Instability of the craniovertebral junction and treatment outcomes in patients with Down's syndrome

Measurement of Deformity at the Craniovertebral Junction: Correlation of Triangular Area and Myelopathy

OBJECTIVE

Diseases of the craniovertebral junction (CVJ) are commonly associated with deformity, malalignment, and subsequent myelopathy. The misaligned CVJ might cause compression of neuronal tissues and subsequently clinical symptoms. The triangular area (TA), measured by magnetic resonance imaging/images (MRI/s), is a novel measurement for quantification of the severity of compression to the brain stem. This study aimed to assess the normal and pathological values of TA by a comparison of patients with CVJ disease to age- and sex-matched controls. Moreover, postoperative TAs were correlated with outcomes.

METHODS

Consecutive patients who underwent surgery for CVJ disease were included for comparison to an age- and sex-matched cohort of normal CVJ persons as controls. The demographics, perioperative information, and pre- and postoperative 2-year cervical MRIs were collected for analysis. Cervical TAs were measured and compared.

RESULTS

A total of 201 patients, all of whom had pre- or postoperative MRI, were analyzed. The TA of the CVJ deformity group was larger than the healthy control group (1.62 ± 0.57 cm2 vs. 1.01 ± 0.18 cm2, p < 0.001). Moreover, patients who had combined anterior odontoidectomy and posterior laminectomy with fixation had the greatest reduction in the TA (1.18 ± 0.58 cm2).

CONCLUSION

In CVJ deformity, the measurement of the cervical TA could indicate the severity of brain stem compression. After surgery, the TA had a varying degree of improvement, which could represent the efficacy of surgery.

Assessment of craniocervical motion in Down syndrome: a pilot study of two measurement techniques

OBJECTIVE

Hypermobility of the craniocervical junction (CCJ) in patients with Down syndrome (DS) is common. Whereas atlantoaxial (C1-2) hypermobility is well characterized, occipitoatlantal (Oc-C1) laxity is recognized but poorly defined. A clear understanding of the risks associated with DS-related hypermobility is lacking. Research efforts to address the topic of axial cervical spine instability in the patient with DS require a reliable and reproducible means of assessing CCJ mobility. The authors conducted a pilot study comparing two methods of quantifying motion of the CCJ on dynamic (flexion/extension) plain radiographs: the delta-condyle-axial interval (ΔCAI) and the delta-basion-axial interval (ΔBAI) methods.

METHODS

Dynamic radiographs from a cohort of 10 patients with DS were evaluated according to prescribed standards. Independent movement of Oc-C1, C1-2, and Oc-C2 was calculated. Interrater and intrarater reliability for CCJ mobility was then calculated for both techniques.

RESULTS

Measurement using the ΔCAI technique had excellent fidelity with intraclass correlation coefficients (ICCs) of 0.77, 0.71, and 0.80 for Oc-C1, C1-2, and Oc-C2, respectively. The ΔBAI technique had lower fidelity, yielding respective ICCs of 0.61, 0.65, and 0.50.

CONCLUSIONS

This pilot study suggests that ΔCAI is a superior measurement technique compared to ΔBAI and may provide reliable assessment of the mobility of the CCJ on dynamic radiographs in the pediatric patient with DS. The use of reliable and reproducible measurement techniques strengthens the validity of research derived from pooled database efforts.

Suture Repair in Endoscopic Surgery for Craniovertebral Junction

Objective

Endoscopic approaches to the craniovertebral junction (CVJ) have been established as viable and effective surgical treatments in the past decade. One of the major complications is leakage of the cerebrospinal fluid (CSF). This study aimed to investigate the efficacy and feasibility of suture closure at the nasopharyngeal mucosa upon durotomy.

Methods

A series of consecutive patients who underwent different endoscopic approaches to the CVJ were retrospectively reviewed. The pathologies, surgical corridors, neurological and functional outcomes, radiological evaluations, and complications were analyzed. Different strategies of repair for the intraoperative CSF leakage were described and compared.

Results

A total of 22 patients covering 13 years were analyzed. There were 12, 2, and 8 patients who underwent transnasal, transoral, and combined approaches, respectively. There were 8 patients (36.4%) who experienced intraoperative CSF leakage, and were grouped into 2: 4 in the nonsuture (NS) group and 4 in the suture-repaired (SR) group. The NS group had 3 (75%) persistent CSF leakages postoperation that caused 1 mortality, whereas patients of the SR group had only 1 minor CSF rhinorrhea that healed spontaneously within days.

Conclusion

In this series of 22 patients who required anterior endoscopic resection of pathologies at the CVJ, there was 1 (4.5%) serious complication related to CSF leakage. For patients who had no durotomy, the mucosal incision at the nasopharynx usually healed rapidly and there were few procedure-related complications. For patients with intraoperative CSF leakage, suture closure was technically challenging but could significantly lower the risks of postoperative complications.

Atlantoaxial Subluxation Secondary to Unstable Os Odontoideum in a Patient With Arrested Hydrocephalus Due to Congenital Aqueductal Stenosis: A Case Report

BACKGROUND

In a small percentage of children born with congenital hydrocephalus, enlargement of the head and the presence of ventriculomegaly may halt and ultimately stabilize the condition designated as arrested hydrocephalus. Arrested hydrocephalus in children is typically due to congenital aqueduct stenosis, which can be described appropriately as a stasis existing within the channel between the third and fourth ventricles. Os odontoideum (OO) is an uncommonly occurring pathology at the craniovertebral junction. Although the clinical and radiologic features of its existence and the therapeutic options for its pathology have been widely discussed within the medical literature, its true etiology has been a source of divisive debate, proposing both a traumatic as well as a congenital mechanism. The etiology of OO has been heartily debated in the literature for several years as well. Most authors have come to support a posttraumatic causality. However, strong evidence exists to support a congenital origin to this rarely observed malformation.

METHODS

Within this case study we present a 24-year-old woman with atlantoaxial subluxation that exists secondary to an orthotropic OO. The patient had a history of arrested hydrocephalus due to congenital aqueductal stenosis beginning in early childhood. She presented with normal intelligence and was neurologically without deficits before the occurrence of an atlantoaxial dislocation. Unfortunately, the pathology was initially misdiagnosed as a decompensation state of the arrested hydrocephalus, and after 8 months the patient became wheelchair bound. Following this unfortunate event the correct diagnosis was ultimately uncovered. Subsequently a C2-1 instrumentation procedure resulted in excellent alignment and fusion.

CONCLUSIONS

To the best of our knowledge, this is the first example of an aqueduct stenosis in the setting of an existing OO, a combination that might be another clue in favor of a congenital etiology.

Reduction of atlantoaxial dislocation prevented by pathological position of the transverse ligament in fixed, irreducible os odontoideum: operative illustrations and radiographic correlates in 41 patients

OBJECTIVE Os odontoideum (OO) is a craniovertebral junction (CVJ) abnormality in which an ossicle (small bone) is cranial to a hypoplastic dens by a variable gap. This abnormality can result in instability, which may be reducible or irreducible. What leads to irreducibility in OO is unclear. Therefore, the authors sought to better understand the causes of irreducibility in OO. METHODS A retrospective review was conducted, which identified more than 200 patients who had undergone surgical treatment for OO between 1978 and 2015 at the University of Iowa Hospitals and Clinics. Only the 41 patients who had irreducible OO were included in this study. All inpatient and outpatient records were retrospectively reviewed, and patient demographics, clinical presentation, radiographic findings, surgical treatment, and operative findings were recorded and analyzed. RESULTS The cohort of 41 patients who were found to have irreducible OO included both children and adults. A majority of patients were adults (61% were 18 years or older). Clinical presentation included neck pain and headache in the majority of patients (93%). Weakness, sensory disturbances, and myelopathy were invariably present in all 41 patients (100%). Down syndrome was much more common in the pediatric cohort than in the adult cohort; of the 16 pediatric patients, 6 had Down syndrome (38%), and none of the adults did. Of the 16 pediatric patients, 5 had segmentation failure (31%) in the subaxial spine, and none of the adults did. A form of atlantoaxial dislocation was seen in all cases. On CT imaging, atlantoaxial facets were dislocated in all 41 cases but did not have osseous changes that would have prevented reduction. On MRI, the transverse ligament was identified anterior and inferior to the ossicle and superior to the hypoplastic odontoid process in all cases in which these studies were available (i.e., post-MRI era; 36 of 36 cases). The ligament was hypointense on T2-weighted images but also had an associated hyperintense signal on T2 images. Intraoperatively, the transverse ligament was identified anterior and inferior to the ossicle and superior to the hypoplastic odontoid process in all 41 cases. CONCLUSIONS In the largest series to date of irreducible OO and the only study to examine variable factors that lead to irreducibility in OO, the authors found that the position of the transverse ligament anterior and inferior to the ossicle is the most common factor in the irreducibility of OO. The presence of granulation tissue and of the dystopic variant of OO is also associated with irreducibility. The presence of Down syndrome and segmentation failure probably leads to faster progression of ligamentous incompetence and therefore earlier presentation of instability and irreducibility. This is the first study in which intraoperative findings regarding the transverse ligament have been correlated with MRI.

Surgical approaches: postoperative care and complications "transoral-transpalatopharyngeal approach to the craniocervical junction"

INTRODUCTION

The ventral approach to the craniocervical border has been described for decompression of irreducible extradural pathology. The procedures utilized encompass the transoropharyngeal and median mandibulotomy with glossotomy and the transpalatal procedures. This study was aimed to review the utility of the transoral-transpalatopharyngeal approach.

CLINICAL MATERIALS AND METHODS

Seven hundred thirty-three patients underwent transpalatopharyngeal approach for decompression of the brain stem and cervicomedullary junction. Of these, 280 were children below the age of 16 years. The main indication was irreducible ventral pathology compressing the brain stem and cervicomedullary junction. Two hundred two children had irreducible basilar invagination, 28 had proatlas segmentation abnormalities, os odontoideum with a dystopic os odontoideum in 30, and spinal tumors in seven (chordoma, fibrous dysplasia, osteoblastoma). Seven patients with Down's syndrome and irreducible bony compression of the ventral cervicomedullary junction were seen. There were six other miscellaneous diagnoses. All children required craniocervical stabilization which was carried out under the same anesthetic as the transoral procedure.

OPERATIVE PROCEDURE

The procedure entailed fiber-optic intubation. The patient was placed in cervical traction prior to the anterior procedure. The soft palate was split only in individuals with a short clivus with a high riding clivus-odontoid articulation. Craniocervical stabilization was performed in the prone position under the same anesthetic.

RESULTS

There was one retropharyngeal infection postoperatively. No cesium fluoride leaks were encountered. Velopalatine incompetence was seen in five children who already had preoperative brain stem dysfunction. Neurological recovery was the rule. Patients who had preoperative syringohydromyelia had resolution of the syrinx on postoperative magnetic resonance imaging.

DISCUSSION

The author's technique is described. Since 1977, the procedure has been performed in 732 patients (280 children) and has evolved into a safe and direct approach to the ventral cervicomedullary junction with minimal morbidity and mortality.

Specific entities affecting the craniocervical region: Down's syndrome

INTRODUCTION

The ligamentous laxities and bony abnormalities associated with Down's syndrome, os odontoideum, achondroplasia, osteogenesis imperfecta, and basilar invagination have been discussed with the imaging of the craniocervical junction. These are significant and require suspicion when dealing with children with the previously mentioned entities.

CONCLUSION

Previous adverse surgical results in managing these patients reflect the lack of understanding of the underlying pathology and the appropriate surgical treatment.

Evaluation and treatment of congenital and developmental anomalies of the cervical spine. Invited submission from the Joint Section Meeting on Disorders of the Spine and Peripheral Nerves, March 2004

Congenital and developmental osseous abnormalities of the cervical spine can result in neural compression ranging from the medulla oblongata to the cervicothoracic spinal cord junction. These may present in infancy as scoliosis and even limb weakness. A high index of suspicion is essential. Neurodiagnostic imaging relies on high-resolution computerized tomography (CT) scanning and three-dimensional CT reconstructions as well as magnetic resonance imaging and angiography. The anatomical/physiological CT factors considered when developing a surgical approach are: 1) the stability and reducibility of the lesions; 2) direction and manner of encroachment of the lesion on the neural structures; 3) neural and vascular abnormalities; and 4) growth potential of the affected area. Primary stabilization is required for reducible lesions, whereas irreducible lesions are decompressed in the manner in which encroachment has occurred. Instability, whether present before or after operative intervention, required spinal stabilization. Illustrative examples of this approach are presented.