Bone union rate was higher with bilateral than unilateral TAS fixation (P less then 0.05). There were no complications regarding screw malposition. Deep wound infection was observed in 1 case in the C-group. CONCLUSIONS O-arm use improved TAS fixation accuracy. Blood loss was equivalent between the groups. O-arm-assisted TAS fixation did not prolong operative time despite the time required for setting and scanning. The O-arm is safe and useful for TAS fixation in atlantoaxial instability. BACKGROUND Primary dedifferentiated liposarcoma of the orbit is a very rare condition. CASE DESCRIPTION A 41-year-old man presented with a history of right ophthalmalgia with eye movement and exophthalmos that had developed two months earlier. Neuroimages revealed a right orbital mass located above the superior rectus muscle. The tumor resection through the right frontal craniotomy was performed. Histopathological findings showed the dedifferentiated liposarcoma. CONCLUSIONS Primary orbital dedifferentiated liposarcomas remain challenging for their diagnosis and standard treatment. Clinicians should keep in mind the possibility of liposarcoma with orbital tumors. OBJECTIVE This study proposes to analyze the sellar floor morphology of patients with pituitary adenoma, and to find a simple yet reliable method to determine the location of bone window opening. METHOD Clinical information of 144 consecutively admitted patients was retrospectively analyzed. Enhanced MR image of the mid-sagittal plane was selected as the reference for classifying the sellar floor. Intra-operative tumor locating, extent of tumor resection, and follow-up results were analyzed for different types of sellar floor. Briefly, the tuberculum sellae, lowest point of the sphenoid sinus, and the lowest point of the sellar floor and three lines related to them were used to classify the sellar floor. This is being refer to as "three points and three line" method. RESULTS Based on its location in the sphenoid sinus, the sellar floor can be classified into four types 12 (8.3%) patients with high sellar, 70 (48.6%) with medium sellar, 30 (20.8%) with low sellar, and 32 (22.8%) with steep sellar. The maximum tumor diameter, maximum sellar floor diameter, and the intercarotid distance were all significantly different between patients with different types of sellar floor (P less then 0.001). For all patients, quick intra-operative locating of the sellar floor opening was achieved. 104 (72.2%) patients had total tumor resection, 28(19.40%) had subtotal tumor resection, and four (2.8%) had partial tumor resection. 20 (13.9%) patients experienced cerebrospinal fluid (CSF) leak, and there was no significant difference in CSF leak rate between groups. CONCLUSIONS Pre-surgical classification and locating of the sellar floor is critical for understanding and assessing the transsphenoidal approach. Different types of sellar floor appeared in the surgery with different morphological features, the "three points and three lines" method helps the surgeon to pre-determine location of sellar floor opening and to shorten surgical time. OBJECTIVE Our aim was to define a treatment strategy for patients with severe cervical deformity(sCD). METHODS Surgical patients with sCD were isolated based on preop radiographic parameters. We sent 10 sCD cases to 7 surgeons to find consensus on approach, upper instrumented vertebrae (UIV), lower instrumented vertebrae (LIV), osteotomy. We performed a descriptive analysis and created a treatment algorithm from the survey then analyzed a database of surgical patients to find the frequency of following our algorithm. RESULTS We found consensus on 7 cases for posterior approach due to cervicothoracic deformity and of 15 patients within our sCD database that had cervicothoracic deformity, 13/15 had posterior approach. There was consensus on 2 cases for antero-posterior approach due to local kyphosis and of 25 patients that had local kyphosis, 18/25 had an anterior approach. In 4 cases there was consensus of UIV of C2 and of 35 cases that had posterior fusion >6 levels, 20/35 had a UIV of C2. In 3 cases there was consensus of a LIV below a previously fused spine. Of 36 patients that had a fusion of T6 or higher, 34 had a LIV below the previous UIV. In 6 cases there was consensus against an osteotomy due to cervical spine flexibility and 9/12 patients that had an osteotomy in our database had no flexibility on dynamic radiographs.  https://www.selleckchem.com/products/zanubrutini-bgb-3111.html  CONCLUSION We outline here an algorithm for deciding approach, UIV, LIV and whether to do an osteotomy for patients with sCD based on consensus recommendations amongst spine surgeons. BACKGROUND Departments of neurosurgery in the United States have had a long history of hosting international visitors for the advancement of their neurosurgical education. The goal of the present study was to determine if a geographic profile existed of international visitors for education purposes, both students and graduates, to the United States through the anecdotal experience of one department to explore the reach and worth of hosting such opportunities. METHODS Administrative records were retrospectively reviewed for international visitors over the preceding 10 years, 2009-2019, were surveyed at one institution. Visitors were grouped as either medical students or graduates, visiting for either clinical or research purposes. Geographic trends were compared using Chi-squared test. RESULTS 128 visitors from 33 countries were identified during the study period. The most common home countries were Italy (10%), China (9%), and India (7%). The cohort involved 62 (48%) students and 66 (52%) graduates, and 59 (46%) and 69 (54%) visited for clinical and research purposes respectively. The geographic distribution of student versus graduate visitors was statistically significant by region (P less then 0.01). However, the geographic distribution of clinical versus research visitors was not statistically different by region (P=0.62). CONCLUSION There appears to be international appeal worldwide to participate in neurosurgical education in the United States. At our institution, every geographic region was represented in our most recent decade of experience. International visitor profiles appear to be associated with particular geographic patterns depending on their status as either a medical student or graduate.