C1 Anterior Arch Research Articles

Endoscopic transnasal and transoral resection of the odontoid process and C1 combined with occipitocervical fusion for osteoradionecrosis of the upper cervical spine: a case report and literature review

BackgroundOsteoradionecrosis (ORN) of the upper cervical spine is a rare but severe complication of head and neck cancer radiotherapy. To raise awareness of this condition, we describe a patient with a history of nasopharyngeal carcinoma who developed ORN of the upper cervical spine and review the published literature reporting surgical management.Case presentationA 59-year-old female patient with persistent neck pain for one month and limited range of neck motion who had undergone radiotherapy for nasopharyngeal carcinoma with a total dose of 69.96 Gy 15 years ago presented to our hospital. The patient underwent endoscopic transnasal and transoral resection of the odontoid process and C1 anterior arch, combined with occipitocervical fusion. To better understand surgical management of ORN of the upper cervical spine, the literature published in the PubMed, Ovid MEDLINE, and Embase databases was reviewed. Our patient experienced alleviation of cervical pain and did not exhibit any postoperative complications. Since 2005, 11 cases of surgical management of ORN of the upper cervical spine (including the present case) have been published. Basilar invagination and/or atlantoaxial subluxation were observed in 4 /11 cases. Endoscopic procedures were performed in 4/11 cases, and occipitocervical fusion was performed in 8 /11 cases.ConclusionEndoscopic transnasal and transoral resection of the odontoid process and C1 anterior arch is a safe and effective treatment option for ORN of the upper cervical spine. Occipitocervical fusion is useful in patients with basilar invagination and atlantoaxial subluxation.

Differences in Cervical Spine Fractures in Patients Younger or Older Than 65 Years of Age: Implications for the Canadian C-Spine Rule.

There has been a distinction made in the 2001 Canadian C-Spine Rule regarding patients 65 and older and younger than 65 years of age as far as indications for cervical spine CT scanning. We sought to determine if there are differences in the symptoms, mechanisms of injury, fracture locations, and types that are still relevant in 2024. The institutional review board approved this retrospective study of cervical spine CT emergency department results from 2 hospitals in our health system after reviewing 5 years of data in patients experiencing trauma. In addition to the primary variable of age (younger than 65 years and 65 years and older), we looked at injury mechanism, fracture types, sites, symptoms, and operative or medical treatments. Because the demographics of our home site is different from most towns in the United States, we provide race/ethnicity data. Of 21,986 cervical spine CTs, 190/9455 (2.0%) participants 65 years of age and older and 199/12,531 (1.6%) participants younger than 65 years of age had fractures (total, 389/21,986, 1.8%). There were more cases of falls from standing (106, 55.8%) and falls from a height (46, 4.2%) in those 65 years and older and this mechanism was associated with a higher risk of C1 and C2 fractures (52, 27.4%; and 78, 41.1%, respectively). Among the C1 fractures, anterior and posterior arch fractures predominated (37, 19.5%). For C2 fractures, types 2 and 3 odontoid fractures (39, 20.5%; and 12, 6.3%) were more common in the older cohort. Motor vehicle collisions were more common in the younger cohort (89, 44.7%), and they were associated with more C5-C7 fractures (47, 23.6%; 60, 30.2%; and 66, 33.2%, respectively) including the facets (49, 24.6%), spinous processes (31, 15.6%), and transverse processes (52, 26.1%). Overall, the rates of instability, surgical intervention, and asymptomatic fractures were similar in the 2 age groups. Cervical spine fractures appear in about 1.8% of the CT scans performed in a busy emergency department environment. Fractures in the elderly occur more commonly due to falls, are located at C1 and C2, and may involve ligamentous injuries. Younger patients incur trauma more commonly due to motor vehicle collisions, and they are more likely to affect the posterior elements, especially C5-C7. The differences in trends for fractures in the 65 years of age and older and younger than 65 years of age groups have persisted since the Canadian C-Spine Rule 1996-1998 data were collected.

Navigated Anterior Full-Endoscopic Transcervical Approach Odontoidectomy for Traumatic Posterior Atlantoaxial Dislocation Without Odontoid Fracture.

Complete posterior atlantoaxial dislocation (PAAD) with an unfractured odontoid process is a rare condition where a dislocated but intact odontoid process is positioned ventrally to the anterior arch of C1. This lesion is related to transverse and alar ligament rupture secondary to hyperextension and rotatory traumatic injury and is often associated with neurological deficit. The treatment strategy remains controversial, and in many cases, odontoidectomy is required. Traditional approaches for odontoidectomy (transnasal and transoral) are technically demanding and are related to several complications. This article describes a 360° reduction and stabilization technique through a navigated anterior full-endoscopic transcervical approach (nAFETA) as a novel technique for odontoidectomy and C1-C2 anterior transarticular fixation supplemented with posterior fusion. A 21-year-old man presented to the emergency room by ambulance after a motorcycle accident. On evaluation, incomplete ASIA B spinal cord injury was documented. Imaging revealed a complete PAAD. We performed a two-staged procedure, a nAFETA odontoidectomy plus C1-C2 anterior transarticular fixation followed by posterior C1-C2 wired fusion. At a 2-year follow-up, the patient had a 10-point Oswestry Disability Index score and neurological improvement to ASIA E. PAAD can be successfully treated through minimally invasive nAFETA. Noteworthy, the risks of the transoral and endonasal routes were avoided through this approach. In addition, nAFETA allows anterior transarticular fixation during the same procedure providing spinal stability. Further studies are required to expand the use of nAFETA in this field.

Anatomical determinants of occipitocervical fusion in skull base chordoma resection: a systematic review of the literature with illustrative cases.

Skull base chordomas are rare, locally osseo-destructive lesions that present unique surgical challenges due to their involvement of critical neurovascular and bony structures at the craniovertebral junction (CVJ). Radical cytoreductive surgery improves survival but also carries significant morbidity, including the potential for occipitocervical (OC) destabilization requiring instrumented fusion. The published experience on OC fusion after CVJ chordoma resection is limited, and the anatomical predictors of OC instability in this context remain unclear. PubMed and Embase were systematically searched according to the PRISMA guidelines for studies describing skull base chordoma resection and OC fusion. The search strategy was predefined in the authors' PROSPERO protocol (CRD42024496158). The systematic review identified 11 surgical case series describing 209 skull base chordoma patients and 116 (55.5%) who underwent OC instrumented fusion. Most patients underwent lateral approaches (n = 82) for chordoma resection, followed by midline (n = 48) and combined (n = 6) approaches. OC fusion was most often performed as a second-stage procedure (n = 53), followed by single-stage resection and fusion (n = 38). The degree of occipital condyle resection associated with OC fusion was described in 9 studies: total unilateral condylectomy reliably predicted OC fusion regardless of surgical approach. After lateral transcranial approaches, 4 studies cited at least 50%-70% unilateral condylectomy as necessitating OC fusion. After midline approaches-most frequently the endoscopic endonasal approach (EEA)-at least 75% unilateral condylectomy (or 50% bilateral condylectomy) led to OC fusion. Additionally, resection of the medial atlantoaxial joint elements (the C1 anterior arch and tip of the dens), usually via EEA, reliably necessitated OC fusion. Two illustrative cases are subsequently presented, further exemplifying how the extent of CVJ bony elements removed via EEA to achieve complete chordoma resection predicts the need for OC fusion. Unilateral total condylectomy, 50% bilateral condylectomy, and resection of the medial atlantoaxial joint elements were the most frequently described independent predictors of OC fusion in skull base chordoma resection. Additionally, consistent with the occipital condyle harboring a significantly thicker joint capsule at its posterolateral aspect, an anterior midline approach seems to tolerate a greater degree of condylar resection (75%) than a lateral transcranial approach (50%-70%) prior to generating OC instability.

Three-Stage Surgical Resection in Semisitting Position of Sphenocavernopetroclival-Foramen Magnum Meningioma: 3-Dimensional Operative Video.

Large meningiomas extending through the middle cranial fossa, posterior fossa, and foramen magnum (FM) represent a surgical challenge even for experienced skull base surgeons.1 Although decompression may be necessary for offering clinical improvement, surgical risks may involve cranial nerves and vascular injury. We present a case of a sphenocavernopetroclival-FM meningioma, with our surgical plan extending through the sphenoid region, FM, and posterior fossa to the anterior arch of C1. We designed a 2-day, 3-stage surgical strategy to achieve complete surgical resection for offering better long-term prognosis and satisfactory postoperative neurological outcome.2 The surgical plan was completed in 2 days of surgery: the first day the extradural part for achieving optimal tumor exposure and the second day the intradural part to tackle tumor resection in a 3-stage fashion. The first stage consisted in a far lateral approach to access the lower portion of the tumor extending from the FM to the spinal region; the second stage focused on the portion of the tumor extending through the inferior clivus and the petroclival region; and the third stage consisted in resecting the tumor extending from the petroclival region to the sphenoid region.3 A near-total resection was achieved, with a very small tumor remnant observed at the level of the tentorium on postoperative MRI, which was treated with radiosurgery owing to the young age of the patient. This is a 3-dimensional operative video showing the surgical steps of the tumor resection. The patient consented to the procedure and to the publication of her image.

Anatomical Step-by-Step Dissection of Complex Skull Base Approaches for Trainees: Surgical Anatomy of the Endoscopic Endonasal Middle-Inferior Clivectomy, Odontoidectomy, and Far-Medial Approach.

Introduction The clival, paraclival, and craniocervical junction regions are challenging surgical targets. To approach these areas, endoscopic endonasal transclival approaches (EETCAs) and their extensions (far-medial approach and odontoidectomy) have gained popularity as they obviate manipulating and working between neurovascular structures. Although several cadaveric studies have further refined these contemporary approaches, few provide a detailed step-by-step description. Thus, we aim to didactically describe the steps of the EETCAs and their extensions for trainees. Methods Six formalin-fixed cadaveric head specimens were dissected. All specimens were latex-injected using a six-vessel technique. Endoscopic endonasal middle and inferior clivectomies, far-medial approaches, and odontoidectomy were performed. Results Using angled endoscopes and surgical instruments, an endoscopic endonasal midclivectomy and partial inferior clivectomy were performed without nasopharyngeal tissue disruption. To complete the inferior clivectomy, far-medial approach, and partially remove the anterior arch of C1 and odontoid process, anteroinferior transposition of the Eustachian-nasopharynx complex was required by transecting pterygosphenoidal fissure tissue, but incision in the nasopharynx was not necessary. Full exposure of the craniocervical junction necessitated bilateral sharp incision and additional inferior mobilization of the posterior nasopharynx. Unobstructed access to neurovascular anatomy of the ventral posterior fossa and craniocervical junction was provided. Conclusion EETCAs are a powerful tool for the skull-base surgeon as they offer a direct corridor to the ventral posterior fossa and craniocervical junction unobstructed by eloquent neurovasculature. To facilitate easier understanding of the EETCAs and their extensions for trainees, we described the anatomy and surgical nuances in a didactic and step-by-step fashion.

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.

Anatomical Description and Literature Review of the Endoscopic Endonasal Transclival Transodontoid Approach Combined with Endoscopic Transoral Decompression to the Anterior Craniovertebral Junction: A New Strategy

To describe and evaluate the steps required to perform a combined endoscopic endonasal/transoral transclival transodontoid approach for anterior decompression of the craniovertebral junction. The endoscopic endonasal transclival transodontoid approach combined with endoscopic transoral decompression was performed on 4 cadaveric specimens. Evaluation of this combined technique; a review of the literature; and the nuances, advantages, and pitfalls are reported. Adequate wide anterior decompression was achieved in all specimens. This combined approach allowed the preservation of the anterior arch of C1 without injuring the eustachian tube anatomy and avoiding internal carotid artery manipulation. Mastery of both techniques allows for a safe and comfortable surgical corridor. The transoral and transnasal approaches should not be considered as either/or techniques, but rather as a complement to each other. However, as with all new or developing techniques, there is a steep learning curve, which requires ample training in the skull base laboratory.

Abstract Number ‐ 76: Bow hunter’s syndrome‐ a rare case of hearing loss associated with co‐dominant vertebral artery compression

Introduction Bow hunter’s syndrome (BHS), also known as rotational vertebral artery syndrome, refers to symptomatic vertebrobasilar insufficiency (VBI) caused by mechanical compression and severe stenosis or occlusion of the vertebral artery (VA) during neck and head rotation. Etiologies include bony spurs and osteophytes, or hypertrophic muscles and ligaments compressing typically on the dominant vertebral artery. Upon turning their head, patients experience posterior circulation symptoms such as vertigo, dizziness, syncope, nausea, tinnitus, or headache. These patients are at risk of stroke due to repetitive mechanical damage to the vessel and thromboembolism. [1] We present a rare case of BHS associated with hearing loss that was caused by bony spurs compressing on a left co‐dominant vertebral artery seen on turning head to both sides. Methods A woman in her 50s presented with sporadic progressive episodes of dizziness which started about 4 years. In addition, she reported experiencing episodic tinnitus in her left ear, frequent headaches, neck pain, and syncopal episodes. She was diagnosed with severe left ear sensorineural hearing loss (SNHL). Vestibular therapy and multiple neuropathic medications (nortriptyline, gabapentin) only provided her with minimal relief. Results Examination showed left SNHL and neck tenderness. X‐ray of cervical spine showed bony hypertrophy adjacent to the dens and inferior to the anterior arch of C1, suggestive of large osteoarthritic bony spurs. CT angiogram showed narrowing of the left vertebral artery at C1 due to severe hypertrophic arthropathy of the lateral mass articulation. It also showed impingement of the left VA in the left transverse foramen. The intradural portion of the VA (V4) appeared to be co‐dominant with normal size. Dynamic cerebral angiogram revealed near occlusion of the left VA at the level of C1‐C2 with head to the right. Left VA remained patent in neutral position, and experienced reduction in flow with head rotation to the left. The dynamic stenosis of VA caused by mechanical compression upon head turn leading to VBI, and reversal of stenosis when rotating head to neutral position was consistent with diagnosis of Bow hunters syndrome. Conclusions This case report highlights a rare presentation of VBI caused by dynamic stenosis of VA as a sequela of mechanical compression of a co‐dominant VA upon head turn to both sides. Only about 2% of the BHS patients experience symptoms during head turn to both sides [2], which was the finding in our patient. Furthermore, this case illustrates an association between BHS and SNHL. Hearing loss is previously described in vertebral artery atresia [3]; however, we present a novel association between acquired BHS and SNHL. Although we could not prove the causality, the coexistence of the two conditions in this patient may help to elicit further clinical consideration and evaluation in patients with SNHL of unknown etiology.

MR documented craniocervical ligamentous injury at age 18months: delayed formation of OS odontoideum. Complex management issues. Case-based review.

There are two separate theories regarding the genesis of os odontoideum: congenital and post-traumatic. Trauma documentation in the past has been the presence of a normal odontoid process at the time of initial childhood injury and subsequent development of the os odontoideum. True MR documentation of craniocervical injury in early childhood and subsequent os odontoideum formation has been very rare. An 18-month-old sustained craniocervical ligamentous injury documented on MRI with transient neurological deficit. Chiari I abnormality was also recorded. Subsequent serial imaging of craniocervical region showed the formation of os odontoideum and instability. He became symptomatic from the os odontoideum and the Chiari I abnormality. The patient underwent decompression and intradural procedure for Chiari I abnormality and occipitocervical fusion. Postoperative course was complicated by the failure of fusion and redo. He later required transoral ventral medullary decompression. He recovered. This is an MR documented craniocervical ligamentous injury with sequential formation of os odontoideum with accompanying changes in the atlas. Despite a subsequent successful dorsal occipitocervical fusion, he became symptomatic requiring transoral decompression. Os odontoideum here is recognized as a traumatic origin with the presence of congenital Chiari I abnormality as a separate entity. The changes of the anterior arch of C1 as well as the os formation were serially documented and give credence to blood supply changes in the os and atlas as a result of the trauma. The recognized treatment of dorsal occipitocervical fusion failed in this case requiring also a ventral decompression of the medulla.

Styloid Jugular Nutcracker: The Possible Role of the Styloid Process Spatial Orientation-A Preliminary Morphometric Computed Study.

Styloid Jugular Nutcracker (SJN, also known as Eagle Jugular Syndrome EJS) derives from a jugular stenosis caused by an abnormal styloid process, compressing the vessel in its superior portion (J3) against the C1 anterior arch. It could be considered a venous vascular variant of Eagle Syndrome (ES). Main clinical features of this ES variant are headache, pulsatile tinnitus and dizziness, possibly related to venous hypertension and impaired cerebral parenchyma drainage. In our opinion, conceptually, it is not the absolute length of the styloid bone that defines its abnormality, but its spatial direction. An elongated bone pointing outward far away from the midline could not compress the vein; vice versa, a short styloid process tightly adherent to the cervical spine could be pathological. To prove this hypothesis, we developed a semi-automatic software that processes CT-Angio images, giving quantitative information about distance and direction of the styloid process in three-dimensional space. We compared eight patients with SJN to a sample of healthy subjects homogeneous for sex and age. Our results suggest that SJN patients have a more vertically directed styloid, and this feature is more important than the absolute distance between the two bony structures. More studies are needed to expand our sample, including patients with the classic and carotid variants of Eagle Syndrome.

Eagle jugular syndrome: a morphometric computed study on styloid process orientation

Cerebral venous drainage impairment is related to a wide spectrum of pathologies, both acute or chronic. Among the most intriguing and less explained there are those caused by a long-lasting compression on internal jugular vein (IJV), mono or bilaterally. Recently, a jugular variant of the Eagle syndrome has been described,1,2 in which an elongated styloid process, coming from the mastoid tip down through the neck, compresses the IJV (more frequently J3) in its passage on the C1 anterior arch. Interestingly, those patients often complaint of typical symptoms of intracranial hypertension, such as headache (not frequent in classic Eagle syndrome), tinnitus, dizziness. They also seem to have an increased risk of perimesencephalic hemorrhages. Conceptually, it is not the styloid process length in itself to determine the compression, but rather its spatial orientation. We could therefore expect to find patients suffering from Eagle jugular syndrome who present normal or short styloid process, but in close proximity to C1. To test this hypothesis, we are developing a novel software to analyze 3-D spatial orientation of styloid process in patient with a previously diagnosed Eagle jugular syndrome compared to healthy controls. Methods We collected cervical computed tomography angiography (CTA) images from 8 patients with EJS confirmed by venous angiography at our institution, and a control group of 7 random patients, homogenous for sex and age. A blind operator created with a dedicated pre-existing software3, an editable 3-D model (.stl file) of the 3 main region of interest (ROI), namely: right styloid, left styloid, C1 anterior arch. Starting from this dataset, our software, written using the open-source package management system Anaconda4 ver. 2-2.4.0, compares all the possible couples of points between each styloid process and the C1 arch, detecting the minimum and maximum distance. Then, it provides the mean spatial orientation of the process respect the CT-axis: x-axis (from left to right), y-axis (from occiput to nose) and z-axis (cranio-caudal). Results By now we included 15 patients (8 cases, 7 controls), homogeneous for sex and age. Preliminary data (Table 1), although not statistically significant yet, seems to indicate that Eagle jugular patients effectively have a more vertical styloid process, meaning an angle between styloid and y-axis greater than controls, rather than a longer one. Conclusions Our preliminary results could confirm that spatial orientation is more important in Eagle jugular patients than styloid process length. This study is currently ongoing and we planned to enroll at least 20 subjects for each arm. At the same time, we are collecting data from patients with carotic variant of Eagle syndrome, to better characterize morphometric structure of styloid in various subset of this pathology.

Endoscopy-assisted high anterior cervical approach in craniovertebral junction (CVJ)

Surgical procedures in the craniovertebral junction (CVJ) suffer from specific challenges due to the proximity between the cranium and spine containing the critical neurovascular structures and the brainstem, respectively. Owing to the complex transitional zone, it is highly challenging for classic surgical approaches to practically acquire the additional exposure to neurovascular structures of the CVJ. Inspired by these facts, we explore the feasibility of an endoscopy-assisted high anterior cervical approach in the CVJ. To explore the feasibility of an endoscopy-assisted approach, we quantitatively assessed the surgical corridor and extent of exposure of the CVJ in 6 cadaveric specimens using 0° and 30° endoscopes. The applied endoscopes provided adequate exposure to neurovascular structures and the brainstem in the CVJ. Notably, the resection of the anterior arch of C1 is avoided in minimal anterior clivectomy. Further, improved exposure of the CVJ is obtained after removing the odontoid. An endoscope-assisted high anterior cervical approach in the CVJ significantly preserved the cervical spine stability while minimalizing the risk of neurovascular injury within the surgical corridor.

492 Calcific Tendonitis of the Longus Colli: A Rare Cause of Neck Pain

Abstract Cervical tendonitis of the Longus Colli muscle (CTLC) is a rare but clinically significant cause of neck pain. It can mimic other more serious pathologies in the retro-pharygneal area and requires sufficient investigation for diagnosis. This case presented with a fit and well 54-year-old gentleman suffering from progressive left sided neck pain, stiffness, and odynophagia. His imaging demonstrated a prevertebral fluid collection of unclear aetiology and an area of calcification just below the anterior arch of C1. Along with the differential diagnosis of calcific tendonitis of longus colli, the fluid collecting inferior to C1 could have represented a retropharyngeal abscess - a potentially life-threatening infection. This patient required input from multiple specialities to safely reach diagnosis and exclude more significant pathology. Although CTLC represents a benign and perhaps under-recognised condition, this case highlights the importance of considering other differential diagnoses and multidisciplinary management in a patient presenting with limited neck movements.

C1-C2 Rotatory Subluxation in Adults "A Narrative Review".

The atlantoaxial joint C2 (axis) with the anterior arch of C1 (atlas) allows 50% of cervical lateral rotation. It is responsible for precise and important movements that allow us to perform precise actions, both in normal and working life. Due to low incidence in adults, this condition often goes undiagnosed, or the diagnosis is delayed and the outcome is worse. An early diagnosis and treatment are essential to ensure satisfactory neurological and functional outcomes. The aim of this review is to analyze C1-C2 rotatory subluxation in adults, given its rarity. The time between injury and reduction is key, as it is directly related to prognosis and the severity of the treatment options. Due to low incidence in adults, this condition often goes undiagnosed, or the diagnosis is delayed as a lot of cases are not related to a clear trauma, with a poor prognosis just because of the late diagnosis and the outcome is worse. The correct approach and treatment of atlantoaxial dislocation requires a careful study of the radiological findings to decide the direction and plane of the dislocation, and the search for associated skeletal anomalies.

Anatomical and Radiological Description of the <i>Macaca fascicularis</i> Spine in Comparison with the Human Spine

Background: This paper describes and displays the spinal radiological anatomy and associated pathology in a Macaca fascicularis and compares it to the spinal anatomy of humans. Animal models are commonly used in research. As compared to Macaca mulatta, the anatomy of M. fascicularis is less well described in the literature. Materials and methods: The authors anatomically reconstructed and reviewed the defleshed spine of a single adult M. fascicularis visually, radiographically, and with high resolution CT. Results: 7 cervical, 12 thoracic, 6 lumbar, 3 sacral, and 16 caudal vertebrae were identified. Similarities in the spine to humans were seen as well as differences such as the beaked anterior arch of C1, the anterior pointed lower lumbar vertebrae, the upward curved transverse processes, and presence of three sacral segments. Degenerative changes were seen at multiple locations similar to humans though most pronounced at T3-4. Conclusions: This paper addresses the normal spinal anatomy and degenerative changes in an adult M. fascicularis and compares it to humans.

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

ObjectiveOdontoidectomy 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. MethodsA 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). ResultsThe 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). ConclusionsPreservation 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.

Predictive value of sagittal craniocervical roentgenographic parameters for HRQOL after craniocervical fusion.

Loss of "physiological" sagittal alignment following craniocervical fusion (CCF) for degenerative disease may be associated with loss of horizontal gaze, dysphagia and poor HRQOL. This study reports on sagittal craniocervical roentgenographic predictors of HRQOL (SF-36) in patients following uncomplicated CCF for fresh upper cervical traumatic (UCT) injuries. Twenty-two consecutive adult patients (group P) aged 50 ± 16years, who had undergone CCF for fresh unstable C1 and C2AO/type UCT injuries, were evaluated 39 ± 12months postoperatively with upright lateral cervical roentgenograms and SF-36as HRQOL measure. Physiological data for cervical sagittal alignment and SF-36 were taken from an age-matched control group (C) of 30 individuals aged 52 ± 12years. Several commonly used sagittal cervical roentgenographic parameters were tested as potential predictors of the SF-36 domains in both groups. Roentgenographic predictors for each of the nine SF-domains were calculated using stepwise multilinear regression analysis (MLRA). The roentgenographic predictors in patients included (1) the angle created by McGregor's line and the inferior surface of the axis (OC2a) for physical function (PF, P = 0.049), role limitations due to physical health (RLPH, P = 0.004),role limitation due to emotional problems (RLEP, P = 0.004), emotional functioning (EF) (P = 0.012), social functioning (SF) (P = 0.028) and general health (GH, P = 0.041). (2) The angle formed between a horizontal line and the superior endplate of T1-vertebra (T1-slope) was predictor for SF (P = 0.017) and pain (P = 0.021), and (3) the angle between McGregor's line and the line that links the center of the C1 anterior arch and the apex of cervical sagittal curvature (PIA) was predictor for health change (HC, P = 0.002). This study showed that postoperative OC2a, PIA and T1-slope safely predict HRQOL outcomes (SF-36) following CCF for fresh trauma. It seems theoretically that the adequate restoration of the upper cervical alignment including C1-C2 upper cervical lordosis (OC2a) and PIA, in interaction with T1-slope, is important for postoperative HRQOL scores close to physiological values. The authors speculate that C0-C4 fusion restores horizontal gaze and allows for painful regain of pre-trauma quality of life. Spine surgeons should realign and stabilize the craniocervical junction taking in consideration these roentgenographic predictors.

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

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. 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. 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. 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.

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 .