Bridging veins at the craniocervical junction: from anatomy to clinical significance in dural arteriovenous shunts.

PURPOSE: Bridging veins (BVs) serve as a route of pial venous reflux, and its anatomy is essential to understand the pathophysiology of dural arteriovenous shunts (dAVSs) around the craniocervical junction (CCJ) (from the jugular foramen level to the atlantal level). However, the anatomical variations of the BVs and their proximal connections remained poorly elucidated. This study aimed to radiologically investigate the anatomy of the bridging veins around CCJ and discuss the clinical significance of these BVs in the dAVS. METHODS: We investigated normal venous anatomy of the BVs from the jugular foramen level to the atlantal level using preoperative computed tomography digital subtraction venography in patients undergoing elective neurosurgery. BVs affected by the dAVSs in the same region were also evaluated. The three types of dAVS, craniocervical junction, anterior condylar, and proximal sigmoid sinus, were investigated. RESULTS: We identified six BV groups: superolateral, anterolateral, lateral, posterior, inferolateral, and inferoposterior. The superolateral and inferolateral groups, connected with the proximal sigmoid sinus and suboccipital cavernous sinus, respectively, were the largest groups. Each group has a specific downstream venous connection. The association with dVASs was observed only in the inferolateral group, which was typically the sole venous drainage in most dAVSs at the CCJ. CONCLUSION: We reported detailed anatomy of BVs from the jugular level to the atlantal level, which enhanced our understanding of the pathophysiology of dAVSs in the corresponding region.

Surgical resection of pediatric craniocervical junction Rosai-Dorfman histiocytosis-a case report and literature review.

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.

The surgical role of C1 nerve root identification for the disconnection of the spinal dural arteriovenous fistula at the craniocervical junction: a single center restrospective experience.

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.

Autologous rib grafts for craniocervical junction surgery in children: a clinical application.

OBJECTIVE: Autologous iliac bone is commonly used as a bone graft material to achieve solid fusion in craniocervical junction (CVJ) surgery. However, the developing iliac bone of children is less than ideal as a bone graft material. The matured rib bone of children presents a potential substitute material for iliac bone. The aim of this study was to evaluate the efficacy of autologous rib grafts for craniocervical junction surgery in children. METHODS: The outcomes of 10 children with abnormalities of the craniocervical junction who underwent craniocervical junction surgery between January 2020 and December 2022 were retrospectively reviewed. All patients underwent posterior fusion and internal fixation surgery with autologous rib grafts. Pre- and post-operative images were obtained and clinical follow-ups were conducted to evaluate neurological function, pain level, donor site complications, and bone fusion rates. RESULTS: All surgeries were successful. During the 8- to 24-month follow-up period, all patients achieved satisfactory clinical results. Computed tomography at 3-6 months confirmed successful bone fusion and regeneration of the rib defect in all patients with no neurological or donor site complications. CONCLUSION: Autologous rib bone is a safe and effective material for bone grafting in craniocervical junction fusion surgery for children that can reduce the risks of donor site complications and increase the amount of bone graft, thereby achieving a higher bone fusion rate.

Osseous bridging of the condylar fossa: report of a rare anatomical variation at the outer skull base.

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.

Proposing novel dorsal Proatlas-manifestations: Description and classification of three rare phenomena in humans.

The craniocervical junction (CCJ) of humans and other vertebrates is a developmental restless region. Due to complex phylogenetic and ontogenetic processes, many anatomical variations can be found in that transitional area. Therefore, newly described variants must be registered, named, and classified into existing concepts explaining their genesis. This study aimed to describe and classify anatomical peculiarities that have not or rarely been reported on before in the literature. This study is based on the observation, analysis, classification, and documentation of three rare phenomena of three different human skull bases and upper cervical vertebrae, which come from the body donor program of the RWTH Aachen. As a result, three osseous phenomena (accessory ossicles, spurs, and bridges) at the CCJ of three different body donors could have been documented, measured, and interpreted. Due to extensive collecting efforts, careful maceration, and accurate observation, it is still possible to add new phenomena to the long list of Proatlas-manifestations. Further on, it could have been shown again that these manifestations can cause damage to the elements of the CCJ due to altered biomechanic conditions. Finally, we have succeeded in showing that phenomena can exist that can imitate the presence of a Proatlas-manifestation. Here, a precise differentiation between Proatlas-based supernumerary structures and the results of fibroostotic processes is necessary.

Angioarchitectural features of arteriovenous fistulas at craniocervical junction predicting clinical presentation and unfavorable neurological function: insight from a multicenter cohort and pooled analysis.

Arteriovenous fistulas (AVFs) at the craniocervical junction (CCJ) are uncommon conditions with complex angioarchitecture. The objective of this study was to identify the angioarchitectural features of CCJ-AVF that were predictive of clinical presentation and neurological function. The study encompassed a total of 68 consecutive patients with CCJ-AVF at two neurosurgical centers between 2014 and 2022. Additionally, a systematic review was conducted, including 68 cases with detailed clinical data obtained via PubMed database spanning 1990 to 2022. Clinical and imaging data were collected and pooled together to analyze factors associated with subarachnoid hemorrhage (SAH), myelopathy, and modified Rankin scale (mRS) at presentation. The mean age of the patients was 54.5 ± 13.1 years, with 76.5% of them being male. The most common feeding arteries were V3-medial branches (33.1%), and drainage was frequently through the anterior or posterior spinal vein/perimedullary vein (72.8%). SAH was the most common presentation (49.3%), and an associated aneurysm was identified as a risk factor for SAH (adjusted OR, 7.44; 95%CI, 2.89-19.15). Anterior or posterior spinal vein/perimedullary vein (adjusted OR, 2.78; 95%CI, 1.00-7.72) and male gender (adjusted OR, 3.76; 95%CI, 1.23-11.53) were associated with higher risk for myelopathy. Myelopathy at presentation was an independent risk factor for unfavorable neurological status (adjusted OR per score, 4.73; 95%CI, 1.31-17.12) in untreated CCJ-AVF. The present study identifies risk factors associated with SAH, myelopathy, and unfavorable neurological status at presentation in patients with CCJ-AVF. These findings may help treatment decisions for these complex vascular malformations.

Comparison between 2D TSE and 3D SPACE in the evaluation of craniocervical ligaments.

PURPOSE: To evaluate the MRI findings of the craniocervical junction ligaments and compare the 2D TSE sequence and 3D SPACE sequence on cervical spine MRI. METHODS: Eighty cervical spine MRIs were retrospectively analyzed, including 2D TSE and 3D SPACE sequences. The visibility and morphology of the transverse ligament (TL) and alar ligament (AL) were evaluated by two readers using a five-point grading scale for visibility (1 = not visible, 2 = barely visible, 3 = adequately visible, 4 = good visibility, 5 = excellent visibility) and a four-point grading scale for morphology (0 = homogeneous low SI with normal thickness, 1 = high SI with normal thickness, 2 = reduced thickness, 3 = full-thickness rupture or indistinguishable from surrounding structures). The grades of the two sequences were compared. Reader agreements were measured using the percentage of exact agreement. RESULT: The visibility grade of TL was significantly higher in 3D, indicating better visualization. The morphology grade of TL was significantly lower in the 3D, indicating more normal-appearing ligament. The exact agreements of visibility and morphology grade of TL tended to be higher in 3D. On the other hand, there was no significant difference in visibility grade of AL between the two sequences. The morphological grade of AL was significantly higher in 3D. The agreement of the morphological grade of AL tended to be lower in 3D. CONCLUSION: The utilization of 3D sequences significantly improves the visibility of TL and could potentially reduce false-positive diagnoses of ligament injury.

Far lateral craniotomy for disconnection of vertebral dural arteriovenous fistula: how I do it.

BACKGROUND: Craniocervical junction (CCJ) vascular abnormalities can be challenging to treat because of the surrounding density of critical neurovascular anatomy. Although most dural arteriovenous fistulas (dAVFs) are now treated with endovascular surgery, dAVFs near the CCJ are often better suited for microsurgical obliteration with precise vascular control. METHODS: We describe our microsurgical approach to treating dAVFs at the CCJ. This includes a far-lateral approach with a small incision centered over the transverse process of the atlas and circumferential skeletonization of the vertebral artery in addition to clipping the fistula to limit lesion recurrence. CONCLUSIONS: Definitive microsurgical treatment of CCJ dAVFs can be accomplished using a minimally invasive approach.

Intramedullary feeder aneurysm of a cervical epidural arteriovenous fistula causing myelopathy: a case report and literature review.

While a craniocervical junction (CCJ) epidural arteriovenous fistula (EDAVF) may present with hemorrhagic myelopathy from an associated feeder aneurysm on rare occasions, non-hemorrhagic myelopathy from such an aneurysm remains unreported. A woman in her late sixties presented with cervical myelopathy due to a non-hemorrhagic intramedullary aneurysm associated with CCJ-EDAVF. The intramedullary aneurysm originated from the spinal pial artery supplied by the anterior spinal artery. Direct surgical fistula coagulation and feeder obliteration resulted in the disappearance of the aneurysm and myelopathy improvement. This report illustrates the first case of a non-hemorrhagic intramedullary aneurysm associated with CCJ-EDAVF successfully treated with direct surgery.

Radiographic measurements for the prediction of dysphagia after occipitocervical fusion: a systematic review.

BACKGROUND: Occipitocervical fusion (OCF) is a procedure performed for multiple upper cervical pathologies. A common postprocedural complication of OCF is dysphagia, which has been linked to the narrowing of the pharyngeal space due to fixation in a hyper-flexed angle. Postoperative dysphagia is linked to reduced quality of life, prolonged hospital stay, aspiration pneumonia, and increased mortality. This has led to investigations of the association between sagittal radiographic angles and dysphagia following OCF. METHODS: A systematic review of the literature was performed to explore the current evidence regarding cervical sagittal radiographic measurements and dysphagia following OCF. A search strategy was carried out using the PubMed, Embase, and Web of Science databases from their dates of inception until August 2022. Only original English-language studies were considered. Moreover, studies had to include the correlation between dysphagia and at least one radiographic measurement in the sagittal plane. RESULTS: The search and subsequent selection process yielded eight studies that were included in the final review, totaling 329 patients in whom dysphagia had been assessed and graded. The dysphagia score by Bazaz et al. (Spine 27, 22:2453-2458, 2002) was used most often. The pooled incidence of dysphagia, in the early postoperative period, was estimated at 26.4%. At long-term follow-up (range: 17-72 months), about one-third of patients experienced resolution of symptoms, which resulted in a long-term post-OCF dysphagia incidence of 16.5%. Across the studies included, six different radiographic parameters were used to derive several measures which were repeatedly and significantly associated with the occurrence of dysphagia. CONCLUSIONS: The high incidence of postoperative dysphagia following OCF warrants close monitoring of patients, especially in the short-term postoperative period. These patients may be assessed through standardized tools where the one by Bazaz et al. was the most commonly used. Moreover, there are several radiographic measurements that can be used to predict the occurrence of dysphagia. These findings may serve as a basis for strategies to prevent the occurrence of dysphagia after OCF.

Cervical MRI assessment of traumatic anterior atlanto-occipital membrane complex injuries with evaluation of ancillary findings.

BACKGROUND AND PURPOSE: The purpose of this study was to identify and classify the different types of anterior atlanto-occipital membrane complex injuries on MRI and evaluate for the presence, size, and location of a prevertebral effusion on the preceding CT exams. MATERIALS AND METHODS: Patients who suffered an anterior atlanto-occipital membrane complex injury were identified retrospectively utilizing Nuance mPower software. An anatomic-based description of the location of the anterior atlanto-occipital membrane complex injury was recorded along with any additional osteoligamentous trauma of the craniocervical junction. The preceding cervical CT exams for these patients were reviewed for the presence and location of a prevertebral effusion. RESULTS: Fifty patients were identified with an acute, post-traumatic anterior atlanto-occipital membrane complex injury. Three distinct patterns of anterior atlanto-occipital membrane complex injury were observed. Nineteen patients demonstrated increased STIR signal with disruption of the anterior atlanto-occipital membrane, ten patients demonstrated increased STIR signal with disruption of the anterior atlanto-axial membrane, and twenty-one patients demonstrated increased STIR signal with disruption of both the anterior atlanto-occipital membrane and anterior atlanto-axial membrane. An effusion at the C1-C2 level was present in greater than 90% of patients with anterior atlanto-occipital membrane complex injury. CONCLUSIONS: The presence of a craniocervical prevertebral effusion on CT in trauma patients may raise suspicion for an injury to the anterior atlanto-occipital membrane complex and potentially trigger additional investigation with cervical MRI.

A case of craniocervical junction pial arteriovenous fistula causing postoperative medullary and spinal cord edema.

OBJECTIVES: Pial arteriovenous fistulas (pAVFs) are direct connections between the pial artery and vein without an intervening nidus. We report a rare case of craniocervical junction (CCJ) pAVF causing medullary and spinal cord edema resulting from surgical removal of the varix with remnant shunt after coil embolization. CASE DESCRIPTION: A 16-year-old man presented with subarachnoid hemorrhage. Digital subtraction angiography revealed a CCJ pAVF with multiple fistulas at the 2 varices (varix A and varix B), which was fed by the bilateral lateral spinal arteries and anterior spinal artery (ASA), and drained into the median posterior vermian vein with varix (varix C) and anterior spinal vein (ASV). Varices A and B were embolized using coils, but the shunts remained in varix C. Then, varix C was surgically removed. After this operation, medullary and spinal cord edema occurred. Digital subtraction angiography showed the ASV drainage responsible for edema. Finally, surgical removal of varices A and B was performed. However, arteriovenous shunts, supplied by the ASA and drained into the ASV via the intrinsic vein, were found in the medulla oblongata and coagulated, resulting in disappearance of edema. CONCLUSIONS: Edema was probably caused by concentration of drainage from the arteriovenous shunt in the medulla oblongata into the ASV by surgical removal of varix C acting as another draining route. High flow AVF can induce angiogenesis and secondary arteriovenous shunt. Precise analysis of the angioarchitecture is important to treat such cases without complications.

CT diagnosis of occipital condyle fracture in a dog presented for severe cervical hyperesthesia.

A 9-month-old male entire Doberman Pinscher presented with acute onset of severe cervical hyperesthesia after a fall. Neurological examination revealed a normal gait with low head carriage and severe cervical hyperesthesia. A CT scan of the cervical vertebral column revealed the presence of a comminuted fracture at the dorsomedial aspect of the right occipital condyle and sclerosis of the underlying bone. Medical management was initiated consisting of an external bandage, strict rest, and pain medication. Due to the lack of clinical improvement, the dog was euthanized 2 months after diagnosis. Histopathology of the lesion was compatible with a healing fracture.

Role of endovascular treatment for ruptured aneurysms involving the anterior spinal artery at the craniocervical junction.

Ruptured aneurysms at the craniocervical junction (CCJ) involving the anterior spinal artery (ASA) are rare and consist of heterogenous lesions with variable clinical entities. However, the standard therapeutic strategy for the lesions has not been well-established. Moreover, despite advances in modern neurointervention, reports describing endovascular treatment for this specific lesion have been few. Here, we report three cases of ruptured aneurysms on the pial tributary of the ASA at the CCJ, which were subsequently treated by transarterial glue injection or coil embolization. Endovascular treatment can be a therapeutic option, particularly for these ruptured aneurysms. Either transarterial glue injection or coil embolization can be effective depending on the type of etiology and the surrounding vasculature anatomy.

Craniocervical junction involvement in inflammatory arthritis: a single-center radiologic study.

Background/aim: Craniocervical junction (CCJ) can be involved in inflammatory arthritis. We aimed to define types of CCJ involvement in rheumatoid arthritis (RA), spondyloarthritis (SpA), and psoriatic arthritis (PsA) and compare them with patients without inflammatory arthritides. Materials and methods: In this retrospective analysis, cervical CT or MRIs of patients with RA, SpA, or PsA, taken for any reason between 2010 and 2020, according to ICD-10 codes, were scanned. Demographic data of the patients were recorded. CCJ involvements (atlantoaxial, vertical, or subaxial subluxation, odontoid process involvement) were reevaluated by an experienced radiologist. The control group consisted of consecutive patients without inflammatory arthritis. Results: Exactly 459 patients (204 RA, 200 SpA, and 55 PsA) and 78 patients in the control group were included in the study. CCJ involvement was detected in 101 (49.5%) RA, 53 (26.5%) SpA, 10 (18.2%) PsA, and 4 patients (5.1%) in the control group (p < 0.001). The odontoid process was one of the main targets, especially in RA patients (69 (33.8%)), which was significantly higher than in the SpA, PsA, and control groups. Although vertical subluxation (VS) was numerically higher in the RA and SpA groups compared to the control group, VS-related brainstem compression was relatively uncommon: 6 (2.9%) in RA, 1 (0.5%) in AS, and none in the PsA and control groups. Conclusion: CCJ involvement can often be detected in patients with inflammatory arthritis, especially in RA and SpA patients. The odontoid process is the main target of inflammation.

Endovascular treatment of medullary bridging vein-draining dural arteriovenous fistulas: foramen magnum vs. craniocervical junction lesions.

PURPOSE: Dural arteriovenous fistulas (AVFs) draining to medullary bridging vein (MBV) are located at foramen magnum (FM) and craniocervical junction (CCJ). Such fistulas are rare but pose a challenge to endovascular management. This study was undertaken to assess clinical manifestations, angiographic features, and outcomes of endovascular treatment in patients with MBV dural AVFs. METHODS: A number of our patients (N = 22) were diagnosed with MBV dural AVF and treated by endovascular means. There were 9 FM lesions and 13 CCJ lesions. We reviewed clinical records and imaging studies to define clinical characteristics, vascular anatomic details, and treatment outcomes, comparing FM- and CCJ-level subsets. RESULTS: Subjects ranged from 37 to 74 years of age (mean, 57.7 years) with male predominance (2.7:1). They presented with intracranial hemorrhage (11/22, 50%), myelopathy (8/22, 36%), or nonspecific symptoms (3/22, 14%). In 17 patients (77.3%), the shunts showed complete or near-complete occlusion following endovascular treatment (FM, 100%; CCJ, 61.5%). However, seven patients experienced ischemic events (FM, 11.1%; CCJ, 46.2%) and one patient sustained a hemorrhagic complication. No hemorrhages recurred during follow-up monitoring, and myelopathic symptoms abated. CONCLUSION: MBV dural AVFs are highly aggressive lesions for which proper diagnosis and treatment are of utmost importance. Although transarterial embolization proved highly successful in FM lesions, shunt occlusion was less frequent in the CCJ subset, with greater risk of ischemic complications.

Extracranial prevertebral venous network of the craniocervical junction: CT-digital subtraction venography analysis.

PURPOSE: Although the craniocervical junction has a complex anatomical structure associated with clinical diseases, its ventral venous network has not been well studied. This study aimed to clarify the extracranial ventral venous structure at the craniocervical junction. METHODS: Head computed tomography digital subtraction venography (CT-DSV) images of 273 patients (age 6 months to 93 years) taken at our department were retrospectively analyzed. We analyzed the frequency and anatomical features of the venous channels, as well as their upstream and downstream connections with the surrounding channels at the ventral craniocervical junction, from the level of the hypoglossal canal to the second cervical vertebra. RESULTS: In 54% of the cases, the vein descended from the anterior condylar confluence, running medially along the basioccipital and fusing with its counterpart in the midline at the level of the atlanto-occipital membrane. Furthermore, 24% of this vein was connected caudally to the anterior external vertebral venous plexus. We also identified venous channels, either as a sole vein or venous plexus, on the tip of the odontoid process (10%), which has not been well described previously. The vein around the odontoid process was connected to several veins, including the aforementioned vein anterior to the condyle and the anterior internal vertebral venous plexus. CONCLUSIONS: CT-DSV analysis revealed a detailed venous architecture ventral to the craniocervical junction. Venous structures identified in this study may be involved in diseases in this area.

Minimally invasive lateral occipitocervical fixation: case series and technique description.

PURPOSE: Occipitocervical junction (OCJ) instability is commonly treated with fixation via open posterior approach. The use of intraoperative navigation allows us to perform occipitocervical fixation via minimally invasive approach. We report a series of patients treated with percutaneous occipitocervical fixation, describing the surgical procedure in detail and discussing the technique. METHODS: We prospectively enrolled 8 patients affected by OCJ instability secondary to trauma and rheumatoid arthritis. Traumatic patients were preoperatively evaluated with CT scan and MRI scan if needed. Rheumatoid arthritis group was evaluated with both CT and MR. Patients underwent percutaneous occipitocervical fixation with the assist of intraoperative 3D imaging and navigation. All patients were functionally and radiologically evaluated pre-, at 6 weeks, and at 1 year postoperatively. RESULTS: Percutaneous occipitocervical fixation was successfully performed in all of the patients. 33 screws were placed. 29 (87.88%) were placed without any pedicle breach. In 3 (9.09%) screws we observed a minor; and in 1 (3.03%) screw we observed a major pedicle breach. We did not have any postoperative complications. CONCLUSIONS: Described method of occipitocervical fixation is a minimally invasive method that has a similar outcome to the open technique. It requires the experience in open techniques and the assist of intraoperative 3D imaging and navigation to be performed efficiently.

Foramen magnum decompression for Chiari malformation type I - UK surgical practice.

Background: Symptomatic Chiari 1 malformation (CM1) is a common condition in Neurosurgery. Surgery involves hindbrain decompression and restoration of CSF flow through different surgical approaches. No Class 1 evidence exists to suggest the superiority of any of the surgical techniques.Aims: To investigate current surgical practice for symptomatic CM1 patients in the United Kingdom (UK) and determine the willingness to participate in a randomised controlled trial (RCT) comparing different surgical techniques.Methods: An electronic survey was sent to consultant members of the Society of British Neurological Surgeons and the British Chiari-Syringomyelia Group. The questions covered pre-operative and intra-operative management, presence of equipoise/uncertainty in optimal technique and willingness to participate in an RCT.Results: 98 responses were received. 67% operate on adults. 30% on adult and paediatric patients. There is variation in routine pre-operative use of: ICP monitoring (18%), flexion/extension x-rays (16%), venography (20%) and ophthalmology assessment (26%). 18% of neurosurgeons would not offer foramen magnum decompression when the presenting symptom is only refractory cough/sneeze headache. 15% routinely perform bony decompression alone in adults vs 8% in children. In 68% of adult cases, durotomy is performed routinely (46% of them leave the dura open, 54% perform a type of duroplasty) and 16% routinely resect the cerebellar tonsils. Only 17% leave the dura open in children. The most common indicators for durotomy are syringomyelia and intra-operative ultrasound findings. 61% believe there is equipoise/uncertainty in the optimal strategy for decompression and would be willing to participate in an RCT. Comments also mention the heterogeneity of CM1 and that treatment should be tailored to each patient.Conclusion: There is wide variation in pre- and intra-operative management of CM1 patients in the UK and the majority of neurosurgeons would be willing to participate in an RCT comparing bony decompression alone vs dural opening with/without duroplasty.