Craniovertebral junction anomalies in inherited disorders: part of the syndrome or caused by the disorder?

Adult Morquio syndrome requiring occipito-thoracic fusion

Morquio syndrome is a relatively rare entity that is often associated with atlantoaxial instability from early childhood due to odontoid dysplasia based on a mucopolysaccharoidal disorder. Here, we present the case of a 55-year-old male patient with Morquio syndrome who developed cervical myelopathy, which is an extremely rare condition in the older population. Myelopathy developed gradually with upper-limb paresthesia and clumsiness of both hands. The patient had a characteristic "gargoyle-like" coarse face with a trunk shortening-type short stature. Imaging of the cervical spine demonstrated several problems, including diminutive structures called platyspondyly with small pedicles and fragile bone quality, hypoplasia of the C1 posterior arch that migrated into the spinal canal, and os odontoideum with atlantoaxial instability. With intraoperative navigation guidance, posterior decompression of C1 followed by occipito-cervico-thoracic spinal fusion was successfully performed in this complicated case. Clinical and radiographic outcomes were both excellent and have been maintained for 2 years postoperatively.

Technical outcome of atlantoaxial transarticular screw fixation without supplementary posterior construct for rheumatoid arthritis

Background

transarticular screw (TAS) fixation without a supplementary posterior construct, even in rheumatoid arthritis (RA) patients, provides sufficient stability with acceptable clinical results. Here, we present our experience with 15 RA patients who underwent atlantoaxial (AA) TAS fixation without utilizing a supplementary posterior fusion.

Methods

To treat AA instability, all 15 RA patients underwent C1-C2 TAS fixation without a supplementary posterior construct. Patients were followed for at least 24 months. Pre- and postoperative sagittal measures of C1- C2, C2-C7, and C1-C7 angles, atlanto-dens interval (ADI), posterior atlanto-dens interval (PADI), and adjacent segment (i.e., C2-C3) anterior disc height (ADH) were retrospectively recorded from lateral X-ray imaging. The presence or absence of superior migration of the odontoid (SMO), cervical subaxial subluxation, C1-C2 bony fusion, screw pull-out, and screw breakage were also noted.

Results

There was little difference between the pre- and postoperative studies regarding angles measured. Following TAS fixation, the mean ADI shortened, and mean PADI lengthened. There was no difference in the mean measures of C2-C3 ADH. There was no evidence of SMO pre- or postoperatively. Two patients developed anterior subluxation at C5-C6; one of the two also developed anterior subluxation at C2-C3. All patients subsequently showed C1-C2 bony fusion without screw pull-out or breakage.

Conclusion

In RA patients who have undergone C1-C2 TAS fixation, eliminating a supplementary posterior fusion resulted in adequate stability.

Pattern of Pulmonary Dysfunctions in Craniovertebral Junction Anomaly and Its Persistence after Rigid Occipitocervical Fixation

Introduction Despite a significant advancement in operative techniques of occipitocervical fixation, there is a poor postoperative patient outcome. This can be attributed to restrictive lung pattern in craniovertebral junction anomalies (CVJAs) patients resulting from repeated trauma to cervicomedullary junction by the pincer action of the bony anomalies and compression of the brainstem. We evaluate the changes in pulmonary function tests (PFTs) following rigid occipitocervical fixation in CVJA.

Methods PFTs of 20 CVJA patients were measured pre and postoperatively using spirometry. Measurements included forced vital capacity (FVC), forced expiratory volume in one second (FEV1), maximum forced mid-expiratory flow rate (FEF25–75%), and ratio of FEV1 and FVC (FEV1%). The parameters were compared with the predicted normal values based on their age and sex. PFTs were repeated on the seventh postoperative day. McCormick grading was used to assess neurological function.

Results  The values of PFTs in the preoperative period were significantly lower than predicted normal values. The mean values of FVC, FEV1, FEF25–75% were 72, 68, and 71% of their mean predicted values, with FEV1% in the range of 70 to 95% with a mean of 81.4%. Postoperatively there was further significant reduction in the mean values of FVC, FEV1, FEF25–75%, and FEV1% compared with the preoperative values. There was neurological improvement in McCormick grades of patients postoperatively (from grade III and IV to grade II).

Conclusion A significant restrictive lung disease is present in patients of CVJA, even though not clinically apparent, and it persists in the early postoperative period. However, a long-term follow-up is required to assess whether pulmonary function parameters improve subsequently.

Atlantoaxial dislocation due to os odontoideum in patients with Down's syndrome: literature review and case reports

PURPOSE

To clarify etiology, clinical features, and diagnostic and treatment options of atlantoaxial dislocation (AAD) due to os odontoideum (OsO) in patients with Down's syndrome (DS).

METHODS

We described and analyzed three clinical cases of AAD due to OsO in DS patients and reviewed descriptions of similar cases in the scientific sources.

RESULTS

According to literature review, more than 80% of DS patients with odontoid ossicles had atlantoaxial instability (AAI). AAI in DS patients with OsO is more often manifested in childhood and adolescence, rarely in adults when ligament relaxation is reduced. Some patients had acute clinical manifestation after a minor trauma without any precursors; in some of the cases, neurological deterioration increased during several years. We found that the earlier surgical treatment of AAD due to OsO in DS patients carries the higher recovery potential.

CONCLUSIONS

Most patients with DS and OsO had AAI. The method of appropriate treatment in such cases is a posterior screw fixation. Preoperative halo traction and posterior fusion have proved to be a very useful tool in the treatment of AAD due to OsO in DS patients. Even if irreducibility of the AAD established preoperatively, it should not be an absolute indication for anterior decompression. In such cases, an attempt to reduce the AAD should be made under general anesthesia during posterior fixation.

Cervical medullary syndrome secondary to craniocervical instability and ventral brainstem compression in hereditary hypermobility connective tissue disorders: 5-year follow-up after craniocervical reduction, fusion, and stabilization

A great deal of literature has drawn attention to the "complex Chiari," wherein the presence of instability or ventral brainstem compression prompts consideration for addressing both concerns at the time of surgery. This report addresses the clinical and radiological features and surgical outcomes in a consecutive series of subjects with hereditary connective tissue disorders (HCTD) and Chiari malformation. In 2011 and 2012, 22 consecutive patients with cervical medullary syndrome and geneticist-confirmed hereditary connective tissue disorder (HCTD), with Chiari malformation (type 1 or 0) and kyphotic clivo-axial angle (CXA) enrolled in the IRB-approved study (IRB# 10-036-06: GBMC). Two subjects were excluded on the basis of previous cranio-spinal fusion or unrelated medical issues. Symptoms, patient satisfaction, and work status were assessed by a third-party questionnaire, pain by visual analog scale (0-10/10), neurologic exams by neurosurgeon, function by Karnofsky performance scale (KPS). Pre- and post-operative radiological measurements of clivo-axial angle (CXA), the Grabb-Mapstone-Oakes measurement, and Harris measurements were made independently by neuroradiologist, with pre- and post-operative imaging (MRI and CT), 10/20 with weight-bearing, flexion, and extension MRI. All subjects underwent open reduction, stabilization occiput to C2, and fusion with rib autograft. There was 100% follow-up (20/20) at 2 and 5 years. Patients were satisfied with the surgery and would do it again given the same circumstances (100%). Statistically significant improvement was seen with headache (8.2/10 pre-op to 4.5/10 post-op, p < 0.001, vertigo (92%), imbalance (82%), dysarthria (80%), dizziness (70%), memory problems (69%), walking problems (69%), function (KPS) (p < 0.001). Neurological deficits improved in all subjects. The CXA average improved from 127° to 148° (p < 0.001). The Grabb-Oakes and Harris measurements returned to normal. Fusion occurred in 100%. There were no significant differences between the 2- and 5-year period. Two patients returned to surgery for a superficial wound infections, and two required transfusion. All patients who had rib harvests had pain related that procedure (3/10), which abated by 5 years. The results support the literature, that open reduction of the kyphotic CXA to lessen ventral brainstem deformity, and fusion/stabilization to restore stability in patients with HCTD is feasible, associated with a low surgical morbidity, and results in enduring improvement in pain and function. Rib harvest resulted in pain for several years in almost all subjects.

Modified Inside-outside Occipito-Cervical Plate System: Preliminary Results

Context:

Internal rigid fixation provides immediate stability of the occipito-cervical (OC) junction for treatment of instability; however, in current practice, the optimal OC junction stabilization method is debatable.

Aims:

The aim of this study to test the safety and efficacy of a newly designed modified inside-outside occipito-cervical (MIOOC) plate system for the treatment of instability.

Settings and Design:

This was a feasibility study of MIOCC plate system.

Subjects and Methods:

Five male and four female patients with OC instability were treated using MIOOC plate system. Stabilization rate, safety, and efficacy were evaluated radiologically and clinically.

Results:

Mean age of the patients was 35 ± 11 (range: 22–58) years. Etiology of OC instability included trauma, neoplasm, congenital abnormalities, and iatrogenic. The fusion levels ranged from occiput-C3 to occiput-C6. Mean follow-up duration was 22 ± 10 (range: 6–46) months. There were neither complication nor was there any need for plate revision or screw pullout. Mortality occurred in one patient due to primary malignancy at 6 months; otherwise, no morbidity was observed. During the follow-up, no recurrent subluxation or newly developed instability at adjacent levels occurred. All patients showed a satisfactory union at the most recent follow-up examination.

Conclusions:

These preliminary results suggest that the MIOCC plate system is a useful and safe method for providing immediate internal stability of the OC junction. Using a multi-piece plate design in this plate system provided easy implantation and a better interface between plate and OC bones. Further, clinical studies and long-term results are needed to determine the reliability of the MIOOC plate system.

Fatal atlantoaxial dislocation due to an odontoid synchondrosis fracture in a child with chromosome 9 abnormality: A case report

A 5-year-old boy with a chromosome-9 abnormality and multiple external and visceral malformations was found in cardiopulmonary arrest during a regular visit to the hospital; he did not respond to cardiopulmonary resuscitation and died. An odontoid process fracture and calcification and fibrosis of the muscles around the superior cervical vertebra were observed during the autopsy. Postmortem computed tomography revealed an anterior dislocation of the atlas; odontoid synchondrosis fracture; and delayed, incomplete bony fusion of the odontoid process relative to his age. The cause of his death was a superior spinal cord injury. The tissue surrounding the upper cervical spine presented with myositis ossificans, suggesting a prior injury. He experienced a minor traffic accident 3 months before his death. It was concluded that the odontoid synchondrosis fracture occurred during the accident based on the incomplete bony fusion and atlantoaxial instability, which were consistent with the findings of myositis ossificans. Delayed fatal dislocation may then have occurred under the influence of a minor external force. Odontoid process abnormalities and atlantoaxial instability are common in patients with trisomy 21 and other congenital diseases; however, the condition's association with chromosome-9 abnormalities has not been reported. In children with various chromosomal abnormalities, periodic assessment of instability and morphology of the cervical spine, and a lowered examination threshold for the children at risk, could prove useful in the prevention injuries leading to fatality, and provide additional information to rule out abuse.

Assessment of the corticospinal fiber integrity in mirror movement disorder

Mirror movements are unintended movements occurring on one side of the body that mirror the contralateral voluntary ones. It has been proposed that mirror movements occur due to abnormal decussation of the corticospinal pathways. Using detailed multidisciplinary approach, we aimed to enlighten the detailed mechanism underlying the mirror movements in a case subject who is diagnosed with mirror movements of the hands and we compared the findings with the unaffected control subjects. To evaluate the characteristics of mirror movements, we used several techniques including whole exome sequencing, computed tomography, diffusion tensor imaging and transcranial magnetic stimulation. Computed tomography showed the absence of a spinous process of C5, fusion of the body of C5-C6 vertebrae, hypoplastic dens and platybasia of the posterior cranial fossa. A syrinx cavity was present between levels C3-C4 of the spinal cord. Diffusion tensor imaging of the corticospinal fibers showed disorganization and minimal decussations at the lower medulla oblongata. Transcranial magnetic stimulation showed that motor commands were distributed to the motor neuron pools on the left and right sides of the spinal cord via fast-conducting corticospinal tract fibers. Moreover, a heterozygous missense variation in the deleted in colorectal carcinoma gene has been observed. Developmental absence of the axonal guidance molecules or their receptors may result in abnormalities in the leading of the corticospinal fibers. Clinical evaluations and basic neuroscience techniques, in this case, provide information for this rare disease and contribute to our understanding of the normal physiology of bimanual coordination.

Dysphagia After Occipitothoracic Fusion is Caused by Direct Compression of Oropharyngeal Space Due to Anterior Protrusion of Mid-cervical Spine

STUDY DESIGN

This was a retrospective study.

OBJECTIVE

To investigate the relationship among the craniocervical alignment, the oropharyngeal space, and the incidence of dysphagia after occipitothoracic fusion (OTF).

SUMMARY OF BACKGROUND DATA

Craniocervical malalignment after OTF is one of a trigger of dysphagia. However, there has been no logical explanation for the etiology yet.

METHODS

A total of 32 patients who underwent OTF (5 male, 27 female) were reviewed. Following 4 parameters on the lateral cervical radiogram, pharyngeal tilt angle (PTA); the angle between the McGregor's line and the line that links the center of C2 pedicle and the center of vertebral body at the apex of cervical sagittal curvature, diameter of oropharyngeal airway space (dPS), O-C2 angle, and C2-C7 angle were measured at follow-up and then the relationship of these parameters and their influence to the incidence of dysphagia were analyzed.

RESULTS

Six of 32 cases (18.8%) exhibited postoperative dysphagia. ROC curves showed that PTA and dPS had moderate accuracy for the predictor of the dysphagia after OTF with the area under the curve (AUC) of 0.76 and 0.86 respectively, whereas O-C2 angle had low accuracy with AUC of 0.69 and C2-C7 angle was almost useless for prediction of postoperative dysphagia with AUC of 0.51. A multiple linear regression analysis showed that only PTA was significantly correlated with dPS (β=0.822, P=0.014), whereas the O-C2 angle (β=0.101, P=0.779) and C2-C7 angle (β=0.352, P=0.157) had negligibly small influence on dPS.

CONCLUSIONS

Our results demonstrated strong relationships between PTA and the value of dPS, and the incidence of dysphagia. As PTA reflects anterior protrusion of mid-cervical spine, these results indicated that dysphagia after OTF is caused by narrowing of oropharyngeal space due to direct compression from anteirorly protruded mid-cervical spine.

The Prediction and Prevention of Dysphagia After Occipitospinal Fusion by Use of the S-line (Swallowing Line)

STUDY DESIGN

Clinical case series and risk factor analysis of dysphagia after occipitospinal fusion (OSF).

OBJECTIVE

The aim of this study was to develop new criteria to avoid postoperative dysphagia by analyzing the relationship among the craniocervical alignment, the oropharyngeal space, and the incidence of dysphagia after OSF.

SUMMARY OF BACKGROUND DATA

Craniocervical malalignment after OSF is considered to be one of the primary triggers of postoperative dysphagia. However, ideal craniocervical alignment has not been confirmed.

METHODS

Thirty-eight patients were included. We measured the O-C2 angle (O-C2A) and the pharyngeal inlet angle (PIA) on the lateral cervical radiogram at follow-up. PIA is defined as the angle between McGregor's line and the line that links the center of the C1 anterior arch and the apex of cervical sagittal curvature. The impact of these two parameters on the diameter of pharyngeal airway space (PAS) and the incidence of the dysphagia were analyzed.

RESULTS

Six of 38 cases (15.8%) exhibited the dysphagia. A multiple regression analysis showed that PIA was significantly correlated with PAS (β = 0.714, P = 0.005). Receiver-operating characteristic curves showed that PIA had a high accuracy as a predictor of the dysphagia with an AUC (area under the curve) of 0.90. Cases with a PIA less than 90 degrees showed significantly higher incidence of dysphagia (31.6%) than those with a 90 or more degrees of PIA (0.0%) (P = 0.008).

CONCLUSION

Our results indicated that PIA had the high possibility to predict postoperative dysphagia by OSF with the condition of PIA <90°. Based on these results, we defined "Swallowing-line (S-line)" for the reference of 90° of PIA. S-line (-) is defined as PIA <90°, where the apex of cervical lordosis protruded anterior to the "S-line," which should indicate the patient is at a risk of postoperative dysphagia.

LEVEL OF EVIDENCE

4.

Craniocervical instability in the setting of os odontoideum: assessment of cause, presentation, and surgical outcomes in a series of 279 cases

BACKGROUND

Our clinical understanding of os odontoideum (OO) remains incomplete. Congenital and traumatic causes have been proposed and advocated. Clinical presentations range from asymptomatic to axial pain to myelopathy or vertebral-basilar ischemia. A consensus for surgical management exists for those found to have an unstable atlantoaxial complex or symptomatic cranial-vertebral junction compression.

OBJECTIVE

To evaluate the clinical presentation and surgical outcomes of patients with OO and an unstable atlantoaxial complex or symptomatic cranial-vertebral junction compression.

METHODS

Patients with a diagnosis of OO who underwent surgical management were included. Patients were excluded on the basis of previous C2 fracture, Fielding diagnostic criteria, and inadequate follow-up. History of trauma and presenting symptoms were assessed. Clinical and neurological improvements were measured with the use of patient satisfaction scores and the Japanese Orthopaedic Association scores. Fusion status was documented with the use of radiographs and computed tomographic imaging.

RESULTS

Of 279 patients, 112 reported a history of cranial-vertebral junction trauma, whereas 28 were diagnosed with congenital malformations. Clinically, 84.9% of patients presented with myelopathy, with pain presented in 42.6%. Atlantoaxial fixation was performed in 240 patients, occiput-to-C2 fixation in 35 patients, and extended occipito-cervical fixation in 4 patients. Mean follow-up was 40.3 months. Complications were reported in 2.4% of patients. Japanese Orthopaedic Association scores improved from a preoperative mean of 12.4 to 14.8. Two hundred thirty-five patients (77.7%) improved, with 30 patients experiencing no change in symptoms and 14 patients deteriorating. Fusion was achieved in 96.8% of patients.

CONCLUSION

Our data reveal that surgical treatment for OO using the indications and techniques delineated is associated with high satisfaction rates, improved functional scores, and high fusion rates with low complication rates.

Os odontoideum syndrome: pathogenesis, clinical patterns and indication for surgical strategies in childhood

Os odontoideum is a rare condition with a controversial pathogenesis and poorly understood natural history. Hypoplasia of the odontoid associated with an independent oval ossicle, with smooth margins widely separated from C2 and well above the superior facets of the axis, is termed "os odontoideum". The neurological manifestations arise from bulbospinal compression both at rest and during motion, due to the craniovertebral junction (CVJ) instability itself. Consequently, the surgical management of os odontoideum should aim at achieving both neural decompression and stabilization of the CVJ. The aims of this paper are to introduce the embryological steps involved in the CVJ development, to underline the updated theories propounded to interpret developmental and congenital disorders of the os odontoideum, to introduce the most updated surgical techniques and to discuss some exemplary cases selected from our personal experience.

Imaging of the craniovertebral junction anomalies in children

The craniovertebral junction (CVJ) is interposed between the unsegmented skull and the segmented spine; it is functionally unique as it allows the complex motion of the head. Because of its unique anatomy, numerous craniometric indices have been devised. Because of its complex embryology, different from that of the adjacent skull and spine, it is commonly the seat of malformations. Because of the mobility of the head, and its relative weight, the craniovertebral junction is vulnerable to trauma. Like the rest of the axial skeleton, it may be affected by many varieties of dysplasia. In addition, the bony craniovertebral junction contains the neural craniovertebral junction and its surrounding CSF: any bony instability or loss of the normal anatomic relationships may therefore compromise the neural axis. In addition, the obstruction of the meningeal spaces at this level can compromise the normal dynamics of the CSF and result in hydrocephalus and/or syringohydromyelia. To image the CVJ, plain X-rays are essentially useless. MR is optimal in depicting the soft tissues (including the neural axis) and the joints, as well as the bone itself. CT still may be important to better demonstrate the bony abnormalities.

Juvenile chronic arthritis and the craniovertebral junction in the paediatric patient: review of the literature and management considerations

INTRODUCTION

Juvenile chronic arthritis (JCA) is a systemic disease of childhood affecting particularly joints. JCA is a heterogeneous group of inflammatory joint disorders with onset before the age of 16 years and is comprised of 7 subtype groups. The pathogenesis of JCA seen in the cervical spine is synovial inflammation, hyperaemia, and pannus formation at the occipitoatlantoaxial joints resulting in characteristic craniovertebral junction findings. Treatment of craniovertebral junction instability as a result of JCA is a challenge. The best treatment strategy may be difficult because of various radiological and clinical severities. A review of the literature and management considerations is presented.

REVIEW

No randomised controlled trial or systematic review on this subject has been published. Only experts' opinions, case reports, and case series have been described. Thirty-four studies have been reviewed in this study. Involvement of the cervical spine in patients with JCA can lead to pain and functional disability. The subtypes that usually affect the cervical spine are the polyarticular type and systemic onset type and rarely the pauciarticular type. The most common cervical spine changes related to JCA are as follows: (1) apophyseal joint ankylosis at C2-C3, (2) atlantoaxial subluxation, (3) atlantoaxial impaction, (4) atlantoaxial rotatory fixation, and (5) growth disturbances of the cervical spine. The incidence of severe subluxations has decreased in the last decade as result of antirheumatoid drugs and biologicals. However, neurological compromise still occurs in JCA patients necessitating surgical treatment.

CONCLUSION

Whenever the cervical spine is involved in rheumatoid arthritis patients without neurological deficits, conservative treatment is legitimate. Once patients develop neurological signs and symptoms, surgical treatment should be considered with particular focus to age, severity of the disease, and general health condition. Skilled anaesthesia is crucial and the surgical procedure should only be carried out in centres with experience in craniovertebral junction abnormalities.

Embryology, classification, and surgical management of bony malformations of the craniovertebral junction

The embryology of the bony craniovertebral junction (CVJ) is reviewed with the purpose of explaining the genesis and unusual configurations of the numerous congenital malformations in this region. Functionally, the bony CVJ can be divided into a central pillar consisting of the basiocciput and dental pivot; and a two-tiered ring revolving round the central pivot, comprising the foramen magnum rim and occipital condyles above, and the atlantal ring below. Embryologically, the central pillar and the surrounding rings descend from different primordia, and accordingly, developmental anomalies at the CVJ can also be segregated into those affecting the central pillar and the surrounding rings, respectively. A logical classification of this seemingly unwieldy group of malformations is thus possible based on their ontogenetic lineage, morbid anatomy, and clinical relevance. Representative examples of the main constituents of this classification scheme are given, and their surgical treatments are selectively discussed.

Craniovertebral junction pathological features and their management in the mucopolysaccharidoses

The mucopolysaccharidoses (MPS) are multisystemic inherited metabolic diseases caused by the deficiency of the enzymes involved in the degradation of glycosaminoglycans (GAGs), which variably involve the central nervous system, heart, lungs, and bones.Undegraded or only partly degraded GAGs accumulate in the extracellular matrix, joint fluid, and connective tissue leading to widespread tissue and organ dysfunction.The introduction of hematopoietic stem cell transplantation (HSCT) and enzyme replacement therapy (ERT) has positively affected the natural history of MPS patients and their life expectancy. However, the presence of spinal abnormalities and deposition of GAGs in soft tissues remains nearly unaltered.Abnormalities of the craniovertebral junction (CVJ) and GAG deposits can result in spinal cord compression with slowly progressive myelopathy or acute posttraumatic tetraplegia.The current paper discusses neuroimaging findings in a consecutive series of 42 MPS patients followed at our Center for Metabolic Diseases and their neurosurgical issues.Current recommendations for decompression and fusion will be discussed according to our experience and review of the literature.

Congenital axis dysmorphism in a medieval skeleton : …secunda a vertendo epistropheus…

PURPOSE

We describe here the axis dysmorphism that we observed in the skeletal remains of a human child dug up from a fifteenth century cemetery located in north-eastern Italy. This bone defect is discussed in the light of pertinent literature.

METHODS

We performed macroscopical examination and CT scan analysis of the axis.

RESULTS

Axis structure was remarkably asymmetric. Whilst the left half exhibited normal morphology, the right one was smaller than normal, and its lateral articular surface showed horizontal orientation. In addition, the odontoid process appeared leftward deviated and displayed a supplementary articular-like facet situated on the right side of its surface.

CONCLUSIONS

These findings suggest a diagnosis of unilateral irregular segmentation of atlas and axis, a rare dysmorphism dependent upon disturbances of notochordal development in early embryonic life. Likewise other malformations of the craniovertebral junction, this axis defect may alter the delicate mechanisms of upper neck movements and cause a complex series of clinical symptoms. This is an emblematic case whereby human skeletal remains may provide valuable information on the anatomical defects of craniovertebral junction.

Successful cranio-cervical fusion in a patient with Down syndrome

We present a patient with Down syndrome with neck pain and severe cervical myelopathy. Imaging revealed occipito-atlantal and atlanto-axial instability with severe spinal cord compression. There are no standardized radiological or clinical guidelines to aid in managing this unique subset of patients. We demonstrate a successful occiput-C3 internal fixation and fusion without complication. Due to the largely unknown natural history and ongoing management difficulties in this population, we demonstrate a case that may aid future decision making for this specialized field. We also discuss an approach to reduce this deformity, which, to our knowledge, has not been published before.

Computer-assisted C1-C2 Transarticular Screw Fixation "Magerl Technique" for Atlantoaxial Instability

STUDY DESIGN

A retrospective study.

PURPOSE

To evaluate the surgical results of computer-assisted C1-C2 transarticular screw fixation for atlantoaxial instability and the usefulness of the navigation system.

OVERVIEW OF LITERATURE

We used a computed tomography (CT)-based computer navigation system in planning and screw insertion in Magerl's procedure, which provides the most rigid atlantoaxial fusion, to avoid risk of vertebral artery (VA) tear by avoiding high-riding VA during screw insertion.

METHODS

Twenty patients who underwent atlantoaxial fusion under the CT-based navigation system were studied. The mean observation period was 33.5 months. The evaluated items included the existence of VA stenosis by preoperative magnetic resonance angiography, surgical time, blood loss volume, Japanese Orthopaedic Association (JOA) score and Ranawat's pain criteria before surgery and at final follow-up, postoperative screw position evaluated by CT, and bony fusion.

RESULTS

The mean operation time was 205 minutes, with the mean blood loss volume of 242 ml. The mean JOA score was 11.6 points before surgery and 13.7 at final follow-up. Occipital and/or cervical pain presented before operation was remitted or resolved in all patients. Evaluation of screw insertion by CT revealed correct penetration to atlantoaxial joints, with a perforation rate of 2.6%. There was no complication, including VA tear, and all patients who were followed-up during one year or more after surgery achieved bony fusion. Some subjects who appeared inappropriate for surgery from CT images were assessed as eligible for surgery based on the evaluation results obtained using the navigation system.

CONCLUSIONS

It was demonstrated that the CT-based navigation system is an effective support device for Magerl's procedure.

Posterior instrumentation for occipitocervical fusion

Since 1995, 29 consecutive patients with craniocervical spine instability due to several pathologies were managed with posterior occipitocervical instrumentation and fusion. Laminectomy was additionally performed in nineteen patients. The patients were divided in two groups: Group A which included patients managed with screw-rod instrumentation, and Group B which included patients managed with hook-and-screw-rod instrumentation. The patients were evaluated clinically and radiographically using the following parameters: spine anatomy and reconstruction, sagittal profile, neurologic status, functional level, pain relief, complications and status of arthrodesis. The follow-up was performed immediately postoperatively and at 2, 6, 12 months after surgery, and thereafter once a year. Fusion was achieved in all but one patient. One case of infection was the only surgery related complication. Neurological improvement and considerable pain relief occurred in the majority of patients postoperatively. There were neither intraoperative complications nor surgery related deaths. However, the overall death rate was 37.5% in group A, and 7.7% in group B. There were no instrument related failures. The reduction level was acceptable and was maintained until the latest follow-up in all of the patients. No statistical difference between the outcomes of screw-rod and hook-and-screw-rod instrumentation was detected. Laminectomy did not influence the outcome in either group. Screw-rod and hook-and-screw-rod occipitocervical fusion instrumentations are both considered as safe and effective methods of treatment of craniocervical instability.

Embryology and bony malformations of the craniovertebral junction

BACKGROUND

The embryology of the bony craniovertebral junction (CVJ) is reviewed with the purpose of explaining the genesis and unusual configurations of the numerous congenital malformations in this region. Functionally, the bony CVJ can be divided into a central pillar consisting of the basiocciput and dental pivot and a two-tiered ring revolving round the central pivot, comprising the foramen magnum rim and occipital condyles above and the atlantal ring below. Embryologically, the central pillar and the surrounding rings descend from different primordia, and accordingly, developmental anomalies at the CVJ can also be segregated into those affecting the central pillar and those affecting the surrounding rings, respectively.

DISCUSSION

A logical classification of this seemingly unwieldy group of malformations is thus possible based on their ontogenetic lineage, morbid anatomy, and clinical relevance. Representative examples of the main constituents of this classification scheme are given, and their surgical treatments are selectively discussed.

Failure of cervical arthroplasty in a patient with adjacent segment disease associated with Klippel-Feil syndrome

Cervical arthroplasty may be justified in patients with Klippel-Feil syndrome (KFS) in order to preserve cervical motion. The aim of this paper is to report an arthroplasty failure in a patient with KFS. A 36-year-old woman with KFS underwent two-level arthroplasty for adjacent segment disc degeneration. Anterior migration of the cranial prosthesis was encountered 5 months postoperatively and was successfully revised with anterior cervical fusion. Cervical arthroplasty in an extensively stiff and fused neck is challenging and may lead to catastrophic failure. Although motion preservation is desirable in KFS, the special biomechanical features may hinder arthroplasty. Fusion or hybrid constructs may represent more reasonable options, especially when multiple fused segments are present.

Deformative stress associated with an abnormal clivo-axial angle: A finite element analysis

Background:

Chiari malformation, functional cranial settling and subtle forms of basilar invagination result in biomechanical neuraxial stress, manifested by bulbar symptoms, myelopathy and headache or neck pain. Finite element analysis is a means of predicting stress due to load, deformity and strain. The authors postulate linkage between finite element analysis (FEA)-predicted biomechanical neuraxial stress and metrics of neurological function.

Methods:

A prospective, Internal Review Board (IRB)-approved study examined a cohort of 5 children with Chiari I malformation or basilar invagination. Standardized outcome metrics were used. Patients underwent suboccipital decompression where indicated, open reduction of the abnormal clivo-axial angle or basilar invagination to correct ventral brainstem deformity, and stabilization/ fusion. FEA predictions of neuraxial preoperative and postoperative stress were correlated with clinical metrics.

Results:

Mean follow-up was 32 months (range, 7-64). There were no operative complications. Paired t tests/ Wilcoxon signed-rank tests comparing preoperative and postoperative status were statistically significant for pain, bulbar symptoms, quality of life, function but not sensorimotor status. Clinical improvement paralleled reduction in predicted biomechanical neuraxial stress within the corticospinal tract, dorsal columns and nucleus solitarius.

Conclusion:

The results are concurrent with others, that normalization of the clivo-axial angle, fusion-stabilization is associated with clinical improvement. FEA computations are consistent with the notion that reduction of deformative stress results in clinical improvement. This pilot study supports further investigation in the relationship between biomechanical stress and central nervous system (CNS) function.

C1-C2 transarticular screw fixation for atlantoaxial instability due to rheumatoid arthritis: a seven-year analysis of outcome

STUDY DESIGN.: Observational study. Retrospective analysis of prospectively collected data. OBJECTIVE.: The purpose of this article was to report long-term (minimum 7 years) clinical and radiologic outcome of our series of patients with Rheumatoid Arthritis who underwent transarticular screw fixation to treat atlantoaxial subluxation. SUMMARY OF BACKGROUND DATA.: The indications for intervention in patients with atlantoaxial instability are pain, myelopathy, and progressive neurologic deficit. The various treatment options available for these patients are isolated C1-C2 fusion, occipitocervical fusion with or without transoral surgery. Review of current literature suggests that C1-C2 transarticular screw fixation has significant functional benefits, although there is discrepancy in this literature regarding improvement in function following surgery. METHODS.: Myelopathy was assessed using Ranawat myelopathy score and Myelopathy Disability Index. Pain scores were assessed using Visual Analogue Scale. The radiologic imaging was assessed and the following data were extracted; atlanto-dens interval, space available for cord, presence of signal change on T2 weighted image, and fusion rates. RESULTS.: Thirty-seven patients, median age 56, were included in the study. Average duration of neck symptoms was 15.8 months. Average duration of rheumatoid arthritis before surgery was 20.6 years. Preoperative symptoms: suboccipital pain in 26 patients; neck pain, 32; myelopathy, 22; and 5 were asymptomatic. After surgery: suboccipital pain, 2; neck pain, 3; and myelopathy, 10. Ninety percent patients with neck and suboccipital pain improved after surgery in their Visual Analogue pain scores, with all of them having >50% improvement in VAS scores (6.94-2.12 [P < 0.05]).Preoperative Ranawat grade was as follows: grade 1 in 15 patients, grade 2 in 7, and grade 3a in 14, grade 3b in 1.After surgery: grade 1 in 27 patients, grade 2 in 7, grade 3a in 1, and grade 3b in 2. The mean myelopathy score improved after surgery (59.62-32.75, P < 0.05).The space available for the cord was improved in 63%, unchanged in 33%, and worse in 4%.Twenty-seven percent had T2 signal change and 18% had cervicomedullary compression; 97% had bony fusion. BILATERAL SCREWS WERE USED IN 33 PATIENTS AND UNILATERAL SCREWS IN 4 PATIENTS (ABERRANT VERTEBRAL ARTERY).: Computer image guidance was used in 73%. CONCLUSION.: C1-C2 transarticular screw fixation is a safe technique for atlantoaxial subluxation for patients with rheumatoid arthritis. This study clearly demonstrates improvement in Visual Analogue Scale, Ranawat grading and the Myelopathy Disability Index even at long-term follow up.

Reducible and irreducible os odontoideum in childhood treated with posterior wiring, instrumentation and fusion. Past or present?

BACKGROUND

The aim of the study was to evaluate the results of instrumented rod and wire fusion in children with craniovertebral junction (CVJ) instability and os odontoideum.

METHODS

We evaluated seven children (mean age 9.85 years) with Down and Morquio's syndromes and primary os odontoideum. X-ray, computerized tomography (CT) scan and magnetic resonance (MR) imaging of the CVJ showed reducible instability in all of the cases but one. All the children underwent surgical correction by means of posterior wiring, instrumentation, fusion and external orthosis. A posterior wiring technique was also utilized in the only child with irreducible preoperative atlantoaxial instability, which, however, proved to be reducible under general anesthesia.

FINDINGS

At maximum follow-up (observation range 28 to 106 months, mean 59.42 months), the clinical picture was improved in all the patients. The postoperative neuroradiological investigations demonstrated satisfactory bony fusion with neural decompression in all patients.

CONCLUSIONS

A wiring technique to correct atlantoaxial instabilities has been shown to be more relevant in these children with syndromic atlantoaxial dislocation and os odontoideum due to its simplicity, safety (continuous fluoroscopic assistance is not necessary and there is no risk of neuro-vascular injuries) and lower costs (no complex hardware devices; no neuronavigation systems are required). Preoperative irreducibility of the C1-C2 shift is not an absolute criterion for transoral decompression in children since os odontoideum can be reduced under general anesthesia.

Safe angle scope for posterior atlanto-occipital transarticular screw fixation

OBJECTIVE

To study the technical parameters related to, and explore the clinical significance of, posterior atlanto-occipital transarticular screw fixation.

METHODS

Posterior implantation of Kirschner wires via the atlanto-occipital joint was performed on 20 dry bone specimens with complete atlanto-occipital joints. The angle of the Kirschner wire was measured on a postimplantation x-ray. Three-dimensional computed tomographic reconstruction of the atlanto-occipital joint of 30 healthy adults was performed to measure the simulative safety range for screw placement in posterior atlanto-occipital transarticular screw fixation. The procedure was then conducted on 12 fresh cadaver occipitocervical specimens. X-rays and 3-dimensional computed tomographic reconstruction were performed postsurgery to verify exact screw positioning.

RESULTS

The ideal angles for screw placement were cephalocaudal angle in the sagittal plane of 53.3 +/- 3.4 degrees, mediolateral angle in the coronal plane of 20.0 +/- 2.6 degrees, a maximum allowable cephalocaudal angle of 74.6 +/- 2.8 degrees (67.9-80.5 degrees), a minimum allowable cephalocaudal angle of 24.9 +/- 1.9 degrees (22.1-29.4 degrees), a maximum allowable mediolateral angle of 40.5 +/- 2.9 degrees (31.1-49.4 degrees), and a minimum allowable mediolateral angle of 0.7 +/- 1.6 degrees (-4.1-5.9 degrees). Surgery simulation in the fresh cadaver specimens indicated that this safe scope is reliable.

CONCLUSION

There is a safe scope for the angle of the screw placement in posterior atlanto-occipital transarticular screw fixation. Posterior transarticular screw fixation can be safely performed for occipitocervical fusion fixation when utilizing careful screw placement.

REMNANTS OF OCCIPITAL VERTEBRAE

OBJECTIVE

Developmental remnants around the foramen magnum, or proatlas segmentation abnormalities, have been recorded in postmortem studies but very rarely in a clinical setting. Because of their rarity, the pathological anatomy has been misunderstood, and treatment has been fraught with failures. The objectives of this prospective study were to understand the correlative anatomy, pathology, and embryology and to recognize the clinical presentation and gain insights on the treatment and management.

METHODS

Our craniovertebral junction (CVJ) database started in 1977 and comprises 5200 cases. This prospective study has retrieval capabilities. Neurodiagnostic studies changed with the evolution of imaging. Seventy-two patients were recognized as having symptomatic proatlas segmentation abnormalities.

RESULTS

Ventral bony masses from the clivus or medial occipital condyle occurred in 66% (44/72), lateral or anterolateral compressive masses in 37% (27 of 72 patients), and dorsal bony compression in 17% (12 of 72 patients). Hindbrain herniation was associated in 33%. The age at presentation was 3 to 23 years. Motor symptoms occurred in 72% (52 of 72 patients); palsies in Cranial Nerves IX, X, and XII in 33% (24 of 72 patients); and vertebrobasilar symptoms in 25% (18 of 72 patients). Trauma precipitated symptoms in 55% (40 of 72 patients). The best definition of the abnormality was demonstrated by 3-dimensional computed tomography combined with magnetic resonance imaging. Treatment was aimed at decompression of the pathology and stabilization.

CONCLUSION

Remnants of the occipital vertebrae around the foramen magnum were recognized in 72 of 5200 CVJ cases (7.2%). Magnetic resonance imaging with 3-dimensional computed tomography of the CVJ provides the best definition and understanding of the lesions. Brainstem myelopathy and lower cranial nerve deficits are common clinical presentations in the first and second decades of life. Treatment is aimed at decompression of the pathology and CVJ stabilization.

Pre-operative irreducible C1-C2 dislocations: intra-operative reduction and posterior fixation. The "always posterior strategy"

BACKGROUND

According to Menezes' algorithm, pre-operative dynamic neuroradiological investigation in C1-C2 dislocations (C1C2D) instability is strongly advocated in order to exclude those patients not eligible for posterior fixation and fusion without previous anterior trans-oral decompression. Anterior irreducible compression due to C1C2D instability, it is said, needs trans-oral anterior decompression. We reviewed our experience in order to refute such a paradigm.

METHODS

The study involves 23 patients who were operated on for cranio-vertebral junction (CVJ) instability; all of them had C1C2D of varying degree on x-ray, computerised tomography (CT) and magnetic resonance (MR) imaging of the CVJ. Pre-operatively, irreducible C1C2D was demonstrated only in 3 patients, (2 with Down's Syndrome, one of them was harbouring os odontoideum, 1 Rheumatoid Arthritis), i.e. 13.04%; the remaining 19 (86.9%) had reducible C1-C2 dislocation. After an unsuccessful traction test conducted in the pre-operative phase under sedation, it was possible to completely reduce the C1C2D (with a combination of axial traction with light extension of the neck on the chest and a light flexion of the head on the neck by using a Mayfield head holder) and proceed to posterior fixation in all the patients under general anaesthesia using a precise "timing sequences fixation technique". Wiring (C0 and C3 were fixed first being stretched up to approximately 10 lbs, then C2 in order to pull up this vertebra last by forcing approximately 8 lbs) or screw fixation methods were used to achieve fusion along with post-operative external orthosis and neuroradiological assessment of the C1C2D. The instrumentation produced a lever and pulley effect which assisted reduction of the dislocation.

FINDINGS

At follow up (range 34-55 months-mean 45.33 months) the clinical picture was improved or stable in all patients.

CONCLUSIONS

Pre-operative irreducibility of the C1C2D should not be an absolute indication for trans-oral decompression. An attempt to reduce the dislocation under general anaesthesia and during posterior fixation should be attempted in Down's syndrome, os odontoideum and rheumatoid arthritis.

Upper cervical ligament testing in a patient with os odontoideum presenting with headaches

STUDY DESIGN

Resident's case problem.

BACKGROUND

The role of premanipulative testing of the cervical spine is an area of controversy, and there are very few data to inform and guide practitioners on the use of ligamentous stability tests when assessing the upper cervical spine.

DIAGNOSIS

A 23-year-old female was referred to physical therapy by a neurologist for the management of intractable headaches of possible musculoskeletal origin. Her Neck Disability Index score was 54% and she rated her headache pain from 3/10 to 9/10 on a Numerical Pain Rating Scale. She reported a 2-year history of intermittent lower extremity paresthesias without a known mechanism or current symptoms. She was treated in physical therapy for 11 visits with improvements in cervical range of motion, strength, and intensity of her headaches, but noted no change in the frequency of headaches. She was subsequently referred to the primary author for a second opinion and potential manual therapy interventions. Initial neurological screening examination for upper and lower motor neuron lesions was unremarkable. Assessment of the transverse ligament, using the anterior shear test in supine, brought on paresthesias in both feet and her toes. The paresthesias continued after the cessation of the test. The Sharp-Purser test performed in sitting, immediately after the transverse ligament test, abolished the paresthesias. She was then referred back to her primary care physician for further evaluation. Subsequent radiographs and magnetic resonance imaging revealed that the patient had a C2-C3 Klippel-Feil congenital fusion and os odontoideum. The patient was examined by a neurosurgeon who concluded that she was not a surgical candidate. Her neurological symptoms completely resolved, but she continued to have headaches.

DISCUSSION

Os odontoideum is a clinically important condition, given that the mobile dens may render the transverse ligament incompetent, leading to atlantoaxial instability. Both the role and sequencing of upper cervical ligamentous testing is controversial. The results of this case report suggest that physical therapists should be cognizant of this condition and consider screening the upper cervical ligaments prior to manual or mechanical interventions to this region.

LEVEL OF EVIDENCE

Differential diagnosis, level 4.

C1-2 vertebral anomalies in 22q11.2 microdeletion syndrome

BACKGROUND

Chromosome 22q11.2 microdeletion syndrome (22q11DS) is characterized by cleft palate, cardiac anomalies, characteristic facies, high prevalence of skeletal anomalies and learning disability.

OBJECTIVE

To evaluate the prevalence of craniovertebral junction anomalies in children with 22q11DS and compare these findings to those in nonsyndromic children with velopharyngeal insufficiency (VPI).

MATERIALS AND METHODS

Sequential CT scans performed for presurgical carotid assessment in 76 children (45 children positive for chromosome 22q11.2 deletion and 31 negative for the deletion) with VPI were retrospectively evaluated for assessment of C1-2 anomalies.

RESULTS

C1-2 vertebral anomalies, specifically midline C1 defects, uptilted or upswept posterior elements of C2 and fusions of C2-3, were nearly universal in our cohort of 22q11DS patients with VPI. They were strikingly absent in the majority of non-22q11DS patients with VPI.

CONCLUSION

C1-2 vertebral anomalies, particularly those listed above, are important radiographic markers for 22q11DS.

Intermittent atlantoaxial subluxation caused by a prolapsing neurofibroma. Case report

In this report, the authors describe a unique case of intermittent high cervical cord compression caused by a prolapsing neurofibroma at the C1-2 level. This 21-year-old man with known neurofibromatosis Type 1 presented with a mass between the anterior arch of the atlas and the odontoid peg, causing atlantoaxial dissociation and cord compression. The cervicomedullary compression appeared to be caused in part by the neurofibroma but also by the abnormal alignment and thickening of the ligaments between the clivus and C-2. Preoperative imaging repeated on the morning of surgery revealed that the atlantoaxial dissociation had reduced with relief of cord compression and the lesion prolapsed inferiorly. The authors discuss this unusual lesion and describe the associated operative findings and surgical management.

Association of methylenetetrahydrofolate reductase genetic polymorphisms with atlantoaxial dislocation

Object

Genetic mechanisms of atlantoaxial dislocation (AAD) have not previously been elucidated. The authors studied association of polymorphisms in the methylenetetrahydrofolate reductase (MTHFR) gene, which encodes enzymes of the folate pathway (implicated in causation of neural tube defects [NTDs]), in patients with AAD.

Methods

Molecular analysis of MTHFR polymorphisms (677C→T, cytosine to thymine and, 1298A→C, adenine to cytosine, substitutions) was carried out using polymerase chain reaction and restriction enzyme digestion in 75 consecutive patients with AAD and in their reducible (nine patients, 12%) and irreducible (66 patients, 88%) subgroups. Controls were 60 age- and sex-matched patients of the same ethnicity. Comparisons of genotype and allele frequencies were performed using a chi-square test (with significance at p < 0.05).

Results

The CT genotype frequency of MTHFR 677C→T polymorphism was significantly increased in the full group of patients with AAD (odds ratio [OR] 3.00, 95% confidence interval [CI] 1.28–7.14, p = 0.005) as well as in the irreducible subgroup (OR 2.81, 95% CI 1.17–6.86, p = 0.01). The frequency of T alleles was also higher in the AAD group (25.3%) than in controls (15%). The comparison of the combined frequency of CT and TT genotypes with the frequency of the CC genotype again showed significant association in AAD (OR 2.63, 95% CI 1.98–5.90, p = 0.009) and the irreducible (OR 2.5, 95% CI 1.1–5.74, p = 0.016) subgroup. There was, however, no significant association of MTHFR 1298A→C polymorphism with AAD.

Conclusions

Both MTHFR 677C→T polymorphism and higher T allele frequency have significant associations with AAD, especially the irreducible variety. Perhaps adequate supplementation of periconceptional folic acid to circumvent effects of this missense mutation (as is done for prevention of NTDs) would reduce the incidence of AAD.

[Rare pathological alterations of the upper cervical spine requiring surgical treatment]

Because of its unique anatomy, specific diseases and lesions arise in the upper cervical spine, which differ widely from the rest of the spine. During the last two decades standardised diagnostic and therapeutic algorithms have been defined for most of the craniocervical pathologies often occurring in combination with an underlying disease requiring surgical intervention as well. On the other hand there are some very rare phathological alterations: about 20% of the patients suffering from neurofibromatosis type I develop spinal deformities. These are mostly found in the thoracic and lumbar spine (dystrophic/non-dystrophic type). In rare cases the dystrophic neurofibromatosis type I involves the upper cervical spine leading to bizarre deformities endangering the spinal cord. An aggressive, timely and combined operative therapy is necessary. Patients with Down syndrome should be investigated regularly for affections of the upper cervical spine. Though only in about 1% of all patients with Down syndrome do instabilities require surgical intervention, the upper cervical spine should be screened on a regular basis, since neurological changes due to the pathognomy of the underlying disease often remain undetected for a long time. The operative therapy of the instable os odontoideum in Down syndrome follows the general principles of this pathoanatomical variation. Even though the Klippel-Feil syndrome is generally not linked with neuropathological findings, rare associated deformities of the upper cervical spine should be excluded by proper diagnostic procedures.

Chiari malformation and odontoid panus causing craniovertebral stenosis in a child with Crouzon's syndrome

Crouzon's disease is a well-known disorder affecting multiple organ systems, specifically a craniofacial disorder with highly variable penetrance and severity of deformity. Crouzon's patients typically have anomalies of the skull base leading to gross distortion of the cranium and in some cases the cervicocranium. We present a 5-year-old girl with Crouzon's disease who suffered from an acquired Chiari I malformation after insertion of a ventriculoperitoneal shunt and a coexistent ventral odontoid panus. Both these lesions were causing cervicomedullary compression. The literature is controversial on the surgical management of anterior and posterior compression at the craniocervical junction. We review the literature on surgical options for decompression at the craniocervical junction and offer our surgical case as a treatment option for patients in this rare clinical situation.

Complications of fixation to the occiput-anatomical and design implications

Internal fixation provides an increased immediate stability for the craniovertebral junction; however, there is no current consensus on the optimal method of occipitocervical (OC) fusion. In this report, we present 25 cases of craniovertebral instability treated with OC fusion by plates and screws instrumentation. The 25 cases comprised 12 men and 13 women, whose ages ranged 20 to 78 years. The principal aetiologies that lead to the OC instability of the patients in this series included trauma, rheumatoid arthritis, neoplasm and congenital abnormality. The fusion levels ranged from occiput-C3 to occiput-C6. Two mortalities occurred. The other patients showed satisfactory union after a follow-up of eight to 24 months. OC fusion using a plates and screws system is a safe and highly effective method for providing immediate internal stability to the OC junction. The internal occipital anatomy, which cannot be seen at surgery, is important when dealing with this taxing and potentially dangerous aspect of surgery.

Dysplastic dens of the axis: case report

In a patient injured in a bicycle accident, radiological evaluation of the cervical spine revealed an oblique orientation of a dysplastic dens of the axis, which, to our knowledge, has not been reported in the literature. There were no other bony or soft tissue anomalies and no associated instability. This case should draw attention to congenital anomalies of the cranio-cervical junction in trauma patients.

A case of mucopolysaccharidosis IV with lower leg paresis due to thoraco-lumbar kyphoscoliosis

We treated a patient of type IV mucopolysaccharidosis (Morquio's disease) with lower leg paresis due to kyphoscoliosis. A 65-year-old woman presented with Morquio's disease. A lateral radiograph demonstrated the classic bullet-shaped vertebrae and a 65 degrees thoraco-lumbar kyphosis. After the age of 60, she suffered from numbness in both lower legs and walking disturbance. Bilateral patellae-tendon reflexes were exaggerated. MRI showed compression of the spinal cord around T12 to L2 with a highlighted area of change inside the spinal cord. Myelography and computed tomography after the myelography showed narrowing of the sub-arachnoidal space and deformation of the spinal cord around the T12 to L2 levels. Severe vertebral osteoporosis made it necessary to first perform posterior correction of the kyphosis and fusion. The curve was stabilised with the Luque method from T7 to L4. Her neurological condition markedly recovered, but 1 year after surgery her neurological condition again began to deteriorate, resulting in walking disturbance. For this reason, anterior decompression and fusion through a lateral thoracotomy was undertaken. Decompression of the spinal cord and a bone graft from the iliac crest were attained. The patient's neurological condition again improved, but not as much as immediately after the first operation.

Occipitocervical reconstruction with the Ohio Medical Instruments Loop: results of a multicenter evaluation in 30 cases

OBJECT

Stabilization of the craniocervical junction (CCJ) remains a significant challenge. In this multicenter study, the authors present the results of an evaluation of a precontoured titanium implant, the Ohio Medical Instruments (OMI) Loop, for craniocervical fixation.

METHODS

In this multicenter retrospective study the authors evaluated 30 patients (16 female, 14 male; mean age 53.8 years) with rheumatoid arthritis (15 cases), traumatic occipitoatlantoaxial instability (six cases), congenital vertebral anomalies (two cases), instability due to basilar invagination in the setting of Chiari malformation (two cases), or Down syndrome (one case), tumor (one case), os odontoideum (two cases), and pseudarthrosis/other (one case), who underwent OMI Loop-assisted occipitocervical reconstruction. The mean follow-up period was 25.4 months (range 6-60 months). A solid reconstruction was achieved in 29 of 30 cases; there was only one case of hardware failure requiring reoperation. Noncritical hardware failure occurred in two patients in whom partial occipital screw backout occurred but did not necessitate reoperation. There were no perioperative neurological complications. One patient (3.3%) experienced a delayed postoperative worsening of myelopathy at 1 year that resolved with further surgery. Postoperatively, in 66.6% of patients the degree of myelopathy remained stable (as measured by American Spinal Injury Association [ASIA] scores), whereas 30% improved by one or more ASIA grade. The rate of osseous fusion was 96.6% at a mean follow-up period of 25.4 months.

CONCLUSIONS

The authors found that the OMI Loop is a versatile precontoured occipitocervical fixation device that can be applied to a wide range of CCJ lesions. It provides excellent immediate rigid fixation of the CCJ, a high rate of osseous fusion, and a low rate of hardware failure.

Histology of the craniocervical junction in chronic rheumatoid arthritis: a clinicopathologic analysis of 33 operative cases

STUDY DESIGN

A histologic review of surgical specimens with clinical and radiographic correlations.

OBJECTIVE

To analyze the histopathology at the craniocervical junction in chronic rheumatoid arthritis (RA).

SUMMARY OF BACKGROUND DATA

It has been assumed that the tissue identified on radiography at the craniocervical junction causing anterior spinal cord compression in patients with chronic RA is hypertrophic rheumatoid synovium. To date, no study has positively identified the histology of this tissue.

METHODS

Transoral resection of the dens and spinal cord decompression were performed in 33 myelopathic rheumatoid patients with craniocervical instability. The resected specimens were examined histologically.

RESULTS

Two unique histologic patterns were identified. Type I synovium has a recognizable synovial structure but without a hyperplastic synovial layer, significant inflammatory cell population, or lymphocytic infiltration typical of early active rheumatoid synovium. Type II synovium is a bland, fibrous, hypercellular tissue that is hypovascular, with little synovium and few inflammatory cells. Clinically and radiologically the two groups are distinct. Patients with Type II synovium are older ( = 0.008) and present with more advanced neurologic involvement caused by spinal cord compression ( = 0.0001). The mean difference in the spinal cord area between the two groups was 20.6 mm (95% confidence interval, 10.0-31.2 mm; = 0.004).

CONCLUSIONS

The histologic specimens suggest that ligamentous destruction is followed by replacement of the rheumatoid synovium with fibrous tissue, whereas the osseous structures reveal severe destruction secondary to mechanical instability, rather than to an acute inflammatory process. Early, preemptive surgical intervention may prevent the development of spinal cord injury caused by instability.

Congenital anomaly of craniovertebral junction: atlas-dens fusion with C1 anterior arch cleft

A rare case of congenital atlantoaxial block is reported. A 13-year-old boy had a fusion of a non-separated odontoid process with the anterior arch of the atlas, in association with an anterior midline C1 arch cleft.

Vertebral artery pseudoaneurysm complicating posterior C1-2 transarticular screw fixation: case report

BACKGROUND

Vertebral artery injury during posterior C1-2 transarticular screw fixation occurs in approximately 3% of patients and may remain asymptomatic or result in arteriovenous fistulae, occlusion, narrowing, or dissection of the vertebral artery, and lead to transient ischemic attacks, stroke, or death.

CASE DESCRIPTION

This is the first report of a pseudoaneurysm resulting from damage to the vertebral artery during the procedure. This 31-year-old male underwent posterior C1-2 transarticular screw fixation for unstable os odontoideum. Injury to the left vertebral artery occurred while the hole for the left screw was being drilled. Temporary control of bleeding with local pressure was followed by immediate postoperative angiography that revealed a left vertebral artery pseudoaneurysm. Although the patient remained asymptomatic, therapeutic anticoagulation was instituted 6 hours postoperatively. Increasing size of the pseudoaneurysm was noted on routine follow-up angiography 4 weeks later. Endovascular occlusion of the pseudoaneurysm and left vertebral artery, with preservation of vertebrobasilar flow through the right vertebral artery, was accomplished without neurological consequence.

CONCLUSIONS

Vertebral artery pseudoaneurysm complicating posterior C1-2 transarticular screw fixation may be effectively treated with endovascular approaches.

Congenital arthrogryposis associated with atlantoaxial subluxation and dysraphic abnormalities. Case report

The authors report the case of a 27-year-old woman with an arthrogryposis multiplex congenita (AMC) associated with atlantoaxial subluxation. To the authors' knowledge, this is the first report of its kind. The authors review the literature with reference to dysraphic abnormalities associated with atlantoaxial subluxation and with AMC. The patient presented with severe tetraparesis following a minor traffic accident. She underwent a procedure in which transoral decompression and dorsal stabilization were performed and, postoperatively, made a good clinical outcome. The authors stress the need for diagnostic neuroimaging of the craniocervical junction in patients with AMC.

Symptomatic cervical synovial cyst associated with an os odontoideum diagnosed by magnetic resonance imaging: case report and review of the literature

STUDY DESIGN

The first case of a synovial cyst of the upper cervical spine associated with os odontoideum diagnosed by magnetic resonance imaging is presented.

OBJECTIVES

To evaluate distinct magnetic resonance imaging findings of a cervical synovial cyst located anterior to the cord and discuss its association with os odontoideum. These findings may guide further investigations.

BACKGROUND

Synovial cysts of the spine are uncommon findings. They occur mostly dorsolaterally and with greatest frequency in the lumbar spine and are rarely symptomatic. No association with os odontoideum has been reported before.

METHODS

A single subject with symptoms of deterioration in his hand functions was examined by a 2. 0-T magnetic resonance imager.

RESULTS

Magnetic resonance imaging of the cervical spine showed an os odontoideum connected to the body of C2 by a synovial joint that had a cystic extension posteriorly compressing the cord.

CONCLUSION

Synovial cysts should be considered in the differential diagnosis of an extradural mass of the upper cervical spine. Magnetic resonance imaging should be the choice in the investigation of such cases.