Superior Cervical Sympathetic Ganglion: Normal Imaging Appearance on 3T-MRI

Horner syndrome immediately after deep dissection of upper thyroid pole: a case report and review of the literature

Objectives

Horner syndrome (HS) is a rare complication of thyroid surgery. However, the relationship between the occurrence of HS and thyroid upper pole injury is still not completely clear, and there are only few reports.

Case presentation

A 24-year-old female underwent endoscopic thyroidectomy for thyroid papillary carcinoma. The intraoperative examination found that the upper pole of the thyroid was bleeding. During hemostasis, the ultrasonic knife consciously peeled too deep and stopped. The patient developed HS immediately after operation. We analyzed the association between deep dissection of the upper thyroid pole and an increase in the HS incidence rate through literature searches and anatomical relationships.

Conclusions

Our case report discussed the potential relationship between the degree of thyroid upper pole dissection and the occurrence of HS in routine thyroid surgery, and provided a warning for the degree of thyroid upper pole dissection in the clinic to avoid HS.

Sono-anatomy of the middle cervical sympathetic ganglion verified with pathology

Objectives

Cervical discomfort and other symptoms may be attributable to the middle cervical sympathetic ganglion. The aim of this study was to explore the sonographic features of this ganglion in anatomical specimens and cadavers and evaluate the feasibility of its visualization using high-resolution ultrasonography.

Methods

We examined three cervical sympathetic-ganglion specimens and two fresh cadavers using high-resolution ultrasound to explore the sonographic features of this ganglion. Basic imaging characteristics examined included the shape, echo intensity, and location of the ganglion. Core-needle biopsy was performed to examine the suspected middle cervical sympathetic ganglion in the two fresh cadavers and verify the accuracy of the sonographic identification via pathological examination.

Results

The middle cervical sympathetic ganglion appeared on high-resolution ultrasonography as an oval-shaped hypoechoic structure, with at least one continuous hypoechoic line connected to each ending in the anatomical specimens and fresh cadavers, and it was distinctly different from the adjacent lymph nodes.

Discussion

Based on an adequate understanding of both its location and sonographic features, the direct visualization of the middle cervical sympathetic ganglion using high-resolution ultrasonography is feasible.

Microanatomical findings with relevance to trigeminal ganglion enhancement on post-contrast T1-weighted magnetic resonance images in dogs

Introduction

Trigeminal ganglion contrast enhancement (TGCE) is reported to be a normal and a common finding on magnetic resonance imaging studies of dogs, cats and humans. The intent of the present study was to describe the anatomical characteristics of the trigeminal ganglion, its surrounding structures, and histological features that are relevant to explain or hypothesize on the reason for TGCE on T1-weighted post-contrast MRI studies of the brain in dogs.

Methods

Eight dog cadavers were dissected to study the anatomy of the trigeminal ganglion. The presence and anatomy of vessels was studied by dissection and by histological techniques. Two trigeminal ganglia were isolated and stained with hematoxylin-eosin (HE). Two other trigeminal ganglia included in the trigeminal canal and trigeminal cavity were decalcified with formic acid/formalin for 12 weeks and stained with HE to study the related vessels. Additionally, a corrosion cast was obtained from a separate canine specimen.

Results

Leptomeninges and a subarachnoid space were identified at the level of the trigeminal nerve roots and the trigeminal ganglion. No subarachnoid space was identified and leptomeninges were no longer present at the level of the three trigeminal nerve branches. Small arterial vessels ran to and supplied the trigeminal ganglion, passing through the dura mater. No venous plexus was visualized at the level of the trigeminal ganglion in the dissections. A complex arterial vascular network was identified within the leptomeningeal covering of the trigeminal ganglion and was best appreciated in the corrosion cast. Histological examination revealed small-to moderate-sized blood vessels located in the epineurium around the ganglion; from there a multitude of arterioles penetrated into the perineurium. Small endoneurial branches and capillaries penetrated the ganglion and the trigeminal nerve branches.

Discussion

Limitations to this study include the limited number of canine specimens included and the lack of electron microscopy to further support current hypotheses included in our discussion. In conclusion, this study provides further support to the theory that TGCE in dogs may be due an incomplete blood-nerve barrier or blood-ganglion barrier at the interface between the central nervous system and the peripheral nervous system.

Horner syndrome after thyroid-related surgery: a review

BACKGROUND

Horner syndrome (HS) is caused by damage to the cervical sympathetic nerve. HS is a rare complication after thyroidectomy. The main manifestations of HS include miosis and ptosis of the eyelids, which seriously affect esthetics and quality of life. At present, there is a lack of research on HS after thyroidectomy, and its etiology is not completely clear. This review aimed to evaluate how to reduce the incidence of HS and promote the recovery from HS as well as to provide a reference for the protection of cervical sympathetic nerves during surgery.

RESULTS

HS caused by thyroid surgery is not particularly common, but it is still worthy of our attention. After searching with "Horner Syndrome," "Thyroid" as keywords, a total of 22 related cases were screened in PubMed. The results showed that open surgery, endoscopy, microwave ablation, and other surgical methods may have HS after operation. In addition, the statistics of 1213 thyroid surgeries in our hospital showed that the incidence of HS after endoscopic surgery (0.39%) was slightly higher than that after open surgery (0.29%). Further, this review analyzed potential causes of HS after thyroidectomy, so as to provide a theoretical basis for reducing its incidence.

CONCLUSION

Preventing HS during thyroidectomy is a difficult problem. The close and highly variable anatomical relationship between the thyroid and cervical sympathetic nerves increases the risk of sympathetic nerve damage during thyroidectomy. Surgery and the use of energy equipment are also closely related to the occurrence of HS.

Ocular Autonomic Nervous System: An Update from Anatomy to Physiological Functions

The autonomic nervous system (ANS) confers neural control of the entire body, mainly through the sympathetic and parasympathetic nerves. Several studies have observed that the physiological functions of the eye (pupil size, lens accommodation, ocular circulation, and intraocular pressure regulation) are precisely regulated by the ANS. Almost all parts of the eye have autonomic innervation for the regulation of local homeostasis through synergy and antagonism. With the advent of new research methods, novel anatomical characteristics and numerous physiological processes have been elucidated. Herein, we summarize the anatomical and physiological functions of the ANS in the eye within the context of its intrinsic connections. This review provides novel insights into ocular studies.

Radiological evaluation of the localization of sympathetic ganglia in the cervical region

PURPOSE

To determine local variations of cervical sympathetic ganglia (CSG) according to vertebral levels on preoperative neck magnetic resonance imaging (MRI) by designating carotid artery (CA) as the standard landmark at the center, in attempts to prevent injury to CSG in the anterior-anterolateral approaches performed in the cervical spinal region.

MATERIALS AND METHODS

The retrospective study reviewed neck MRI images of 281 patients, of which the images of 231 patients were excluded from the study based on the exclusion criteria. As a result, the MRI images of the remaining 50 patients were included in the study. The circumference of carotid artery (CA) was divided into eight equal zones with CA defined as the standard landmark at the center. High-risk zones were determined based on the anterior-anterolateral approaches.

RESULTS

At C1 level, a superior ganglion was located on the right side in 32 (64%) and on the left side in 30 (60%) patients. At this level, it was most commonly located in Zone 6. Middle ganglion was observed most frequently at C3 level, which was detected on the right side in 17 (34%) and on the left side in 17 (34%) patients. At this level, it was most commonly located in Zone 2.

CONCLUSION

Variations in the localizations of superior and middle cervical ganglia should be taken into consideration prior to surgical procedures planned for this region. This study sheds light on high-risk zones in the surgical site and could guide surgeons to better understand the location of cervical sympathetic ganglia before surgical planning.

Magnetic resonance imaging features of the superior cervical ganglion and expected changes after radiation therapy to the head and neck in a long-term follow-up

PURPOSE

This study aimed to assess the magnetic resonance (MRI) features of the superior cervical ganglion (SCG) and to track changes to it induced using radiotherapy across a long-term follow-up.

METHODS

In total, 75 patients who underwent radiotherapy for head and neck malignancies and who were studied with MRI were recruited from two centers. MRI was performed before and after radiotherapy, with a median long-term follow-up of 4.5 years. Baseline SCG features were assessed. Changes in axial cross-sectional area, T2-normalized signal, and apparent diffusion coefficient (ADC) (the latter available in about half of the patients) were analyzed. Repeated measures analysis of variance with Bonferroni's correction was used to analyze changes in the aforementioned parameters (significance level 0.05).

RESULTS

Out of a potential 149 SCGs, 136 were visible at baseline MRI. A variable spatial relationship with the internal carotid artery was found. SCGs showed the "black dot" sign in almost all of the patients. ADC was higher in SCGs than in regional lymph nodes. Cross-sectional area, normalized T2, and ADC increased in the period up to 1 year after radiotherapy and then remained stable in subsequent longer-term follow-up.

CONCLUSION

The SCG has unusual features that allow differentiation from the regional lymph nodes. Changes in morphology and signal after radiotherapy must be taken into account by radiologists to avoid misdiagnosis as recurrent nodal disease. Changes induced using radiotherapy are stable in long-term follow-up and are thus likely attributed to other factors (such as Schwann cell hypertrophy/proliferation) rather than edema.

Serial magnetic resonance imaging evaluations of irradiated superior cervical sympathetic ganglia: Not every retropharyngeal enlarging mass is a sign of malignancy

INTRODUCTION

To describe serial changes in irradiated superior cervical sympathetic ganglia (SCSGs) on MRI (magnetic resonance imaging) evaluation in patients with head and neck squamous cell carcinoma (HNSCC) and to find the features differentiating them from the metastatic retropharyngeal lymph nodes.

MATERIALS AND METHODS

This retrospective study evaluated 52 consecutive patients with definitive radiotherapy with/without chemotherapy for pathologically confirmed HNSCC and pre- and postradiation MRI follow-up evaluations. MR images of SCSGs were analyzed including enhancement pattern, margin, and the presence of intraganglionic hypointensity.

RESULTS

MRI evaluations were performed in 36 men and 16 women with HNSCC with an average age of 58 years, range 23-80 years before irradiation (n=52), and at 6 (n=21) and 13-18 (n=52)months follow-up. Mean total radiation dose was 6351±483 cGy (range, 5640-7000 cGy). Intraganglionic hypointensity, homogeneous enhancement pattern, and well-defined margins were observed in 96%, 97%, and 97% of ganglia on the last follow-up, which showed no difference between pretreatment and 6-month follow-up (P>0.05). Mixed linear model analysis revealed significant increases in diameter and normalized T2SI of SCSGs after irradiation (P< 0.05).

CONCLUSIONS

Despite of the increase in diameter and normalized T2SI of SCSGs, preservation of intraganglionic hypointensity, well-defined margins and homogeneous enhancement might be helpful for radiologists to identify SCSGs during the follow-up of HNSCC patients.

MR Imaging of the Superior Cervical Ganglion and Inferior Ganglion of the Vagus Nerve: Structures That Can Mimic Pathologic Retropharyngeal Lymph Nodes

BACKGROUND AND PURPOSE

The superior cervical ganglion and inferior ganglion of the vagus nerve can mimic pathologic retropharyngeal lymph nodes. We studied the cross-sectional anatomy of the superior cervical ganglion and inferior ganglion of the vagus nerve to evaluate how they can be differentiated from the retropharyngeal lymph nodes.

MATERIALS AND METHODS

This retrospective study consists of 2 parts. Cohort 1 concerned the signal intensity of routine neck MR imaging with 2D sequences, apparent diffusion coefficient, and contrast enhancement of the superior cervical ganglion compared with lymph nodes with or without metastasis in 30 patients. Cohort 2 used 3D neurography to assess the morphology and spatial relationships of the superior cervical ganglion, inferior ganglion of the vagus nerve, and the retropharyngeal lymph nodes in 50 other patients.

RESULTS

All superior cervical ganglions had homogeneously greater enhancement and lower signal on diffusion-weighted imaging than lymph nodes. Apparent diffusion coefficient values of the superior cervical ganglion (1.80 ± 0.28 × 10^-3mm²/s) were significantly higher than normal and metastatic lymph nodes (0.86 ± 0.10 × 10^-3mm²/s, P < .001, and 0.73 ± 0.10 × 10^-3mm²/s, P < .001). Ten and 13 of 60 superior cervical ganglions were hypointense on T2-weighted images and had hyperintense spots on both T1- and T2-weighted images, respectively. The latter was considered fat tissue. The largest was the superior cervical ganglion, followed in order by the retropharyngeal lymph node and the inferior ganglion of the vagus nerve (P < .001 to P = .004). The highest at vertebral level was the retropharyngeal lymph nodes, followed, in order, by the inferior ganglion of the vagus nerve and the superior cervical ganglion (P < .001 to P = .001). The retropharyngeal lymph node, superior cervical ganglion, and inferior ganglion of the vagus nerve formed a line from anteromedial to posterolateral.

CONCLUSIONS

The superior cervical ganglion and the inferior ganglion of the vagus nerve can be almost always differentiated from retropharyngeal lymph nodes on MR imaging by evaluating the signal, size, and position.

High-resolution Imaging of Neural Anatomy and Pathology of the Neck

The neck has intricately connected neural structures, including cervical and brachial plexi, the sympathetic system, lower cranial nerves, and their branches. Except for brachial plexus, there has been little research regarding the normal imaging appearance or corresponding pathologies of neural structures in the neck. The development in imaging techniques with better spatial resolution and signal-to-noise ratio has made it possible to see many tiny nerves to predict complications related to image-guided procedures and to better assess treatment response, especially in the management of oncology patients. The purposes of this review is to present imaging-based anatomy of major nerves in the neck and explain their relevant clinical significance according to representative pathologies of regarded nerves in the neck.