Retro-Odontoid and Retro-C2 Body Pseudotumor, Pannus, and/or Cyst. A Study Based on Analysis of 63 Cases

Post-Traumatic Central or Axial Atlantoaxial Dislocation Presenting with "Atypical" Symptoms-Analyzing the Role of Dynamic Imaging on the Basis of Experience with 14 Patients Treated by Atlantoaxial Fixation surgery

BACKGROUND

This is a report of a series of 14 patients who presented with a range of "atypical" cranial, spinal, and systemic symptoms that started after they suffered a relatively severe injury to the head and/or neck several months or years before surgical treatment. The implications of diagnosing and treating central or axial atlantoaxial dislocation (CAAD) is discussed. Also, the role of dynamic rotatory and lateral head tilt imaging in the diagnosis and treatment is analyzed.

METHODS

Of the 14 patients, 7 were men and 7 were women, with an age range of 21-64 years (average, 42 years). Due to the severity of the presenting neurological and non-neurological symptoms, all the patients had lost their occupation and were heavily dependent on painkillers and/or antidepressant drugs. In addition to other characteristic clinical and radiological evidence, CAAD was diagnosed made based on the facet alignments on lateral profile imaging in the neutral head position. Dynamic head flexion-extension, lateral head tilt, and neck rotation imaging findings confirmed and subclassified CAAD. All 14 patients underwent atlantoaxial fixation surgery.

RESULT

A personalized self-assessment clinical scoring parameter and the World Health Organization Disability Assessment Schedule 2.0 was used to evaluate the outcome. One patient did not follow-up after surgery. At a minimum follow-up of 6 months after atlantoaxial fixation surgery, the remaining 13 patients experienced relief from all major symptoms.

CONCLUSIONS

Diagnosing and treating CAAD can have major therapeutic implications for patients presenting with progressively worsening disabling clinical symptoms following relatively severe head and/or neck trauma.

Real-time ultrasound guidance in the endoscopic endonasal resection of a retro-odontoid pannus: Technical note and case illustration

Background and Objectives

Odontoidectomy is a surgical procedure indicated in the setting of various pathologies, with the main goal of decompressing the ventral brain stem and spinal cord as a result of irreducible compression at the craniovertebral junction. The endoscopic endonasal approach has been increasingly used as an alternative to the transoral approach as it provides a straightforward, panoramic, and direct approach to the odontoid process. In addition, intraoperative ultrasound (US) guidance is a technique that can optimize safety and surgical outcomes in this context. It is used as an adjunct to neuronavigation and provides intraoperative confirmation of decompression of craniovertebral junction structures in real time. The authors aim to present the use and safe application of real-time intraoperative US guidance during endonasal endoscopic resection of a retro-odontoid pannus.

Methods

A retrospective chart review of a single case was performed and presented herein as a case report and narrated operative video.

Results

A minimally invasive US transducer was used intraoperatively to guide the resection of a retro-odontoid pannus and confirm spinal cord decompression in real time. Postoperative examination of the patient revealed immediate neurological improvement.

Conclusions

Intraoperative ultrasonography is a well described and useful modality in neurosurgery. However, the use of intraoperative US guidance during endonasal endoscopic approaches to the craniovertebral junction has not been previously described. As demonstrated in this technical note, the authors show that this imaging modality can be added to the ever-evolving armamentarium of neurosurgeons to safely guide the decompression of neural structures within the craniocervical junction with good surgical outcomes.

Cervical Myelopathy Caused by Non-Rheumatic Retro-Odontoid Pseudotumor: An Investigation of Underlying Mechanisms and Optimal Surgical Strategy

STUDY DESIGN

Retrospective case-control study.

OBJECTIVE

This study aimed to identify the underlying pathologies of non-rheumatic retro-odontoid pseudotumors (NRPs), which would help establish an appropriate surgical strategy for myelopathy caused by NRP.

METHODS

We identified 35 patients with myelopathy caused by NRP who underwent surgery between 2006 and 2017. An age- and sex-matched control group of 70 subjects was selected from patients with degenerative cervical myelopathy. Radiographic risk factors for NRP were compared between cases and controls. We also assessed surgical outcomes following occipital-cervical (O-C) fusion, atlantoaxial (C1-2) fusion, or C1 laminectomy.

RESULTS

Patients with NRP had significantly lower C1 sagittal inner diameter, C2-7 range of motion (ROM), C2-7 Cobb angle, and C7 tilt, as well as significantly higher C1-2 ROM, atlantodental interval (ADI), and C1-2 to O-C7 ROM ratio. Multivariate regression analysis revealed that ADI, C2-7 ROM, and C7 tilt were independent risk factors for NRP. Neurological recovery and pseudotumor size reduction were comparable among surgical procedures, whereas post-operative cervical spine function was significantly lower in the O-C fusion group than in the other groups.

CONCLUSION

Non-rheumatic retro-odontoid pseudotumor was associated with an increase in ADI, suggesting that spinal arthrodesis surgery is a reasonable strategy for NRP. C1-2 fusion is preferable over O-C fusion because of the high prevalence of ankylosis in the subaxial cervical spine. Given that 29% of patients with NRP have C1 hypoplasia, such cases can be treated by posterior decompression alone. Our study highlights the need to select appropriate surgical procedures based on the underlying pathology in each case.

Transdural Approach for Resection of Craniovertebral Junction Cysts: Case Series

BACKGROUND

Craniovertebral junction (CVJ) cysts, including retro-odontoid pseudotumors, are challenging pathologies to treat and manage effectively. Surgical intervention is indicated when these lesions result in progressive myelopathy, intractable pain, or instability.

OBJECTIVE

To present a case series of older patients who underwent successful resection retro-odontoid lesions using transdural approach.

METHODS

A single-center, retrospective observation study of older patients who underwent transdural resection of CVJ cysts at a single institution was performed. Summary demographic information, clinical presentation, perioperative and intraoperative imaging, and Nurick scores were collected and analyzed.

RESULTS

Eight patients were included (mean age [±SD] 75.88 ± 9.09 years). All patients presented with retro-odontoid lesions resulting in severe cervical stenosis, cord compression, and myelopathy. The mean duration of surgery was 226 ± 83.7 minutes. The average intraoperative blood loss was 181.2 cc. The average hospital stay was 4.5 days ± 1.3 (range, 3-7 days). The average follow-up time was 12.5 ± 9.5 months. No intraoperative complications were encountered. The Nurick classification score for myelopathy improved at the final postoperative examination (2.38 ± 1.06 vs 1 ± 1.07). Three patients demonstrated a pre-existing deformity prompting an instrumented fusion. Both computed tomography and MRI evidence of complete regression of retro-odontoid cyst were noted in all patients on the final follow-up.

CONCLUSION

Posterior cervical transdural approach for ventral lesions at the CVJ is a safe and effective means of treating older patients with progressive myelopathy. This technique provides immediate spinal cord decompression while limiting neurological complications commonly associated with open or endoscopic anterior transpharyngeal approaches.

Os odontoideum associated with a retro-odontoid cyst treated with posterior C1-C3 fixation: A case report and literature review

Background

Os odontoideum is a rare abnormality of the upper cervical spine, and os odontoideum associated with a retro-odontoid cyst has been described as a marker of local instability.

Case description

This paper reports a case of a 52-year-old female patient who was diagnosed with os odontoideum associated with a retro-odontoid cyst. The patient underwent posterior C1-C3 fixation without surgical removal of the cyst. Magnetic resonance imaging (MRI) two days later revealed that the retro-odontoid cyst was still present and that there were no significant changes to it when compared with the preoperative MRI.

Conclusion

Retro-odontoid cysts associated with unstable os odontoideum can lead to symptomatic spinal cord compression. Posterior C1-C3 fixation can restore atlantoaxial stability by allowing the gradual resorption of the cyst and ensuring spinal cord decompression. Fixation can also avoid the surgical risk associated with a high-riding vertebral artery.

Central Atlantoaxial Dislocation: Presenting Symptoms, Diagnostic Parameters, and Surgical Treatment from Reports on 15 Surgically Treated Patients

AIM

This chapter reviews the clinical entity of central or axial atlantoaxial instability (CAAD).

MATERIAL AND METHODS

From January 2018 to November 2020, 15 patients were identified as having CAAD, wherein there was no atlantoaxial instability when analyzed by conventional radiological parameters and wherein there was no evidence of neural or dural compression due to the odontoid process. The patients were identified as having atlantoaxial instability on the basis of the alignment of facets on lateral profile imaging and a range of telltale clinical and radiological indicators. The clinical statuses of the patients were recorded both before and after surgical treatment by using the specially designed Goel symptom severity index and visual analog scale (VAS) scores. All patients were treated via atlantoaxial fixation.

RESULTS

There were six men and nine women ranging in age from 18 to 45 years (average: 37 years). The presenting clinical symptoms were relatively subtle and long-standing. Apart from symptoms that are generally related to neural compromise at the craniovertebral junction, a range of nonspecific cranial and spinal symptoms were prominent. The follow-up time after surgery ranged from 6 to 34 months. All patients showed early postoperative and sustained clinical recovery.

CONCLUSIONS

The correct diagnosis and appropriate surgical treatment of CAAD can provide an opportunity for quick and lasting clinical recovery.

Atlantoaxial Intradural Synovial Cyst Mimicking an Extradural Lesion Adjacent to a Retro-odontoid Pseudotumor: A Case Report

Atlantoaxial synovial cysts can very rarely penetrate the dura mater into the thecal sac and cause direct neural compression. Several case reports have been available on "intradural synovial cysts" (IDSCs). In this study, we report on a case with an atlantoaxial IDSC mimicking an extradural lesion. A 90-year-old man was diagnosed with a cystic lesion located laterally to the atlantoaxial joint adjacent to the retro-odontoid pseudotumor (ROP) causing cervical spinal cord compression. Thus, surgical removal was planned. On preoperative examination, the cyst, which had a two-layer structure showing a T2-isointense small mass inside a T2-hyperintense lesion, was thought to be located in the extradural region. However, operative findings showed that the cyst was located inside the dura mater. Histopathological examination suggested a synovial cyst. No recurrence of the cyst was observed until the latest follow-up after 3 years, and the ROP decreased in size. Almost all IDSCs reported previously were observed in the medial site of the atlantoaxial joint. In our case, however, the cyst was observed adjacent to the posteromedial site of the right atlantoaxial joint and the ROP, mimicking an extradural lesion. We had no knowledge regarding the IDSC before the surgery and assumed an extradural lesion. Albeit rare, the existence of such a condition should be considered.

Retro-odontoid pseudotumor presenting double layer on MRI: A case report

Background:

Retro-odontoid pseudotumors (ROPs) typically present as a single mass posterior to the odontoid ranging from isointense to hypointense relative on T1-weighted magnetic resonance (MR) imaging (MRI T1WI). Here, a patient with ROP exhibited the double-layer sign on the MRI T1WI characterized by an initial ventral layer posterior to the odontoid process followed by a secondary dorsal layer.

Case Description:

An 84-year-old male presented with cervical myelopathy attributed to ROP resulting in atlantoaxial instability on dynamic X-ray studies, and the double-layer sign on the T1 MR accompanied by a cystic component. MR following C1–C2 posterior fusion, the patient’s myelopathy resolved and both layers spontaneously regressed on the follow-up MR studies.

Conclusion:

The MR-documented double layer sign with ROP, likely attributable to reactive hypertrophy of the transverse ligament with cystic components, may demonstrate spontaneous MR regression with symptom resolution following a C1–C2 posterior fusion.

Regression of retro-odontoid pseudotumor following botulinum injection into cervical muscles

Background:

Posterior fixation of C1/2 has become more commonly performed to treat retro-odontoid pseudotumor (ROP). Here, we report a 60-year-old female with cervical dystonia (CD), whose ROP regressed and whose quadriparesis improved after a series of cervical intramuscular botulinum injections.

Case Description:

A 60-year-old female with 30 years of CD newly presented with a progressive quadriparesis. When the MRI showed ROP compression the cervical spinal cord, she refused surgery and underwent multiple cervical muscular botulinum injections over the next 2 years. Following these injections, the patient’s quadriparesis improved as the ROP regressed on subsequent MR studies.

Conclusion:

Over a 2-year period, multiple cervical botulinum injections caused regression of a retro-odontoid cervical pseudotumor improvement in the patient’s quadriparesis.

Lateral Suboccipital Craniotomy With C1-C2 Hemilaminectomies and C1-C3 Fusion for the Treatment of a C1-C2 Synovial Cyst Causing Spinal Cord Compression: 2-Dimensional Operative Video

Atlantoaxial synovial cysts are a rare cause of cervical myelopathy. Here we describe a case of a 26-yr-old woman who presented with progressively decreasing right arm and leg strength and associated gait imbalance. On examination, she had diffuse weakness in the right upper and lower extremities, a positive right-sided Hoffman sign, and clonus in the right lower extremity. Computed tomography demonstrated an os odontoideum and a retro-odontoid cyst. Magnetic resonance imaging demonstrated a T1 hypointense, T2 hyperintense, slightly rim-enhancing retro-odontoid cyst causing a marked narrowing of the spinal canal, with resultant flattening and leftward deviation of the spinal cord. The patient consented to undergo cyst fenestration via a right suboccipital craniotomy and right C1-C2 hemilaminectomies, along with a C1-C3 instrumented posterior spinal fusion. This approach was chosen because it allows for cyst fenestration and instrumentation of the hypermobile cervical spine within the same incision. After the dura was opened and the arachnoid was dissected, the cyst was visualized compressing the spinal cord. The cyst was fenestrated just inferior to the C1 nerve rootlets, resulting in immediate egress of a gelatinous content; thereafter, all accessible cyst wall portions were removed. Fusion was performed with lateral mass screws at C1 and C3 and pars screws at C2. Pathological analysis described the cyst content as reactive fibrovascular tissue with cholesterol deposition. There were no complications associated with the procedure, and the patient's right-sided weakness had nearly resolved by postoperative day 1. Patient consent was granted for publication.