A reassessment of cervical surface anatomy via CT scan in an adult population

Does three-dimensional intraglandular location predict malignancy in parotid tumors?

Tumors arising within the parotid encompass a heterogeneous mix of benign and malignant neoplasms and other tissue growths. The purpose of this study was to determine the association between the location of intraparotid masses and the risk of malignancy. A retrospective cohort study was performed of patients diagnosed with parotid tumors following open tumor excision. The primary predictor variable was the location of the epicenter of the tumor in three-dimensional space, as determined from preoperative imaging. Other variables were patient demographics and clinical parameters. The primary outcome variable was the final histopathologic diagnosis of a benign or malignant process. A χ² analysis was performed to test for any significant associations between demographic, clinical, and radiographic factors in relation to the outcome, and backwards stepwise logistic regression analysis was used to control for variables. Both increasing age (P = 0.002) and the presence of local pain (P = 0.020) were associated with malignancy. Tumors located anterior to the posterior border of the retromandibular vein had 2.18 times higher odds of malignancy (95% confidence interval 1.13-4.21; P = 0.020). Multivariate regression analysis suggested that patient age, the presence of pain, and tumor location anterosuperiorly and superoinferiorly could all assist in determining the odds of malignancy.

Vascular tortuosity in endovascular mechanical thrombectomy

Endovascular mechanical thrombectomy effectively removes occlusive thrombi from the arterial lumen; however, there is little literature supporting the relevance of vascular geometry on surgical outcomes. Critical vessel characteristics including the degree of angulation and tortuosity influence the ability to advance stent retriever devices toward the site of occlusion. Therefore, it is crucial to evaluate the impact of carotid artery catheter pathway accessibility on the thrombectomy outcomes in acute ischemic stroke (AIS) patients. Traditional imaging modalities generate incomplete pictures of the vascular tortuosity and are prone to clinical judgment errors. Recent three-dimensional computed tomography angiography image analysis techniques circumvent these limitations to calculate accurate tortuosity and angulation measurements. These novel images facilitate classifying common anatomical variant patients into groups that may be treated with specially designed catheter devices. Importantly, this image analysis method reveals significant angulation in the common carotid artery and extracranial internal carotid artery that correlates with delays in reaching the occlusion site. Increased age, which is associated with increased risk of stroke, also increases the incidence of severe tortuosity. The semi-automated measurements technique also demonstrate that full 360° arterial loops are present in nearly 3% of catheter pathways and that the overall degree of angulation differs bilaterally. In this review, we examine the utility of this novel image analysis procedure and evaluate the recent literature relevant to neuroendovascular thrombectomy in AIS patients. Three literature databases – PubMed, Embase, and Web of Science were queried for original articles investigating both preclinical and clinical thrombectomy applications.

Preoperative Localization of the Carotid Bifurcation for Cervical Carotid Exposure Using the Mastoid-Hyoid Line

Background and Importance:

The location of the carotid bifurcation (CB) is highly variable, which makes precise exposure of the cervical carotid artery difficult, especially in transverse incisions. The method for preoperative localization of the CB is not well established. We used the distance from the mastoid-hyoid (M-H) line to the CB, measured preoperatively with computed tomography angiography, to localize the location of the transverse skin incision. We describe and evaluate the accuracy of a method for preoperative localization of the CB for cervical carotid exposure.

Methods:

The researchers retrospectively evaluated 16 patients with aneurysms arising from the internal carotid artery (ICA) who had received cervical carotid exposure using the localization method of incision and were retrospectively evaluated from February 2018 to November 2019. The method of measurement and localization of the skin incision are described, and two illustrative cases are demonstrated.

Results:

Saccular aneurysms of the ophthalmic (C2) segment and communicating (C1) segment of the ICA were found in 8 and 8 patients, respectively. Nine patients had left-sided exposure, and 7 patients had right-sided exposure. The mean distance from the M-H line to the CB was 2.1 cm (range 0.5–3.5 cm). The accuracy of this method was 93.8%. No paralysis of the depressor anguli oris or the depressor labii inferioris was found postoperatively.

Conclusion:

The distance from the M-H line to the CB can be used to estimate transverse skin incisions for cervical carotid exposure.

Semi-automated measurement of vascular tortuosity and its implications for mechanical thrombectomy performance

PURPOSE

Few studies have examined the geometry of endovascular mechanical thrombectomy pathways. Here we examine the tortuosity and angulations of catheter pathways from the aortic arch to the termination of the internal carotid artery (ICA) and its association with thrombectomy performance.

METHODS

We included 100 consecutive anterior circulation large vessel occlusion thrombectomy patients over 12 months. Computed tomography angiograms (CTA) were used for 3D segmentation of catheter pathway from the aortic arch to ICA termination. Tortuosity index (TI) and angulations of the catheter pathway were measured in a semi-automated fashion. TI and angulation degree were compared between sides and correlated with age and procedural measures.

RESULTS

We analyzed 188 catheter pathways in 100 patients. Severe angulation (≤ 30°) was present in 5.8% and 39.4% of common carotid artery (CCA) and extracranial ICA segments, respectively. Five pathways (2.6%) had 360° loop. CCA and extracranial ICA tortuosity had a weak but significant correlation with age (r = 0.17, 0.21, p value = 0.05, 0.02 respectively), time from groin puncture to the site of occlusion (r = 0.29, 0.25, p values = 0.008, 0.026 respectively), and fluoroscopy time (r = 0.022, 0.31, p values = 0.016, 0.001 respectively). There was a significant difference in the pattern of angulation (p value = 0.04) and tortuosity between right and left side in CCA segment (TI = 0.20 ± 0.086 vs. 0.15 ± 0.82, p value < 0.001).

CONCLUSIONS

There was a significant difference in CCA angulation between right and left sides. TI of extracranial CCA and ICA correlated with age and influenced time from groin puncture to the occlusion site and total fluoroscopy time.

Treatment of Cervical Spine Fractures and Subluxations without the Use of Intraoperative Fluoroscopy in Resource-Limited Settings

Background  Surgical management of subaxial cervical spine injuries remains challenging. Although intraoperative fluoroscopy is usually used for intraoperative spinal level localization (SLL), it is unavailable in most developing countries. The surgeon therefore has to rely on anatomic landmarks. In our setting, in the absence of intraoperative fluoroscopy, we used the carotid tubercle for SLL. Herein we evaluate the accuracy and reliability of the carotid tubercle as a landmark during surgery for traumatic cervical spine injury.

Methods  This was a retrospective cohort study on 34 patients undergoing anterior cervical surgery for subaxial cervical spine fractures and/or subluxation between January 2005 and February 2011. From their medical records, the patients’ sociodemographic, clinical, radiological, and operative data were retrieved and analyzed.

Results  Thirty-four patients were included in the study. The mean age was 36.2 years. Thirty patients were males. The mean duration between the trauma and surgical intervention was 9.6 days. Six patients were completely tetraplegic. Fourteen patients had fractures and 20 patients had subluxation. The carotid tubercle was palpable in all the 34 cases. Twenty-two (68.8%) patients had partial or complete neurologic recovery. Complete anatomic reduction was achieved in 30 cases. One case of slight malalignment of the plate was observed. No case of significant deviation nor penetration of the screw into the vertebral canal was found. One patient died.

Conclusions  Carotid tubercle, a palpable intrinsic marker, is an attractive anatomic landmark for SLL during surgeries for traumatic spine injuries in resource-limited settings.

A New Method for Determining the Level of the Carotid Artery Bifurcation

Exact localization of the bifurcation of the common carotid artery using skin surface landmarks is important for various diagnostic and therapeutic purposes, including emergency cases. Traditional methods have confirmed their accuracy in only a certain percentage of cases and there are inconsistencies among various publications. The cervical computed tomography-angiographic examinations for any diagnostic purpose between June 2017 and December, 2017 in the authors' hospital were examined. Measurements were performed for (MT-CB) and (MT-SE) distances and the results were recorded [MT = The tip of the mastoid process; CB = common carotid artery bifurcation; SE = sternal extremity of the clavicle]. Cervical computed tomography angiography was found in the records of 91 patients in the 6-month period between June 2017 and December 2017. After exclusion criteria were applied, a total of 116 carotid bifurcation levels on the right and left sides were measured in 58 patients. The mean MT-CB distance was 6.29 ± 0.9 cm (range: 2.9-8.4 cm). The mean distance between MT and SE was 15.3 ± 1.7 cm (range: 9.9-19.0 cm). The (MT-CB): (MT-SE) ratios ranged from 29% to 51% with a mean of 41 ± 4.2% (95% CI: 39.88%-42.10%) and a median of 41.1% (P < 0.05) (Kolmogorov-Smirnov test). The distance ratio values did not change significantly according to age and gender (respectively P = 0.341, P = 0.093). These results show that the CB is usually located at two-fifths of the distance from the mastoid tip to the sternal extremity of the clavicle and closer to the mastoid tip.

Triangles of the neck: a review with clinical/surgical applications

The neck is a geometric region that can be studied and operated using anatomical triangles. There are many triangles of the neck, which can be useful landmarks for the surgeon. A better understanding of these triangles make surgery more efficient and avoid intraoperative complications. Herein, we provide a comprehensive review of the triangles of the neck and their clinical and surgical applications.

Avoiding the Esophageal Branches of the Recurrent Laryngeal Nerve During Retractor Placement: Precluding Postoperative Dysphagia During Anterior Approaches to the Cervical Spine

STUDY DESIGN

Anatomical cadaver study.

OBJECTIVES

Postoperative dysphagia is a significant complication following anterior approaches to the cervical spine and the etiology of this complication is poorly understood. Herein, we studied the esophageal branches of the recurrent laryngeal nerves to improve understanding of their anatomy and potential involvement in dysphagia.

METHODS

Ten fresh frozen cadaveric human specimens were dissected (20 sides). All specimens were adults with no evidence of prior surgery of the anterior neck. The recurrent laryngeal nerves were identified under a surgical microscope and observations and measurements of their esophageal branches made.

RESULTS

For each recurrent laryngeal nerve, 5-7 (mean 6.2) esophageal branches were identified. These branches ranged from 0.8 to 2.1 cm (mean 1.5 cm) in length and 0.5 to 2 mm (mean 1 mm) in diameter. They arose from the recurrent laryngeal nerves between vertebral levels T1 and C6. They all traveled to the anterior aspect of the esophagus. No statistical differences were seen between left and right sides or between sexes.

CONCLUSION

The esophageal branches of the recurrent laryngeal nerve have been poorly described and could contribute to complications such as swallowing dysfunction following anterior cervical discectomy and fusion procedures. Therefore, a better understanding of their anatomy is important for spine surgeons. Our study revealed that these branches are always present on both sides and the anterior surface of the esophagus should be avoided while retracting it in order to minimize the risk of postoperative dysphagia.

Internal Morphology of the Odontoid Process: Anatomic and Imaging Study with Application to C2 Fractures

OBJECTIVE

Fracture of the odontoid process is a critical injury to diagnose and often treat. The aim of this anatomic study was to present a comprehensive understanding of this part of the C2 vertebra.

METHODS

We used 20 C2 vertebrae. Samples underwent imaging (computed tomography [CT] with and without three-dimensional reconstruction, micro-CT, 1.5T magnetic resonance imaging) and sagittal and coronal sectioning using a bone saw. Sectioned specimens were imaged under a digital handheld microscope, and transillumination of the bone was used to highlight its internal trabecular pattern. Three samples underwent infusion of the odontoid process with a hardening substance and were then decalcified.

RESULTS

Internal trabecular patterns of the odontoid process of all specimens were discernible. In sagittal and coronal sections, trabecular patterns were highlighted with transillumination, but the patterns were much clearer using the digital microscope. Magnetic resonance imaging and CT provided the least detail of the imaging methods, but the trabecular patterns could be identified. Three-dimensional reconstruction of CT data was the preferred imaging method over magnetic resonance imaging and CT without three-dimensional reconstruction. The most distinct trabecular and cortical patterns were seen using micro-CT. Osteoporosis was seen in 2 specimens (10%). Five specimens (25%) were found to have a subdental synchondrosis. For most specimens, the trabeculae were found throughout the odontoid process.

CONCLUSIONS

Improved knowledge of the anatomy, structural composition, and variations within the C2 vertebra may allow for better treatment options and patient care.

The Great Auricular Nerve: Anatomical Study with Application to Nerve Grafting Procedures

BACKGROUND

When it comes to autogenous nerve grafting, the sural and great auricular nerve (GAN) are the 2 nerves predominately used for trigeminal and facial nerve repair. Arising from the second and third cervical ventral rami, the GAN emerges from the posterior border of the sternocleidomastoid coursing superiorly and anteriorly toward the ear.

METHODS

Eleven sides from 5 Caucasian and 1 Asian cadaveric heads (all fresh-frozen) were used. One man and 5 women were used with an age at death ranging from 57 to 91 years, with a mean of 80.3 years. Measurements were made from the inferior border of the ear to the GAN, the GAN to the external jugular vein, and the inferior border of the mastoid process to the GAN; the proximal, medial, and distal diameters of the GAN and the length of the GAN that was obtained from this exposure were also measured.

RESULTS

The mean distance from the inferior border of the mastoid process to the GAN, inferior border of the ear to the GAN, and GAN to the external jugular vein was 27.71, 31.03, and 13.28 mm, respectively. The mean length of the GAN was 74.86 mm. The mean diameter of its distal, middle, and proximal portions was 1.51, 1.38, and 1.58 mm, respectively.

CONCLUSIONS

The GAN is an excellent option for use in nerve grafting for repair of, for example, facial dysfunction. In this study, we review our measurements, techniques for identification, and dissecting techniques for the GAN. The proximity to the operative area and minimal complications associated with GAN grafting might contribute to improved patient satisfaction and better outcomes regarding functional restoration.

Gerber's Ligament-A Forgotten Structure of the Craniocervical Junction

BACKGROUND

Ligaments of the craniocervical junction play a critical role in stabilizing this region. Gerber's ligament has more or less been forgotten and, to our knowledge, never studied.

METHODS

Dissection of the craniocervical junction was performed in 15 fresh frozen cadavers. In the prone position, the posterior elements of the upper cervical vertebrae and occiput were removed. After removing the contents of the spinal canal and posterior cranial fossa, the dura mater and tectorial membrane were reflected. The superior band of the cruciform ligament was reflected. When Gerber's ligament was identified, its attachments and morphometry were recorded. Lastly, Gerber's ligament was observed while range of motion of the craniocervical junction was performed.

RESULTS

Gerber's ligament was identified in 7 specimens (46.7%). This structure arose anteriorly from the junction of the superior band and transverse part of the cruciform ligament. Gerber's ligament was always found to be just deep to the superior band of the cruciform ligament but traveled more anteriorly to attach onto the posterior aspect of the dens approaching, but not attaching onto, its apex. Mean length was 11 mm, and mean width was 7 mm. Thickness of the ligament was 0.5-1.1 mm. The ligament was found to become taut with minimal rotation of the atlantoaxial joint and extension of the craniocervical junction.

CONCLUSIONS

A good understanding of all ligaments of the craniocervical junction is important to surgeons and physicians treating patients with injury to the upper cervical spine.

Bilateral sternocleidomastoid variant with six distinct insertions along the superior nuchal line

Anatomical variations of the sternocleidomastoid muscle (SCM) have been observed to occupy multiple origins and insertion points and have supernumerary heads, sometimes varying in thickness. During routine dissection, a SCM was observed to have six distinct insertions that interface with the course of the superior nuchal line, ending at the midline, bilaterally. This variation was also seen to receive innervation from the accessory nerve as well as the great auricular nerve. To our knowledge, this variant of supernumerary insertions and nerve innervations has not yet been reported. These variants may pose as problematic during surgical approaches to the upper neck and occiput, and should thus be appreciated by the clinician. Herein we discuss the case report, possible embryological origins, and the clinical significance of the observed variant SCM.

Superficial anterior atlanto-occipital ligament: Anatomy of a forgotten structure with relevance to craniocervical stability

Introduction

The superficial anterior atlanto-occipital ligament (SAAOL) is a narrowband located anterior to the anterior atlanto-occipital membrane. Nearly forgotten, it has not been well described in older anatomical textbooks and is missing in the current anatomical literature. As all of the binding structures of the craniocervical junction (CCJ) are important in maintaining stability, this study aims to clarify the anatomy and potential function of the SAAOL.

Materials and Methods

The CCJ from ten fresh-frozen cadavers was studied. These specimens were derived from three males and seven females, and the age at death ranged from 57 to 91 years (mean, 79.8 years). The length, width, and thickness of the SAAOL were measured. In five specimens, the force to failure was recorded.

Results

The SAAOL was found between the anterior tubercle of the atlas and the occiput and located as central thick fibers in front of the anterior atlanto-occipital membrane in 9 (90%) specimens. In one specimen, the vertical band to the occipital bone did not attach to the anterior tubercle of the atlas, but extended to the anterior aspect of the axis. The mean length, width, and thickness of the SAAOL were 19.8, 6.2, and 0.6 mm, respectively. The force to failure for the ligament was 38.8 N.

Conclusion

The SAAOL was a constant structure of the anterior atlanto-occipital joint. This ligament seems to be a secondary stabilizer of the CCJ by limiting the extension of CCJ. Knowledge of this ligament may help in further understanding of craniocervical stability.

An Unusual Finding of the Hyoid Bone

The hyoid contributes to many biomechanical processes including swallowing. Additionally, the hyoid bone has been studied for over a century in an effort to catalog and categorize many observed biometric differences. This has led to the hyoid being a major structure involved in forensic pathology. In this paper, we discuss a very unusual finding of an adult female hyoid bone.

Review of the Variations of the Superficial Veins of the Neck

The venous drainage of the neck can be characterized into superficial or deep. Superficial drainage refers to the venous drainage of the subcutaneous tissues, which are drained by the anterior and external jugular veins (EJVs). The brain, face, and neck structures are mainly drained by the internal jugular vein (IJV). The superficial veins are found deep to the platysma muscle while the deep veins are found encased in the carotid sheath. The junction of the retromandibular vein and the posterior auricular vein usually form the EJV, which continues along to drain into the subclavian vein. The anterior jugular vein is usually formed by the submandibular veins, travels downward anterior to the sternocleidomastoid muscle (SCM), and drains either into the EJV or the subclavian vein. Other superficial veins of the neck to consider are the superior, middle, and inferior thyroid veins. The superior thyroid and middle thyroid veins drain into the IJV whereas the inferior thyroid vein usually drains into the brachiocephalic veins.

An Unusual Back Muscle Identified Bilaterally: Case Report

Most muscular structures in the human body are named based on their function, origin/insertion, or shape. During routine dissection of the back, an unusual muscle was found deep to the rhomboid muscles. The details of this case and a review of the extant literature are provided.