A 37-year-old female with a carotid body tumor (paraganglioma): A rare case report from Syria.

INTRODUCTION AND IMPORTANCE: This case study presents the clinical details of a 37-year-old woman who presented with an asymptomatic swelling in the right supraclavicular region, ultimately diagnosed as a carotid body tumor (CBT). CASE PRESENTATION: The patient's medical background, which included her brother's CBT, prompted further investigation. Upon clinical examination and imaging studies, a tissue mass surrounding the right internal carotid artery was identified. Subsequent surgical resection of the tumor was performed, and histological analysis confirmed a neoplastic proliferation consistent with paraganglioma. CLINICAL DISCUSSION: This case highlights the significance of taking into account familial history and conducting comprehensive diagnostic assessments for patients exhibiting similar symptoms. The successful multidisciplinary management of this rare tumor underscores the importance of early detection and appropriate therapeutic interventions. CONCLUSION: This report offers valuable insights into the clinical presentation, diagnostic process, and treatment of CBTs, emphasizing the necessity for a comprehensive approach to managing this uncommon neoplasm.

Extra-Adrenal Paraganglioma on Fine-Needle Aspiration Cytology: A Case Series.

Paragangliomas (PGs) are rare tumors that most commonly occur in the head and neck region and along the sympathetic chain. Fine-needle aspiration cytology is not commonly used for the diagnosis of PG due to the potential risk of hemorrhage and hypertensive crisis. As a result, limited studies describe the cytological features of PGs. In this case series, we will discuss the fine-needle aspiration features of three cases of extra-adrenal PGs. The cellular arrangement in smears was either singly scattered or loosely cohesive clusters. The cells were polygonal with pleomorphic nuclei, abundant granular cytoplasm, and bland chromatin. Cellblock showed two types of cells with focal acinar formation. Immunohistochemistry also confirmed the diagnosis. These results were also in keeping with radiological findings. Fine-needle aspiration cytology, along with clinicoradiological findings, can help in making an accurate preoperative diagnosis of PG.

Carotid body interoception in health and disease.

Interoception entails perceiving or being aware of the internal state of the body, playing a pivotal role in regulating processes such as heartbeat, digestion, glucose metabolism, and respiration. The carotid body (CB) serves as an interoceptive organ, transmitting information to the brain via its sensitive nerve, the carotid sinus nerve, to maintain homeostasis. While traditionally known for sensing oxygen, carbon dioxide, and pH levels, the CB is now recognized to possess additional interoceptive properties, detecting various mediators involved in blood pressure regulation, inflammation, and glucose homeostasis, among other physiological functions. Furthermore, in the last decades CB dysfunction has been linked to diseases like sleep apnea, essential hypertension, and diabetes. In this review manuscript, we make a concise overview of the traditional interoceptive functions of the CB, acting as a sensor for oxygen levels, carbon dioxide levels, and pH, and introduce the novel interoceptive properties of the CB related to vascular, glucose and energy regulation. Additionally, we revise the contribution of the CB to the onset and progression of metabolic diseases, delving into the potential dysfunction of its interoceptive metabolic functions as a contributing factor to pathophysiology. Finally, we postulate the use of therapeutic interventions targeting the metabolic interoceptive properties of the CB as a potential avenue for addressing metabolic diseases.

The Radiological Assessment of Carotid Space Lesions: A Case Series.

Carotid space lesions present diagnostic challenges due to their diverse etiology and varied clinical manifestations. This article critically reviews the anatomy of the carotid space and highlights the spectrum of pathologies within this complex region, illustrated by three case studies. The cases were examined with ultrasonography (USG), computed tomography (CT), and magnetic resonance imaging (MRI). Schwannomas appeared heterogeneously hypodense on plain CT and partially hyperdense on contrast-enhanced CT (CECT), with displacement of adjacent vessels. Vagal-origin schwannomas caused the anteromedial displacement of the internal carotid artery. Paragangliomas were typically homogeneously hyperdense on CECT, with lateral displacement of the internal carotid artery when of carotid body origin. The management of carotid space lesions depends on the resectability of the tumors; unresectable tumors are managed with chemotherapy. This overview enhances clinical understanding and diagnostic accuracy, facilitating improved patient outcomes in managing carotid space lesions.

Perioperative evaluation and follow-up analysis of carotid body tumor by Color Doppler Ultrasound.

OBJECTIVES: The value of Color Doppler Ultrasound (CDU) for perioperative evaluation and follow-up outcomes of carotid body tumor (CBT) remains elusive. This study aimed to investigate the role of CDU in CBT in our center. METHODS: From January 2015 to December 2020, 75 patients with CBT were included in the study. Computed Tomography Angiography (CTA) and CDU data of patients were collected and analyzed. The postoperative recovery and follow-up outcomes were summarized. RESULTS: A total of 91 CBTs in 75 patients were included in the study. 73.3% of patients had unilateral lesions, while 26.7% had bilateral lesions. Lesions were categorized as Shamblin I (4.4%), Shamblin II (52.7%), and Shamblin III (42.9%). 79.5% lesions were treated by surgical resection, 12.3% were treated by surgical resection with internal carotid artery reconstructed by artificial vessel, while 8.2% were treated by surgical resection with internal carotid artery reconstructed by autogenous great saphenous vein. Compared with CTA, the sensitivity of CDU for detection of CBT was 96.7%, the sensitivity and specificity of CDU for detection of Shamblin Ⅰ lesions were both 100%, the sensitivity and specificity for Shamblin Ⅱ were 100% and 72.1%, respectively, while the sensitivity and specificity for Shamblin Ⅲ were 69.2% and 100%, respectively. There were no statistically significant differences between CTA and CDU for detection of the maximal diameter, volume of CBT and distance between the end of the tumor and the mastoid process. 79.7% of patients were followed up with CDU. Recurrence of CBT occurred in 1 patient. CDU showed that stenosis and occlusion of artificial vessel occurred in 1 and 6 patients, respectively. Occlusion of autogenous great saphenous vein was found in 2 cases. CONCLUSIONS: CDU can accurately diagnose Shamblin Ⅰ CBT, have high sensitivity for Shamblin Ⅱ and high specificity for Shamblin Ⅲ CBT. It plays an important role in diagnosis, perioperative evaluation and follow-up analysis of CBT.

Pulmonary Vascular Responses to Chronic Intermittent Hypoxia in a Guinea Pig Model of Obstructive Sleep Apnea.

Experimental evidence suggests that chronic intermittent hypoxia (CIH), a major hallmark of obstructive sleep apnea (OSA), boosts carotid body (CB) responsiveness, thereby causing increased sympathetic activity, arterial and pulmonary hypertension, and cardiovascular disease. An enhanced circulatory chemoreflex, oxidative stress, and NO signaling appear to play important roles in these responses to CIH in rodents. Since the guinea pig has a hypofunctional CB (i.e., it is a natural CB knockout), in this study we used it as a model to investigate the CB dependence of the effects of CIH on pulmonary vascular responses, including those mediated by NO, by comparing them with those previously described in the rat. We have analyzed pulmonary artery pressure (PAP), the hypoxic pulmonary vasoconstriction (HPV) response, endothelial function both in vivo and in vitro, and vascular remodeling (intima-media thickness, collagen fiber content, and vessel lumen area). We demonstrate that 30 days of the exposure of guinea pigs to CIH (FiO2, 5% for 40 s, 30 cycles/h) induces pulmonary artery remodeling but does not alter endothelial function or the contractile response to phenylephrine (PE) in these arteries. In contrast, CIH exposure increased the systemic arterial pressure and enhanced the contractile response to PE while decreasing endothelium-dependent vasorelaxation to carbachol in the aorta without causing its remodeling. We conclude that since all of these effects are independent of CB sensitization, there must be other oxygen sensors, beyond the CB, with the capacity to alter the autonomic control of the heart and vascular function and structure in CIH.

Presentation of metastatic carotid body paraganglioma on F-18 FDG PET/CT: a rare disease.

Carotid body paraganglioma is a slow growing tumor of head and neck region. It can rarely be malignant in nature which is characterized by distant metastases on anatomical imaging. We share an interesting presentation of a malignant carotid body on F-18 FDG PET/CT in form of liver and skeletal metastases.

Carotid body tumor: characteristics and surgical outcome.

BACKGROUND: Carotid body tumors are uncommon neuroendocrine growths near the carotid bifurcation. While some advocate preoperative embolization to minimize bleeding, others avoid it due to complications. This study shares the experience of a single center in managing patients with carotid body tumors without practicing preoperative embolization. METHODS: This was a cross-sectional study of patients with carotid body tumors managed between 2020 and 2024. Data were collected from the hospital's registry. When necessary, routine blood tests, neck ultrasonography, and computed tomography scans were conducted. The tumors were categorized according to Shamblin's classification. The average duration of follow-up was 20 months. RESULTS: The study involved 25 patients, 22 (88%) females and 3 (12%) males. Their ages ranged from 27 to 85 years old. Twenty (80%) cases presented with neck swelling, and six (24%) had a positive medical history. Tumors were mainly on the right side (52%), with 20 (80%) showing ill-defined neck masses. Tumor sizes ranged from 1.5 to 7 cm, with Shamblin type II tumors being discovered in the majority of cases (72%). Types of tumors were significantly associated with the tumor size (p-value < 0.05). Blood transfusion was required in five cases (20%), three from type III and two from type II, with none from type I (p-value = 0.001). Temporary neurological deficits occurred in 3 cases (12%). No functional impairment or mortality was recorded. CONCLUSIONS: Carotid body tumors are rare tumors with an unknown etiology. Operation without practicing preoperative embolization may be feasible with an acceptable outcome.

A Case of Bilateral Carotid Body Tumors.

Sporadic bilateral carotid body tumors are a rare paraganglioma of the head and neck that are often asymptomatic and incidentally found during workup for other pathologies. These tumors arise from the chemoreceptor organ located at the carotid bifurcation and can be locally invasive, resulting in the involvement of adjacent neurovascular structures. With the majority of bilateral carotid body tumors having an association with familial syndromes, such as MEN2 or Von Hippel Lindau, the incidence of sporadic bilateral disease is exceedingly rare. In this case report, we report a case of bilateral carotid body tumors in a 54-year-old female with anxiety and tachycardia who underwent MRI and CTA evaluation showing evidence of left greater than right carotid body tumors. The patient was managed operatively in a staged fashion with a resolution of her presenting symptoms and no post-operative morbidity or mortality. Pathologic examination of the bilateral masses confirmed evidence of paraganglioma with immunohistochemical stains showing neoplastic cells positive for synaptophysin, chromogranin, and S100 without lymph node involvement.

Carotid body plastic behavior: evidence for D2-H3 receptor-receptor interactions.

Dopamine and histamine receptors D2R and H3R are G protein-coupled receptors (GPCRs) which can establish physical receptor-receptor interactions (RRIs), leading to homo/hetero-complexes in a dynamic equilibrium. Although D2R and H3R expression has been detected within the carotid body (CB), their possible heterodimerization has never been demonstrated. The aim of this work was to verify D2R and H3R colocalization in the CB, thus suggesting a possible interplay that, in turn, may be responsible of specific D2R-H3R antagonistic functional implications. The CBs of both Sprague-Dawley rats (n = 5) and human donors (n = 5) were dissected, and immunolocalization of D2R and H3R was performed; thereafter, in situ proximity ligation assay (PLA) was developed. According to experimental evidence (immunohistochemistry and double immunofluorescence), all the samples displayed positive D2R/H3R elements; hence, PLA assay followed by confocal microscopy analysis was positive for D2R-H3R RRIs. Additionally, D2R-H3R heterodimers were mainly detected in type I cells (ßIII-tubulin-positive cells), but type II cells' involvement cannot be excluded. RRIs may play a role in functional modulation of CB cells; investigating RRIs in the CB may guide toward the comprehension of its plastic changes and fine regulatory role while also unveiling their possible clinical implications.

Carotid baroreceptor dysfunction after carotid body tumour resections.

OBJECTIVE: Carotid body tumours (CBTs) and baroreceptor failure (BRF) are two distinct but interrelated conditions, affecting the carotid body and its regulatory mechanisms. We aim to describe and quantify BRF after unilateral and bilateral CBT resections. METHODS: Prospective cohort study. We included all patients with unilateral or bilateral CBT undergoing resection from April 2021 to January 2023. Demographics and CBTs characteristics were analysed; baroreceptor sensitivity assessment was conducted using the Composite Autonomic Severity Score (CASS). Statistical analyses were performed using R. Significance level was set at a 2-tailed α = 0.05. RESULTS: A total of 30 patients with CBT underwent surgical resection, twenty-three were included in the study (18 unilateral and 5 bilateral CBTs). All 23 (100 %) were females, median age of 60 years. Regarding patients with unilateral CBT; preoperatively, 13 had BRF, the most common dysfunction subtype was mixed. Postoperatively, the most common dysfunction subtype was sympathetic failure. With regards to bilateral CBTs; 2 patients did not have autonomic dysfunction preoperatively. After bilateral surgical resection one patient remained without autonomic dysfunction; however, all other patients persisted with BRF. CONCLUSION: BRF was present in 13 patients with unilateral CBT and 3 patients with bilateral tumours preoperatively; most will remain with BRF and will only change the characteristics postoperatively. No associations were found between type, severity of BRF and Shamblin classification or laterality. It is paramount that research in this area continues as many features are yet unknown regarding CBT pathogenesis, hence, BRF may be present yet not affect significantly quality of life.

Carotid body tumor in a nine-year-old patient.

Carotid body tumors are rarely encountered pathologies in the pediatric age group but still exist in the differential diagnosis of cervical painless masses. Genetic and familial background should be studied in addition to contrast imaging studies. Complete subadventitial resection, with or without prior embolization, which is still controversial, is the mainstay of therapy. Follow-up gains importance due to its nature. Herein, we report a nine-yearold girl presented with a unilateral asymptomatic mass on the neck with a diagnosis of carotid body tumor treated surgically without embolization. We emphasize the specific aspects of the pediatric age group.

Outcomes of Head and Neck Neurogenic Tumors.

BACKGROUND: Lateral neck mass management frequently challenges surgeons. Nerve tissue neoplasms are an uncommon cause of such nodules. Neurogenic tumors form a tiny percentage of the head and neck neoplastic lesions. Considering the number of nerves in this area, it is surprising that such neoplasms are not more frequently seen. METHODS: A retrospective study was conducted on all patients who presented to the National Cancer Institute of Cairo, Egypt, with head and neck neurogenic neoplasms. RESULTS: During the last 10 years at the National Cancer Institute of Egypt (2006-2015), 40 cases of neurogenic tumors of the head and neck were treated at the head and neck unit. Patients' ages ranged from two to 78 years with a mean age of 34.7 years. Childhood neurogenic tumors accounted for nine cases (22.5%) only in this study. Male patients diagnosed with these tumors comprised 16 cases, while female patients comprised 24 cases, with a female-to-male ratio of 1.5:1. Patient presentation depends on the biological behavior of the tumor; for instance, some of them present by slowly growing painless well-circumscribed mobile swelling, and others present by rapidly growing swelling with neurological deficit. Clinical picture and imaging studies such as CT and MRI raise suspicion and may help delineate such tumors, but a definitive diagnosis is obtained by tissue biopsy. Surgery is the mainstay of treatment in most head and neck neurogenic tumors, whereas adjuvant therapy is of limited benefit in some types of neurogenic tumors. The five-year survival rate was 60% for the malignant group, while death was reported in six out of 15 cases (40%).  Conclusion: Most neurogenic head and neck tumors are benign. Accurate preoperative assessment and a high degree of suspicion are the initial steps in the management. Proper treatment involves complete surgical excision; however, debulking procedures have an important role. Malignant neurogenic tumors are aggressive and are treated with combined radical surgical resection and radiation. Chemotherapy is tried for locally advanced unresectable or metastatic disease.

Baroreflex and chemoreflex interaction in high-altitude exposure: possible role on exercise performance.

The hypoxic chemoreflex and the arterial baroreflex are implicated in the ventilatory response to exercise. It is well known that long-term exercise training increases parasympathetic and decreases sympathetic tone, both processes influenced by the arterial baroreflex and hypoxic chemoreflex function. Hypobaric hypoxia (i.e., high altitude [HA]) markedly reduces exercise capacity associated with autonomic reflexes. Indeed, a reduced exercise capacity has been found, paralleled by a baroreflex-related parasympathetic withdrawal and a pronounced chemoreflex potentiation. Additionally, it is well known that the baroreflex and chemoreflex interact, and during activation by hypoxia, the chemoreflex is predominant over the baroreflex. Thus, the baroreflex function impairment may likely facilitate the exercise deterioration through the reduction of parasympathetic tone following acute HA exposure, secondary to the chemoreflex activation. Therefore, the main goal of this review is to describe the main physiological mechanisms controlling baro- and chemoreflex function and their role in exercise capacity during HA exposure.

Paraganglioma of the Neck: A Rare Case With Spinal Metastasis.

Paragangliomas are rare neuroendocrine tumors that arise from the paraganglia, which are clusters of neuroendocrine cells associated with the autonomic nervous system. These tumors are commonly found in the adrenal medulla but can also occur in other locations outside the adrenal gland. Here, we present a case report of a slow-growing paraganglioma in the left neck with spinal metastasis in a 60-year-old man. This case highlights the importance of considering paraganglion tumors in the differential diagnosis of neck masses and the need for early diagnosis and management to prevent potential complications. Importantly, both the clinical picture and anatomical location of these tumors is important when determining treatment plans.

Use of the Amplatzer vascular plug to treat carotid body tumors extending to the skull base.

BACKGROUND: Carotid body tumors extending to the skull base are hypervascular tumors which are difficult to access using a traditional lateral cervical approach. Preoperative embolization can reduce intraoperative blood loss. CASE PRESENTATION: We report two patients with a carotid body tumor extending to the skull base who underwent preoperative embolization of the external carotid artery using an Amplatzer vascular plug. Two days after embolization, surgical resection was performed. Embolization was successful in both patients and resection proceeded smoothly. Both were discharged on postoperative day 9 without complications. The tumor in each patient was classified as Shamblin group III. Computed tomography angiography of the neck six months after surgery showed patency of the ipsilateral internal carotid artery and no tumor recurrence. CONCLUSION: Preoperative embolization of the external carotid artery using the Amplatzer vascular plug is safe and feasible for patients with carotid body tumors extending to the skull base.

Fish gill chemosensing: knowledge gaps and inconsistencies.

In this review, we explore the inconsistencies in the data and gaps in our knowledge that exist in what is currently known regarding gill chemosensors which drive the cardiorespiratory reflexes in fish. Although putative serotonergic neuroepithelial cells (NEC) dominate the literature, it is clear that other neurotransmitters are involved (adrenaline, noradrenaline, acetylcholine, purines, and dopamine). And although we assume that these agents act on neurons synapsing with the NECs or in the afferent or efferent limbs of the paths between chemosensors and central integration sites, this process remains elusive and may explain current discrepancies or species differences in the literature. To date it has been impossible to link the distribution of NECs to species sensitivity to different stimuli or fish lifestyles and while the gills have been shown to be the primary sensing site for respiratory gases, the location (gills, oro-branchial cavity or elsewhere) and orientation (external/water or internal/blood sensing) of the NECs are highly variable between species of water and air breathing fish. Much of what has been described so far comes from studies of hypoxic responses in fish, however, changes in CO2, ammonia and lactate have all been shown to elicit cardio-respiratory responses and all have been suggested to arise from stimulation of gill NECs. Our view of the role of NECs is broadening as we begin to understand the polymodal nature of these cells. We begin by presenting the fundamental picture of gill chemosensing that has developed, followed by some key unanswered questions about gill chemosensing in general.

Carotid Body Function in Tyrosine Hydroxylase Conditional Olfr78 Knockout Mice.

The Olfr78 gene encodes a G-protein-coupled olfactory receptor that is expressed in several ectopic sites. Olfr78 is one of the most abundant mRNA species in carotid body (CB) glomus cells. These cells are the prototypical oxygen (O2) sensitive arterial chemoreceptors, which, in response to lowered O2 tension (hypoxia), activate the respiratory centers to induce hyperventilation. It has been proposed that Olfr78 is a lactate receptor and that glomus cell activation by the increase in blood lactate mediates the hypoxic ventilatory response (HVR). However, this proposal has been challenged by several groups showing that Olfr78 is not a physiologically relevant lactate receptor and that the O2-based regulation of breathing is not affected in constitutive Olfr78 knockout mice. In another study, constitutive Olfr78 knockout mice were reported to have altered systemic and CB responses to mild hypoxia. To further characterize the functional role of Olfr78 in CB glomus cells, we here generated a conditional Olfr78 knockout mouse strain and then restricted the knockout to glomus cells and other catecholaminergic cells by crossing with a tyrosine hydroxylase-specific Cre driver strain (TH-Olfr78 KO mice). We find that TH-Olfr78 KO mice have a normal HVR. Interestingly, glomus cells of TH-Olfr78 KO mice exhibit molecular and electrophysiological alterations as well as a reduced dopamine content in secretory vesicles and neurosecretory activity. These functional characteristics resemble those of CB neuroblasts in wild-type mice. We suggest that, although Olfr78 is not essential for CB O2 sensing, activation of Olfr78-dependent pathways is required for maturation of glomus cells.

Surgical outcomes for carotid body tumour resection without preoperative embolization: a 10-year experience.

Background: Carotid body tumours (CBTs) are neoplasms originating from the paraganglionic cells of the carotid body. Excision is the main route of treatment. This study sought to assess the surgical outcomes of post-carotid body tumour resection without preoperative embolization and discern any underlying relationships between modified Shamblin classes (MSC) and related complications. Methods: A retrospective medical record review of prospectively collected data is performed at Sulaymaniyah Teaching Hospital between 2008 and 2019, for 54 patients. Presurgical and postsurgical variables such as comorbidities and complications were noted, respectively. Results: Patient ages ranged between 26 and 60 years (x̄=40.06) with a minimal female predominance (57.4%). Complications included one minor stroke. MSC and postoperative complications were significantly related (P≤0.001). Our analyses also suggested a significant relationship between intraoperative blood loss and the incidence of postoperative complications (P=0.001, χ²=25). The MSC III subtype was significantly associated with intraoperative blood loss (P=0.000), length of stay (P=0.000), and operating time (P=0.001). Conclusions: Our study purports a strong relationship between greater MSC and complications of all types. As such, surgeons may benefit from preoperative strategies to minimize complications.

Our Experience in Subadventitial Dissection vs. Intracapsular Dissection Technique of Carotid Body Tumors Surgery.

This study provides a single-center experience involving intracapsular dissection for Shamblin II carotid body tumors (CBTs) and compares the outcomes with the classic technique of subadventitial resection. Based on the preliminary results, it seems that the enucleation technique facilitates the dissection of carotid body tumors, offering protection to cranial nerves and the internal/external/common carotid artery by utilizing the capsule as a barrier. The classic subadventitial resection approach and the enucleation technique have comparable postoperative complications. However, it is crucial to continue following the patients who underwent these resection techniques to determine the long-term outcomes. Moreover, the enucleation technique significantly reduces surgery duration and intraoperative blood loss.