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BACKGROUND CONTEXT: Our recent studies indicated that a high-riding vertebral artery (HRVA) is a common variant posing a risk of injuring the vessel during C2 instrumentation. However, several different types fit in the current definition of HRVA, which may require a different strategy for C2 screw placement. PURPOSE: To classify HRVA and provide a clinical aid for preoperative planning of C2 instrumentation. A secondary goal was to estimate coexistence of each HRVA type with the ipsilateral narrow C2 pedicle (NP). STUDY DESIGN: A retrospective observational study involving radiologic measurements of the estimated number of anonymized cervical computed tomography (CT) scans. STROBE checklist was applied. PATIENT SAMPLE: 908 potential screw insertion sites (PSIS) of 454 consecutive cervical CT scans were analyzed. The sample size was estimated using ScalaR SP function in RStudio. OUTCOME MEASURES: Three types of HRVA based on a series of C2 vertebral morphological parameters including the C2 isthmus height (C2IsH) and C2 internal height (C2InH). Also, the prevalences of each HRVA type and coexisting NP based on the C2 pedicle width (C2PW). METHODS: HRVA was defined as C2IsH of ≤ 5 mm and/or C2InH of ≤ 2 mm measured 3 mm lateral to the lateral border of the spinal canal. A narrow pedicle was defined as C2PW of ≤ 4 mm. Measurements were done using Syn.govia software. Interobserver, intraobserver, and inter-software agreement coefficients for C2IsH, C2InH, and C2PW parameters were adopted from our previous study. K-means cluster analysis was applied. RESULTS: Prevalence of at least one HRVA was 24.9% (n = 113 subjects) and 16.2% of PSIS (n = 147 sites). Based on the measurements and K-means clustering, the following three types of HRVA have been distinguished: type 1 - isthmic with only C2IsH being reduced and normal C2InH; type 2 - internal with only C2InH being reduced and C2IsH within normal limits; type 3 - isthmo-internal with both C2IsH and C2InH being reduced. Kruskal-Wallis test followed by unadjusted and Bonferroni-adjusted post-hoc multiple comparison analysis detected significant differences across the types. The prevalences of the newly identified types were as follows: 78.2%, 8.8%, and 12.9% for type 1, type 2, and type 3, respectively. 73.9% of type 1 HRVA, 53.8% of type 2 HRVA, and 100% of type 3 HRVA had a concomitant ipsilateral NP. Prediction of the HRVA types by the K-means clustering has been evaluated. Screw placement techniques for each type are proposed and discussed. CONCLUSION: We present the first classification system for the high-riding vertebral artery distinguishing three types based on the large homogenous cohort, which may serve as an adjunct to preoperative planning of C2 instrumentation. External validation of this classification scheme shall determine its further clinical utility.

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Cervical pain has been linked to increased motor unit activity, potentially associated with the initiation and progression of chronic neck pain. Therefore, this study aimed to compare the time-course changes in cervical superficial muscle activation patterns among dental students with and without neck pain throughout their initial semester of clinical training. We used an online Nordic Musculoskeletal Questionnaire for group allocation between neck pain (NP) (n = 21) and control group (CG) (n = 23). Surface electromyography (sEMG) of the sternocleidomastoid and upper bilateral trapezius was recorded before starting their clinical practice and after their first semester while performing a cranio-cervical flexion test (CCFT) in five increasing levels between 22 mmHg and 30 mmHg. After the first semester, both the CG (p < 0.001) and NP (p = 0.038) groups showed decreased sternocleidomastoid activation. The NP group exhibited a concomitant increase in upper trapezius coactivation (p < 0.001), whereas the muscle activation pattern in asymptomatic students remained unchanged (p = 0.980). During the first semester of clinical training, dental students exhibited decreased superficial flexor activity, but those with neck pain had increased co-contraction of the upper trapezius, likely to stabilize the painful segment. This altered activation pattern could be associated with further dysfunction and symptoms, potentially contributing to chronicity.

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Posterior fossa decompression for symptomatic Chiari malformation is an effective and frequently performed procedure, but it does carry risks of significant complications including cerebrospinal fluid leak and craniocervical instability. Patients sometimes do not improve or worsen after decompression, which may discourage neurosurgeons from performing Chiari decompression surgery. In this chapter, management strategies and surgical approaches are discussed that minimize the risks of complications and maximize favorable outcomes in Chiari malformation surgery.

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PURPOSE: Instrumentation of the C1 vertebra requires either mobilization or transection of the C2 nerve root. This study investigates clinical and radiological outcomes and incidences of C2 neuropathic pain after posterior instrumented fusion in the cranio-cervical junction with or without division of the C2 nerve roots. METHODS: This retrospective study compared two cohorts of patients who underwent instrumented fusion in the cranio-cervical junction. Fifty patients (22 males and 28 females) were operated with complete resection of C2 nerve root ganglion (Ex group), and fifty-one patients (30 men, 21 women) with C2 nerve roots preservation (No group). RESULTS: The incidence of postoperative C2 neuropathy was eight times lower in the Ex group compared to the No group that was statistical significant, p = 0.039. Surgical time was significantly shorter in the No group (p = 0.001). The fusion rates were very high for both groups, without difference between groups (p = 1.0). Autografting from the iliac crest (p = 0.001) as well as postoperative immobilisation with a hard collar (p < 0.001) were required in fewer patients in the Ex group. Also, patients in the Ex group were mobilised faster after surgery (p = 0.49). Overall, complication rates were similar between groups, but the Ex group demonstrated fewer major medical complications (16% vs 31%). Male sex and iliac bone harvesting demonstrated significantly higher OR for development of postoperative complications (p = 0.023 and p = 0.034 respectively) and postoperative mobilization demonstrated significant higher OR for development of postoperative major complications (p = 0.042). CONCLUSIONS: Resection of the C2 nerve root ganglion during posterior instrumented fusion of the cranio-cervical junction is safe and rarely leads to C2 neuropathy. The technique tends to mitigate the odds of developing postoperative complications.

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This study aims to discuss the identification of the C1 nerve root as an effective surgical approach to successfully locate the shunting point of craniocervical junction spinal dural arteriovenous fistula (CCJ-SDAVF) intraoperatively. This study included all patients with CCJ-SDAVF who underwent surgical treatment using the far-lateral transcondylar approach at a single institution from January 2017 to June 2023. Data on patient demographics, clinical and angiographic characteristics of CCJ-SDAVF, surgical details, and treatment outcomes were collected. Follow-up assessments were conducted for all patients until December 31, 2023. The study included a total of 7 patients, comprising 5 men(71.4%) and 2 women (28.6%), with an average age of 57.6 years. Among them, 4 patients (57.1%) developed diffuse subarachnoid hemorrhage(SAH), while 2 patients (28.6%) experienced progressive cervical myelopathy. The shunting points of all CCJ-SDAVFs, which exhibited engorged veins, were identified next to the C1 root. Complete obliteration of CCJ-SDAVFs was successfully achieved in all patients, as confirmed by postoperative angiography one month later. No recurrent CCJ-SDAVFs were observed two years after the operation. Among the patients, 5 (71.4%) experienced good functional recovery, as indicated by an mRS score ranging from 0 to 1, while the remaining 2 patients (28.6%) showed incomplete functional recovery. The surgical interruption of CCJ-SDAVFs is the preferred treatment option, given its high obliteration rate and favorable functional recovery outcomes. We advocate the identification of C1 spinal nerve root as a crucial surgical step to identify the shunting points of CCJ- SDAVFs.

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Atlanto-occipital assimilation is a congenital craniovertebral junction malformation where the partial or complete fusion of the atlas and occiput occurs. Atlanto-occipital assimilation can be associated with numerous complications, including basilar invagination, atlantoaxial subluxation, Chiari malformation, congenital vertebral bodies fusion, and cord compression. As a result, vigilant identification and accurate reporting of atlanto-occipital assimilation are essential. The purpose of this review article is to discuss the numerous complications and associations of atlanto-occipital assimilation, such that an accurate diagnosis could be made for this commonly missed pathology.

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The Ehlers-Danlos Syndromes (EDS) represent a group of hereditary connective tissue disorders, with the hypermobile subtype (hEDS) being the most prevalent. hEDS manifests with a diverse array of clinical symptoms and associated comorbidities spanning the musculoskeletal, neurological, gastrointestinal, cardiovascular, and immunological systems. hEDS patients may experience spinal neurological complications, including cervico-medullary symptoms arising from cranio-cervical and/or cervical instability/hypermobility, as well as tethered cord syndrome (TCS). TCS is often radiographically occult in nature, not always detectable on standard imaging and presents with lower back pain, balance issues, weakness in the lower extremities, sensory loss, and bowel or bladder dysfunction. Cervical instability due to ligament laxity can lead to headaches, vertigo, tinnitus, vision changes, syncope, radiculopathy, pain, and dysphagia. TCS and cervical instability not only share clinical features but can also co-occur in hEDS patients, posing challenges in diagnostics and clinical management. We present a review of the literature and a case study of a 20-year-old female with hEDS, who underwent surgical interventions for these conditions, highlighting the challenges in diagnosing and managing these complexities and underscoring the importance of tailored treatment strategies to improve patient outcomes.

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Dural arteriovenous fistula (DAVF) of the craniocervical junction is exceptionally rare. The anatomy of the craniocervical junction area is very complex and is composed of the medulla and spinal cord along with intricate neurovascular structures. A thorough assessment of the angioarchitecture of the fistula is obligatory for choosing the most appropriate treatment for the patient. In this report, we describe the nuance of microsurgical obliteration of craniocervical junction DAVF utilizing intraoperative angiography. A 38-year-old male in a normal state of health was referred to our hospital for an abnormality in his brain checkup. Workup diagnostics showed a DAVF on the craniocervical junction area with feeders from ascending pharyngeal, vertebral, and occipital arteries, with the draining vein mainly to the basal vein of Rosenthal. Microsurgical obliteration of the main draining vein was done with the help of intraoperative digital subtraction angiography with a good outcome. Craniocervical DAVF is a rare entity. Meticulous evaluation of arterial and venous fistula points is necessary to decide the best treatment option for this case. Microsurgical obliteration is a feasible and more straightforward procedure for treating craniocervical DAVF.

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OBJECTIVES: Body posture of patients with temporomandibular disorders (TMD) has been investigated using different methods, whereas outcome and conclusions were controversial. The present clinical trial aimed to investigate the effects of splint therapy on global body posture. MATERIALS AND METHODS: 24 subjects (20 females, 4 males; age 24.2 ± 4.0 years) with TMD symptoms were examined clinically (RDC/TMD) and subsequently, splint fabrication was initiated. Along with routine therapy, all subjects underwent three-dimensional pre- and post-treatment full body scans in standing and upright sitting posture using a Vitus Smart XXL 3D scanner. Each scan was acquired in triplicate and evaluated in duplicate, measuring twelve standing and nine sitting postural parameters. Influencing factors were analyzed using analysis of variance (ANOVA), and additional Bland-Altman analyses verified the significance of the ANOVA results. RESULTS: The increase of Forward Head angles and the decrease of Round Shoulders angles were consistent for both positions and sides. Forward Head angles were significantly influenced by limited mandibular mobility and myofascial pain. Round Shoulders angles showed a significant correlation with myofascial pain, joint noises and the absence of limited mandibular mobility. CONCLUSION: The influence of occlusal splints on global posture is limited and only small effects on cervicocranial parameters were found. In the present study, the average head position of post treatment measurements was more centered on the body's core, whereas the shoulders were tilted more anteriorly. CLINICAL RELEVANCE: Understanding the limited influence of occlusal splints on cervicocranial parameters underscores the need for multimodal treatment strategies for TMD patients.

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Rosai-Dorfman disease (RDD) with craniocervical junction involvement is a rare clinical entity. We present herein a case of a pediatric patient with craniocervical junction RDD which was surgically treated. A 10-year-old female with a history of B-cell acute lymphoblastic leukemia (B-ALL) in remission and RDD presented with frontal migraine headaches. She previously had a right posterior chest wall lesion which was biopsy-proven RDD. She was found on imaging to have a dural-based right craniocervical junction lesion. Given her history of B-ALL, after a multidisciplinary discussion, the decision was made to proceed with resection with possible initiation of cobimetinib or clofarabine. The patient underwent a suboccipital craniotomy, C1 laminectomy, and resection of the dural-based lesion. Gross total resection was achieved, and histopathology confirmed the diagnosis of RDD. She was discharged home on postoperative day 4. No recurrence was seen on follow-up imaging at 3 months. We conducted a systematic literature review examining all cases of pediatric intracranial RDD and all cases of craniocervical junction RDD. This represents, to the best of our knowledge, only the second case of pediatric craniocervical junction RDD. Although RDD is often self-limiting, medical treatment is often considered for intracranial disease, but tissue confirmation is necessary. Surgical resection provides histopathologic diagnosis and can sometimes serve as definitive treatment for a particular lesion.

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Schwannomas overall account for approximately 8% of primary brain tumors, with the majority of them arising from the vestibular nerves.1,2 Non-vestibular schwannomas are considered rare, particularly ones arising from the accessory nerve, constituting only around 4% of craniovertebral junction schwannomas.3,4 The far lateral approach and its variations is an important tool in the armamentarium of skull base neurosurgeons. It allows adequate exposure for accessing ventral and ventrolateral lesions of the craniocervical junction.5-13 A 60-year-old female patient presented with a 3-month history of difficulty walking and progressive right-sided weakness. Magnetic resonance imaging demonstrated an extra-axial solid lesion at the craniocervical junction with significant enhancement on post-contrast imaging. The lesion was ventrolateral to the medulla, causing compression, displacement, and peritumoral edema. The patient consented to the procedure and underwent a far lateral suboccipital craniotomy with C1 hemilaminectomy in a lateral position. Tumor origins were identified at the left accessory nerve rootlet. The patient's postoperative course was uneventful. Follow-up magnetic resonance imaging revealed gross total resection and complete resolution of hemiparesis 3 months after the surgery. Microsurgical resection of tumors at the craniocervical junction is challenging. Preoperative planning and tailoring the approach are essential in the decision-making process to safely perform surgery. This video demonstrates, in detail, the steps, relevant anatomy, and technical nuances for accessory nerve schwannoma ressmoval. To the best of our knowledge, this is the first operative video showing the resection of a pure accessory nerve schwannoma with compression of the medulla. Under our institutional ethical review board regulations, approval was not necessary.

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BACKGROUND: Neurenteric cysts are relatively rare benign congenital intracranial cystic lesions that enlarge rarely and very slowly. The authors present a case of an enlarging neurenteric cyst at the craniocervical junction with a fluid-fluid level on magnetic resonance imaging (MRI). OBSERVATIONS: A 34-year-old man with no significant medical history underwent head MRI to investigate mild headaches. An incidental cystic lesion, approximately 8 mm in diameter, was revealed at the craniocervical junction. Serial follow-up MRI showed cyst enlargement with a fluid-fluid level. Four years later, the cyst reached a size of 15 mm and was surgically removed. The cyst contained cloudy fluid with a high protein concentration, without any bleeding or tissue fragments. Pathological examination confirmed the diagnosis of a neurenteric cyst. The patient recovered well, was discharged home, and has remained recurrence free for 2 years. LESSONS: The growth dynamics of the relatively rapidly expanding neurenteric cyst at the craniocervical junction were monitored over time using MRI. This cyst exhibited the distinctive feature of a fluid-fluid level as it enlarged. Investigating the mechanisms underlying fluid-fluid level formation may offer novel insights into the pathogenesis of cyst enlargement. https://thejns.org/doi/10.3171/CASE24180.

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Spinal arteriovenous fistulae (AVFs) of the craniocervical junction are rare lesions that have variable angioarchitecture. These lesions are generally characterized by arteriovenous shunting at a single fistulous point, the disconnection of which is generally curative.1 We present a case of bilateral dural AVF at the C2 level treated with surgical ligation (Video 1). Our patient was an elderly woman who presented after cervical magnetic resonance imaging was performed as part of work-up for right-sided shoulder tingling. This study demonstrated prominent flow voids along the dorsal and ventral surfaces of the craniocervical junction, concerning for an underlying vascular malformation. Formal angiography demonstrated arteriovenous shunting into the perimedullary venous plexus from a dural branch of the vertebral artery at the C2 level. Significant retrograde cortical venous drainage was noted. She was treated with a C1 and partial C2 laminectomy and clip ligation of the right-sided fistula. Postoperative angiography confirmed obliteration of the fistula but now demonstrated persistent arteriovenous shunting from second fistulous point at the contralateral C2 level. She was then taken back to surgery for ligation of the second fistula. Instances of multiple, distinct, and synchronous arteriovenous fistulae have been rarely reported in the literature.2 In addition to demonstrating the nuances of surgical treatment of AVFs at this location, this case demonstrates the potential for synchronous AVFs and emphasizes the importance of thorough postoperative angiography. The patient provided consent to the production of this surgical video.

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Background: Dural arteriovenous fistulas (DAVFs) at the craniocervical junction (CCJ) involving the first spinal nerve represent a particularly rare and challenging subtype of DAVFs, with holocord myelopathy secondary to cerebrospinal DAVFs being an exceedingly rare presentation. Case Description: We report the case of a 70-year-old woman who presented with progressive paraparesis over 2 weeks. Initial magnetic resonance imaging (MRI) of the spine showed extensive holocord myelopathy, leading to a misdiagnosis of inflammatory myelopathy and subsequent inappropriate steroid treatment at a local hospital, which exacerbated her neurological symptoms. On transfer to our institution and further evaluation with MRI and magnetic resonance angiography, a lower thoracic DAVF was initially suspected. However, comprehensive spinal angiography failed to localize the fistula, prompting cranial angiography, which ultimately identified a DAVF at the CCJ along the C1 nerve root, supplied by a small radiculomeningeal branch of the left vertebral artery. Successful management involved coagulation of the proximal draining vein, with follow-up imaging confirming complete fistula obliteration and resolution of the holocord edema. Conclusion: This case highlights the diagnostic and therapeutic challenges associated with DAVFs at the CCJ, particularly when presenting with holocord myelopathy. It underscores the importance of a high index of suspicion and the need for timely, accurate diagnosis and intervention to prevent permanent spinal cord damage in such rare and complex cases.

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OBJECTIVE: To evaluate the feasibility of a novel method for occipitocervical fixation (OCF) through the endonasal corridor. METHODS: Thin-cut computed tomography scans were obtained for 5 cadaveric specimens. Image segmentation was used to reconstruct 3D models of each O-C1 joint complex. Using computer-aided design software, plates were custom-designed to span each O-C1 joint, sit flush onto the bony surface, and accommodate screws. The final models were 3D-printed in titanium. For implantation, specimens were held in pin-fixation and registered to neuronavigation. A rigid 0º endoscope was used for endonasal visualization. An inverted U-shaped nasopharyngeal flap was raised to expose the occipital condyles and C1. The plates were introduced and fixed with bone screws. Computed tomography scans were obtained to assess screw accuracy and proximity to critical neurovascular structures. Screw entry points and trajectories were recorded. RESULTS: Endonasal OCF was performed on 5 cadaveric specimens. The mean starting point for occipital condyle screws was 6.17 mm lateral and 5.38 mm rostral to the medial O-C1 joint. Mean axial and sagittal trajectories were 7.98° and 6.71°, respectively. The mean starting point for C1 screws was 16.11 mm lateral to the C1 anterior tubercle and 6.39 mm caudal to the medial O-C1 joint. Mean axial and sagittal trajectories were 10.97° and -9.91°, respectively. CONCLUSIONS: Endonasal OCF is technically and anatomically feasible. The application of this technique may allow for same-stage endonasal decompression and fixation, offering a minimally invasive alternative to current methods of fixation and advancing surgeons' ability to treat pathology of the craniovertebral junction. Next steps will focus on biomechanical testing.

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Arteriovenous fistula (AVF) occurring within the craniocervical junction (CCJ) is an uncommon vascular anomaly. A 56-year-old man presented with cervical pain and gait disturbances. Computed tomography revealed a hematoma in the epidural space at the cervical spinal level. Subsequent cerebral angiography revealed an epidural shunt at the CCJ, leading to a diagnosis of epidural AVF (EDAVF). Transvenous embolization, performed under general anesthesia, successfully resolved the shunt. Transarterial embolization of CCJ-EDAVFs carries a substantial risk of ischemic complications. Conversely, transvenous embolization poses a lower risk of ischemic complications and has potential as a beneficial treatment option for CCJ-EDAVFs. Herein, we present a unique case of CCJ-EDAVF that was successfully treated with transvenous embolization.

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OBJECTIVE: Craniocervical dystonia (CCD) is a common type of segmental dystonia, which is a disabling disease that has been frequently misdiagnosed. Blepharospasm or cervical dystonia is the most usual symptom initially. Although deep brain stimulation (DBS) of the globus pallidus internus (GPi) has been widely used for treating CCD, its clinical outcome has been primarily evaluated in small-scale studies. This research examines the sustained clinical effectiveness of DBS of the GPi in individuals diagnosed with CCD. METHODS: The authors report 24 patients (14 women, 10 men) with refractory CCD who underwent DBS of the GPi between 2016 and 2023. The severity and disability of the dystonia were evaluated using the Burke-Fahn-Marsden Dystonia Rating Scale (BFMDRS). The BFMDRS scores were collected preoperatively, 6 months postoperatively, and at the most recent follow-up visit. RESULTS: The mean age at onset was 52.0 ± 11.0 years (range 33-71 years) and the mean disease duration was 63.3 ± 73.3 months (range 7-360 months) (values for continuous variables are expressed as the mean ± SD). The mean follow-up period was 37.5 ± 23.5 months (range 6-84 months). The mean total BFMDRS motor scores at the 3 different time points were 13.3 ± 9.4 preoperatively, 5.0 ± 4.7 (55.3% improvement, p < 0.001) at 6 months, and 4.5 ± 3.6 (56.6% improvement, p < 0.001) at last follow-up. The outcomes were deemed poor in 6 individuals. CONCLUSIONS: Inferences drawn from the findings suggest that DBS of the GPi has long-lasting effectiveness and certain limitations in managing refractory CCD. The expected stability of the clinical outcome is not achieved. Patients with specific types of dystonia might consider targets other than GPi for a more precise therapy.

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BACKGROUND: The diagnostic impact of deep learning computed tomography (CT) reconstruction on intracranial aneurysm (IA) remains unclear. PURPOSE: To quantify the image quality and diagnostic confidence on IA in craniocervical CT angiography (CTA) reconstructed with DEep Learning Trained Algorithm (DELTA) compared to the routine hybrid iterative reconstruction (HIR). MATERIAL AND METHODS: A total of 60 patients who underwent craniocervical CTA and were diagnosed with IA were retrospectively enrolled. Images were reconstructed with DELTA and HIR, where the image quality was first compared in noise, signal-to-noise ratio (SNR), and contrast-to-noise ratio (CNR). Next, two radiologists independently graded the noise appearance, arterial sharpness, small vessel visibility, conspicuity of calcifications that may present in arteries, and overall image quality, each with a 5-point Likert scale. The diagnostic confidence on IAs of various sizes was also graded. RESULTS: Significantly lower noise and higher SNR and CNR were found on DELTA than on HIR images (all P < 0.05). All five subjective metrics were scored higher by both readers on the DELTA images (all P < 0.05), with good to excellent inter-observer agreement (κ = 0.77-0.93). DELTA images were rated with higher diagnostic confidence on IAs compared to HIR (P < 0.001), particularly for those with size ≤3 mm, which were scored 4.5 ± 0.6 versus 3.4 ± 0.8 and 4.4 ± 0.7 versus 3.5 ± 0.8 by two readers, respectively. CONCLUSION: The DELTA shows potential for improving the image quality and the associated confidence in diagnosing IA that may be worth consideration for routine craniocervical CTA applications.

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PURPOSE: The topic of osseous variations of the craniocervical junction is a complex morphological and embryological chapter of human anatomy, with a possible impact on neurogical and vascular functionality in this morphological variable region. MATERIAL & METHODS: An until now undescribed anatomical variation of the exoccipital part of the occipital bone has been observed after maceration at the outer skull base of a West-European 68-year-old male body donor. RESULTS: On both sites of the foramen magnum accessory osseous processes were observed that arise from the jugular process and point towards the lateral margin of the foramen magnum. On the left site this process forms a full arc that bridges the condylar fossa completely. CONCLUSION: The observed osseous bridge over the condylar fossa has not been reported on before and can be explained by the partial persistence of a primordial vertebra between atlas and occipital bone: the Proatlas. The resulting accessory structure may affect due to its topographic conditions the V3-Segment of the vertebral artery and its accompanying nerves, and thus, play a role in diagnosis and therapy of vascular and/or neurological symptoms of head and neck.

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