The efficacy of carotid tubercle as an anatomical landmark for identification of cervical spinal level in the anterior cervical surgery: comparison with preoperative C-arm fluoroscopy

Accessory articulation of the transverse processes in the cervical spine

Accessory articulation between the transverse processes of the C6 and C7 vertebrae is an extremely rare anatomic variant that has only been previously described in two instances. In this report, we present the case of a 25-year-old male who sustained numerous injuries associated with a physical assault. A CT study of the cervical spine revealed a linear lucency mimicking a fracture but found on closer inspection to represent an accessory articulation between the anterior tubercles of the right transverse processes of the C6 and C7 vertebrae. In this report, we summarize this patient's clinical course, and provide an up-to-date review of the current literature, imaging characteristics, and potential mechanisms of the development of this anatomic variant. Our case also includes an incomplete version of the anomaly contralaterally as well as features of secondary osseous stress hypertrophy; these features have not been previously described and may aid in diagnosis. Finally, we provide the first-ever augmented reality model of this variant to fully convey its geometry and facilitate its unequivocal identification.

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.

Reliability and Accuracy of Palpable Anterior Neck Landmarks for the Identification of Cervical Spinal Levels

Study Design

A descriptive experimental study.

Purpose

The purpose of this study was to describe the reliability and accuracy of palpable anterior neck landmarks (angle of the mandible, hyoid bone, thyroid cartilage, and cricoid cartilage) for the identification of cervical spinal levels in a slight neck-extended position as in anterior approach cervical spinal surgery.

Overview of Literature

Standard, palpable anatomical landmarks for the identification of cervical spinal levels were described by Hoppenfeld using the midline palpable anterior structures (angle of the mandible [C2 body], hyoid bone [C3 body], thyroid cartilage [C4–C5 disc], cricoid cartilage [C6 body], and carotid tubercle [C6 body]) to determine the approximate level for skin incisions. However, in clinical practice, patients are positioned with a slight neck extension to achieve cervical lordosis. This positioning (neck extension) may result in changes in the locations of anatomical landmarks compared with those reported in previous studies.

Methods

This experimental study was conducted on 96 volunteers. Each volunteer was palpated for locating four anatomical landmarks three times by three different orthopedic surgeons. We collected data from the level of the vertebral body or the vertebral disc matching the surface anatomical landmarks from the vertical reference line.

Results

Accuracy of the angle of the mandible located at the C2 vertebral body was 95.5%, the hyoid bone located at the C2/3 intervertebral disc was 51.7%, the thyroid cartilage located at the C4 vertebral body was 42%, and the cricoid cartilage located at the C5/6 intervertebral disc was 43.4%.

Conclusions

With the neck in a slightly extended position to achieve cervical lordosis, the angle of the mandible, the hyoid bone, the thyroid cartilage, and the cricoid cartilage were most often located at the C2 body, the C2/3 disc, the C4 body, and the C5/6 disc, respectively. The angle of the mandible and the hyoid bone are highly reliable surface anatomical landmarks for the identification of cervical spinal levels than the thyroid cartilage and the cricoid cartilage.

Radiographic Evaluation of the Reliability of Neck Anatomic Structures as Anterior Cervical Surgical Landmarks

BACKGROUND

Accurate location of the skin incision is helpful to decrease the technical difficulty and save the operative time in anterior cervical spine surgery. Spine surgeons usually use the traditional neck anatomic structures (the hyoid bone, thyroid cartilage, and cricoid cartilage) as landmarks during the surgery. However, the reliability of these landmarks has not been validated in actual practice.

OBJECTIVE

To find out which landmark is the most accurate for identifying the cervical levels in anterior cervical spine surgery.

METHODS

The lateral flexion and extension radiographs of cervical spine in standing position from 30 consecutive patients from January 2015 to February 2015 were obtained. The cervical vertebral bodies from C2 to C7 were divided equally into 2 segments. The cervical segments corresponding to each of the surface landmarks were recorded on the flexion and extension radiographs, respectively, and the displacement of corresponding cervical segments from the flexion to extension radiographs for each landmark was calculated.

RESULTS

Based on the measurements, the main corresponding cervical levels for the mandibular angle were C2 on both of the flexion and extension films, for the hyoid bone were the C3-C4 interspace on flexion film and C3 on extension film, for the thyroid cartilage C5 on both of flexion and extension films, and for the cricoid cartilage C6 on flexion film and C5-C6 interspace on extension film, respectively. The ratios of displacement within 2 segments from flexion to extension were 83.3% (25/30) for mandibular angle, 56.7% (17/30) for hyoid bone, 66.7% (20/30) for thyroid cartilage, and 56.7% (17/30) for cricoid cartilage, respectively. The mean displacement from flexion to extension films were significantly less than 2 cervical segments for the mandibular angle but greater than 2 segments for the other landmarks. Significant differences were found between mandibular angle and the other 3 landmarks for the displacement from flexion to extension.

CONCLUSIONS

The angle of mandible was found to be the most accurate landmark for identifying the cervical level, which corresponded to C2 and C2-C3 disc space. The hyoid bone, thyroid cartilage, and cricoid cartilage were not reliable to predict the cervical levels.

Intrinsic Vertebral Markers for Spinal Level Localization in Anterior Cervical Spine Surgery: A Preliminary Report

Study Design

Prospective clinical study.

Purpose

To observe the usefulness of anterior cervical osteophytes as intrinsic markers for spinal level localization (SLL) during sub-axial cervical spinal surgery via the anterior approach.

Overview of Literature

Various landmarks, such as the mandibular angle, hyoid bone, thyroid cartilage, first cricoid ring, and C6 carotid tubercle, are used for gross cervical SLL; however, none are used during cervical spinal surgery via the anterior approach. We present our preliminary assessment of SLL over anterior vertebral surfaces (i.e., intrinsic markers) in 48 consecutive cases of anterior cervical spinal surgeries for the disc-osteophyte complex (DOC) in degenerative diseases and granulation or tumor tissue associated with infectious or neoplastic diseases, respectively, at an ill-equipped center.

Methods

This prospective study on patients undergoing anterior cervical surgery for various sub-axial cervical spinal pathologies aimed to evaluate the feasibility and accuracy of SLL via intraoperative palpation of disease-related morphological changes on anterior vertebral surfaces visible on preoperative midline sagittal T1/2-weighted magnetic resonance images.

Results

During a 3-year period, 48 patients (38 males,10 females; average age, 43.58 years) who underwent surgery via the anterior approach for various sub-axial cervical spinal pathologies, including degenerative disease (n= 42), tubercular infection (Pott's disease; n=3), traumatic prolapsed disc (n=2), and a metastatic lesion from thyroid carcinoma (n=1), comprised the study group. Intrinsic marker palpation yielded accurate SLL in 79% of patients (n=38). Among those with degenerative diseases (n=42), intrinsic marker palpation yielded accurate SLL in 76% of patients (n=32).

Conclusions

Intrinsic marker palpation is an attractive potential adjunct for SLL during cervical spinal surgeries via the anterior approach in well-selected patients at ill-equipped centers (e.g., those found in developing countries). This technique may prove helpful when radiographic visualization is occasionally inadequate.