omic malformations. The authors aimed to fill this knowledge gap offering guidelines and recommendations with a global outreach and applicability. Materials and Methods. A group of expert spine surgeons and World Federation of Neurosurgical Societies Spine Committee members, most of which were extensively published on CVJ anomalies in the past, reviewed the literature issued from 2011 to 2022. Following a common methodology, based on the Delphi method, the authors analyzed the strength of the literature and voted on statements concerning the diagnosis and management of these conditions. Results. A total of 8 papers were produced: (1) CM diagnosis, classifications, natural history, and conservative management, (2) CM: indications for surgery and surgical options, (3) pediatric CM, (4) syndromic atlantoaxial instability, (5) os odontoideum, (6) BI: diagnosis, radiology, and classification, (7) surgical treatment of BI, and (8) BI with associated CM. Conclusions. Despite grey zones on the

gement, but the ongoing opioid epidemic led physicians to look for alternatives. GPs are used for various indications, and chronic use for any indication may lead to a higher risk of adverse events, especially when combined with opioids. Materials and Methods. Patients aged 18 years and older who underwent posterior fusion of the lumbosacral spine and ≥1-year follow-up were included. Patients were grouped according to their preoperative chronic GP and opioid usage as GP and opioid nonuser (−/−), GP user opioid nonuser (+/−), GP nonuser and opioid user (−/+), and GP and opioid user (+/+). Results. A total of 563 patients (M/F%=41/59, mean age 61.1 y) were included. Two hundred eighty (49%) patients were in the group −/−, while 110 (19%) were in +/−, 78 (15%) were in −/+, and 95 (17%) were in +/+. For ODI, back pain and leg pain, +/+ had the worst outcomes at all time points, while −/− had the best. Chronic GP users (+/−) showed back pain improvement similar to the −/− group; however, th

and (iii) whether syndromic patients can safely participate in sports activities. Summary Background Data. Syndromic abnormalities of CVJ may lead to potentially devastating neurological deficits. As of now, there is no international consensus on how to handle syndromic patients with atlanto-axial instability. Methods. International spine specialists of the WFNS spine committee reviewed statements from articles published between 2012 and 2022 to reach an expert agreement. Each statement was voted for on a Likert scale. The Delphi method was used to achieve a high level of validity. Results. Because of the high incidence of craniovertebral instability in Down’s patients, close neurological and radiologic screening is advocated. In Morquio’s patients older than 5 years, it is recommended to perform an annual neurological examination and imaging studies to detect cervical stenosis or instability. For atlanto-axial instability (AAI), the recommended screening should include cervical spine

e suboptimal in predicting adverse events (AEs). Materials and Methods. Adults undergoing complex ASD surgery were included. Estimated blood loss (EBL) was extracted for investigation, and estimated blood volume loss (EBVL) was calculated by dividing EBL by the preoperative blood volume utilizing Nadler’s formula. “Least Absolute Shrinkage and Selection Operator” regression was performed to identify 5 variables from demographic and perioperative parameters. Logistic regression was subsequently performed to generate a receiver operating characteristic curve and estimate an optimal threshold for EBL and EBVL. Finally, the proportion of patients with AE was plotted against EBL and EBVL to confirm the identified thresholds. Results. In total, 552 patients were included with a mean age of 60.7 ± 15.1 years, 68% females, mean Charlson Comorbidity Index was 1.0 ± 1.6, and 22% experienced AEs. Least Absolute Shrinkage and Selection Operator regression identified the American Society of Anesthe

rowing body of knowledge on CM, there are diverse and sometimes contradicting perspectives about surgical indications and procedures in both pediatric and adult populations. Methods. The authors reviewed the literature on CM published from 2011 to 2022. Two consensus conferences were organized by WFNS Spine Committee. The first one was held in Sao Paulo, Brazil on August 2022, and the second one was held in Porto, Portugal on December 2022. Using the Delphi method, a panel of expert spine surgeons and members of the WFNS Spine Committee examined the strength of the literature, elaborated and voted statements about the surgical management of CM. Results. We present 11 consensus statements on the surgical management of CM. Surgery is recommended for patients who have symptoms or if an MRI shows progression in asymptomatic patients. In pediatrics, osteoligamentous decompression only is indicated, whereas adults can have foramen magnum decompression with duroplasty, which is usually suffic