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.

Transnasal Endoscopic Approach for Osteoid Osteoma of the Odontoid Process in a Child: Technical Note and Systematic Review of the Literature

Osteoid osteoma (OO) is a primary benign tumor that accounts for up to 3% of all bone tumors. The cervical spine is less affected by OOs, and very few cases of C2 OOs have been reported in the literature, both in adults and children. Surgery may be required in case of functional torticollis, stiffness, and reduced range of motion (ROM) due to cervical OOs refractory to medical therapy. Several posterior and anterior surgical techniques have been described to remove C2 OOs. In particular, anterior approaches to the cervical spine represent the most used surgical route for treating C2 OOs. We describe the first case of OO of the odontoid process removed through a transnasal endoscopic approach with the aid of neuronavigation in a 6-year-old child. No intraoperative complications occurred, and the post-operative course was uneventful. The patient had immediate relief of neck pain and remained pain-free throughout the follow-up period, with complete functional recovery of the neck range of motion (ROM). In this case, based on the favorable anatomy, the transnasal endoscopic approach represented a valuable strategy for the complete removal of an anterior C2 OO without the need for further vertebral fixation since the preservation of ligaments and paravertebral soft tissue.

Biomechanical evaluation of the craniovertebral junction after odontoidectomy with anterior C1 arch preservation: A finite element study

OBJECTIVE

Odontoidectomy with preservation of the anterior C1 arch can be increasingly achieved by an endoscopic endonasal approach. It is controversial whether preservation of the anterior C1 arch after odontoidectomy can prevent instability of the craniovertebral junction （CVJ） and avoid posterior fixation. The aim of this research was to investigate the biomechanical effect of the preserved anterior C1 arch after odontoidectomy.

METHODS

A validated finite element model of a whole cervical spine (occipital bone to T1) was constructed to study the biomechanical changes due to traditional odontoidectomy (TO) and odontoidectomy with preservation of the anterior C1 arch (OPC1).

RESULTS

The greatest biomechanical changes in the cervical spine model after TO and OPC1 occurred at C0-C1 and C1-C2. At C0-C1 and C1-C2, the motion changes of the TO and OPC1 models had no significant difference in flexion, extension and lateral bending. Compared with the intact model, motion increases of the two surgical models were both extremely significant at C1-C2 in extension (128.2% vs. 128.1%) and lateral bending (178% vs. 156%). In axial rotation, the TO approach produced more motions than the OPC1 approach, especially at C1-C2(90.3° under TO approach, and 74.6° under OPC1 approach).

CONCLUSIONS

Preservation of the anterior C1 arch after odontoidectomy can preserve the axial rotational motion at C0-C1 and C1-C2, whereas the motions in extension and lateral bending continue to have an extremely abnormal increase at C1-C2. Thus, instability of the CVJ still exists, and posterior internal fixation may also be required after OPC1.

Staged Repositioning in Endoscopic Endonasal Odontoidectomy Maximizes Decompression While Allowing Preservation of the C1 Anterior Arch: A Technical Note

BACKGROUND

Preservation of the anterior arch of C1 in endoscopic endonasal odontoidectomy has been proposed as an alternative to complete C1 arch resections, potentially affording less destabilization of the craniocervical junction. Nonetheless, this approach may limit the decompression achieved. In this case, intraoperative repositioning allowed maximal decompression while preserving the anterior arch of C1.

METHODS

A 79-year-old woman presented with suboccipital pain caused by an expansile and compressive mass centered on the dens. Notably, the mass occluded both vertebral arteries resulting in small cerebellar strokes. An endoscopic endonasal approach for diagnosis and decompression was performed followed by posterior fixation.

RESULTS

Given the significant compression, the patient was initially positioned in slight cervical extension. After rhinopharyngeal flap harvest, the top half of the anterior arch of C1 was resected, maintaining its structural integrity. The odontoidectomy was completed flush to the superior border of the reduced C1 arch. After an intraoperative computed tomography (CT) scan, performed in a neutral position, the patient was then repositioned with cervical flexion. This maneuver presented the residual odontoid above the C1 arch, but, given the partial removal of the dens, it did not result in any change in neuromonitoring. Further odontoid resection was then completed and follow-up CT scan revealed maximal dens removal, extending below the C1 anterior arch in neutral position.

CONCLUSIONS

In cases of odontoid/atlantoaxial pathology causing significant neural compression, staged intraoperative repositioning can safely maximize the odontoidectomy, while affording preservation of the structural integrity of the anterior arch of C1.

Surgery for craniovertebral junction pathologies: minimally invasive anterior submandibular retropharyngeal key-hole approach

Background

Our objective was to develop a new, minimally invasive surgical technique for the resolution of craniovertebral junction pathologies, which can eliminate the complications of the previous methods, like liquor-leakage, velopharyngeal insufficiency and wound-dehiscence associated with the transoral or lateral approaches.

Methods

During the first stage of the operation, three patients underwent occipito-cervical dorsal fusion, while the fourth patient received C1–C2 fusion according to Harms. C1–C2 decompressive laminectomy was performed in all four cases. Ventral C1–C2 decompression with microscope assisted minimally invasive anterior submandibular retropharyngeal key-hole approach (MIS ASR) method was performed in the second stage. The MIS ASR—similarly to the traditional anterior retropharyngeal surgery—preserves the hard and soft palates, yet can be performed through a 25 mm wide incision with the use of only one retractor.

Results

The MIS ASR approach was a success in all four cases, there were no intra- and postoperative complications. This method, compared to the transoral approach, provided on average 23% (4.56 cm²/6.05 cm²) smaller dural decompression area; nonetheless, the entire pathology could be removed in all cases. After the surgery, all patients have shown significant neurological improvement.

Conclusion

Based on the outcome of these four cases we think that the MIS ASR approach is a safe alternative to the traditional methods while improving patient safety by reducing the risk of complications.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12893-021-01198-z.

Endoscopic Endonasal Approach for Urgent Decompression of Craniovertebral Junction in Syringobulbia

BACKGROUND

Syringobulbia is an uncommon lesion that occurs in the central nervous system; it is often defined as a pathologic cavitation in the brainstem. The cases with partial blockage of the cerebrospinal fluid pathways at the level of the foramen magnum are more common and the most important group. The most common treatment of syringobulbia is craniovertebral decompression.

CASE DESCRIPTION

This paper reports a case of a symptomatic syringobulbia in which an urgent endoscopic endonasal approach to the craniovertebral junction (CVJ) was done to limit bulbo-medullary compression and rapid neurologic deterioration. A 69-year-old man was admitted to the hospital because of acute onset of dysphonia, dysphagia, imbalance, and vomiting. Magnetic resonance imaging revealed a cystic lesion in the brainstem, suggestive of a syringobulbia in Klippel Feil syndrome with CVJ stenosis.

CONCLUSIONS

This case report details the successful use of endoscopic endonasal anterior decompression to treat syringobulbia, and adds to the growing literature in support of the endonasal endoscopic approach as a safe and feasible means for decompressing the craniocervical junction, even in the setting of urgency. However, prudent patient selection, combined with sound clinical judgment, access to instrumentation, and intraoperative imaging cannot be overemphasized.

Coil Extrusion into the Naso- and Oropharynx Ten Years after Internal Carotid Artery Pseudoaneurysm Embolization: A Case Report

Coil migration and extrusion outside the cranial compartment after embolization of cerebral aneurysms represents a very rare complication of the endovascular procedures and few cases are reported in the literature. Instability of the vascular malformation wall and the resolution of the intramural hematoma, especially in pseudoaneurysm, might generate extravascular migration of the coils in the first months after embolization. However, to the best of our knowledge, an extrusion of coil 10 years after embolization has never been reported. We reported the unique case of a patient with coil extrusion into the naso- and oropharynx 10 years after internal carotid artery pseudoaneurysm embolization. The pseudoaneurysm occurred after an internal carotid artery injury during an endoscopic endonasal surgery for a clival giant cell tumor.

Modified Pure Endoscopic Approach to Pineal Region: Proof of Concept of Efficient and Inexpensive Surgical Model Based on Laboratory Dissections

OBJECTIVE

In recent decades endoscopic techniques have been increasingly used in neurosurgery as they may offer a valuable close-up view of the working area through a minimally invasive surgical corridor. Herein, we present an inexpensive and efficient endoscopic surgical model using a borescope, which was used for a "modified pure endoscopic approach" to the pineal region.

METHODS

A borescope video camera was connected to a 16-inch personal computer monitor. A standard midline suboccipital craniotomy was performed on 2 cadaveric heads in the Concorde position. Then, a "borescopic" supracerebellar infratentorial approach was executed, thus reaching the pineal region, which was exposed through an extensive arachnoid dissection.

RESULTS

Using the previously described model, we were able to provide excellent exposure of the main neurovascular structures of the pineal region, as shown by the intraoperative videos. In 1 specimen we identified an incidental pineal cyst that was meticulously dissected and removed.

CONCLUSIONS

Our proposed "borescopic" surgical model may represent an inexpensive and efficient alternative to conventional endoscopic techniques and could be used for training purposes, as well as even for clinical procedures, after a proper validation, particularly in economically challenging environments.

Quantitative evaluation of different far lateral approaches to the cranio-vertebral junction using the microscope and the endoscope: a cadaveric study using a tumor model

BACKGROUND

Several far lateral approaches have been proposed to deal with cranio-vertebral junction (CVJ) tumors including the basic, transcondylar, and supracondylar far lateral approaches (B-FLA, T-FLA, and S-FLA). However, the indications on when to use one versus the other are not well systematized yet. Our purpose is to evaluate in an experimental cadaveric setting which approach is best suited to remove tumors of different sizes.

METHODS

We implanted at the CVJ, using a transoral approach, tumor models of different sizes (five 1-cm³ and five 3-cm³ tumors) in ten embalmed cadaveric heads. The artificial tumors were exposed via the three approaches using endoscopic-assisted microneurosurgical technique and neuronavigation. The skull base area exposed and the maneuverability linked to each approach were evaluated using neuronavigation.

RESULTS

In 1-cm³ tumors, the T-FLA and the S-FLA exposed a significantly larger skull base area than the B-FLA both using the microscope and the endoscope (P < 0.05); the T-FLA executed with the microscope provided wider vertical and horizontal maneuverability than the B-FLA (P = 0.030 and 0.017, respectively); the S-FLA executed with the endoscope provided wider vertical maneuverability than the T-FLA (P = 0.031). The S-FLA executed using the microscope and the endoscope provided wider vertical maneuverability than the B-FLA both in 1 and 3-cm³ tumors (P < 0.05).

CONCLUSIONS

In 1-cm³ tumors, the S-FLA and the T-FLA expose a wider skull base area than the B-FLA. In larger tumors, the exposure is similar for all three approaches. Use of the endoscope in an assistive mode may further increase the surgical exposure and maneuverability.

Supraorbital subfrontal trans-laminar endoscope-assisted approach for tumors of the posterior third ventricle

BACKGROUND

Different surgical approaches have been developed for dealing with third ventricle lesions, all aimed at obtaining a safe removal minimizing brain manipulation. The supraorbital subfrontal trans-lamina terminalis route, commonly employed only for the anterior third ventricle, could represent, in selected cases with endoscopic assistance, an alternative approach to posterior third ventricular lesions.

METHODS

Seven patients underwent a supraorbital subfrontal trans-laminar endoscope-assisted approach to posterior third ventricle tumors (two craniopharyngiomas, one papillary tumor of the pineal region, one pineocytoma, two neurocytomas, one glioblastoma). Moreover, a conventional third ventriculostomy was performed via the same trans-laminar approach in four cases.

RESULTS

Complete tumor removal was accomplished in four cases, subtotal removal in two cases, and a simple biopsy in one case. Adjuvant radiotherapy and/or chemotherapy was administered, if required, on the basis of the histologic diagnosis. No major complications occurred after surgery except for an intratumoral hemorrhage in a patient undergoing a biopsy for a glioblastoma, which simply delayed the beginning of adjuvant radiochemotherapy. No ventriculoperitoneal shunt placement was needed in these patients at the most recent clinical and radiologic session (average 39.57 months, range 13-85 months). Two illustrative cases are presented.

CONCLUSIONS

The supraorbital subfrontal trans-laminar endoscope-assisted approach may provide, in selected cases, an efficient and safe route for dealing with posterior third ventricular tumors.