A Dual Approach for the Management of Complex Craniovertebral Junction Abnormalities: Endoscopic Endonasal Odontoidectomy and Posterior Decompression with Fusion

Case report of bilateral middle ear effusion requiring myringotomy and tube placement following inferior U-shaped nasopharyngeal flap elevation for endonasal odontoidectomy: investigation of causality

We describe a patient with symptomatic os odontoideum and a previous history of C1-2 wiring who underwent successful treatment with a staged endonasal odontoidectomy and C1-2 revision of instrumentation. Access to the odontoid process was gained through the endonasal corridor using an inverted U-shaped nasopharyngeal flap (IUNF). Post-operatively, the patient experienced resolution of her presenting neurologic symptoms but developed conductive hearing loss secondary to bilateral middle ear effusion, requiring bilateral myringotomy and tube placement 3 months post-operatively. We hypothesize this dysfunction may have resulted from surgical edema, packing buttressing the IUNF, or some combination thereof. In this manuscript, we review the evolution of the nasopharyngeal exposure for odontoidectomy and whether an IUNF may predispose to this complication.

Endoscopic Endonasal Approach to the Craniovertebral Junction Lesions: A Case Series of 18 Patients

Introduction  Odontoid pathologies constitute a special category because they may lead to instability. Instability is defined by abnormal spinal alignment under physiologic conditions (loads) such as standing, walking, bending, or lifting. Since instability poses a risk of cord damage, surgical interventions may be required for durable long-term stabilization. This study demonstrates operative technique and results of endoscopic endonasal approach to the odontoid pathologies. Methods  We conducted a retrospective study involving 18 patients who underwent endoscopic endonasal odontoidectomy (EEO) due to craniovertebral pathologies. Demographic data, clinical features of the patients, risk factors, and intraoperative and postoperative complications were reported in this series. Results  Satisfactory outcomes achieved in 16 patients based on comparing the modified Rankin scale before and after the surgery ( p  = 0.0001). The mean duration for EEO was 232.6 ± 18.8 minutes. The mean blood loss during surgery was 386.67 ± 153.04 mL. The mean duration of hospital stay was 7 days. All patients were extubated within a few hours after surgery. Despite of successful anterior decompression in the aforementioned cases, intraoperative cerebrospinal fluid (CSF) leakage, postoperative meningitis, and pulmonary thromboembolism occurred as complications. However, two intraoperative CSF leakages were managed by direct dural repair and fat graft; two patients died due to postoperative meningitis and pulmonary thromboembolism at 7 and 4 days after the second surgery. Conclusion  In conclusion, EEO can be effectively used for anterior decompression of the odontoid pathologies, despite the risk of complications.

Craniovertebral Junction Instability after Oncological Resection: A Narrative Review

The craniovertebral junction (CVJ) is a complex transition area between the skull and cervical spine. Pathologies such as chordoma, chondrosarcoma and aneurysmal bone cysts may be encountered in this anatomical area and may predispose individuals to joint instability. An adequate clinical and radiological assessment is mandatory to predict any postoperative instability and the need for fixation. There is no common consensus on the need for, timing and setting of craniovertebral fixation techniques after a craniovertebral oncological surgery. The aim of the present review is to summarize the anatomy, biomechanics and pathology of the craniovertebral junction and to describe the available surgical approaches to and considerations of joint instability after craniovertebral tumor resections. Although a one-size-fits-all approach cannot encompass the extremely challenging pathologies encountered in the CVJ area, including the possible mechanical instability that is a consequence of oncological resections, the optimal surgical strategy (anterior vs posterior vs posterolateral) tailored to the patient's needs can be assessed preoperatively in many instances. Preserving the intrinsic and extrinsic ligaments, principally the transverse ligament, and the bony structures, namely the C1 anterior arch and occipital condyle, ensures spinal stability in most of the cases. Conversely, in situations that require the removal of those structures, or in cases where they are disrupted by the tumor, a thorough clinical and radiological assessment is needed to timely detect any instability and to plan a surgical stabilization procedure. We hope that this review will help shed light on the current evidence and pave the way for future studies on this topic.

Craniocervical instability in patients with Ehlers-Danlos syndrome: controversies in diagnosis and management

Ehlers-Danlos syndrome (EDS) is a rare hereditary condition that can result in ligamentous laxity and hypermobility of the cervical spine. A subset of patients can develop clinical instability of the craniocervical junction associated with pain and neurological dysfunction, potentially warranting treatment with occipitocervical fixation (OCF). Surgical decision-making in patients with EDS can be complicated by difficulty distinguishing from hypermobility inherent in the disease and true pathological instability necessitating intervention. Here we comprehensively review the available medical literature to critically appraise the evidence behind various proposed definitions of instability in the EDS population, and summarize the available outcomes data after OCF. Several radiographic parameters have been used, including the clivo-axial angle, basion-axial interval, and pB-C2 measurement. Despite increasing recognition of EDS by spine surgeons, there remains a paucity of data supporting proposed radiographic parameters for spinal instability among EDS patients. Furthermore, there is a lack of high-quality evidence concerning the efficacy of surgical treatments for chronic debilitating pain prevalent in this population. More standardized clinical measures and rigorous study methodologies are needed to elucidate the role of surgical intervention in this complex patient population.

The Impact of C1 Anterior Arch Preservation on Spine Stability After Odontoidectomy: Systematic Review and Meta-Analysis

BACKGROUND

Odontoidectomy for symptomatic irreducible ventral brainstem compression at the craniovertebral junction may result in spine instability requiring subsequent instrumentation. There is no consensus on the importance of C1 anterior arch preservation in prevention of iatrogenic instability. We conducted a systematic review of the impact of C1 anterior arch preservation on postodontoidectomy spine stability.

METHODS

PubMed, Embase, Scopus, Web of Science, and Cochrane were searched following the PRISMA guidelines to include studies of patients undergoing odontoidectomy. Random-effect model meta-analyses were performed to compare spine stability between C1 anterior arch preservation versus removal and posttreatment outcomes between transoral approaches (TOAs) versus endoscopic endonasal approaches (EEAs).

RESULTS

We included 27 studies comprising 462 patients. The most common lesions were basilar invagination (73.3%) and degenerative arthritis (12.6%). Symptoms included myelopathy (72%) and neck pain (43.9%). Odontoidectomy was performed through TOA (56.1%) and EEA corridors (34.4%). The C1 anterior arch was preserved in 16.7% of cases. Postodontoidectomy stabilization was performed in 83.3% patients. Median follow-up was 27 months (range, 0.1-145). Rates of spine instability were significantly lower (P = 0.004) when the C1 anterior arch was preserved. Postoperative clinical improvement and pooled complications were reported in 78.8% and 12.6% of patients, respectively, with no significant differences between TOA and EEA (P = 0.892; P = 0.346). Patients undergoing EEA had significantly higher rates of intraoperative cerebrospinal fluid leaks (P = 0.002).

CONCLUSIONS

Odontoidectomy is safe and effective for treating craniovertebral junction lesions. Preservation of the C1 anterior arch seems to improve maintenance of spine stability. TOA and EEA show comparable outcomes and complication rates.

Evolution and Revolution of Imaging Technologies in Neurosurgery

We understand only a small fraction of the events happening in our brains; therefore, despite all the progress made thus far, a whole array of questions remains. Nonetheless, neurosurgeons invented new tools to circumvent the challenges that had plagued their predecessors. With the manufacturing boom of the 20th century, technological innovations blossomed enabling the neuroscientific community to study and operate upon the living brain in finer detail and with greater precision while avoiding harm to the nervous system. The purpose of this chronological review is to 1) raise awareness among future neurosurgeons about the latest advances in the field, 2) become familiar with innovations such as augmented reality (AR) that should be included in education given their ready applicability in surgical training, and 3) be comfortable with customizing these technologies to real-life cases like in the case of mixed reality.

Posterior midline approach to odontoidectomy: A novel method to treat basilar invagination

Background:

Basilar invagination (BI) is a common malformation of the craniocervical region where the odontoid process protrudes into the foramen magnum. Surgery in this region is difficult because of the complex anatomy of the craniocervical junction. Serious life-threatening complications have been observed with previously described approaches. Therefore, we conceived a novel surgical approach that can be implemented by neurosurgeons with different skill levels to facilitate better outcomes.

Methods:

We describe a new surgical technique for the treatment of BI that we used in two patients in whom cervical myelopathy and direct ventral compression of the cervicomedullary junction were confirmed through clinical and radiological findings. We present the technique of posterior odontoidectomy in a step-by-step, didactic, and practical manner with surgical tips and tricks.

Results:

The resection was completed without intraoperative or postoperative complications in both cases. The patients experienced substantial neurological improvements, and full recovery was observed during the 9-month and 12-month follow-up visits after discharge. Compared with the transoral approach, our technique provides a larger decompression area.

Conclusions:

We describe a novel method for the treatment of BI that was applied in two patients and suggest that the posterior approach might be a safe and effective method for ventral decompression of the craniocervical junction. Posterior odontoidectomy followed by craniocervical fixation helped achieve complete cervicomedullary decompression.

Increase in clivo-axial angle is associated with clinical improvement in children undergoing occipitocervical fusion for complex Chiari malformation: patient series

BACKGROUND

The authors analyzed the pre- and postoperative morphometric properties of pediatric patients with complex Chiari malformation undergoing occipitocervical fusion (OCF) to assess clinical outcomes and morphometric properties that might influence postoperative outcomes.

OBSERVATIONS

The authors retrospectively reviewed 35 patients younger than 22 years with Chiari malformation who underwent posterior fossa decompression and OCF with or without endoscopic endonasal odontoidectomy at their institution (13 with and 22 without odontoidectomy). Clivo-axial angle (CXA), pB-C2, atlantodental interval, basion-dens interval, basion-axial interval, and canal diameter at the level of C1 were measured on preoperative and approximately 3-month postoperative computed tomography or magnetic resonance imaging. The authors further stratified the patient cohort into three age groups and compared the three cohorts. The most common presenting symptoms were headache, neck/shoulder pain, and dysphagia; 80% of the cohort had improved clinical outcomes. CXA increased significantly after surgery. When stratified into those who showed postoperative improvement and those who did not, only the former showed a significant increase in CXA. After age stratification, the significant changes in CXA were observed in the 7- to 13-year-old and 14- to 21-year-old cohorts.

LESSONS

CXA may be the most important morphometric predictor of clinical outcomes after OCF in pediatric patients with complex Chiari malformation.

Predicting clinical outcomes using morphometric changes in adults with complex Chiari malformation undergoing occipitocervical fusion with or without ventral decompression: patient series

BACKGROUND

The authors assessed the connection between clinical outcomes and morphometrics in patients with complex Chiari malformation (CM) who have undergone posterior fossa decompression (PFD) and subsequent occipitocervical fusion (OCF) with or without ventral decompression (VD).

OBSERVATIONS

The authors retrospectively reviewed 33 patients with CM aged over 21 years who underwent PFD and OCF with or without endoscopic endonasal odontoidectomy at the authors’ institution (21 OCF only and 12 OCF + VD). Clivoaxial angle (CXA), pB-C2 (perpendicular line to the line between the basion and C2), atlantodental interval (ADI), basion-dens interval (BDI), basion-axial interval (BAI), and C1 canal diameter were measured on preoperative and approximately 3-month postoperative computed tomography or magnetic resonance imaging scans. Common symptoms included headache, paresthesia, and bulbar symptoms. Clinical improvement after surgery was observed in 78.8% of patients. CXA, ADI, and BDI all significantly increased after surgery, whereas pB-C2 and BAI significantly decreased. OCF + VD had a significantly more acute CXA and longer pB-C2 preoperatively than OCF only. Patients who clinically improved postoperatively showed the same significant morphometric changes, but those who did not improve showed no significant morphometric changes.

LESSONS

Patients showing improvement had greater corrections in skull base morphometrics than those who did not. Although there are various mutually nonexclusive reasons why certain patients do not improve after surgery, smaller degrees of morphometric correction could play a role.

The management of Chiari malformation type 1 and syringomyelia in children: a review of the literature

In anticipation of the "Chiari and Syringomyelia Consensus Conference" held in Milan in 2019, we performed a systematic literature review on the management of Chiari malformation type 1 (CM1) and syringomyelia (Syr) in children.We aimed to summarize the available evidence and identify areas where consensus has not been reached and further research is needed.In accordance with PRISMA guidelines, we formulated seven questions in Patients-Interventions-Comparators-Outcomes (PICO) format. Six PICOs concerned CM1 children with/without additional structural anomalies (Syr, craniosynostosis, hydrocephalus, tethered cord, and cranio-vertebral junction anomalies), and one PICO Syr without CM1. We searched Medline, Embase, Cochrane, and NICE databases from January 1, 1999, to May 29, 2019. Cohort studies, controlled and randomized clinical trials (CCTs, RCTs), and systematic reviews were included, all pertinent only to patients ≤ 18 years of age.For CM1, 3787 records were found, 460 full texts were assessed and 49 studies (46 cohort studies, one RCT, and two systematic reviews) were finally included. For Syr, 376 records were found, 59 full texts were assessed, and five studies (one RCT and four cohort studies) were included. Data on each PICO were synthetized narratively due to heterogeneity in the inclusion criteria, outcome measures, and length of follow-up of the included studies.Despite decades of experience on CM1 and Syr management in children, the available evidence remains limited. Specifically, there is an urgent need for collaborative initiatives focusing on the adoption of shared inclusion criteria and outcome measures, as well as rigorous prospective designs, particularly RCTs.

Ventral Tonsillar Herniation Predicts Headaches in Adults With Chiari Malformation

BACKGROUND

Radiographic characterization of Chiari malformation (CM) has historically focused on caudal tonsillar herniation (CH) below the foramen magnum. Previously, we published evidence linking ventral tonsillar herniation (VH) and medullary symptoms in very young children. We sought to extend that investigation by studying the radiographic and clinical significance of VH in adults diagnosed with CM.

METHODS

We retrospectively reviewed adults with cerebellar ectopia who underwent posterior fossa decompression with or without duraplasty (PFD/D) at our institution. VH was defined as tonsils crossing a line bisecting the caudal medulla at the level of the foramen magnum on axial MRI. Degree of VH was measured as distance between this bisecting line and the ventral tip of the herniated tonsil. Dorsal brainstem compression was qualitatively determined by assessing for obliteration of CSF space between the dorsal brainstem and the tonsils.

RESULTS

Out of 89 cases reviewed, 54 had some degree of VH. Compared with those without VH, the VH group was significantly older in age and more likely to also present with dorsal brainstem compression and headaches. No correlation was observed between degrees of CH and VH in the VH group. The degree of VH significantly decreased 3 months after PFD/D.

CONCLUSIONS

VH is relatively common in CM patients and might be an important independent radiographic metric to evaluate and consider as part of the decision-making process, especially in those presenting with Chiari-like symptomatology referable to the medulla but who do not meet the traditional criteria of cerebellar ectopia greater than 5 mm.

Endoscopic Endonasal Resection of Cranio-Cervical Junction Chordoma and Ventral Chiari Decompression: A Case Report

BACKGROUND

Chiari I malformations secondary to other causes represent a small subset of presenting symptomatic cases. Typically, the primary cause of the malformation is addressed first and results in resolution of the malformation and symptoms. However, in some cases, a patient may present with both a primary Chiari I malformation and another unrelated neurosurgical lesions.

OBJECTIVE

To present a unique case in which resection of a ventral tumor allowed for spontaneous resolution of a simultaneously noted dorsal Chiari I malformation.

METHODS

Pertinent data, including presenting symptoms, hospital course, surgical notes, preoperative images, and postoperative images, were collected using the electronic medical record.

RESULTS

We present a case of a 46-yr-old man with a Chiari I malformation in conjunction with a ventral cranio-cervical junction chordoma. Endoscopic endonasal resection of the chordoma and ventral foramen magnum decompression resulted in radiographic resolution of the Chiari malformation and resolution of his symptoms. Our report represents a rare case of ventral foramen magnum decompression as a treatment for Chiari I malformation.

CONCLUSION

It is felt that the chordoma mass effect was not the source of the Chiari I malformation. Thus, both ventral and dorsal decompressions of the posterior fossa may be considered for Chiari I decompression in select circumstances.

Interlayer dural split technique for Chiari I malformation treatment in adult-Technical note

OBJECTIVE

To present an alternative surgical technique in treating cases of Chiari I Malformation with mild-to-moderate syringomyelia after decompressive suboccipital craniectomy: incising only the outer layer of the dura mater, then dissecting it from the inner layer without opening the latter.

PATIENTS AND METHODS

We utilized this technique in a short series of three cases who were admitted to our department for mild symptoms such as intermittent headache and dissociated sensory loss in the upper limbs, caused by a Chiari Malformation Type I. The patients were placed in the sitting position. We performed a reduced median suboccipital craniectomy and resection of the posterior arch of C1 adapted to the level of tonsil descent, from a limited superior half to complete resection. Afterward, we incised the outer dural layer, while sparing the inner one. Using a fine dissector, we then split apart the outer and inner layers to the margin of the craniectomy. Through the transparency of the inner layer and the arachnoid, the cerebellum and the medulla were visible and pulsating. An autologous fascia duraplasty was then performed.

RESULTS

The postoperative course was favorable in all cases, the patients being discharged without any deficits and with complete symptom resolution. Follow-up at 3, 6, and 12 months after surgery revealed a significant reduction in brainstem compression and syringomyelia.

CONCLUSIONS

Interlayer dural split technique can be used effectively in treating symptomatic cases of type I Chiari malformation in adults, with mild-to-moderate syringomyelia. It is less invasive than opening the dura and possibly more effective than decompressive craniectomy and C1 laminectomy alone. This technique must be validated in a larger case-control series.

Endoscopic transnasal/transoral odontoid resection in children: results of a combined neurosurgical and otolaryngological protocolized, institutional approach

OBJECTIVE

Odontogenic ventral brainstem compression can be a source of significant morbidity in patients with craniocervical disease. The most common methods for odontoidectomy are the transoral and endoscopic endonasal routes. In this study, the authors investigated the use of an institutional protocol for endoscopic transnasal/transoral odontoidectomy in the pediatric population.

METHODS

From 2007 to 2017, a multidisciplinary institutional protocol was developed and refined for the evaluation and treatment of pediatric patients requiring odontoidectomy. Preoperative assessment included airway evaluation, a sleep study (if indicated), discussion of possible tonsillectomy/adenoidectomy, and thorough imaging review by the neurosurgery and otolaryngology teams. Further preoperative anesthesia consultation was obtained for difficult airways. Intraoperatively, adenoidectomy was performed at the discretion of otolaryngology. The odontoidectomy was performed as a combined procedure. Primary posterior pharyngeal closure was performed by the otolaryngologist. The postoperative protocol called for immediate extubation, advancement to a soft diet at 24 hours, and no postoperative antibiotics. Outcome variables included time to extubation, operative time, estimated blood loss, hospital length of stay, and postoperative complications.

RESULTS

A total of 13 patients underwent combined endoscopic transoral/transnasal odontoid resection with at least 3 years of follow-up. All patients had stable to improved neurological function in the postoperative setting. All patients were extubated immediately after the procedure. The average operative length was 201 ± 46 minutes, and the average estimated blood loss was 44.6 ± 40.0 ml. Nine of 13 patients underwent simultaneous tonsillectomy and adenoidectomy. The average hospital length of stay was 6.6 ± 5 days. The first patient in the series required revision surgery for removal of a small residual odontoid. One patient experienced pharyngeal flap dehiscence requiring revision.

CONCLUSIONS

A protocolized, institutional approach for endoscopic transoral/transnasal odontoidectomy is described. The use of a combined, multidisciplinary approach leads to streamlined patient management and favorable outcomes in this complex patient population.

Occipital-Cervical Fusion and Ventral Decompression in the Surgical Management of Chiari-1 Malformation and Syringomyelia: Analysis of Data From the Park-Reeves Syringomyelia Research Consortium

BACKGROUND

Occipital-cervical fusion (OCF) and ventral decompression (VD) may be used in the treatment of pediatric Chiari-1 malformation (CM-1) with syringomyelia (SM) as adjuncts to posterior fossa decompression (PFD) for complex craniovertebral junction pathology.

OBJECTIVE

To examine factors influencing the use of OCF and OCF/VD in a multicenter cohort of pediatric CM-1 and SM subjects treated with PFD.

METHODS

The Park-Reeves Syringomyelia Research Consortium registry was used to examine 637 subjects with cerebellar tonsillar ectopia ≥ 5 mm, syrinx diameter ≥ 3 mm, and at least 1 yr of follow-up after their index PFD. Comparisons were made between subjects who received PFD alone and those with PFD + OCF or PFD + OCF/VD.

RESULTS

All 637 patients underwent PFD, 505 (79.2%) with and 132 (20.8%) without duraplasty. A total of 12 subjects went on to have OCF at some point in their management (PFD + OCF), whereas 4 had OCF and VD (PFD + OCF/VD). Of those with complete data, a history of platybasia (3/10, P = .011), Klippel-Feil (2/10, P = .015), and basilar invagination (3/12, P < .001) were increased within the OCF group, whereas only basilar invagination (1/4, P < .001) was increased in the OCF/VD group. Clivo-axial angle (CXA) was significantly lower for both OCF (128.8 ± 15.3°, P = .008) and OCF/VD (115.0 ± 11.6°, P = .025) groups when compared to PFD-only group (145.3 ± 12.7°). pB-C2 did not differ among groups.

CONCLUSION

Although PFD alone is adequate for treating the vast majority of CM-1/SM patients, OCF or OCF/VD may be occasionally utilized. Cranial base and spine pathologies and CXA may provide insight into the need for OCF and/or OCF/VD.