Exploring the Pathogenesis of Atlanto-Occipital Instability in Chiari Malformation With Type II Basilar Invagination: A Systematic Morphological Study

BACKGROUND

Our previous study suggested that atlanto-occipital instability (AOI) is common in patients with type II basilar invagination (II-BI).

OBJECTIVE

To further understand the pathogenesis of AOI in Chiari malformations (CM) and CM + II-BI through systematic measurements of the bone structure surrounding the craniocervical junction.

METHODS

Computed tomography data from 185 adults (80 controls, 63 CM, and 42 CM + II-BI) were collected, and geometric models were established for parameter measurement. Canonical correlation analysis was used to evaluate the morphological and positional relationships of the atlanto-occipital joint (AOJ).

RESULTS

Among the 3 groups, the length and height of the condyle and superior portion of the lateral masses of the atlas (C1-LM) were smallest in CM + II-BI cases; the AOJ had the shallowest depth and the lowest curvature in the same group. AOJs were divided into 3 morphological types: type I, the typical ball-and-socket joint, mainly in the control group (100%); type II, the shallower joint, mainly in the CM group (92.9%); and type III, the abnormal flat-tilt joint, mainly in the CM + II-BI group (89.3%). Kinematic computed tomography revealed AOI in all III-AOJs (100%) and some II-AOJs (1.5%) but not in type I-AOJs (0%). Morphological parameters of the superior portion of C1-LM positively correlated with those of C0 and the clivus and significantly correlated with AOI.

CONCLUSION

Dysplasia of the condyle and superior portion of C1-LM exists in both CM and II-BI cases yet is more obvious in type II-BI. Unstable movement caused by AOJ deformation is another pathogenic factor in patients with CM + II-BI.

[Efficacy comparison of minimally invasive atlantoaxial mass fusion and open atlantoaxial fusion in the treatment of atlantoaxial dislocation]

Objective: To compare the clinical effects of minimally invasive intermuscular atlantoaxial lateral mass fusion (Mis-PALF) and open atlantoaxial fusion in patients with atlantoaxial dislocation. Methods: The clinical data of patients with atlantoaxial dislocation who received Mis-PALF operation (17 cases) or open atlantoaxial fusion (88 cases, as control) in the Third Hospital of Peking University from September 2015 to September 2021 were analyzed retrospectively. In Mis-PALF group, there were 9 males and 8 females, aged (45.8±19.8) years; and there were 48 males and 40 females in the control group, aged (50.0±13.9) years. The operation time, perioperative blood loss, postoperative body temperature, postoperative pain [assessed with visual analogue scale (VAS)], postoperative additional analgesic drugs, postoperative hospitalization time, the improvement rate of Japanese Orthopedic Association (JOA) scores of spinal cord function in three-months follow-up and complications were compared between the two groups. Results: Mis-PALF group had less perioperative blood loss than control group [(111.8±35.9)ml vs (362.9±18.6)ml, P<0.01], shorter hospitalization time [(3.06±0.63) days vs (4.24±0.14) days, P<0.01] and fewer additional analgesic drugs (3/17 vs 56/88, P<0.01). There was no significant difference between the Mis-PALF and control group in operation time [(125±7)min vs (113±8)min, P=0.525], patients with fever(11/17 vs 37/88, P=0.086) or postoperative pain (1/17 vs 13/88, P=0.357), the improvement rate of JOA score (66.9%±28.8% vs 74.2%±28.6%, P=0.409) and complications rate (1/17 vs 3/88, P=1.000). Conclusion: Mis-PALF can significantly reduce the perioperative blood loss, shorten the postoperative hospitalization time and the additionally use of analgesic drugs without increasing complications.

Craniovertebral Junction Anomalies: An Overlooked Cause of 'Posterior Circulation Stroke'

BACKGROUND

Vertebral artery dissection (VAD) is a treatable cause of vertebrobasilar ischemic stroke and can be spontaneous or more commonly traumatic. Craniovertebral junction (CVJ) anomalies are a rare and often overlooked cause of VAD.

OBJECTIVE

The objective of this study was to study cases where CVJ anomaly presented as posterior circulation infarct and to conduct a relevant literature review.

MATERIALS AND METHODS

The medical records of seven patients who were managed for posterior circulation infarct associated with CVJ anomaly at our center from January 2009 through August 2013 were reviewed. PubMed and MEDLINE databases were also searched for similar cases, and the published case reports/series were reviewed.

RESULTS

Seven patients met our inclusion criteria and were included in the study. The mean age was 17.4 years (range: 10-35 years). All the patients were males. The most common symptoms were headache, vomiting, and gait ataxia. Slurring of speech was seen in one patient. One patient had repeated episodes of gait ataxia with left-sided weakness with complete recovery in between the episodes. One patient presented in unconscious state. Four patients complained of vertigo. The median duration of symptoms was 7 days (range: 3 days-12 months).

CONCLUSIONS

CVJ anomalies can present as posterior circulation infarct. One must evaluate all patients with posterior circulation stroke, especially young patients, for possible CVJ anomalies. Dynamic lateral cervical spine X-ray is an important tool to diagnose AAD. CVJ anomalies represent a treatable cause of VAD.

[Long-term observation of the effect of atlantoaxial fusion on the growth and development of children's cervical spine]

Objective: To explore the effect of atlantoaxial fusion on the growth and development of children's cervical spine. Methods: The clinical data of 12 children with atlantoaxial dislocation who underwent posterior atlantoaxial fusion at Department of Orthopaedics,the 909th Hospital of Joint Logistics Support Force of Chinese People's Liberation Army from June 2002 to September 2013 were retrospective analyzed. There were 7 males and 5 females,with age of (8.1±3.1)years (range:3 to 13 years).Nine cases were traumatic and 3 cases were congenital malformations,1 of the children had Down syndrome. All children underwent posterior atlantoaxial fusion. Furthermore,the information of the height and anteroposterior width of the cervical vertebral bodies and vertical growth rate of the fusion mass were collected from all patients immediately postoperatively and during the follow-up.The range of motion in cervical spine were collected preoperatively and during follow-up period. Data were compared using independent sample t test, paired sample t test and repeated-measurement. Results: All 12 children had regular follow-up within (122.4±25.3)months(range:65 to 163 months). The height and anteroposterior width of the cervical vertebral bodies were similar to these results with those in published reports of growth in normal children of the same age(all P<0.01). At the last follow-up,atlantoaxial fusion of 11 cases had substantial growth (vertical growth rate of the fusion mass:11 cases ≥10%, 1 case <10%);the range of motion in cervical spine was close to the normal level (flexion(55.2±5.0)°,extension (65.3±4.9)°,left bending (41.7±4.5)°,right bending (42.4±4.4)°,left rotation (66.4±5.6)°,right rotation (68.5±5.8)°). Conclusions: Atlantoaxial fusion surgery is satisfactory in the treatment of pediatric atlantoaxial dislocation.During the follow-up,the growth and development of the cervical spine is close to that of normal children of the same age.In long-term observation,it has been found that the operation has no negative effect on the growth and development of the children's cervical spine.

Evaluating craniovertebral stability in Chiari malformation coexisting with Type II basilar invagination: an observational study based on kinematic computed tomography and its clinical application

BACKGROUND

Treatment of Chiari malformation (CM) is controversial, especially when it coexists with "stable" or Type II basilar invagination (CM+II-BI). Precise evaluation of craniovertebral junction (CVJ) stability is crucial in such patients; however, this has never been validated. This study aimed to dynamically evaluate atlanto-condyle and atlantoaxial stability by kinematic computed tomography (CT) and report its surgical treatment.

METHODS

The study recruited 101 patients (control, CM, and CM+II-BI groups: 48, 34, and 19 patients, respectively). During kinematic CT, the CVJ stability-related parameters were measured and compared between the three groups. The surgical strategy for treating CM+II-BI was based on these results. Pre- and postoperative images were acquired, and functional scores were used to assess the outcome.

RESULTS

Among the three groups, the length of the clivus and the height of the condyle were the shortest in the CM+II-BI group, which was accompanied by the greatest rotation of the atlas and atlanto-condyle facet movement on cervical flexion and extension. Moreover, in such patients, increased Chamberlain's baseline violation indicated the aggregate invagination of the odontoid in the flexed position, and asymmetric displacement of atlantoaxial facets was observed. Seventeen CM+II-BI patients underwent surgical treatment with atlantoaxial distraction and occipitocervical fusion. The syringomyelia width and tonsillar herniation decreased significantly, and functional scores indicated symptom relief and good outcomes.

CONCLUSIONS

CVJ instability, especially the ultra-movement of atlanto-condyle facets, commonly exists in II-BI as evaluated using kinematic CT. The surgical strategy of atlantoaxial distraction and occipitocervical fusion should be considered to treat such patients.

Surgical treatment for upper cervical deformity with atlantoaxial joint dislocation using individualized 3D printing occipitocervical fusion instrument: A case report and literature review

To introduce a novel technique of using individualized 3D printing occipitocervical fusion instrument (3D-OCF) for the treatment of upper cervical deformity with atlantoaxial joint dislocation.The surgery for deformity of the craniocervical junction area is a challenge in the field of spine. If the surgical deviation is too large to injure the spinal cord or vertebral artery, it will cause catastrophic damage to the patient. Therefore, it is controversial whether these patients should undergo surgical treatment. We provide a novel surgical approach for the challenging upper cervical surgery through 3D-OCF and a typical patient.We present a 54-year-old female patient, who suffered from dizziness and numbness in her limbs for 8 months. After the patient was admitted, we performed the three-dimensional CT scan, modeled using Mimics software 17.0, and designed customized occipitocervical fusion instrument. Besides, we repeatedly perform simulated surgery based on 3D-printed models before surgery.The operative time was 142 minutes and the intraoperative blood loss was 700 mL. X-ray showed reduction of atlantoaxial dislocation and accurate position of internal fixation. The patient's symptoms were significantly relieved: the sensation of dizziness and numbness of limbs was obviously relieved, and the sense of banding in chest, abdomen, and ankle was disappeared. At the last follow-up, imaging showed that 3D-OCF had bone-integration and Syringomyelia was disappeared. The patient's cervical JOA (Japanese Orthopaedic Association) score increased from 10 points to 17 points.Individualized 3D-OCF can improve the safety and accuracy of upper cervical surgery, reduce the operative time and the number of fluoroscopy. Our study provides a novel surgical approach for the challenging upper cervical surgery.

Two-Stage Approach for Unstable Pediatric Craniocervical Junction Anomalies with a Halo Vest and Delayed Occipitocervical Fusion: Technical Note, Case Series, and Literature Review

OBJECTIVE

Malformations in the craniocervical junction (CCJ) are rare in the pediatric population but often need surgical treatment. We present a pediatric case series of patients treated with a 2-stage surgical approach with a halo vest and occipitocervical fusion and review complications and outcomes.

METHODS

A retrospective analysis of a single-center case series was performed. Pediatric patients affected by congenital craniocervical junction anomalies and treated with a 2-stage approach were included. A halo vest was implanted in the first surgery, and ambulatory progressive reduction was performed. When a favorable anatomic situation was observed, arthrodesis was performed. Safety analysis was undertaken by analyzing the incidence of complications in both procedures. Effectivity analysis was carried out analyzing radiologic and clinical outcome (Goel grade and modified Japanese Orthopaedic Association score). Student t test was used for statistical analysis.

RESULTS

Sixteen cases were included. Mean age of patients was 9.38 years. Safety analysis showed 2 halo loosenings, 1 pin infection, 2 wound infections, 1 cerebrospinal fluid leak, and 2 delayed broken rods. No major complications were observed. Radiologic analysis showed an improvement in the tip of the odontoid process to the McRae line distance (from -3.26 mm to -6.16 mm), atlantodental interval (from 3.05 mm to 1.88 mm), clival-canal angle (from 134.61° to 144.38°), and cervical kyphosis (from 6.39° to 1.54°). Clinical analysis also showed improvement in mean Goel grade (from 1.75 to 1.44) and modified Japanese Orthopaedic Association score (from 15.12 to 16.41).

CONCLUSIONS

The 2-stage approach was a suitable and effective treatment for craniocervical junction anomalies in pediatric patients.

Combined 3-dimensional printing model and 3-dimensional fluoroscopic navigation to assist C2 pedicle screw insertion: A case report

RATIONALE

The misplaced cervical screw can cause catastrophic surgical complications, such as nerve root damage, vertebral artery compromise, spinal cord injury, and even paraplegia. Thus, the present study aims to describe a novel technique of 3-dimensional printing model (3DPM) combined with 3-dimensional fluoroscopic navigation (3DFN) to facilitate C2 pedicle screw insertion.

PATIENT CONCERNS

A 56-year-old male patient presented hypoesthesia of the trunk and extremities, accompanied by a walking disorder.

DIAGNOSES

Congenital atlantoaxial malformation with atlantoaxial dislocation.

INTERVENTIONS

He underwent an occipital cervical fusion. We used 3DPM and 3DFN technology to guide C2 pedicle screws insertion.

OUTCOMES

We inserted 2 pedicle screws and 4 lateral mass screws using the combined 3DPM and 3DFN technology. All screws were classified as excellent position postoperatively. The surgical duration, total fluoroscopic time, and the bleeding volume were 258 minutes, 3.9 minutes, and 237 mL, respectively. No surgical complications, such as neurological compromise, nonunion, dysphagia, infection, polypnea, fixation failure, pseudarthrosis formation, or revision surgery, were observed. The follow-up duration lasted 30 months.

LESSONS

The combination of 3DPM and 3DFN to promote C2 pedicle screws implantation is a safe, accurate, reliable, and useful technology, which can achieve an excellent therapeutic effect and avoid surgical complications. However, using the 3DPM and 3DFN technology may increase the financial burden of patients.

Posterior atlantoaxial facet joint reduction, fixation and fusion as revision surgery for failed suboccipital decompression in patients with basilar invagination and atlantoaxial dislocation: Operative nuances, challenges and outcomes

OBJECTIVE

To report the technical nuances and clinical outcomes of posterior atlantoaxial facet joint reduction, fixation and fusion (AFRF) technique as a revision procedure for BI and AAD patients with failed suboccipital decompression and large occipital bone defect.

PATIENTS AND METHODS

We reviewed 32 patients with BI and AAD who were misdiagnosed as a simple Chiari malformation and received a suboccipital decompression surgery before admission. All patients underwent AFRF as a revision surgery. The separating, fusing, opacifying and false-coloring-volume rendering (SFOF-VR) technique was used to identify the course of the VA. Clinical and radiological outcomes were assessed after revision surgeries.

RESULTS

Clinical symptoms improved in all patients. The postoperative atlantodens interval, Wackenheim line and clivus-canal angle significantly improved (all P < 0.01). Intraoperative dural tear and cerebrospinal fluid leakage occurred in 3 patients and were managed by suture repair and lumbar drain. Abnormal VA was identified in 7 patients and no VA injury occurred with the aid of SFOF-VR technique. The average follow-up was 19.1 months and atlantoaxial bone fusion was confirmed in 31 patients.

CONCLUSION

For BI and AAD patients with failed suboccipital decompression, revision surgery is challenging. Occipitocervical fixation and posterior midline bone grafting are rather difficult due to the large occipital bone defect. The current study demonstrated that the posterior AFRF is a simple, safe and highly effective technique in revision surgery for such cases. For VA variations, the SFOF-VR technique is an effective tool to delineate the course VA.

Usefulness of 3D Printed Models in the Management of Complex Craniovertebral Junction Anomalies: Choice of Treatment Strategy, Design of Screw Trajectory, and Protection of Vertebral Artery

OBJECTIVE

To evaluate the usefulness of 3-dimensional (3D) printed models as an aid for the treatment of complex CVJ anomalies.

METHODS

3D printed models were fabricated for 21 patients with complex CVJ anomalies, including vertebral artery anomaly, thin C2 pedicle, vertical atlantoaxial facet joint, or rotational dislocation combined with atlantoaxial dislocation and basilar invagination. Preoperative planning, surgical simulation, and intraoperative reference were achieved using the 3D model during the surgical treatment. The usefulness of 3D printed models, and postoperative clinical and radiological outcomes were assessed.

RESULTS

Direct posterior reduction and atlantoaxial fixation were achieved in 19 patients. Transoral odontoidectomy followed by posterior fixation was implemented for 2 patients with vertical facet joint and rotational dislocation. All screws were safely inserted with no complication, and 90% patients achieved a >60% reduction of both horizontal and vertical dislocation. Clinical symptoms improved in all patients, with the averaged Japanese Orthopedic Association scores increasing from 11.14 to 14.43 (P < 0.01).

CONCLUSIONS

The patient-specific 3D printed model would be an effective tool for evaluation of the reducibility of the atlantoaxial dislocation and basilar invagination, decision making in choosing the optimal surgical approach and way of fixation, and precise placement of the screw while protecting the vertebral artery and spinal cord. The risk of neurovascular injury was minimized, and encouraging outcomes were achieved with the aid of this technique.

[Teenagers with torticollis]

Teenagers with torticollis In this article we describe three cases of children with torticollis. A 17-year-old patient who appears to have Klippel-Feil syndrome and is treated conservatively. An 11-year-old-patient with torticollis, present since a fall two days earlier and attributed to a subluxation of C1-C2. Ultimately, she had to be treated surgically with an atlantoaxial spondylodesis and has made a good recovery. Finally, a 15-year-old who presents with torticollis which has been present from early childhood. The diagnosis neglected congenital muscular torticollis is made. Because of increasing discomfort she is treated surgically with release of the sternocleidomastoideus. Postoperative, the patient has fewer symptoms. Physicians should be aware of different causes when there is persistent torticollis. Furthermore, children presenting with posttraumatic torticollis require a strict follow-up because atlanto-axial subluxation can lead to permanent deformity.

Chronic posterior atlantoaxial subluxation associated with os odontoideum: a rare condition. A case report and literature review

Introduction

Os odontoideum is a rare cervical lesion. This unusual condition is sometimes associated with atlantoaxial subluxation, which is mostly anterior subluxation. Posterior atlantoaxial subluxation due to os odontoideum is extremely rare.

Case presentation

We report an unusual case of a 60-year-old Thai female, who was diagnosed as having chronic posterior atlantoaxial subluxation associated with os odontoideum with progressive myelopathy. The patient underwent posterior arch of C1 laminectomy and an occipito-C3 fusion using an occipital plate, C2 pedicle screws, C3 lateral mass screws and autologous iliac crest strut bone graft arthrodesis. During three years of follow-up, she was clinically significantly improved and postoperative radiographs showed a solid osseous fusion without loss of correction or implant failure.

Discussion

Chronic posterior atlantoaxial subluxation associated with os odontoideum is rare. This condition can cause occipital-cervical pain, myelopathy, intracranial symptoms, or death. Surgical decompression and stabilization is the treatment of choice. Principles of treatment are to prevent sudden death from neurological compromise, improve neurological status, stabilize the cervical spine, and improve quality of life. Surgical options include atlantoaxial fusion, occipito-C2 fusion, and occipito-C3 fusion. Decision making depends on the location of spinal cord compression, area for arthrodesis, and bone quality.

Bilateral persistent 'second' intersegmental vertebral arteries: illustrated with a case

Congenital craniovertebral junction deformities can be associated with an anomalous vertebral artery (VA). At times, the artery crosses the joint posteriorly (i.e., persistent first intersegmental artery) and is at risk during posterior approach. We report a new variant, wherein the bilateral VA coursed medially after exiting the C3 transverse foramina to lie beneath C2 pars interarticularis and enter the foramen magnum (without passing through C2 transverse foramen anywhere along its course). This is possibly a result of bilateral persistent second intersegmental arteries. It is pertinent to recognize this unusual variant to avoid VA injury, especially while inserting C2 pars/transarticular screw.

Complex congenital atlantoaxial dislocation in an infant: case report

The authors report the case of congenital atlantoaxial dislocation in a 9-month-old female infant, who presented with progressive quadriparesis and respiratory failure. The problems in management due to such an early age of presentation, including atypical clinical presentation, unique radiological findings, limited management options, and variable clinical outcomes discussed. This is the youngest case of non-syndromic congenital atlantoaxial dislocation, reported to date, and is a unique combination of lateral, rotatory, and antero-posterior atlantoaxial dislocation.

Atlantooccipital overlapping and its effect on outcomes after ventral fixation in dogs with atlantoaxial instability

We compared clinical outcomes after ventral fixation in dogs with atlantoaxial instability (AAI) on the basis of the presence or absence of atlantooccipital overlapping (AOO). Of 41 dogs diagnosed with AAI and treated ventral fixation, 12 exhibited AOO (AOO group), whereas 29 did not (non-AOO group). The AOO group had significantly higher neurological scores before (P=0.024) and 1 month after (P=0.033) surgery compared with the non-AOO group; however, no significant differences were observed between the groups 2 months after surgery. The presence of complicating AOO affected the clinical signs for dogs with AAI, but did not directly affect the outcome of surgical stabilization of AAI.

Computed Tomography Imaging Study of Basilar Invagination and Atlantoaxial Dislocation

OBJECTIVE

We sought to analyze axis deformities and the biomechanics related to atlantoaxial dislocation (AAD) in patients with basilar invagination (BI).

METHODS

Seventy-six patients were retrospectively analyzed including 21 patients who had BI (group B), 32 patients with BI and AAD (group C), and 23 nondeformity control subjects (group A). Using 3-dimensional computed tomography imaging the distance from the tip of the dens above the Chamberlain line in the sagittal plane, atlantodental interval, sagittal inclination, coronal inclination, and craniocervical tilt, the height of the odontoid and ratio of the height to the odontoid basal width were measured in each patient. We statistically analyzed the resulting data for correlations among physiologic measurements and disease state.

RESULTS

The height of the odontoid process in groups A, B, and C was 13.38 ± 1.50 mm, 10.87 ± 1.48 mm, and 8.49 ± 2.49 mm, respectively. The ratio of height-to-basal width of the odontoid in groups A, B, and C was 1.32 ± 0.21, 0.91 ± 0.21, and 0.65 ± 0.17, respectively. The sagittal inclination in groups A, B, and C was 85.85 ± 4.55 degrees, 105.76 ± 10.72 degrees, and 123.48 ±12.43 degrees, and the coronal inclination was 108.95 ± 24.09 degrees, 105.40 ± 25.16 degrees, and 108.82 ± 21.41 degrees, respectively. The craniocervical tilt in groups A, B, and C was 60.31 ± 6.98 degrees, 84.53 ± 18.94 degrees, and 71.79 ± 11.69 degrees, respectively. The height of the odontoid, height-to-basal width, and sagittal inclination were significantly correlated with both BI and AAD (P < 0.001). Odontoid height and height-to-basal width ratio were significantly correlated with BI, AAD, and sagittal inclination (P < 0.001). Finally, craniocervical tilt was correlated only with the BI severity (P < 0.001).

CONCLUSION

This study confirms that deformities of the odontoid process and the lateral joint correlate with severity of BI, while deformity of the odontoid process may be a primary factor in AAD for patients with BI.

First Gross Anatomic Findings of an Os Odontoideum

BACKGROUND

Os odontoideum is an uncommon abnormality of the craniovertebral junction where the tip of the odontoid process lacks continuity with the body of C2. The clinical presentation is variable, but severe neurologic impairment can result.

CASE DESCRIPTION

We report the gross and radiologic findings of a cadaver found to harbor an os odontoideum.

CONCLUSIONS

To our knowledge, there are no cadaveric reports in the literature regarding an os odontoideum. Such a case allows a rare window into the anatomy and relationships of this pathologic structure.

Vertebral Malformation, Syringomyelia, and Ventricular Septal Defect in a Dromedary Camel (Camelius Dromedarius)

An occipitoatlantoaxial malformation and ventricular septal defect (VSD) were diagnosed in a 36-hour-old female camel. Physical examination revealed a firm protrusion of the dorsal aspect of the atlas and axis, tilting of the head to the left, and a grade V/VI systolic murmur. Neurological examination revealed proprioceptive deficits and ataxia of all 4 limbs. Radiographic examination and necropsy demonstrated malformation, fusion of the atlas to the occiput and hypoplasia of the dens of the axis, and subluxation of the atlantoaxial joint. Dorsoventral laxity of the atlantoaxial joint was also present, with compression of the cervical spinal cord. A 1.5-cm-diameter VSD was observed also. Histopathologic examination of the cervical spinal cord revealed a cavity extending from the level of the first to fourth cervical segment, dorsal to the central canal, 5 cm long and 1–2 mm in diameter. The cells around the cavity were positive for glial fibrillary acidic protein and sporadically positive for vimentin. This cavitary structure was consistent with syringomyelia, which was lined by glial cells, surrounded by edematous white matter with Wallerian-like degeneration and with neuronal necrosis in the adjacent dorsal horns.

Complete Spontaneous Regression of the Intraspinal Synovial Cyst at the C1-C2 Junction Following with Atlantoaxial Fusion of Non-Union Odontoid Fracture: A Case Report

The author reported an extremely rare case of intraspinal synovial cyst at C1-C2 junction, located posteriorly to the odontoid process, compressing the upper cervical spinal cord. The patient had a history of spinal trauma 40 years ago without prior definitive treatment, presenting with two months of left leg and arm numbness with neck pain. Imaging studies including plain radiographs, computed tomography (CT), and magnetic resonance imaging (MRI) of the cervical spine showed a large synovial cyst associated with atlantoaxial instability from non-union fracture of the odontoid process. The atlantoaxial fusion was performed without a direct excision of the synovial cyst, the patient showed significant improvement of neck pain and numbness of all extremities. In addition to the fracture stabilization, the follow-up post operative MRI revealed spontaneous regression of the intraspinal synovial cyst after atlantoaxial fusion alone

Surgical stabilization of the atlanto-occipital overlap with atlanto-axial instability in a dog

The atlanto-occipital (AO) overlap in combination with atlanto-axial (AA) instability was found in a dog. We hypothesized that ventral fixation of the AA junction can stabilize the atlas and prevent AO overlap by reviewing our past cases with AA instability. A standard ventral fixation of the AA junction using stainless k-wires and polymethyl methacrylate (PMMA) was performed. The dog fully recovered, and no complication was noted. The results of the postoperative CT imaging supported our hypothesis. The ventral fixation of the AA junction is a feasible treatment option for similar cases, although craniocervical junction abnormalities (CJA) including AA instability are varied, and careful consideration is required for each case.

A case of fourth atlanto-axial facet joint: anatomical description

PURPOSE

To report a rare fourth atlanto-axial joint.

METHODS

A cadaveric specimen of a young male adult from occiput to C4 was dissected for anatomical study of craniocervical region. A true fourth atlanto-axial joint was confirmed. Its morphological characteristics were described.

RESULTS

The fourth atlantoaxial joint is rarely seen. The possible embryogenesis is discussed. This case raises an anatomical possibility of a new variant in this region.

CONCLUSIONS

A unique case with an anatomically proven fourth atlantoaxial joint is reported. This anomaly can lead to misdiagnosis. CT scan coupled with MRI can facilitate accurate diagnosis.

Evaluation of Fetal First and Second Cervical Vertebrae: Normal or Abnormal?

OBJECTIVES

To use 3-dimensional sonographic volumes to evaluate the variable appearance of the normal fetal cervical spine and craniocervical junction, which if unrecognized may lead to misdiagnosis of malalignment at the first and second cervical vertebrae (C1 and C2).

METHODS

Three-dimensional sonographic volumes of the fetal cervical spine were obtained from 24 fetuses at gestational ages between 12 weeks 6 days and 35 weeks 1 day. The volumes were reviewed on 4-dimensional software, and the vertebral level was determined by labeling the first rib-bearing vertebra as the first thoracic vertebra. The ossification centers of the cervical spine and occipital condyles were then labeled accordingly and evaluated for alignment and structure by rotating the volumes in oblique planes. The appearance on multiplanar images was assessed for possible perceived anomalies, including malalignment, particularly at the C1 and C2 levels. Evidence of head rotation was correlated with the presence of possible malalignment at C1-C2. Head rotation was identified in the axial plane by measuring the angle of the anteroposterior axis of C1 to the anteroposterior axis of C2.

RESULTS

Of the 24 fetuses, 16 had adequate quality to assess the entire cervical spine and craniocervical junction. All 16 cases showed an osseous component of C1 that did not align directly with C2 on some of the multiplanar images when the volumes were rotated, which could lead to suspected diagnosis of spinal malalignment or a segmental abnormality, as occurred in 2 clinical cases in our practice. All 16 cases showed at least some degree of head rotation, ranging from 2° to 36°, which may possibly explain the apparent malalignment. The lateral offset from C1 to C2 ranged from 0.0 to 3.3 mm.

CONCLUSIONS

The normal C1 and C2 ossification centers may appear to be malaligned due to normal offsetting (lateral displacement) of C1 on C2. An understanding of the normal development of the cervical spine is important in assessing spinal anatomy.

[Application of pedicle screw internal fixation for atlantoaxial instability of children]

OBJECTIVE

To investigate the effectiveness of pedicle screw internal fixation for the atlantoaxial instability of children.

METHODS

Between July 2005 and January 2012, 19 cases of atlantoaxial instability were treated, included 10 boys and 9 girls with an average age of 7.5 years (range, 4-15 years). The X-ray films, CT, and MRI examinations of the cervical spine showed craniocervical malformation in 9 cases, congenital os odontoideum in 3 cases, odontoid fracture (type II) in 1 case, disruption of transverse ligament in 2 cases, atlantoaxial fracture and dislocation in 4 cases; and spinal cord injury in 8 cases, according to the American Spinal Cord Injury Association (ASIA) impairment scale, 1 case was rated as grade B, 2 as grade C, and 5 as grade D. Preoperative skull traction was performed routinely on all cases, and complete reduction was achieved in 17 cases, no reduction in 2 cases. In 17 patients who achieved complete reduction, pedicle screw internal fixation was used through posterior approach, including occipitocervical fusion and fixation in 5 cases, and atlantoaxial fusion and fixation in 12 cases; in 2 patients with no reduction, pedicle screw internal fixation was used through posterior approach (atlantoaxial fusion and fixation) after release by transoral approach.

RESULTS

The operation was successfully performed in all patients. The mean operation time was 89 minutes; the mean intraoperative blood loss was 95 mL; the mean postoperative drainage volume was 73 mL; and the mean hospitalization days were 14 days. The patients were followed up 6-27 months (mean, 18.3 months). Satisfactory atlantoaxial fusion was obtained, and bone fusion was obtained at 3-7 months after operation (mean, 4.5 months). No breakage of screw or rods and re-dislocation occurred during follow-up. At last follow-up, the cervical range of motion (CROM) of the left and right rotation were (62.0 +/- 5.9) degrees and (63.9 +/- 3.8) degrees respectively in 5 patients receiving occipitocervical fusion and fixation, showing significant difference when compared with the values of normal children [(72.3 +/- 7.0) degrees and (74.1 +/- 7.6) degrees, respectively] at the same age (t = -3.915, P = 0.018; t = -5.954, P = 0.004). The CROM of the left and right rotation were (70.5 +/- 5.8) degrees and (72.7 +/- 4.9) degrees respectively in 14 patients receiving atlantoaxial fusion and fixation, showing no significant difference when compared with normal children at the same age (t = -1.417, P = 0.180; t = -1.021, P = 0.323). The visual analogue scale (VAS) score was significantly decreased from 7.8 +/- 1.1 at pre-operation to 3.5 +/- 0.8 at last follow-up (t = 17.267, P = 0.000). In 8 cases having spinal cord injury, 2 cases were rated as grade C, 1 case as grade D, and 5 cases as grade E according to ASIA impairment scale.

CONCLUSION

Technique of pedicle screw internal fixation has been proven to be an effective treatment for the atlantoaxial instability of children. It plays an important part in relieving pain and limitation of the cervical region.

Dental surgery and anesthetic precautions of a patient with Down syndrome and juvenile rheumatoid arthritis: a case report

Down syndrome and juvenile rheumatoid arthritis have been associated with ligament laxity, specifically the atlantoaxial ligament, which maintains the proper positioning of the cervical first and second vertebrae. The joint consists of different pathological processes, and it is paramount that individuals with either condition be screened appropriately before surgery is contemplated. The purpose of this paper was to present a case of an individual with both conditions and describe precautionary measures that were undertaken to safely complete dental treatment under general anesthesia and avoid morbidity.

[Roles of computed tomography in the diagnosis and treatment of complex atlas pillow deformity]

OBJECTIVE

To explore the roles of computed tomography (CT) in the diagnosis and treatment of complex atlas pillow deformity.

METHODS

From January 2010 to February 2012, the preoperative and postoperative CT imaging findings were collected from 32 cases of complicated atlas pillow deformity undergoing surgical treatment at Henan Provincial People's Hospital. There were 18 males and 14 females with a mean age of 36.8 years (range: 23 - 65). The average duration of disease was 4.5 years (range: 0.25 - 10).

RESULTS

In 32 cases, a definite diagnosis was established preoperatively by coronary sagittal CT scans and 3-dimensional reconstruction. And CT re-examinations were performed to review the postoperative curative efficacies.

CONCLUSION

CT imaging examination is of vital importance in the diagnosis, personalized surgical procedures and prognostic evaluation of complex craniocervical junction deformity.

[Treatment strategy of rotatory dislocation of atlantoaxial articulation in children]

OBJECTIVE

To analyze appropriate strategy about treatment of rotatory dislocation of atlantoaxial articulation in children.

METHODS

From March 2005 to February 2009, 36 patients with rotatory dislocation of atlantoaxial articulation were retrospectively analyzed, including 25 males and 11 females, with the average age of 7.8 years (ranged 3 - 14 years). According to Fielding-Hawkins clinical classification, type I 24 cases, type II 8 cases, type III 2 cases, type IV 2 cases. All of the patients were assessed rotatory dislocation of atlantoaxial articulation and whether or not upper cervical spine malformation by X-ray, MRI and CT scan and three-dimensional reconstruction. Thirty-two cases received observational treatments which were reduction after cervical traction, without appearance of the deformity, without neurological symptoms. And another 4 serious cases (irreducible atlantoaxial dislocation or with os odontoideum) received posterior atlantoaxial fixed autograft fusion.

RESULTS

Rotation of atlas decreased from 16.0° ± 4.4° (range, 5° to 26°) pre-therapy to 4.5° ± 1.5° (range, 0° to 8°) post-therapy in 35 cases, rotation of atlas had significant difference between pre-therapy and post-therapy (t = 14.75, P < 0.05). One patient pre-therapy rotation of atlas was 45°, post-therapy was 4°. All patients were followed up for 14 - 38 months (mean, 18 months), 32 cases who received cervical traction and external fixation resulted in satisfactory outcome in which all the ankylodeire were disappear, bilateral masses were symmetrical on anterior-posterior and good functional activities of cervical. All the 4 cases surgically treated obtained reduction, sound bony fusion and neural symptoms were improved obviously after operation.

CONCLUSIONS

Conservative treatment has been proved to be very effective in most of rotatory dislocation of atlantoaxial articulation in children. However, operative treatment should be considered in the following situations: irreducible atlantoaxial dislocation or patients with os odontoideum.

Analysis of the treatment of 576 patients with congenital craniovertebral junction malformations

We aim to report our experience treating craniovertebral junction malformations (CVJM) and to investigate the management of this uncommon condition. Between 2000 and 2009, 629 patients with CVJM underwent surgery in our department. Fifty-three patients were lost to follow-up; therefore 576 patients completed follow-up, for an average period of 3 years and 2 months. All patients were diagnosed on the basis of clinical presentation and imaging features, and we found that anomalies of the occipitocervical junction manifested as four major types. Different microsurgical treatments were carried out in these patients according to disease type, and the effectiveness of individualised treatments was analysed. Categorizing patients with CVJM into these four types to simplify this somewhat unclear area could provide insight into the pathogenesis of the anomaly and a basis for rational surgical treatment.

Accuracy of freehand fluoroscopy-guided placement of C1 lateral mass and C2 isthmic screws in atlanto-axial instability

BACKGROUND

The C1 lateral mass and C2 isthmic stabilization, as introduced by Goel and Laheri and by Harms and Melcher, is a well-known fixation technique. We present the clinical and radiographic results with freehand fluoroscopy guided C1 lateral mass and C2 isthmic fixation in a consecutive series of 28 patients, evaluating the accuracy of screw placement.

METHODS

Twenty-eight consecutive patients suffering from post-traumatic and other C1-C2 instability were operated on between 2001 and 2010. Indications for surgery were: trauma (n = 21 cases), os odontoideum (n = 1), cranio-verterbal malformation (n = 1), and arthritis (n = 3) and idiopathic instability (n = 2). C1 lateral mass and C2 isthmic screws were placed according to the usual anatomical landmarks with lateral fluoroscopy guidance. All patients underwent a postoperative CT scan. The extent of cortical lateral or medial breach was determined and classified as follows: no breach (grade A), 0-2 mm (grade B), 2-4 mm (grade C), 4-6 mm (grade D), more than 6 mm (grade E). Grade A and B screws were considered well positioned.

RESULTS

A total of 56 C1 lateral mass and 55 C2 isthmic screws were placed. Accuracy of screw placement was as follows: 107 grade A (96.4%), four grade B (3.6%), and no grade C, D or E. Clinical and radiological follow-up showed improvement in symptoms (mainly pain) and stability of the implants at the end of the follow-up.

CONCLUSIONS

Freehand fluoroscopy-guided insertion of C1 lateral mass and C2 isthmic screws can be safely and effectively performed.

[Atlantoaxial malformation as a rare cause of dysphagia and snoring]

Abnormalities of the atlantoaxial spine are very rare variants. Bony outgrowths, osteophytes, clefts and aplasia may be misinterpreted as degenerative diseases. One patient presented with intermittent dysphagia and snoring and CT and MRI scans of the cervical spine showed an accessory bone located anterior to the atlas and axis. Atlantoaxial anomalies are often incidental findings without clinical symptoms. Such changes are rarely the cause of intermittent dysphagia and snoring.

[Diagnosis and treatment for complicated atlantoaxial dislocation]

OBJECTIVE

To explore the clinical characteristics and treatment methods for complicated atlantoaxial dislocation.

METHODS

A retrospective evaluation was done to summarize and analyze the clinical characteristics and complicated factors of 54 patients with complicated atlantoaxial dislocation who could not to be treated effectively by using conventional therapy in our hospital from February 2005 to October 2008. According to different complicated factors, different treatment methods mainly including transoral atlantoaxial reduction plate-III (TARP-III) operation, decompression procedure with deep grinding guided by computer aided design-rapid prototyping (CAD-RP), screw placement technique with CAD-RP guide plate and extensile approach surgery were performed.

RESULTS

The average follow-up period was 24 months. Among 54 cases, 48 cases achieved immediate anatomic reduction completely and 6 cases almost achieved anatomical reduction. All the compressed spinal cords were decompressed sufficiently. The decompression rate was 86.0% and the improvement rate of nerve function was 77.8%. Two cases suffered postoperative intracranial infection.

CONCLUSION

Some cases of complicated atlantoaxial dislocation can be effectively treated by using TARP-III operation, decompression procedure with deep grinding guided by CAD-RP, individualized screw placement technique with CAD-RP guide plate and extensile approach surgery.

A case of occipitalization in the human skull

Occipitalization of the atlas is an osseous anomaly of the craniovertebral junction. The aim of this paper is to present an anatomical variant of the fused atlas with the occipital bone and discuss similar cases described in literature. The skull of an adult male analysed in this study belonged to the cranial collection of the Department of Anatomy of the Jagiellonian University, Medical Collage. A tight bony fusion between the anterior arch of the atlas, the left portion of the posterior arch, the lateral masses of the atlas, and the occipital bone was observed. Hence, the left and right superior articular facets of the atlas were fused with the corresponding occipital condyles. The anteroposterior dimension of both inferior articular facets was the same (20 mm), while the transverse diameter of the right one was considerably smaller (12 mm). The transverse diameter of the left inferior articular facets was 17 mm. The right and the left transverse process of the atlas were normally developed, each of them contained transverse foramen, and they were not fused with the occipital bone. The circumference of the foramen magnum was minimally diminished by the osseous structures of the atlas fused to the occipital bone. The sagittal and transverse diameters of the foramen magnum (38 mm x 34 mm) were within the normal range of variation. However, the asymmetrical anatomy of the inferior articular facets of the atlas give rise to speculation that movement in the atlantoaxial joint was disturbed by assimilation with the occipital bone.

Atlanto-axial segmentation defects and os odontoideum in two male siblings with opsismodysplasia

We report two siblings aged 11 and 7 years, respectively, who presented with the clinical and radiographic features of opsismodysplasia (non-lethal type). 3D computed tomography scans of the craniocervical region revealed a split atlas and os odontoideum in both siblings. To the best of our knowledge, this is the first clinical report detailing craniocervical malformations in two siblings with opsismodysplasia.

Specific entities affecting the craniocervical region: syndromes affecting the craniocervical junction

INTRODUCTION

The craniocervical junction is a vital component in understanding the function of the human central nervous system. It is the threshold for major pathways affecting both brain and spinal cord function, and these structures are intricately housed in a network of bone, ligaments, and soft tissues. Abnormal development of any of these components may lead to altered structure, and therefore, altered function in the central nervous system.

MATERIALS AND METHODS

We herein describe a set of genetic syndromes that commonly affect the craniovertebral junction and offer clinical examples from more than 6,000 patients who have been treated for these disorders.

DISCUSSION

The syndromes described include Chiari type I malformation, Conradi syndrome, Goldenhar syndrome, Klippel-Feil syndrome, Larsen syndrome, Morquio syndrome, Pierre-Robin syndrome, spondyloepiphyseal dysplasia congenital and Weaver syndrome. The genetic mechanisms responsible for these disorders may offer unique insight into the developmental pathways and patterning in the musculoskeletal and cranial systems and may, ultimately, guide future diagnosis and treatment.

The mobile Condylus tertius occipitalis and fractures of the hypochordal clasp

The Condylus tertius is defined as a small bony hunch on the anterior surface of the clivus. Its presence means an enormous functional impairment of the upper head joint, looking at the 3-point-contact between the skull base and the upper cervical vertebrae. In 10 of the 2000 forensic examined bodies, analyses of neck vertebra + skull base revealed this feature. The origin of these findings is discussed, as stated in the literature of embryology, to be a suboccipital hypochordal plate. So in one of the cases the condylus was found at the hypochordal plate itself whereas the so-called socket was lying at the margin of the clivus. In three cases there was found a free body between the apex of the Dens and the Clivus forming a mobile Condylus tertius. In our opinion its position varies over the anterior arch of the atlas and the apex of the dens as a result of rotatory forces between the atlas and axis and physiological strain. Examples are given to elucidate this. There is a difference in the differentiation of the deposited material according to functional demand. A pressure bed (i.e. a Condylus tertius) is formed when a bony structure is deposited on the clivus. This functional prospect relativises the hypothesis of a purely constitutional genesis of the Condylus tertius. A fracture of the hypochordal clasp being joined with a bony connection to the anterior atlantic arch is described for the first time.

Medicolegal perspective: interpretation of pretreatment orthodontic radiographs

AIM

To detect the prevalence of anatomic anomalies and pathologic findings that could be screened from pretreatment orthodontic radiographs.

METHODS

A thorough screening was conducted of the pretreatment orthodontic radiographs of a sample of 1,354 patients, collected by the author during the last 15 years from 4 locations, 3 in the Kingdom of Saudi Arabia and 1 in Egypt.

RESULTS

A total of 154 significant anomalies and pathologic findings were recorded among the total sample group of 1,354 orthodontic patients (11.4%). Among these, 22 could have a serious effect on the general health of the patient. The findings included fractured odontoid process of the axis vertebra, os odontoideum, spondylolisthesis, fractured surgical needle in the oropharynx, fractured transpalatal archwire swallowed and stuck in patient's throat, unrecognized carotid artery stenosis, cystic lesions, and calcified stylohyoid ligaments.

CONCLUSION

Medicolegal litigation is a main priority for the clinician, requiring cautiousness through screening of the pretreatment orthodontic radiographs beyond orthodontic purposes to exclude patients with significant anomalies and pathological findings. If not done from the medicolegal prospective, such screening should at least take place from an ethical perspective. The orthodontic clinician needs to know when to consult other medical specialties.

Grisel's syndrome in otolaryngology: a systematic review

AIMS

to assess etiology, treatment and outcome of Grisel's syndrome.

METHODS

A Medline search was performed using the terms Grisel's syndrome, spontaneous atlantoaxial subluxation, head, neck, ear, nose and throat. A systematic review of the literature was performed. Case series of both adult and pediatric cases were included. Only papers focusing on true non-traumatic atlantoaxial subluxation were included.

RESULTS

Seventy-one papers have been published from 1950 to 2006. Forty-eight of these fulfilled our inclusion criteria, totaling 103 patients for review. The main causes of Grisel's syndrome were infection (48%) and post-adenotonsillectomy (31%). Less common causes included other postoperative cases such as pharyngoplasty and ear operations. Neurosurgical consultation was paramount in all cases. In the majority of cases conservative management in the form of bedrest, antibiotics, muscle relaxants, traction and collar was effective; in a few cases only surgery in the form of arthrodesis was deemed necessary. Morbidity was significant in those cases where diagnosis was delayed, with the most devastating consequence a permanent neurological deficit in one case.

CONCLUSIONS

Grisel's syndrome is a rare but dangerous complication that can go unnoticed in its early phase and can be a major cause of morbidity and mortality following infection or head and neck procedures/interventions. Early recognition of any cervical complication following routine otolaryngological operations together with early neurosurgical consultation is mandatory to prevent devastating consequences.

Occipitoatlantoaxial instability and congenital thoracic vertebral deformity in Pierre Robin sequence: a case report

STUDY DESIGN

Case report of a patient with Pierre Robin sequence who presented with occipitoatlantoaxial instability and congenital thoracic deformity.

OBJECTIVE

As there are lack of similar cases in the literature, we would like to introduce a case of a patient with associated malformations, the consultations that we consider that are obligatory, and our decision-making process. We would also like to demonstrate the follow-up plan and the further key points about either the conservative or the surgical solution of the problem.

SUMMARY OF BACKGROUND DATA

The occurrences of 2 malformations (Pierre Robin sequence and occipitoatlantoaxial instability) together are very rare. We have found only 1 publication in the related literature about this topic. We consider that this rare appearance is due to the difficulty in diagnosing this problem. There is no clinical evidence that musculoskeletal examinations are indicated in a patient with Pierre Robin sequence, and it is difficult to check for all the possible deformities.

METHOD

As congenital scoliosis appeared only at 6 years of age in the case of this child with Pierre Robin syndrome, we promptly began to investigate for other musculoskeletal defects. We would like to demonstrate the investigation process and emphasize the necessity of conventional and functional radiographs, computed tomography, and magnetic resonance images.

RESULTS

We have not found similar cases to refer to, so we made our decision about conservative treatment of the craniocervical instability knowing that we will have to follow up the progression of both the congenital thoracic scoliotic deformity and the occipitoatlantoaxial instability later.

CONCLUSION

To recognize a rare case is a big challenge indeed due to the lack of the investigational protocol, the key points of the decision process, the prognostic classification system, and the progression of the disease. We recommend that one should individualize and follow up the patient frequently.

Craniocervical instability in an infant with partial sacral agenesis

Sacral agenesis is an uncommon condition characterised by total or partial absence of the sacrum. The association of this condition with craniocervical junction abnormalities is extremely rare.

CASE REPORT

We describe a 3-year-old girl who, at the age of 8 months, while being investigated for short stature, was found to have significant craniocervical instability associated with anomalies of the odontoid peg. In addition to this she had partial sacral agenesis but genetic tests showed a normal karyotype. Due to the inherent difficulty of surgical fixation and immobilisation in an infant of her age, she was managed conservatively in a soft cervical orthosis. At the age of three years, surgery for decompression and stabilisation was deemed necessary due to the onset of neurological morbidity.

CONCLUSION

The authors describe this extremely rare association and discuss the difficulties faced while deciding the optimum surgical strategy for managing such young children with craniocervical instability.

Persistent torticollis, facial asymmetry, grooved tongue, and dolicho-odontoid process in connection with atlas malformation complex in three family subjects

Congenital clefts and other malformations of the atlas are incidental findings identified while investigating the cervical spine following trauma. A persistent bifid anterior and posterior arch of the atlas beyond the age of 3-4 years is observed in skeletal dysplasias, Goldenhar syndrome, Conradi syndrome, and Down's syndrome. There is a high incidence of both anterior and posterior spina bifida of the atlas in patients with metabolic disorders, such as Morquio's syndrome [Baraitser and Winter in London dysmorphology database, Oxford University Press, 2005; Torriani, Lourenco in Rev Hosp Clin Fac Med Sao Paulo 53: 73-76, 2002]. We report two siblings and their mother, with congenital, persistent torticollis, plagiocephaly, facial asymmetry, grooved tongues, and asymptomatic "dolicho-odontoid process". All are of normal intelligence. No associated Neurological dysfunction, paresis, apnoea, or failures to thrive were encountered. Radiographs of the cervical spine were non-contributory, but 3D CT scanning of this area allowed further visualisation of the cervico-cranial malformation complex in this family and might possibly explain the sudden early juvenile mortality. Agenesis of the posterior arch of the atlas and bifidity/clefting of anterior arch of the atlas associated with asymptomatic "dolicho-odontoid process" were the hallmark in the proband and his female sibling. Some of the features were present in the mother. All the family subjects were investigated. To the best of our knowledge the constellation of malformation complex in this family has not been previously reported.

“Stretched loop sign” of the vertebral artery: a predictor of vertebrobasilar insufficiency in atlantoaxial dislocation

BACKGROUND

Vertebrobasilar territory infarction is one of the rarer presentations of CVJ anomalies. A new radiologic sign due to stretching of the short third segment of VA detected on MRA/DSA may identify patients of AAD at risk of developing VBI.

METHODS

Seven patients who presented with VBI were found to have a coexisting mobile (n = 6) or fixed (n = 1) AAD. None of these patients had the presence of any of the known risk factors for cerebrovascular disease. On identification of VBI on CT/MRI, DSA (n = 7) and MRA (n = 1) were performed to assess bilateral vertebral arteries. The course of normal VA was also studied in 5 control patients without AAD or VBI.

RESULTS

Digital subtraction angiography/MRA showed obstruction of VA at the C1 through C2 level on one side in each of these cases. The third segment of the contralateral VA showed a shortened and straighter loop termed as the stretched loop sign of the VA. On DSA, the latter manifested as (a) opening of the distal loop of the VA as it emerges from the foramen transversarium of the atlas and traverses on the dorsum of the posterior arch of atlas (n = 3), (b) shortened and stretched VA that runs laterally and posteriorly forming the proximal loop after emerging from the foramen transversarium of the axis (n = 2), or (c) both (n = 2). All patients presented with the clinical manifestations of VBI. Only 2 of these had preexisting myelopathy and long tract signs conventionally attributable to AAD.

CONCLUSION

Vertebrobasilar territory infarction in AAD may occur because of the obstruction of the third segment of VA. A shorter and straighter loop of the third segment of VA coexisting with an abnormal translational mobility between the atlas and the axis may be the etiopathogenetic factor.

Halo traction in basilar invagination: technical case report

BACKGROUND

In the management of basilar invagination, traction therapy may help by pulling down the odontoid process away from the brain stem that may result in clinical and radiological improvement. We aimed to discuss the role of the halo vest apparatus traction on the reduction of severe anterior compression pathologies in basilar invagination.

CASE DESCRIPTION

We describe a simple and safe cervical traction method by the halo vest apparatus that is followed by rigid posterior occipitocervical fixation and foramen magnum decompression in a patient who presented with basilar invagination and symptoms of severe brain stem compression. An MR-suitable halo vest apparatus was used for reduction of the deformity. The reduction of the basilar invagination was achieved gradually by distracting the halo crown in stages.

CONCLUSION

The halo vest apparatus can be safely used in complex craniocervical junction anomalies. An effective cervical traction can be performed in basilar invagination, and reduction of the deformity may be achieved without the risk of overdistraction. In some cases, even partial reduction of the deformity may facilitate brain stem and spinal cord relief without any need of posterior decompression. Patients may benefit from ambulatory functions because bed rest is eliminated in this procedure. Neurovascular structures and the degree of the reduction can be observed on MRIs when an MR-suitable device is used.

Craniovertebral malformation complex in a child with Weismann-Netter-Stuhl syndrome

OBJECTIVE

Bowing of the legs is usually thrown into the basket of vitamin D deficiency rickets; therefore, a significant number of affected children can be misdiagnosed and improperly managed. This case illustrates how the careful clinical and radiological assessment of such a case can lead to the adequate understanding of its etiology.

DESCRIPTION

We report a sporadic case of a 2-year-old male child who presented with radiological features that were compatible with Weismann-Netter-Stuhl syndrome. In addition, we observed craniovertebral malformation complex. He was of normal intelligence. To our knowledge, the combination of Weismann-Netter-Stuhl syndrome and presence of a hypoplastic occipitalized atlas and further C2-C3 fusion has not been reported before. The diagnosis of Weismann-Netter-Stuhl is discussed. Classically, Weismann-Netter-Stuhl syndrome is characterized by short stature, mental retardation (in some individuals), dural calcification, and anterior bowing of the tibiae. However, we believe that careful clinical and radiological examinations can reveal more striking data which might positively reflect on the whole process of management.

COMMENTS

We postulate that the congenital limitations in neck movements in our patient developed because of the marked fusion of the hypoplastic and occipitalized atlas and simultaneous C2-C3 fusion. Therefore, if this form of malformation is disregarded, there may be involvement of the atlantoaxial structure, and this can possibly lead to serious neurological and even life-threatening complications. The use of CT scanning for the detection of such abnormalities can be remarkably important.

Pannus resolution after occipitocervical fusion in a non-rheumatoid atlanto-axial instability

Periodontoid pseudotumor or pannus is considered to be an inflammatory mass most frequently associated with rheumatoid arthritis. Transoral resection of the pannus has been the treatment of choice for patients with associated myelopathy, followed in many instances by posterior stabilization. However, some authors have reported resolution of pannus associated with rheumatoid arthritis and other forms of chronic atlanto-axial instability only after posterior stabilization. We report a case of a 69-year-old man who presented with a rapidly progressing myelopathy due to a retro-odontoid mass produced by chronic atlanto-axial instability associated with an occipital assimilation of C1 and tight posterior fossa. An urgent posterior fossa craniectomy followed by occipitocervical fixation was performed. After surgery, the patient's clinical condition improved and 1 year after surgery was asymptomatic, walked without any help and had normal strength. Control MR showed complete resolution of the retro-odontoid pannus.

Atlantoaxial transarticular screw fixation: a review of surgical indications, fusion rate, complications, and lessons learned in 191 adult patients

OBJECT

In this, the first of two articles regarding C1-2 transarticular screw fixation, the authors assessed the rate of fusion, surgery-related complications, and lessons learned after C1-2 transarticular screw fixation in an adult patient series.

METHODS

The authors retrospectively reviewed 191 consecutive patients (107 women and 84 men; mean age 49.7 years, range 17-90 years) in whom at least one C1-2 transarticular screw was placed. Overall 353 transarticular screws were placed for trauma (85 patients), rheumatoid arthritis (63 patients), congenital anomaly (26 patients), os odontoideum (four patients), neoplasm (eight patients), and chronic cervical instability (five patients). Among these, 67 transarticular screws were placed in 36 patients as part of an occipitocervical construct. Seventeen patients had undergone 24 posterior C1-2 fusion attempts prior to referral. The mean follow-up period was 15.2 months (range 0.1-106.3 months). Fusion was achieved in 98% of cases followed to commencement of fusion or for at least 24 months. The mean duration until fusion was 9.5 months (range 3-48 months). Complications occurred in 32 patients. Most were minor; however, five patients suffered vertebral artery (VA) injury. One bilateral VA injury resulted in patient death. The others did not result in any permanent neurological sequelae.

CONCLUSIONS

Based on this series, the authors have learned important lessons that can improve outcomes and safety. These include techniques to improve screw-related patient positioning, development of optimal instrumentation, improved screw materials and design, and defining the role for stereotactic navigation. Atlantoaxial transarticular screw fixation is highly effective in achieving fusion, and the complication rate is low when performed by properly trained surgeons.

Atlantoaxial transarticular screw fixation: a review of surgical indications, fusion rate, complications, and lessons learned in 67 pediatric patients

OBJECT

In this, the second of two articles regarding C1-2 transarticular screw fixation, the authors discuss their surgical experience in treating patients 16 years of age and younger, detailing the rate of fusion, complication avoidance, and lessons learned in the pediatric population.

METHODS

The authors retrospectively reviewed 67 consecutive patients (23 girls and 44 boys) younger than 16 years of age in whom at least one C1-2 transarticular screw fixation procedure was performed. A total of 127 transarticular screws were placed in these 67 patients whose mean age at time of surgery was 9 years (range 1.7-16 years). The indications for surgery were trauma in 24 patients, os odontoideum in 22 patients, and congenital anomaly in 17 patients. Forty-four patients underwent atlantoaxial fusion and 23 patients underwent occipitocervical fusion. Two of the 67 patients underwent halo therapy postoperatively. All patients were followed for a minimum of 3 months. In all 67 patients successful fusion was achieved. Complications occurred in seven patients (10.4%), including two vertebral artery injuries.

CONCLUSIONS

The use of C1-2 transarticular screw fixation, combined with appropriate atlantoaxial and craniovertebral bone/graft constructs, resulted in a 100% fusion rate in a large consecutive series of pediatric patients. The risks of C1-2 transarticular screw fixation can be minimized in this population by undertaking careful patient selection and meticulous preoperative planning.

Atlantoaxial dislocation associated with the maldevelopment of the posterior neural arch of axis causing compressive myelopathy

The craniovertebral junction has a predilection for a variety of congenital anomalies due to its complex development. The association of atlantoaxial dislocation (AAD) with the maldevelopment of the posterior arch of axis is extremely rare. We report two such cases and present the management strategy.