Craniovertebral Junction Malformation Research Articles

Morphometric analysis of posterior cranial fossa and foramen magnum and it’s clinical implications in craniovertebral junction malformations: a computed tomography based institutional study in a tertiary care hospital of northern part of India

BackgroundThe posterior cranial fossa (PCF) and the foramen magnum (FM) are the critical anatomical components of the craniovertebral junction region, which comprise and transmit numerous vital neurovascular structures. So, a fundamental knowledge of the basic radiological anatomy of PCF and FM is of paramount importance in the evaluation of associated pathologies and approaching these areas surgically. The aim of this study is to describe different linear and angular craniometric parameters of PCF, FM and surrounding territory based on reconstructed computed tomography (CT) images.Material and methodsThis study was conducted in our tertiary care hospital in northern India from the period of January 2023 to June 2023 on 120 patients, and CT screening was done for the head and spine region following a history of head injury.ResultsIn this study, 120 patients were included, of whom 50.83% (n = 61) were females and 49.17% (n = 59) were males. Age ranged from 18 to 70 years with mean age of 43.5 ± 14.08 years. The mean values for linear craniometric parameters of PCF were statistically nonsignificant for different age groups. Statistically significant differences were found for twinning line (TL) (p < 0.0001), McRae’s line (< 0.0001), clivus length (< p < 0.0001), internal occipital protuberence -opisthion line (p = 0.01), Klaus’ index (p < 0.0001), height of posterior fossa (h) (p < 0.0001), h/TL (p = 0.028), when these values were compared for the genders. The measurements of FM transverse diameter, anteroposterior diameter and area were 27.12 ± 1.42 mm (range 23.6–30.1 mm), 30.99 ± 2.23 mm (range 27.6–35.8 mm) and 691.32 ± 30.35 mm2 (range 632.7–777.7 mm2). The values of clivus canal angle (p = 0.038) and clivoodontoid angle (p = 0.012) were statistically significant when compared for different age groups. The values of Boogard’s angle (p = 0.021) and tentorial slope (p = 0.031) were statistically significant when these were compared for the genders.ConclusionsThis study described almost all the linear and angular craniometric parameters used in the morphometric analysis of PCF and FM. The findings of this study provide valuable data regarding linear and angular craniometric parameters of PCF and FM which can redefine reference values.

Knockdown of best1 Gene in Zebrafish Caused Abnormal Neuronal and Skeletal Development -A Subtype of Craniovertebral Junction Malformation.

To investigate the developmental defects caused by knockdown of best1 gene in zebrafish as a model for a subtype of craniovertebral junction (CVJ) malformation. Two antisense morpholinos were designed targeting zebrafish best1 to block translation (ATG-MO) or to disrupt splicing (I3E4-MO). Morpholinos were microinjected into fertilized one-cell embryos. Efficacy of splicing morpholino was confirmed by RT-PCR. Phenotypes were analyzed and quantified by microscopy at multiple developmental stages. Neuronal outgrowth was assessed in transgenic zebrafish expressing GFP in neurons. Skeletal ossification was visualized by calcein staining. Knockdown of best1 resulted in zebrafish embryos with shorter body length, curved axis, low survival rate, microcephaly, reduced eye size, smaller head and brain, impaired neuronal outgrowth, and reduced ossification of craniofacial and vertebral bone. Best1 gene plays critical roles in ophthalmologic, neurological and skeletal development in zebrafish. A patient with a premature stop codon in BEST1 gene exhibited simillar phenotypes, implying a subtype of CVJ malformation.

Dissection of mendelian predisposition and complex genetic architecture of craniovertebral junction malformation.

The craniovertebral junction (CVJ) is an anatomically complex region of the axial skeleton that provides protection of the brainstem and the upper cervical spinal cord. Structural malformation of the CVJ gives rise to life-threatening neurological deficits, such as quadriplegia and dyspnea. Unfortunately, genetic studies on human subjects with CVJ malformation are limited and the pathogenesis remains largely elusive. In this study, we recruited 93 individuals with CVJ malformation and performed exome sequencing. Manual interpretation of the data identified three pathogenic variants in genes associated with Mendelian diseases, including CSNK2A1, MSX2, and DDX3X. In addition, the contribution of copy number variations (CNVs) to CVJ malformation was investigated and three pathogenic CNVs were identified in three affected individuals. To further dissect the complex mutational architecture of CVJ malformation, we performed a gene-based rare variant association analysis utilizing 4371 in-house exomes as control. Rare variants in LGI4 (carrier rate = 3.26%, p = 3.3 × 10-5) and BEST1 (carrier rate = 5.43%, p = 5.77 × 10-6) were identified to be associated with CVJ malformation. Furthermore, gene set analyses revealed that extracellular matrix- and RHO GTPase-associated biological pathways were found to be involved in the etiology of CVJ malformation. Overall, we comprehensively dissected the genetic underpinnings of CVJ malformation and identified several novel disease-associated genes and biological pathways.

Endoscopic endonasal odontoidectomy: a long-term follow-up results for a cohort of 21 patients

BackgroundEndoscopic endonasal odontoidectomy (EEO) has been described as a potential approach for craniovertebral junction (CVJ) disease which could cause anterior bulbomedullary compression and encroaching. Due to the atlantoaxial junction’s uniqueness and complex biomechanics, treating CVJ pathologies uncovers the challenge of preventing C1–C2 instability. A large series of patients treated with endonasal odontoidectomy is reported, analyzing the feasibility and necessity of whether or not to perform posterior stabilization. Furthermore, the focus is on the long-term follow-up, especially those whom only underwent partial C1 arch preservation without posterior fixation.MethodsThis study is a retrospective analysis of patients with ventral spinal cord compression for non-reducible CVJ malformation, consecutively treated with EEO from July 2011 to March 2019. Postoperative dynamic X-ray and CT scans were obtained in each case in order to document CVJ decompression as well as to exclude instability. The anterior atlas‐dens interval, posterior atlas‐dens interval and C1–C2 total lateral overhang were measured as a morphological criteria to determine upper cervical spine stability.ResultsTwenty-one patients (11:10 F:M) with a mean age of 60.6 years old at the time of surgery (range 34–84 years) encountered the inclusion criteria. For all 21 patients, a successful decompression was achieved at the first surgery. In 11 patients, the partial C1 arch integrity did not require a posterior cervical instrumentation on the bases of postoperative and constant follow-up radiological examination. In 13 cases, an improvement of motor function was recorded at the time of discharge. Only one patient had further motor function improvement at follow-up. Among the patients that did not show any significant motor change at discharge, 4 patients showed an improvement at the last follow-up.ConclusionsThe outcomes, even in C1 arch preservation without posterior fixation, are promising, and it could be said that the endonasal route potentially represents a valid option to treat lesions above the nasopalatine line.

Congenital Atlanto-Occipital Fusion and its Effect on the Myodural Bridge: A Case Report Utilizing the P45 Plastination Technique

The atlanto-occipital joint is composed of the superior fossa of the lateral masses of the atlas (C1) and the occipital condyles. Congenital Atlanto-occipital fusion (AOF) involves the osseous union of the base of the occiput (C0) and the atlas (C1). AOF or atlas occipitalization/assimilation represents a craniovertebral junction malformation (CVJM) which can be accompanied by other cranial or spinal malformations. AOF may be asymptomatic or patients may experience symptoms from neural compression as well as limited neck movement. The myodural bridge (MDB) complex is a dense fibrous structure that connects the suboccipital muscular and its related facia to the cervical spinal dura mater, passing through both the posterior atlanto-occipital and atlanto-axial interspaces. It is not known if atlas occipitilization can induce structural changes in the MDB complex and its associated suboccipital musculature. The suboccipital region of a cadaveric head and neck specimen from an 87-year-old Chinese male having a congenital AOF malformation with resultant changes to the MDB complex was observed. After being treated with the P45 plastination method, multiple slices obtained from the cadaveric head and neck specimen were examined with special attention paid to the suboccipital region and the CVJM. Congenital atlanto-occipital fusion malformations are defined as partial or complete fusion of the base of the occiput (C0) with the atlas (C1). In the present case of CVJM, unilateral fusion of the left occipital condyle with the left lateral mass of C1 was observed, as well as posterior central fusion of the posterior margin of the foramen magnum with the posterior arch of C1. Also noted was a unilateral variation of the course of the vertebral artery due to the narrowed posterior atlanto-occipital interspace. Surprisingly, complete agenesis of the rectus capitis posterior minor (RCPmi) and the obliques capitis superior (OCS) muscles was also observed in the plastinated slices. Interestingly, the MDB, which normally originates in part from the RCPmi muscle, was observed to originate from a superior bifurcation within an aspect of the nuchal ligament. Therefore, the observed changes involving the MDB complex appear to be an effective compensation to the suboccipital malformations.

Surgical management of os odontoideum: An Algerian center experience.

ABSTRACTBackground:Os odontoideum (OO) is a craniovertebral junction malformation of unknown origin. In most times, this lesion is highly unstable demanding surgical management. We present our series of OO surgical management and we discuss clinical, radiological, and management aspects of this pathology via our experience and literature opinions.Methods:This is a retrospective study of patients operated on at our department between May 2014 and May 2021 for OO. All patients were explored with plane X-rays and computed tomography (CT). In some cases, magnetic resonance imaging (MRI) was necessary. Posterior C1–C2 or C1-C3 fixation with polyaxial screws and rod fixation was used. In postoperative, the patient is asked to put Philadelphia collar for 3 months. Hospitalization periods vary between 3 and 7 days. After discharge, all our patients are followed up regularly in consultation. Control radiographs of the occipito cervical region were performed. After 3 months postoperatively, the CT scan is performed on all our patients to assess the quality of fusion. Patient's follow-up ranges from 4 months to 6 years.Results:Fifteen patients were included in this study; nine males (60%) and six females (40%); with mean age of 32.5 years old. Ten patients (67%) presented motor weakness, three patients (20%) with neck pain, one patient (6.5%) with torticollis, and one patient (6.5%) presented vertigo. No notable cervical trauma was present in six patients (40%) and in nine patients (60%), a remote history of traumatism was noted. All cases of our series presented mobile OO. Normal thickness of the C2 pedicle was noted in nine patients (60%). In two patients (13%), there was hypoplasia of one pedicle and in four patients (27%) both pedicles. MRI showed direct signs of spinal cord aggression: simple compression, myelomalacia, strangulation, or hypotrophy. C1 lateral mass screw fixation was performed in all patients; and according to C2 morphology: nine patients underwent C1-C2 pedicular fixation, in one patient, bilateral crossing C2 laminar screws technique, in three patients, we skipped C2 to perform a C1-C3 articular fixation, and in two patients, C1-C2-C3 fixations were performed. All patients improved clinically. In one patient, we noted an infection resulting in bad wound healing this infection was successfully treated with no complications. In the patient with bilateral crossing C2 laminar screws technique, CT control objectified 4 mm exceeding of one screw; the patient was reoperated and the screw was slightly pulled back. No other complications were noted.Conclusion:Congenital origin of OO is always evoked. C1-C2 fixation according to Goel and Harms technique with grafting proved its safety, providing high fixation quality with the acceptable biodynamic outcome. Once treated, the prognostic of OO is in general good, and improvement is observed in most patients with few complications.

Association between Brachycephaly, Chiari Malformation, and Basilar Invagination.

There is evidence that Chiari malformation (CM) and basilar invagination (BI) are largely due to disproportion between the content and volume of the posterior fossa. A recent study identified an increased association between brachycephaly and BI. In several types of craniosynostosis, the posterior fossa volume is smaller than normal, and this is more pronounced in coronal synostosis. The aim of this study is to evaluate the association between CM and BI. The cephalic index (CI) measured on magnetic resonance imaging (MRI) from a sample of patients with craniocervical malformation was compared with that of normal subjects. The average CI in the craniovertebral junction malformation (CVJM) group was significantly higher in BI patients than in normal subjects. The BI patients also had the highest CI among the whole sample of patients (p = 0.009). In this study, BI patients had the highest CI among patients with CVJM and a significantly higher CI than those in the control group. Our data confirm the association between BI and brachycephaly.

Profiles of Vertebral Artery Dissection with Congenital Craniovertebral Junction Malformation: Four New Cases and a Literature Review.

ObjectiveVertebral artery dissection (VAD) combined with congenital craniovertebral junction malformation (CVJM) is rare. This study aimed to analyze the etiology, clinical and imaging features, treatment, and prognosis of VAD with CVJM.MethodsFour new cases of VAD with congenital CVJM and 28 similar cases found in the literature were included. Detailed clinical data from all cases were retrospectively analyzed.ResultsA total of 32 patients (28 men, four women; mean age 19.01±12.53 years) were included. Seventeen of 32 cases (53.1%) had had multiple ischemic episodes. The most common neurological symptoms were limb numbness/weakness (20/32), ataxia (15/32), and dizziness/vertigo (12/32). In sum, 31 of 32 cases had multiple infarcts scattered throughout the posterior circulation area on cranial computed tomography or resonance imaging. Dissection had occurred in the V3 segment of the VA in 29/31 cases (93.5%). The most common congenital CVJMs were atlantoaxial dislocation and atlantoaxial subluxation (found in 20/32 cases [62.5%]), while 27/32 cases (84.3%) had multiple combined abnormalities. Seven of eleven cases (63.6%) with initial antiplatelet treatment and one of eleven (9.1%) with initial anticoagulation treatment experienced stoke recurrence. Fusion or vertebral fixation was performed in 16 patients and aneurysm resection in one patient. There was no reported recurrence after surgery in 13 patients with follow-up data.ConclusionUnderlying CVJM is a rare but overlooked etiology in VAD, and is prone to induce recurrent ischemic stroke. Patients with VAD, especially that localized in the V3 segment, should be examined for CVJM. Timely assessment is critical for determining the specific cause and to provide targeted intervention.

Endoscopic Endonasal Odontoidectomy Preserving Atlantoaxial Stability: a Pediatric Case.

Objectives We illustrate endoscopic endonasal odontoidectomy for the Chiari-I malformation respecting craniovertebral junction (CVJ) stability. Design Case report of a 12-year-old girl affected by the Chiari-I malformation. Magnetic resonance imaging (MRI) showed tonsillar herniation, basilar invagination, and dental retroversion, causing angulation and compression of the bulbomedullary junction. Patient underwent endoscopic third ventriculostomy (ETV) with reduction of ventricular size and resolution of gait disturbances, but she complained the Valsalva-induced headaches, hiccup, and dysesthesias in the lower limbs. Endoscopic endonasal odontoidectomy was chosen to decompress the cervicomedullary junction. Setting The research was conducted at University Hospital “Ospedale di Circolo,” Department of Neurosurgery at Varese in Italy. Participants Patients were from neurosurgical and ENT (ear, nose, and throat) skull base team. Main Outcome Measures A bilateral paraseptal approach was performed, using a four-hand technique. After resection of posterior edge of the nasal septum, the choana is entered and a rhinopharynx muscle–mucosal flap is dissected subperiosteal and transposed in oral cavity. The CVJ is exposed and, using neuronavigation and neuromonitoring, odontoidectomy is fulfilled until dura is reached, preserving the anterior arch of C1. Reconstruction is obtained suturing the flap previously harvested. Results Postoperative course was unremarkable and the patient experienced improvement of symptoms. Postoperative MRI documented the appearance of tight cerebrospinal fluid (CSF) film anterior to bulbomedullary junction and in retrotonsillar spaces, opening of the bulbomedullary angle, and slight tonsils reduction. No CVJ instability was occurred with any need of posterior fixation. Conclusion Endoscopic endonasal odontoidectomy is a feasible approach for CVJ malformation. In this case, bulbar decompression was achieved preserving CVJ stability and avoiding posterior fixation. The link to the video can be found at: https://youtu.be/VIobocHfCuc .

The role of clivus length and cranial base flexion angle in basilar invagination and Chiari malformation pathophysiology.

The craniovertebral junction is an anatomically well-defined transitional zone located between the skull and the cervical spine. Multiple malformations can affect this region with the most prominent being basilar invagination (BI) and Chiari malformation (CM). Despite numerous studies, the origin, pathophysiology, and classification of these pathologies remain controversial. The objective of this study was to evaluate the implication of cranial base flexion angle and clivus length in the development of these conditions. Midline tomography and magnetic resonance imaging of normal subjects and patients diagnosed with BI (types I and II) and Chiari malformation were evaluated. A craniometric study of the skull base was performed. Linear and angular measurements were used for comparisons between groups. 109 images from patients with craniovertebral junction malformation and controls were evaluated. Seventeen had BI-I, 26 had BI-II, 36 had CM, and 30 were normal subjects. Demographic data for the two groups were not significantly different. Craniometric analysis of images revealed a gradation in linear and angular variables from controls to CM, BI-I, and BI-II patients. Clivus length was significantly smaller in BI-II patients compared with other groups, while basal angle was greater. Moderate or strong correlations were noted among all variables analyzed. Data suggest that clivus length and basal angle may play a role in pathophysiology of BI and CM.

Cefaleia em Malformações da Junção Craniovertebral. Análise de 65 casos operados

Introdução: As malformações da junção craniovertebral são patologias frequentes no nordeste brasileiro, predominando a impressãobasilar (IB) e a malformação de Chiari (MC), por vezes associadas à siringomielia (SM). Objetivo: Analisar a prevalência, o padrão decefaleia e os fatores associados em 65 casos de IB e MC operados entre os anos de 1994 e 2015. Método: Trata-se de um estudo retrospectivorealizado a partir da análise de prontuários médicos de pacientes diagnosticados com malformações da junção craniovertebral por meiode ressonância magnética e cujo quadro clínico refratário era indicativo de cirurgia. A amostra foi composta por pacientes operadospela mesma equipe neurocirúrgica no município de João Pessoa, Paraíba, Brasil, entre agosto de 1994 e maio de 2015. Tabularam-se osdados relacionados ao padrão e prevalência de cefaleia, além de seus fatores associados. A inserção, processamento e análise dos dadosobtidos foi efetuada por meio do software estatístico Statistical Package for Social Sciences (SPSS) versão 21.0. Resultados: A amostrafinal foi composta por 65 pacientes. Observamos que 29 deles (44,6%) eram portadores de IB e MC, 26 (40%) eram portadores de IB, MCe SM, sete, apenas IB, dois, somente MC e em um paciente a associação de MC e SM. Do total de pacientes, 32 (49,2%) apresentavamcefaleia e 43 (66,1%) dor nucal. Houve presença de braquicefalia em 44 casos (67,7%) e brevis collis em 42 (64,6%). Quando cruzadasas variáveis cefaleia, dor nucal, braquicefalia e brevis collis, observamos presença em 9 pacientes (31%) do grupo que possuía IBe MC, e em 8 (30,8%) do grupo com IB, MC e SM. Conclusão: Diante dos resultados, recomendamos que para todos os pacientesportadores de cefaleia e dor nucal advindos de regiões em que epidemiologicamente as malformações da junção craniovertebral sãofrequentes, excluindo-se cefaleia tensional, sejam levantadas a hipótese diagnóstica de IB ou MC, principalmente quando apresentaremalterações no exame físico, como braquicefalia e brevis collis. Neste estudo, ressaltamos a relevância de se evitar a falha diagnóstica ouo diagnóstico tardio em pacientes sintomáticos, realizando-se tratamento cirúrgico oportuno nos que apresentam sintomas refratários eincapacitantes ou déficit neurológico, prevenindo sequelas permanentes.

Atlantoaxial dislocation in an adolescent with juvenile spondyloarthritis

Atlantoaxial dislocation with spinal canal stenosis not associated with craniovertebral junction malformations and traumatic injury is a rare pathology in children and adolescents. A clinical case of the diagnosis and surgical treatment of atlantoaxial dislocation of non-traumatic genesis combined with spinal canal stenosis in an adolescent with juvenile idiopathic arthritis is presented. A minimal instrumental fixation of the upper cervical spine allowed eliminating stenosis of the spinal canal, repairing instability of the upper cervical vertebrae, and jugulating neurological disorders.

The Relationship Between Basilar Invagination and Chiari Malformation Type I: A Narrative Review.

Basilar invagination (BI) and Chiari malformation typeI CM-I) are the most common adult craniovertebral junction malformations, and they are frequently associated with each other and present synchronously. The relationship between BI and CM-I has remained incompletely understood, and the choice of surgical strategy has remained controversial. This brief review focuses on the different aspects of BI and CM-I, and further discusses the relationship between these two concomitant pathologies on the basis of the concepts proposed over the last three decades.

Refinement of the Transoral Approach to Craniovertebral Junction Malformations.

The transoral approach provides the most direct surgical corridor for treatment of congenital bony abnormalities that exert irreducible ventral compression of the cervicomedullary junction. In this paper, based on our experience with the transoral approach over the past three decades, we briefly describe the surgical strategies and the operative nuances that allow effective decompression of the craniovertebral junction (CVJ) while minimizing postoperative morbidity. The surgical strategy is dictated by the type and severity of the malformation. Fibre-optic nasotracheal intubation obviates the necessity of preoperative tracheostomy, and avoidance of a soft-palate incision significantly reduces oropharyngeal morbidity. When feasible, the atlas-sparing technique minimizes postoperative instability. The transoral transatlas approach is generally required in patients with severe basilar invagination and allows wider exposure of the anterior CVJ at the price of a higher incidence of postoperative instability. The transoral approach is extremely effective in providing excellent decompression of the anterior cervicomedullary junction in patients with fixed malformations. Tailoring the approach to the peculiar anatomy of each malformation reduces iatrogenic instability and minimizes postoperative complications.

CLINICAL AND RADIOLOGICAL FEATURES OF ATLANTOAXIAL DISLOCATIONS ASSOCIATED WITH CONGENITAL MALFORMATIONS OF THE CRANIOVERTEBRAL JUNCTION

Objective. To analyze clinical and radiological features of congenital atlantoaxial dislocations (AAD) in congenital craniovertebral junction malformations. Material and Methods. The data of 26 patients with AAD associated with congenital pathology of the craniovertebral junction, who applied to the Ilizarov Center in 2012–2017, were analyzed. Results. Patients were divided into three groups: with nonsyndromic AAD – 6 (23.1 %) patients, with AAD associated with Klippel – Feil syndrome – 11 (42.3 %) and with syndromic AAD – 9 (34.6 %). Odontoid anomalies were observed in 15 (57.7 %) patients, the magnitude of dislocation was determined from the C 1 facet displacement relative to that of C 2 in different planes. Patients with non-syndromic AAD had local pain syndrome (VAS score 4.20 ± 2.64) accompanied by torticollis and restriction of head movements, and myelopathy. In patients with AAD associated with Klippel – Feil syndrome, the local symptoms prevailed: restriction of neck movements, torticollis, neck pain (VAS score 2.40 ± 2.01), and myelopathy. Myelopathy and unpronounced pain syndrome (VAS score 2.30 ± 1.94) were leading symptoms in patients with syndromic AAD. Conclusion. Patients with syndromic AAD more often have myelopathy, whereas AAD with the Klippel-Feil syndrome and non-syndromic AAD are often manifested by local symptoms.

Role of dynamic computed tomography scans in patients with congenital craniovertebral junction malformations.

AIMTo evaluate the role of dynamic computed tomography (CT) scan imaging in diagnosing craniovertebral junction (CVJ) instability in patients with congenital CVJ malformations.METHODSPatients with symptomatic congenital CVJ malformations who underwent posterior fossa decompression and had a preoperative dynamic CT scan in flexion and extended position were included in this study. Measurements of the following craniometrical parameters were taken in flexed and extended neck position: Atlanto-dental interval (ADI), distance of the odontoid tip to the Chamberlain’s line, and the clivus-canal angle (CCA). Assessment of the facet joints congruence was also performed in both positions. Comparison of the values obtained in flexion and extension were compared using a paired Student’s t-test.RESULTSA total of ten patients with a mean age of 37.9 years were included. In flexion imaging, the mean ADI was 1.76 mm, the mean CCA was 125.4° and the mean distance of the odontoid tip to the Chamberlain’s line was + 9.62 mm. In extension, the mean ADI was 1.46 mm (P = 0.29), the mean CCA was 142.2° (P < 0.01) and the mean distance of the odontoid tip to the Chamberlain’s line was + 7.11 mm (P < 0.05). Four patients (40%) had facetary subluxation demonstrated in dynamic imaging, two of them with mobile subluxation (both underwent CVJ fixation). The other two patients with a fixed subluxation were not initially fixed. One patient with atlantoaxial assimilation and C23 fusion without initial facet subluxation developed a latter CVJ instability diagnosed with a dynamic CT scan. Patients with basilar invagination had a lower CCA variation compared to the whole group.CONCLUSIONCraniometrical parameters, as well as the visualization of the facets location, may change significantly according to the neck position. Dynamic imaging can provide additional useful information to the diagnosis of CVJ instability. Future studies addressing the relationship between craniometrical changes and neck position are necessary.

Image-guided transoral approach in severe craniovertebral junction malformations at the golden age of endoscopy: Regarding 2 cases

IntroductionThe image-guided transoral approach (IGTOA) provides a safe exposure to skull base midline lesions and the ventral aspect of the craniovertebral junction (CVJ). The IGTOA has several advantages: the head being placed in the extended position, it decreases the brainstem angulation during surgery; the approach being done through the avascular median pharyngeal raphe, not only lowers the bleeding risk but also provides a direct access to the bony pathology and granulation tissue accessible only via the ventral route. Wide field exposure and maneuverability are necessary to deal with the entire ventral brainstem compression in case of severe CVJ malformation to safely perform partial clivectomy and odontoidectomy. Presentation of two casesWe illustrate the cases of two patients, 52-year-old and 42-year-old males, who presented with an impressive craniovertebral junction malformation, confirmed on CT and MRI images. They first underwent surgery by IGTOA, later completed by occipitocervical fixation. For the two patients, outcomes were assessed respectively at 4 and 5 years and showed satisfactory results both clinically and radiologically. ConclusionIn patients with marked ventral compression, the IGTOA provides direct and guided access to the anterior aspect of the CVJ and effective means for odontoidectomy and clivectomy. This approach is more easily maneuverable compared to the endonasal endoscopic approach. The IGTOA approach is quite a complex technique, requiring multidisciplinary skills, but it should primarily be used in difficult situations. We suggest that endonasal endoscopy is over-utilized. We consider that endoscopy should not be routinely performed and kept only for well-selected cases.

Selection of surgical procedures for basilar invagination with atlantoaxial dislocation

Background ContextBasilar invagination (BI) is a malformation of craniovertebral junction. However, surgical procedures on BI with atlantoaxial dislocation (AAD) remain controversial. PurposeThis research aimed to investigate the selection of surgical procedures and its significance in the surgical treatment of patients with BI and AAD. Study DesignThis was a retrospective study. Patient SampleThis study enrolled 33 patients who were diagnosed with BI and AAD and were followed up for at least 6 months. Outcome MeasureAll of the patients were assessed for neurologic recovery observation in terms of Japanese Orthopaedic Association scores and Odom criteria. X-ray, magnetic resonance imaging, or computed tomography scanning was used to determine reduction, compression, bone graft, and internal fixation before and after operation. MethodsThirty-three patients who suffered from BI with AAD were treated in our department from July 2000 to October 2014. Preoperatively, the patients were divided into two types on the basis of whether dislocation was reduced after anesthesia and traction were performed: reducible dislocation (Type A) and irreducible dislocation (Type B). Reducible dislocation was further divided into two subtypes: full reducible dislocation (Type A1) and partial reducible dislocation (Type A2). Type A1 patients were treated with direct posterior fixation and fusion after traction and reduction. Type A2 patients received posterior atlantoaxial release, fixation, and fusion under traction. Type B patients underwent transoral atlantoaxial release, posterior fixation, and fusion. ResultsThere were 5 Type A1 patients, 10 Type A2 patients, and 18 Type B patients treated in accordance with the proposed scheme. Postoperatively, sufficient reduction and decompression were achieved for all cases. Two Type B patients died. Other patients were followed up from 6 months to 42 months (average=16.6 months); follow-up results showed sufficient decompression, effective fixation and fusion, and no reduction loss. The Japanese Orthopaedic Association Score increased from preoperative 4–12 (average, 7.8) to postoperative 10–17 (average, 14.3), and neurologic recovery was satisfactory. ConclusionsUnder traction, simple posterior fixation and fusion were effective for Type A patients suffering from BI with AAD; anterior atlantoaxial release and posterior fixation and fusion were effective for Type B patients with BI and AAD.

The odontoid process invagination in normal subjects, Chiari malformation and Basilar invagination patients: Pathophysiologic correlations with angular craniometry.

Background:Craniometric studies have shown that both Chiari malformation (CM) and basilar invagination (BI) belong to a spectrum of malformations. A more precise method to differentiate between these types of CVJM is desirable. The Chamberlain's line violation (CLV) is the most common method to identify BI. The authors sought to clarify the real importance of CLV in the spectrum of craniovertebral junction malformations (CVJM) and to identify possible pathophysiological relationships.Methods:We evaluated the CLV in a sample of CVJM, BI, CM patients and a control group of normal subjects and correlated their data with craniocervical angular craniometry.Results:A total of 97 subjects were studied: 32 normal subjects, 41 CM patients, 9 basilar invagination type 1 (BI1) patients, and 15 basilar invagination type 2 (BI2) patients. The mean CLV violation in the groups were: The control group, 0.16 ± 0.45 cm; the CM group, 0.32 ± 0.48 cm; the BI1 group, 1.35 ± 0.5 cm; and the BI2 group, 1.98 ± 0.18 cm. There was strong correlation between CLV and Boogard's angle (R = 0.82, P = 0.000) and the clivus canal angle (R = 0.7, P = 0.000).Conclusions:CM's CLV is discrete and similar to the normal subjects. BI1 and BI2 presented with at least of 0.95 cm CLV and these violations were strongly correlated with a primary cranial angulation (clivus horizontalization) and an acute clivus canal angle (a secondary craniocervical angle).

Intraoperative Computed Tomography With an Integrated Navigation System in Stabilization Surgery for Complex Craniovertebral Junction Malformation

This study was designed to report our preliminary experience with stabilization procedures for complex craniovertebral junction malformation (CVJM) using intraoperative computed tomography (iCT) with an integrated neuronavigation system (NNS). To evaluate the workflow, feasibility and clinical outcome of stabilization procedures using iCT image-guided navigation for complex CVJM. The stabilization procedures in CVJM are complex because of the area's intricate geometry and bony structures, its critical relationship to neurovascular structures and the intricate biomechanical issues involved. A sliding gantry 40-slice computed tomography scanner was installed in a preexisting operating room. The images were transferred directly from the scanner to the NNS using an automated registration system. On the basis of the analysis of intraoperative computed tomographic images, 23 cases (11 males, 12 females) with complicated CVJM underwent navigated stabilization procedures to allow more control over screw placement. The age of these patients were 19-52 years (mean: 33.5 y). We performed C1-C2 transarticular screw fixation in 6 patients to produce atlantoaxial arthrodesis with better reliability. Because of a high-riding transverse foramen on at least 1 side of the C2 vertebra and an anomalous vertebral artery position, 7 patients underwent C1 lateral mass and C2 pedicle screw fixation. Ten additional patients were treated with individualized occipitocervical fixation surgery from the hypoplasia of C1 or constraints due to C2 bone structure. In total, 108 screws were inserted into 23 patients using navigational assistance. The screws comprised 20 C1 lateral mass screws, 26 C2, 14 C3, or 4 C4 pedicle screws, 32 occipital screws, and 12 C1-C2 transarticular screws. There were no vascular or neural complications except for pedicle perforations that were detected in 2 (1.9%) patients and were corrected intraoperatively without any persistent nerves or vessel damage. The overall accuracy of the image guidance system was 98.1%. The duration of interruption during the surgical process for the iCT was 8±1.5 minutes. All patients were clinically evaluated using Nurick grade criteria and for neurological deficits 3 months after surgery. Twenty-one patients (91.3%) improved by at least 1 Nurick grade, whereas the grade remained unchanged in 2 (8.7%) patients. Craniovertebral stability and solid bone fusion was achieved in all patients. NNS was found to correlate well with the intraoperative findings, and the recalibration was uneventful in all cases and had an accuracy of 1.8 mm (range, 0.6-2.2 mm). iCT scanning with integrated NNS was found to be both feasible and beneficial in the stabilization procedures for complex CVJM. In this unusual patient population, the technique seemed to be of value for negotiating complex anatomy and for achieving more control over screw placement.