yule generated random history of size $n$, where the length of an external branch is defined as the rank of its parent node. When $n \rightarrow \infty$, we show that the random variable $\ell_k$, once rescaled as $\frac{n-\ell_k}{\sqrt{n/2}}$, follows a $\chi$-distribution with $2k$ degrees of freedom, with mean $\mathbb E(\ell_k) \sim n$ and variance $\mathbb V(\ell_k) \sim n \big(k-\frac{\pi k^2}{16^k} \binom{2k}{k}^2\big)$. Our results contribute to the study of the combinatorial features of Yule generated gene trees, in which external branches are associated with singleton mutations affecting individual gene copies.

Vocal morbidity related to the external branch of the suprerior laryngeal nerve following thyroidectomy

Vocal morbidity related to the external branch of the suprerior laryngeal nerve following thyroidectomy

Neuropsychiatric Lyme Disease and Vagus Nerve Stimulation.

Lyme disease, the most common tick-borne disease in the United States, is caused by infection with the spirochete Borrelia burgdorferi. While most patients with acute Lyme disease recover completely if treated with antibiotics shortly after the onset of infection, approximately 10-30% experience post-treatment symptoms and 5-10% have residual symptoms with functional impairment (post-treatment Lyme disease syndrome or PTLDS). These patients typically experience pain, cognitive problems, and/or fatigue. This narrative review provides a broad overview of Lyme disease, focusing on neuropsychiatric manifestations and persistent symptoms. While the etiology of persistent symptoms remains incompletely understood, potential explanations include persistent infection, altered neural activation, and immune dysregulation. Widely recognized is that new treatment options are needed for people who have symptoms that persist despite prior antibiotic therapy. After a brief discussion of treatment approaches, the article focuses on vagus nerve stimulation (VNS), a neuromodulation approach that is FDA-approved for depression, epilepsy, and headache syndromes and has been reported to be helpful for other diseases characterized by inflammation and neural dysregulation. Transcutaneous VNS stimulates the external branch of the vagus nerve, is minimally invasive, and is well-tolerated in other conditions with few side effects. If well-controlled double-blinded studies demonstrate that transcutaneous auricular VNS helps patients with chronic syndromes such as persistent symptoms after Lyme disease, taVNS will be a welcome addition to the treatment options for these patients.

Variability in the Arterial Supply of Intracranial Meningiomas: An Anatomic Study.

Intracranial meningiomas are a diverse group of tumors, which vary by grade, genetic composition, location, and vasculature. Expanding the understanding of the supply of skull base (SBMs) and non-skull base meningiomas (NSBMs) will serve to further inform resection strategies. We sought to delineate the vascular supply of a series of intracranial meningiomas by tumor location. A retrospective study of intracranial meningiomas that were studied using preoperative digital subtraction angiograms before surgical resection at a tertiary referral center was performed. Patient, tumor, radiologic, and treatment data were collected, and regression models were developed. One hundred sixty-five patients met inclusion criteria. The mean age was 57.1 years (SD: 12.6). The mean tumor diameter was 4.9 cm (SD: 1.5). One hundred twenty-six were World Health Organization Grade I, 37 Grade II, and 2 Grade III. Arterial feeders were tabulated by Al-Mefty's anatomic designations. SBMs were more likely to derive arterial supply from the anterior circulation, whereas NSBMs were supplied by external carotid branches. NSBMs were larger (5.61 cm vs 4.45 cm, P = <.001), were more often presented with seizure (20% vs 8%, P = .03), were higher grade ( P = <.001) had more frequent peritumoral brain edema (84.6% vs 66%, P = .04), and had more bilateral feeders (47.7% vs 28%, P = .01) compared with SBMs. More arterial feeders were significantly associated with lower tumor grade ( P = .023, OR = 0.59). Higher tumor grade (Grade II/III) was associated with fewer arterial feeders ( P = .017, RR = 0.74). Meningioma location is associated with specific vascular supply patterns, grade, and patient outcomes. This information suggests that grade I tumors, especially larger tumors, are more likely to have diverse vascular supply patterns, including internal carotid branches. This study may inform preoperative embolization and surgical considerations, particularly for large skull base tumors.

Anatomical Variations of the External Branch of the Superior Laryngeal Nerve and its Correlations with the Superior Thyroid Artery and the Upper Pole of the Thyroid Gland: A Review of the Literature

Injury to the external branch of the superior laryngeal nerve (EBSLN) following thyroid or parathyroid surgery often results in devastating voice changes especially noticed by patients who use their voice professionally. The external branch arises from the vagus nerve which provides the motor supply to the cricothyroid muscle, an exclusive tensor of the vocal cords. The course of the EBSLN is subject to great anatomic variability. Damage to the nerve occurs during improper ligation of superior thyroid vessels close to the upper pole of thyroid gland in up to 58% of patients undergoing thyroid surgery. Thus, a thorough knowledge of the anatomy of the EBSLN and its variations, is essential requirement to minimize iatrogenic complications during surgery of the neck. Additionally, nerve monitoring methods have been developed to facilitate the localisation of the nerve, decreasing the possibility of nerve injury during thyroid surgery. The aim of this study is to analyze and review the anatomical variations of the EBSLN and its correlations with the superior thyroid artery and the upper pole of the thyroid gland. The literature search was performed during the period from February 1992 through November 2021. The position of the EBSLN was classified according to the Cernea and Kierner classification. Based on this classification, type 2a variant of EBSLN was the commonest followed by type 1. In addition, neuromonitoring allowed a higher identification rate than the visual identification.