Indirect Ventral Brainstem Decompression by Posterior C1-C2 Distraction and Fixation for Basilar Invagination.

Objective: Basilar invagination usually shows a decrease of clivus axis angle (CAA), which could give rise to progressive neural compression. Exploring a safe and effective fixation technique to achieve atlantoaxial stability and neural decompression remains necessary. In this study, we introduce a modified posterior C1-C2 distraction and fixation technique by which we obtained indirect ventral neural decompression and atlantoaxial stability in a series of patients with decreased CAA.

Can C1 lateral mass and C3 pedicle screw fixation be used as an option for atlantoaxial reduction and stabilization in Klippel-Feil patients? A study of its morphological feasibility, technical nuances, and clinical efficiency.

In Klippel-Feil patients with atlantoaxial dislocation, narrow C2 pedicles are often encountered preventing pedicle screw placement. Alternative techniques, including translaminar screws, pars screws, and inferior process screws could not achieve 3-column rigid fixation, and have shown inferior biomechanical stability. The present study aimed to evaluate the feasibility, safety, and efficacy of C3 pedicle screws (C3PSs) as an option for atlantoaxial stabilization in Klippel-Feil patients, and to introduce a freehand technique, the "medial sliding technique," for safe and accurate C3PS insertion.

Long-term surgical outcomes and prognostic factors of adult symptomatic spinal cord cavernous malformations.

Cervical and thoracic or lumbar intramedullary spinal cavernous malformations (ISCMs) may behave differently. We conducted this retrospective study by using data from adult ISCMs to compare their natural histories and explore prognostic factors for improved clinical outcomes. Neurological functions were assessed by using the Modified McCormick Scale (MMCS) and Aminoff-Logue Disability Scale.

A novel surgical protocol for safe and accurate placement of C1 lateral mass screws in patients with atlas assimilation, basilar invagination and atlantoaxial instability: technical details, accuracy assessment and perioperative complications.

Purpose: To introduce a novel surgical protocol for safe and accurate placement of C1 lateral mass screws in patients with atlas assimilation, basilar invagination and atlantoaxial instability, and to categorize the screw accuracy and perioperative complications regarding this technique in a large case series.

Methods: Between January 2015 and January 2020, patients who had atlas assimilation, basilar invagination and atlantoaxial instability, and underwent atlantoaxial fixation using C1 lateral mass screws were reviewed. C1 lateral mass screws were placed with a novel surgical protocol following a series key steps, including posterior para-odontoid ligament release, panoramic exposure of the invaginated lateral mass, and diligent protection of the abnormal VA.

Feasibility of occipital condyle screw placement in patients with Chiari malformation type I: a computed tomography-based morphometric study.

Background: The occipital condyle (OC) screw is an alternative technique for occipitocervical fixation that is especially suitable for revision surgery in patients with Chiari malformation type I (CMI). This study aimed to investigate the feasibility and safety of this technique in patients with CMI.

Methods: The CT data of 73 CMI patients and 73 healthy controls were retrospectively analyzed.

Treatment of Reducible Atlantoaxial Dislocation and Basilar Invagination Using the Head Frame Reduction Technique and Atlantoaxial Arthrodesis.

Study Design: Retrospective case series.

Object: To evaluate the outcomes of a head frame reduction and atlantoaxial arthrodesis technique for the treatment of reducible basilar invagination (BI) and atlantoaxial dislocation (AAD).

Methods: Seventy-two reducible BI and AAD cases who were treated with the head frame reduction and atlantoaxial arthrodesis technique from June 2015 to December 2018 were retrospectively analyzed.

Clinical characteristics and long-term surgical outcomes of spinal pilocytic astrocytoma: a report of twenty cases.

Background: Primary spinal pilocytic astrocytoma (PA) is an extremely rare low-grade astrocytoma with unclear natural history. The demographic characteristics, imaging features, and long-term surgical outcomes have not been clarified due to low prevalence and limited reports.

Methods: A retrospective review within a single institution between 2004 and 2018 of all patients with pathologically proven PA was conducted.

Surgical Treatment Outcomes of Patients with Conus Medullaris Teratoma: A Single-Center Experience of 39 Patients.

Objective: Conus medullaris teratomas are extremely rare, and the treatment experience has been limited. The purpose of the present study was to evaluate the clinical characteristics, radiological features, surgical outcomes, and prognosis of patients with conus medullaris teratoma.

Methods: We retrospectively reviewed the data from 39 patients who had undergone surgical resection for conus medullaris teratomas from January 2008 to December 2018.

Clinical features and long-term outcomes of pediatric spinal cord cavernous malformation-a report of 18 cases and literature review.

Purpose: Pediatric intramedullary spinal cord cavernous malformation (ISCM) is a rare vascular disease with unclear natural history and long-term outcomes. We aim to determine the demographics, hemorrhagic risk, and long-term outcomes of this rare entity.

Methods: A retrospective review of clinical data and treatment outcomes of pediatric patients treated with ISCM in our institution from 3/2000 to 3/2017 was conducted.

Long-term surgical outcomes of patients with delayed diagnosis of spinal dural arteriovenous fistula.

Spinal dural arteriovenous fistula (dAVF) is an extremely rare vascular entity that is usually misdiagnosed. We sought to determine the long-term clinical outcomes of patients undergoing microsurgical treatment for delayed diagnosis of spinal dAVF. This retrospective study identified patients with delayed diagnosed spinal dAVF at our institution from 2009 to 2018.

Clinical features and long-term surgical outcomes of pure spinal epidural cavernous hemangioma-report of 23 cases.

Background: Pure spinal epidural cavernous malformation (CM) is a rare hypervascular disease that is easily misinterpreted as other imaging-similar epidural lesions. The demographic characteristics, therapeutic strategies, and surgical outcomes associated with this vascular entity remains unclear.

Methods: A retrospective review of patients with pathologically proven, pure epidural CM from 2001 to 2018 was conducted.

The Role of Transverse Connectors in C1-C2 fixation for Atlantoaxial Instability: Is It Necessary? A Biomechanical Study.

Objective: To investigate the biomechanical effect of C1 lateral mass-C2 pedicle screw-rod (C1LM-C2PS) fixation with and without transverse connectors (TC) in an atlantoaxial instability (AAI) model.

Methods: Ten freshly frozen cadaveric specimens were tested using an industrial robot under the following conditions: intact model, AAI model, C1-C2 model, C1-C2 with one TC model, and C1-C2 with two TCs model. Three types of motion, flexion-extension (FE), lateral bending (LB), and axial rotation (AR), were applied (1.

C2 medial pedicle screw: a novel "in-out-in" technique as an alternative option for posterior C2 fixation in cases with a narrow C2 isthmus.

Objective: The authors describe a novel "in-out-in" technique as an alternative option for posterior C2 screw fixation in cases that involve narrow C2 isthmus. Here, they report the preliminary radiological and clinical outcomes in 12 patients who had a minimum 12-month follow-up period.

Methods: Twelve patients with basilar invagination and atlantoaxial dislocation underwent atlantoaxial reduction and fixation.

Posterior atlantoaxial facet joint reduction, fixation and fusion as revision surgery for failed suboccipital decompression in patients with basilar invagination and atlantoaxial dislocation: Operative nuances, challenges and outcomes.

Objective: To report the technical nuances and clinical outcomes of posterior atlantoaxial facet joint reduction, fixation and fusion (AFRF) technique as a revision procedure for BI and AAD patients with failed suboccipital decompression and large occipital bone defect.

Patients And Methods: We reviewed 32 patients with BI and AAD who were misdiagnosed as a simple Chiari malformation and received a suboccipital decompression surgery before admission. All patients underwent AFRF as a revision surgery.

Biomechanical evaluation of two alternative techniques to the Goel-Harms technique for atlantoaxial fixation: C1 lateral mass-C2 bicortical translaminar screw fixation and C1 lateral mass-C2/3 transarticular screw fixation.

Objective: The authors conducted a study to investigate the biomechanical feasibility and stability of C1 lateral mass-C2 bicortical translaminar screw (C1LM-C2TL) fixation, C1 lateral mass-C2/3 transarticular screw (C1LM-C2/3TA) fixation, and C1LM-C2/3TA fixation with transverse cross-links (C1LM-C2/3TACL) as alternative techniques to the Goel-Harms technique (C1 lateral mass-C2 pedicle screw [C1LM-C2PS] fixation) for atlantoaxial fixation.

Methods: Eight human cadaveric cervical spines (occiput-C7) were tested using an industrial robot. Pure moments that were a maximum of 1.

Usefulness of 3D Printed Models in the Management of Complex Craniovertebral Junction Anomalies: Choice of Treatment Strategy, Design of Screw Trajectory, and Protection of Vertebral Artery.

Objective: To evaluate the usefulness of 3-dimensional (3D) printed models as an aid for the treatment of complex CVJ anomalies.

Methods: 3D printed models were fabricated for 21 patients with complex CVJ anomalies, including vertebral artery anomaly, thin C2 pedicle, vertical atlantoaxial facet joint, or rotational dislocation combined with atlantoaxial dislocation and basilar invagination. Preoperative planning, surgical simulation, and intraoperative reference were achieved using the 3D model during the surgical treatment.

Can Posterior Reduction Replace Odontoidectomy as Treatment for Patients With Congenital Posterior Atlantoaxial Dislocation and Basilar Invagination?

Background: For patients with odontoid process protrusion and basilar invagination, posterior screw-rod fixation can usually achieve satisfactory horizontal reduction, but in some cases satisfactory reduction in the vertical direction cannot be achieved at the same time.

Objective: To propose a method for calculation of the theoretical maximum vertical reduction possible in individual patients.

Methods: The computed tomography imaging data of patients with occipitalization and basilar invagination who were treated at our institute between January 2013 and June 2016 were retrospectively analyzed.

Effects of transverse connector on reduction and fixation of atlantoaxial dislocation and basilar invagination using posterior C1-C2 screw-rod technique.

Background Context: The mechanical strength provided by internal fixation is crucial for maintaining reduction and facilitating bony fusion. Though satisfactory results with the C1-C2 technique have been acquired in most clinical reports, the related problems of fusion delay and pseudarthrosis still exist. To increase the chance of bony fusion, a transverse connector (TC) is frequently used to augment torsional stiffness of thoracolumbar screw/rod constructs.

Three-Dimensional Evaluation and Classification of the Anatomy Variations of Vertebral Artery at the Craniovertebral Junction in 120 Patients of Basilar Invagination and Atlas Occipitalization.

Background: Patients with basilar invagination and atlas occipitalization usually present abnormal anatomy of the vertebral arteries (VAs) at the craniovertebral junction (CVJ).

Objective: To describe and further classify different types of VA variations at the CVJ with 3D visualization technology.

Methods: One hundred twenty patients with basilar invagination and atlas occipitalization who had undergone 3-dimensional computed tomographic angiography (3D-CTA) were retrospectively studied.

Posterior C2 Fixation Using Trans-C2 Inferior Articular Process Screws: A Case Series and Technical Note.

Objective: Upper cervical fixation with C2 pedicle screw insertion may predispose patients to vertebral artery injury, in particular, patients with craniovertebral junction anomalies. The aim of this study was to describe an alternative technique with trans-C2 inferior articular process screw (C2IAPS) insertion for rigid C2 fixation, which can be used to anchor the C2 vertebra for upper cervical fixation.

Methods: Records of 19 patients who underwent posterior atlantoaxial fixation using C2IAPS combined with C1 lateral mass screw were retrospectively reviewed.

Morphometric Measurements of the C1 Lateral Mass with Congenital Occipitalization of the Atlas.

Objective: Unfamiliarity with the morphometry of the assimilated C1 lateral mass (C1LM) could make screw placement dangerous. In the present study, we defined the morphometric dimensions of the occipitalized C1LM to provide surgeons with valuable information for preoperative planning.

Methods: Thin-slice computed tomography scanning data from 131 patients with occipitalization of the atlas (OA) and 50 control cases were imported into Mimics software for analysis.

Protective Effects of Astragaloside IV on Delayed Cerebral Vasospasm in an Experimental Rat Model of Subarachnoid Hemorrhage.

Background: Delayed cerebral vasospasm is an important cause of morbidity and mortality in patients with subarachnoid hemorrhage (SAH). This study aimed to assess the effects of Astragaloside IV (AS-IV) on delayed cerebral vasospasm after SAH.

Methods: A rat model of SAH was established by puncturing one side of the internal carotid artery.

Quantitative Measurements of the Skull Base and Craniovertebral Junction in Congenital Occipitalization of the Atlas: A Computed Tomography-Based Anatomic Study.

Objective: To study the craniovertebral junction and determine the anatomic characteristics of occipitalization of the atlas (OC) by computed tomography (CT) imaging.

Methods: We retrospectively reviewed 80 cases of patients with OC who underwent cervical CT scanning between March 2012 and March 2014. Forty healthy subjects were recruited as a control cohort.