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This is a report of a series of 14 patients who presented with a range of "atypical" cranial, spinal, and systemic symptoms that started after they suffered a relatively severe injury to the head and/or neck several months or years before surgical treatment. The implications of diagnosing and treating central or axial atlantoaxial dislocation (CAAD) is discussed. Also, the role of dynamic rotatory and lateral head tilt imaging in the diagnosis and treatment is analyzed. Of the 14 patients, 7 were men and 7 were women, with an age range of 21–64 years (average, 42 years). Due to the severity of the presenting neurological and non-neurological symptoms, all the patients had lost their occupation and were heavily dependent on painkillers and/or antidepressant drugs. In addition to other characteristic clinical and radiological evidence, CAAD was diagnosed made based on the facet alignments on lateral profile imaging in the neutral head position. Dynamic head flexion-extension, lateral head tilt, and neck rotation imaging findings confirmed and subclassified CAAD. All 14 patients underwent atlantoaxial fixation surgery. A personalized self-assessment clinical scoring parameter and the World Health Organization Disability Assessment Schedule 2.0 was used to evaluate the outcome. One patient did not follow-up after surgery. At a minimum follow-up of 6 months after atlantoaxial fixation surgery, the remaining 13 patients experienced relief from all major symptoms. Diagnosing and treating CAAD can have major therapeutic implications for patients presenting with progressively worsening disabling clinical symptoms following relatively severe head and/or neck trauma. [ABSTRACT FROM AUTHOR]

Dens fractures are an increasingly common injury, yet their epidemiology and its implications remain underexamined. We retrospectively analyzed all traumatic dens fracture patients managed at our institution over a 10-year period, examining demographic, clinical, and outcomes data. Patient subsets were compared across these parameters. Among 303 traumatic dens fracture patients, we observed a bimodal age distribution with a strong goodness of fit centered at age 22.3 ± 5.7 (R = 0.8781) and at 77.7 ± 13.9 (R = 0.9686). A population pyramid demonstrated a bimodal distribution among male patients, but not female patients, which was confirmed with a strong goodness of fit for male patient subpopulations age <35 (R = 0.9791) and age ≥35 (R = 0.8843), but a weaker fit for a second female subpopulation age <35. Both age groups were equally likely to undergo surgery. Patients younger than age 35 were more likely to be male (82.4% vs. 46.9%, odds ratio [OR] = 5.29 [1.54, 17.57], P = 0.0052), have motor vehicle collision as their mechanism of injury (64.7% vs. 14.1%, OR = 11.18 [3.77, 31.77], P < 0.0001), and to have a severe trauma injury severity score (17.6% vs. 2.9%, OR = 7.23 [1.88, 28.88], P = 0.0198). Nevertheless, patients age <35 were less likely to have fracture nonunion at follow (18.2% vs. 53.7%, OR = 0.19 [0.041, 0.76], P = 0.0288). The dens fracture patient population comprises 2 subpopulations, distinguished by differences in age, sex, injury mechanism and severity, and outcome, with male dens fracture patients demonstrating a bimodal age distribution. Young, male patients were more likely to have high-energy injury mechanisms leading to severe trauma, yet were less likely to have fracture nonunion at follow-up. [ABSTRACT FROM AUTHOR]

The craniovertebral junction (CVJ), or the "first junction," can be affected by a variety of pathological states. Some of these conditions could represent a gray area in that they can be treated by general neurosurgeons or such specialists as skull base or spinal surgeons. However, some conditions are best managed with a multidisciplinary approach. The importance of in-depth knowledge of the anatomy and biomechanics of this junction cannot be overemphasized. Identifying what represents clinical stability or instability is key to successful diagnosis and, hence, treatment. In this report, the second in a 3-article series, we describe our approach to managing CVJ pathologies in a case-based fashion to illustrate key concepts. [ABSTRACT FROM AUTHOR]

The craniovertebral junction (CVJ) involves the atlas, axis, and occiput along with the atlanto-occipital and atlantoaxial joints. The anatomy and neural and vascular anatomy of the junction render the CVJ unique. Specialists treating disorders that affect the CVJ must appreciate its intricate anatomy and should be well versed in its biomechanics. This first article in a three-article series provides an overview of the functional anatomy and biomechanics of the CVJ. [ABSTRACT FROM AUTHOR]

To investigate whether biologic agents (BAs) reduce a narrow C-2 pedicle screw trajectory, which is often a key stabilizer in surgical treatment, in patients with rheumatoid arthritis (RA). A total of 100 patients with RA treated with and without BAs (BA [+] group [n = 50] and BA [−] group [n = 50]), respectively, were included in the present study. Computed tomography (CT) images of their cervical spine, including C-2, were analyzed. The maximum screw diameter at C-2 that could be inserted without breaching the cortex, measured on 3-dimensional images using a CT-based navigation system, was compared between the groups with and without BA administration. Furthermore, the destruction of the atlantoaxial joint was examined using CT images. The risk factors for a narrow C-2 pedicle were elucidated among the patients treated with BAs. The pedicle in the BA (+) group had a significantly larger C-2 maximum screw diameter than the BA (−) group (6.00 mm vs. 5.13 mm, P < 0.001), with less destruction of the atlantoaxial joint. Among the BA (+) group, a longer period until the initial administration of BAs and RA disease duration were associated with a narrow C-2 pedicle. This study suggests that BAs can maintain the trajectory for C-2 pedicle screws, which acts as a key stabilizer in surgical management for the rheumatoid cervical spine, by halting the destruction of the atlantoaxial joint. Early introduction of BAs can be especially important to prevent the narrowing of the C-2 pedicle. [ABSTRACT FROM AUTHOR]

Occipitocervical fusion is an important surgical procedure to treat instability of the upper cervical and craniocervical junction. Fixation to the dense cortical bone of the occiput, contemporaneously typically accomplished with a plate and screws, is known to be strong and durable, but there are many competing methods used to secure an adequate number of fixation points of sufficient strength at the cervical end. Extension of hardware to the midcervical region to acquire additional fixation points, however, results in loss of subaxial motion segments and additional potential morbidity. The C2 vertebra is unique in that its morphology and dimensions permit fixation with longer screws than are typically possible to place in the midcervical lateral masses. Translaminar and pars screw techniques, both commonly used to achieve C2 fixation, are not mutually exclusive, as their respective trajectories are considerably different and engage different portions of the bony anatomy. We describe a novel, 4-point C2 fixation technique for OC fusion that may avoid the need to extend fusion to the subaxial spine. This technical note illustrates how 4-point C2 fixation can be employed in occiptocervical fusion. 4-point fixation of C2 combining translaminar and pars screw placement is technically feasible and may be a suitable strategy to spare subaxial motion segments in OC fusion procedures. Futher investigation may establish its applicability to additional surgical procedures. [ABSTRACT FROM AUTHOR]

We herein outline the experience matured in our equipped Cranio-Vertebral Junction Laboratory for anatomic dissection. An extreme lateral approach (ELA) was performed on 4 fresh cadavers and submandibular approach was performed on 5. An endoscope and navigation-assisted far lateral approach (FLA) was performed in 5 injected specimens. In these specimens, a transoral approach was also performed, as well as a neuronavigation-assisted comparison between transoral and transnasal explorable distances. As calculated with neuronavigation, statistically significant differences both in the explored craniocaudal (P = 0.003) and lateral (P = 0.008) distances were observed between the transoral approach and endoscopic endonasal approach. In FLA, neuronavigation facilitated identification and partial removal of the occipital condyle; in one case, during endoscopic intradural exploration, tearing of the emerging roots of the 11th cranial nerve occurred. In ELA, the site where the accessory nerve pierces into the sternocleidomastoid muscle was found at a distance from the tip of the mastoid between 3 and 4 cm. During dissections, as in the clinical setting, endoscope and image guidance give the surgeon a constant orientation, increasing the accuracy and the safety of the approach. Nonetheless, the encumbrance of the endoscope could represent a limit in deep and narrow corridors as those running across the craniovertebral junction, especially in "oblique" FLA and ELA, in which the surgical target is often hidden by a delicate tangle of nerves and vessels. Its use appears more suitable and safer in "straight" approaches as transoral and transnasal in which there are no neurovascular structures interposed. [ABSTRACT FROM AUTHOR]

C2 vertebral body (axis) lesions are often approached anteriorly and combined with posterior stabilization of the craniovertebral junction (CVJ). The anterior approach has its limitations. A posterolateral corridor is an alternative access to the C2 body lesions, and this alone may suffice in selected cases. We describe our experience with C2 body lesions, dealt primarily through a posterior approach, and propose an algorithm in the management of such cases. Ten patients with axis lesions were operated through a midline posterior approach followed by posterior stabilization of the CVJ in the same sitting. Their preoperative and follow-up clinico-radiologic details were reviewed. The lesions included aneurysmal bone cysts (n = 2), fibrous dysplasia (n = 2), chordoma (n = 2), Ewing sarcoma (n = 1), metastases (n = 1), post-traumatic malunion (n = 1), and post-inflammatory deformity (n = 1). All patients presented with worsening neck pain. Five also had spastic quadriparesis. There were no perioperative complications. All showed clinical improvement at follow-up. Only 2 patients (chordoma: n = 1; aneurysmal bone cyst: n = 1) required an additional anterior procedure. Adequate debulking or total excision of lesion, neural decompression, and stabilization of the CVJ for axis body lesions can be achieved through a single midline posterior approach in most cases. If required, an anterior approach may be later added depending on the final histopathology. [ABSTRACT FROM AUTHOR]

Surgical approaches for posterior C1–C2 arthrodesis, such as C1–C2 transarticular and C1–C2 screw stabilization, are known to be demanding because of the anatomic close proximity of cervical vertebrae to neurovascular structures. Currently, navigation by fluoroscopy or intraoperative computed tomography (ICT) is the standard practice. However, fluoroscopy has various limitations, and ICT is time consuming and not available in many centers; furthermore, both diagnostic tools lead to exposure of the operating room staff to radiation exposure. We evaluate the safety, efficacy, and facility of a navigation system using only preoperative cervical computed tomography and computed tomographic angiography (CT/CTA), to prevent the risk of neurovascular damage in atlantoaxial stabilization. The authors report a series of 21 patients who underwent posterior upper cervical spine fixation using a navigation system with intraoperative single-level vertebral registration on preoperative cervical CT/CTA (software BrainLab IPlan Spine 3.0). Intraoperative and postoperative comparative analysis was performed to verify the correspondence between the virtual anatomic position of the surgical instruments and screws represented on the neuronavigator, and the actual positions verified intraoperatively and on postoperative CT. Thirteen patients underwent C1–C2 arthrodesis with a Harms construct, 1 patient with transarticular screw fixation and 4 patients with occipitocervical stabilization. Three patients underwent C1–C2–C3 stabilization with C1 hooks, C2–C3 screws, and rod construct. On postoperative CT, the position of all screws appeared satisfactory. No neurovascular damage occurred in any patients. The use of a neuronavigation system, based on preoperative acquired cervical CT and intraoperative single-vertebra registration, may provide a valuable support for the improvement of the surgical accuracy of posterior C1–C2 screw fixation. [ABSTRACT FROM AUTHOR]

Background Posterior arch defect of C2 with an unstable spondylolysis is a rare condition mostly occurring within children. Its management is still controversial. Case Description We report in this article the first minimally invasive surgery (MIS) technique for this condition in an 8-year-old boy. A primary unstable C2 spondylolysis was diagnosed on the exploration of episodic paresthesia of upper limbs associated with headache lasting for several months. The surgical technique consisted in a direct pars repair through an MIS approach: METRx tubular retractor system (Medtronic Sofamor Danek, Memphis, Tennessee, USA), intraoperative C-arm fluoroscopy, surgical microscope, endoscopic spine instrument, and high-speed drill were required. Muscles were split and retracted. One-year postoperative course was excellent. Conclusions After reviewing the past literature of this pathology, we discuss the minimally invasive posterior approach of the upper cervical spine. It is the first case, to our knowledge, describing direct minimally invasive repair for bilateral primary C2 pars defect in a child. Image guidance and surgical microscope help safe and effective screw placement. [ABSTRACT FROM AUTHOR]

Background Congenital absence of C2 posterior arch may present with C2-C3 dislocation. Previously these cases were managed by fusing occiput-C1-C4 without including C2 in the construct. Such constructs are likely to immobilize the long segment of the cervical spine, and exclusion of C2 may not yield the best result. Case Description We report a case with congenital absence of posterior arch of axis with C2-3 and C1-C2 dislocation who presented with progressive spastic quadriparesis. The inferior facets of C2 were rudimentary. In our patient the C1-C2-C3 dislocations were stabilized with C1 and C3 lateral mass along with C2 pedicle screws. Clinical improvement with radiologic realignment occurred. Conclusion Absence of the posterior arch of axis may be associated with adjacent C1-C2 along with C2-C3 dislocation, so both levels need to be addressed. The radiology should be critically evaluated for other structures developing from the C2 neural arch. It is important to include C2 to achieve a stable construct without compromising adjacent-level mobility. [ABSTRACT FROM AUTHOR]

Background Opinions vary regarding optimal treatment of unstable hangman's fractures, including rigid orthosis and internal fixation. The anatomy of upper cervical spine is complex. The advent of intraoperative 3-dimensional navigation systems facilitates safe and accurate instrumentation. Objective To evaluate radiologic parameters of fracture morphology in unstable hangman's fracture in preoperative and postoperative period and accuracy of inserting axis pedicle screws by using intraoperative computed tomography–based navigation. Methods Fifteen patients with unstable hangman's fractures with age ranging from 17 years to 81 years were operated using computed tomography–based navigation from September 2011 to march 2016. Patient's age, sex, mechanism of injury, associated injuries, and neurologic status were noted. Clinical outcome, accuracy of screw insertion, preoperative and postoperative displacement, and angulation of C2 over C3 and bony fusion were assessed. Results Overall, 76 screws were inserted including 30 screws in C2 pedicle with 2 (2/60; 6.7%) malplaced screws in C2 pedicle. Mean follow-up period was 34 ± 18 months (range 7–80 months). Mean hospital stay was 12.8 ± 2.4 days. Mean preoperative and postoperative displacements were 4.09 mm ± 1.78 mm and 1.82 mm ± 1.14 mm respectively with a mean reduction of 2.27 mm ± 1.49 mm. Mean preoperative angulation was 7.23° ± 11.96° and postoperative angulation was 2.32° ± 4.77° with a mean reduction of 5.11° ± 11.96°. Bony fusion was achieved and rotation was preserved at C1–C2 joint in all cases. Conclusions Intraoperative O-arm–based navigation is a safe, accurate, and effective tool for screw placement in patients with unstable hangman fracture and achieves good anatomical reduction. [ABSTRACT FROM AUTHOR]

Background Type 2 odontoid fractures are the most common cervical fractures among the elderly. Neurologic deficit is usually caused by myelopathy as a result of posterior dens migration. Direct anterior screw placement provides stabilization and can preserve C1-C2 movement. The presence of a bony excrescence on the anterior superior tip of the dens may lead to placement of a screw of incorrect length. Methods Twenty C2 dry specimens were examined for the presence of a corona dentis, which is a bony excrescence in the coronal plane near the apex of the dens. When identified, measurements of the corona dentis were performed using calipers and a ruler. In addition, anteroposterior (AP) and lateral fluoroscopy was performed on all specimens found to have a corona dentis. Results A corona dentis was found on 20% of our C2 specimens and had an average width of 9 mm and an average height of 4.5 mm. The average width of the dens did not vary as the normal tip of the dens transitioned into the coronae. In no specimen did the corona dentis seem to be composed of trabecular bone and it was seen as a superior projection of cortical bone on fluoroscopy. On fluoroscopy, the corona dentis could be identified on a true AP projection. In angulated AP views, fluoroscopic images overestimated the length of the corona dentis. Conclusions We describe a new entity termed the corona dentis because of its crownlike feature. It is a superior cortical bone protrusion and should be noted as a variant of the dens during anterior odontoid screw placement. Its propensity to increase the height of the dens markedly can lead to higher rates of neurologic deficits during type 2 odontoid fractures if not appreciated. A true AP view is critical for correct screw size placement. [ABSTRACT FROM AUTHOR]

An alternative caudally directed C2 inferior facetal screw is described. Such screw insertion can form the axial stabilization point in cases undergoing atlantoaxial lateral mass plate/rod and screw fixation and those undergoing C1-2 and C1-2-3 spinal fixation. The C2 screw courses from the medial point of the pedicle-laminar junction and travels caudally and laterally toward the C2-3 articulation. Deploying a longer screw that traverses in a transarticular fashion into the facetal mass of C3 vertebra, one can perform C1-2-3 stabilization. Sixteen patients underwent C2 inferior facetal or C2-3 transarticular screw in combination with a C1 screw for atlantoaxial fixation. Three of these patients with multilevel spinal instability underwent atlantoaxial and C2-3 fixation using the discussed technique. The technical issues, anatomic subtleties, and indication for use of the C2 inferior facetal screws are discussed. With an average follow-up of 9 months, all screws have successfully provided stability that resulted in arthrodesis of the treated spinal segments. A caudally directed C2 inferior facetal screw can enhance the armamentarium of the surgeon, provide an alternative to conventional techniques or a bailout option, and add to the safety of the procedure of atlantoaxial lateral mass fixation in anatomically challenged situations. [ABSTRACT FROM AUTHOR]

Objective Knowledge of the course of the vertebral artery during instrumentation is of paramount importance. It has been shown that erosion of the C2 pedicle and body can occur due to pulsations of the adjacent vertebral artery. This often results in a “cave” for this segment of the artery. The descriptions of this anatomy are limited. The current study was performed with the hope that these data will be of use to spine surgeons during C2 instrumentation. Methods In 40 human adult C2 bone specimens, the position of the vertebral artery in relation to the undersurface of the superior articular facet, pedicle, and C2 body was observed. A classification system was used to better describe these relationships. Pedicle screws were then placed into selected examples of each type. Results We found type 0 specimens, with no cave, on 8 sides (10%). Types I, II, and III caves with minimal, moderate, and significant encroachment of the pedicle were observed on 40%, 35%, and 27.5% sides, respectively. Type IV caves with erosion into the lateral C2 body and undersurface of the superior articular facet were observed on 12.5% of sides. Although larger caves were found on left sides, this did not reach statistical significance. Pedicle screw placement for types III and IV were most likely to enter the vertebral artery cave ( P < 0.05). Conclusions Additional osteologic data regarding the course of the vertebral artery while within C2 may decrease morbidity during surgery in this region. [ABSTRACT FROM AUTHOR]

Objective: The study compared the endoscopic anatomy of the transnasal and transoral approaches to the craniovertebral junction (CVJ). Methods: Structures examined and compared with both the straight and angled telescopes in 10 cadaveric specimens included the pharyngeal walls and adjacent musculature, resected anterior arch of the axis and odontoid, cruciform, axial, and apical ligaments, clival and dural openings, and the intradural exposure. Results: There is considerable overlap at the pharyngeal level in the structures that can be viewed by the transoral and transnasal routes. The transoral approach provides a wider corridor with less restricted manipulation of instruments than the transnasal approach, but the transnasal approach provides a better view of the clivus, upper part of the CVJ, and the structures posterior to the removed odontoid and anterior arch of C1. Combining the two approaches provides significantly better access to the midline anterior CVJ than either approach alone, allows the scopes to be advanced in one cavity and the surgical instruments in the other cavity, and reduces the need to split the palate, tongue, or mandible in order to reach the target area. The transnasal approach also allows access to the superior part of the occipital condyles, paraclival areas, and hypoglossal canals without removal of the condyles, but these structures can be exposed by the transoral route only after at least partial removal of the condyles. Conclusion: The endoscopic transoral and transnasal approaches to the CVJ should be viewed as complementary routes as opposed to strict alternatives. [Copyright &y& Elsevier]

Objective Pedicle screws placed into C2 necessitate a thorough understanding of this bone's unique anatomy. Although multiple landmarks and measurements have been used by surgeons, these are often varied in the literature with no consensus. Herein, we studied one recently proposed landmark using the nutrient foramina of the posterior aspect of C2 for pedicle screw placement. Methods On 19 (38 sides) C2 dry bone specimens, the presence, size, location, and distance from the midline of the nutrient foramina found at the junction between the isthmus and lamina were documented and measured. In addition, to discern the source of the artery entering such foramina, an injected adult cadaver was dissected. Results The number of foramina ranged from 0–5 with a mean of 1.84. On 3 sides, no foramina were identified. The mean diameter of the foramina was 0.57 mm. The location of the foramina was at position 1 on 9.5% of sides, position 2 on 66.4% of sides, and position 3 on 24.1% of sides. The mean horizontal distance from the midline of the spinous process of C2 to the foramina was 25.17 mm. In the cadaveric specimen, the source of the artery entering these C2 nutrient foramina was found to be distal branches of the deep cervical artery. Conclusions We found the nutrient foramina of the C2 laminae are useful for pedicle screw placement. However, there are minor variations of the number and position of these structures. Lastly, on the basis of our study, 7.9% ( n = 3) of sides will not have such foramina. [ABSTRACT FROM AUTHOR]

Background Pedicle screw and translaminar screw fixation in C2 may not be applicable in many patients with anatomic abnormalities or narrow laminar thickness and spinous process height. The aim of this study was to assess morphometric and mechanical feasibilities of a novel alternative screw trajectory that pierces the bifid base of C2. Methods Anatomic measurements that determined the feasibility of spinous process bifid base (SPB) screw fixation were assessed in 14 cadaveric C2 vertebrae. Pullout tests to assess ultimate fixation strength for 3 screw trajectories (transpedicular, translaminar, and SPB) were performed in cadaveric vertebrae for comparison. Results Anatomic measurements included mean spinous process height (10.4 ± 4.2 mm) and mean bilateral bifid base length (10.1 ± 2.2 mm) and thickness (left, 4.4 ± 1.0 mm; right, 4.3 ± 0.9 mm). In 64% (9/14) of specimens, bifid base length was ≥9 mm. Mean pullout strength for transpedicle, translaminar, and SPB screws in 9 viable specimens was 648 ± 305 N, 628 ± 417 N, and 755 ± 279 N. Conclusions SPB screw fixation may be viable anatomically and mechanically for C2 fixation. Feasibility of SPB screw fixation is determined by length, thickness, and mutual angle of the bilateral bifid bases. Patients with thin (<4 mm) and short (<9 mm) bifid bases are not likely to be suitable candidates. SPB screw fixation shows potential as an alternative approach or a salvage technique for patients with high-riding vertebral arteries or severely thin C2 lamina and warrants further investigation. [ABSTRACT FROM AUTHOR]

Background Pseudomeningoceles are a rare cause of bone erosions. Development of such erosions in the C2 vertebral body and the odontoid process can lead to life-threatening instability. Treatment options to regain stability include atlantoaxial and occipitocervical fusion. For patients with a history of Chiari decompression and large C2 lesions, common fusion techniques are not always feasible. In addition, fusion surgery sacrifices physiologic motion and is therefore a disabling procedure, especially for young and active patients. Case Description We report a novel combined open operative and subsequent minimal invasive filling technique of several instable osteolytic/cystic areas within the C2 vertebra of a 28-year-old woman. The underlying cause for the lesions was a pseudomeningocele communicating with the vertebral body. This was an incidental finding 15 years after foramen magnum decompression with C1 and partial C2 laminectomy for Chiari malformation. Novel treatment included open posterior surgery with total laminectomy of the remaining C2 arch and refilling the odontoid with viscous beta tricalcium phosphate and polymethylmethacrylate bone cement. Postoperative 6- and 12-month follow-up computed tomography imaging showed a stable incorporation of the filling. Conclusions Life-threatening fractures at the occipitocervical junction are rare and often are due to high-impact trauma. Osteolytic changes at those bone compartments are a potential cause for pathologic fractures during normal daily activities. In this case, increased pressure on the bone due to a pseudomeningocele resulted in slow bone loss without symptoms. A novel combined technique of bone filling was applied successfully to stabilize the C2 vertebral bone. [ABSTRACT FROM AUTHOR]

Background Congenital spondylolytic spondylolisthesis of C2 vertebra resulting from deficient posterior element of the axis is rarely described in the literature. Case Description We describe a unique case of agenesis of posterior elements of C2 with craniovertebral junction anomalies consisting of osseous, vascular, and soft tissue anomalies. A 26-year-old man presented with symptoms of upper cervical myelopathy of 12 months' duration. A computed tomography scan of the cervical spine including the craniovertebral junction revealed spondylolisthesis of C2 over C3, atlantoaxial dislocation, occipitalization of the atlas, hypoplasia of the odontoid, and cleft posterior C1 arch. Additionally, the axis vertebra was found devoid of its posterior elements except bilaterally rudimentary pedicles. Magnetic resonance imaging revealed tonsilar herniation, suggesting associated Chiari type I malformation. CT angiogram of the vertebral arteries displayed persistent bilateral first intersegmental arteries crossing the posterior aspect of the C1/2 facet joint. This patient underwent foramen magnum decompression, C3 laminectomy with occipito-C3/C4 posterior fusion using screw and rod to maintain the cervical alignment and stability. Conclusion We report this rare constellation of congenital craniovertebral junction anomaly and review the relevant literature. [ABSTRACT FROM AUTHOR]

Background Cervical myelopathy due to bilateral laminar cleft of the axis is extremely rare, and few cases have been previously reported. However, its treatment is relatively simple. Surgical removal of the anomalous bony structure compromising the spinal canal can sufficiently achieve a good outcome. Case Description A 56-year-old man presented with a 2-year history of stiffness of the left upper and lower extremities. Cervical spine computed tomography showed a bony cleft at both laminae of the posterior arch of the axis, with obvious cord compression on magnetic resonance imaging. Although absence of right pedicle and spina bifida of C7 were also detected, there was no cord compression at this level. The patient underwent surgical removal of the anomalous laminar cleft and the spinous process of the axis. Postoperatively, he improved rapidly and was discharged on the seventh postoperative day. He was asymptomatic at the 3-year follow-up. After surgery, the preoperative myelopathy status was much improved. About 7 years after surgery, radiographs showed no kyphosis and instability. Conclusion Invaginated bilateral laminar cleft of the axis is a rare cause of cervical myelopathy. The findings in our case should broaden the radiographic differential diagnosis in patients with cervical myelopathy. Surgical removal is an appropriate and simple treatment for this patient, resulting in a satisfactory outcome. [ABSTRACT FROM AUTHOR]

Background The craniocervical junction is a complex anatomic location that contains the occipital bone, atlas, axis, and important complex ligamentous structures. The stability of this region is ensured only with the help of ligaments. Case Description A 6-year-old boy was admitted to our clinic for neck pain. Computed tomography and magnetic resonance imaging revealed a lytic bone lesion involving the C2 vertebral body and pedicle without odontoid tip. The tumor was resected using an anterior retropharyngeal approach and a wide marginal resection method. The odontoid tip and alar ligaments were protected, and the costal autografts were located between the C1-odontoid tip and the C3 body. The costal graft was stabilized in the C3 body with a miniplate. Then, C1-C3 posterior fixation with fusion was performed. The craniocervical junction was not considered unstable because the occipital bone was not involved in the fusion. Histologic examination confirmed the diagnosis of eosinophilic granuloma. Fusion was detected on a 1-year postoperative cervical computed tomography scan. Conclusions The occiput should not be involved in the fusion area when the alar ligaments are preserved during surgery for a C2 lesion. [ABSTRACT FROM AUTHOR]