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Introduction: Harlequin syndrome (HS) is an uncommon condition affecting the sympathetic nervous system, characterized by asymmetrical flushing and sweating impairment, which can affect the face or half of the body. When the dysfunction results from external factors like damage or compression, it's referred to as Harlequin Sign. Our objective was to document an exceedingly rare presentation of Harlequin Sign caused by a T3-T4 paravertebral mass and conduct the first systematic literature review on this subject., Methods: We conducted a systematic review of English-language studies using PubMed, Scopus, and Embase databases. We excluded abstracts, posters, congenital and idiopathic Harlequin Syndrome cases, as well as iatrogenic and secondary Harlequin Sign cases related to pathologies other than upper thoracic lesions., Results: We employed the PRISMA protocol and reviewed 1,538 papers, identifying 8 single case reports describing the Harlequin sign resulting from upper thoracic paravertebral lesions. The mean age of the patients was 41.25 years, with 6 (75 %) being female. The average time from onset to presentation was 8 months, and all patients (100 %) exhibited hemifacial flushing, while 4 (50 %) also had hemifacial anhidrosis. Stress or exercise exacerbated these symptoms in 50 % of cases. Additionally, 3 patients (37.5 %) presented with associated Horner Syndrome. The most commonly used diagnostic tool was a CT scan (50 %), revealing an average tumor diameter of 3.95 cm, with 50 % of cases located at T2-T3. Diagnosis indicated 57 % of cases as schwannomas and 29 % as lung adenocarcinoma (Superior Sulcus). Unfortunately, surgical treatment resolved symptoms in only 25 % of patients., Conclusions: Hemifacial or hemibody autonomic symptoms should raise concern for paraspinal lesions in the thoracic spine. In addition to the first comprehensive review on this topic, we present a rare case of a T3/4 paraspinal schwannoma causing Harlequin Syndrome successfully managed with neurosurgical intervention., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Background: Accurate identification of pain generators in the context of low back and spine-related pain is crucial for effective treatment. This review aims to evaluate the potential usefulness of single photon emission computed tomography with computed tomography (SPECT/CT) as an imaging modality in guiding clinical decision-making., Methods: A broad scoping literature review was conducted to identify relevant studies evaluating the use of SPECT/CT in patients with spine-related pain. Studies were reviewed for their methodology and results., Results: SPECT/CT appears to have advantages over traditional modalities, such as magnetic resonance imaging and CT, in certain clinical scenarios. It may offer additional information to clinicians and improve the specificity of diagnosis. However, further studies are needed to fully assess its diagnostic accuracy and clinical utility., Conclusions: SPECT/CT is a promising imaging modality in the evaluation of low back pain, particularly in cases where magnetic resonance imaging and CT are inconclusive or equivocal. However, the current level of evidence is limited, and additional research is needed to determine its overall clinical relevance., Clinical Relevance: SPECT/CT may have a significant impact on clinical decision-making, particularly in cases in which traditional imaging modalities fail to provide a clear diagnosis. Its ability to improve specificity could lead to more targeted and effective treatment for patients with spinal pathology., Competing Interests: Declaration of Conflicting Interests : The authors report no conflicts of interest in this work., (This manuscript is generously published free of charge by ISASS, the International Society for the Advancement of Spine Surgery. Copyright © 2024 ISASS. To see more or order reprints or permissions, see http://ijssurgery.com.)

Background: Delayed cerebrospinal fluid (CSF) leaks are a known complication following intradural spinal tumor surgery. The placement of subfascial drains in these patients undergoing requisite intradural surgery is controversial. Here, we demonstrated that placing a subfascial drain on partial suction for 48 h, with early ambulation, proved to be safe and effective in preventing early/delayed recurrent CSF fistulas., Methods: Medical records of 17 patients undergoing surgery for intradural spinal tumors over a 30-month were reviewed. All patients underwent intradural tumor resection followed by primary dural closure, placement of Gelfoam in a non-compressive fashion, application of fibrin sealant, and utilization of a subfascial drain placed on partial suction for 48 h postoperatively. Patients are mobilized the morning following surgery. We tracked the incidence of postoperative recurrent CSF leaks, over drainage, infection, wound dehiscence, pseudo meningocele formation, and the reoperation rate., Results: For the 17 patients, our programmed average utilization of subfascial drains was 48 h. Moreover, the average drain output was 165 mL. Over the 1-year follow-up period, no patient developed a recurrent early/ delayed CSF leak, there were no wound complications, nor need for revision surgery., Conclusion: Utilizing subfascial drains on partial suction following the resection of intradural spinal tumors with primary dural closure proved to be safe and effective., Competing Interests: There are no conflicts of interest, (Copyright: © 2024 Surgical Neurology International.)

Objective: Selecting C2 versus C3 or C4 (i.e., C3/C4) as the rostral anchoring level in long-segment cervical fusions is a common clinical conundrum. The data regarding proximal failure in long constructs of the cervical spine is scarce. The objective of this study was to systematically review the published literature and perform a meta-analysis of the incidence for proximal adjacent-segment disease (ASD) in the context of long cervical fusions and cervicothoracic fusions ending in C2 versus those ending in the subaxial spine (C3 or C4)., Methods: Using the PRISMA guidelines, the authors performed a search of the PubMed/MEDLINE, Embase/Ovid, and Cochrane Central databases to identify all full-text articles in the English-language literature with the following inclusion criteria: 1) studies including patients with the upper instrumented vertebra (UIV) at C2 versus C3/C4; 2) patients undergoing ≥ 3-level posterior cervical fusion; and 3) indication for surgery of degenerative disc disease, cervical spondylotic myelopathy, or cervical deformity. Studies that were not published in the English language, case reports, review articles, letters to the editor, and meeting abstracts were excluded. A meta-analysis was conducted using a fixed-effects model when I2 values were below 70%. Conversely, when I2 values were equal to or greater than 70%, a random-effects model was used. A funnel plot was used to assess the presence of publication bias., Results: Seven studies consisting of 1215 patients were included in the meta-analysis. There were 403 (32.8%) patients in the C2 UIV group and 812 (67.2%) patients in the C3/C4 UIV group. When the 7 studies were analyzed, the overall rate of reoperation was comparable between the C2 (9.2%) and C3/C4 (9.4%) UIV groups (p = 0.93) but the rate of surgical ASD due to proximal pathology was 1.2% and 3%, respectively (OR 0.36, 95% CI 0.15-0.86; p = 0.02). When comparing between groups, no statistical difference was found regarding the rate of reoperation due to distal pathology or surgical infection., Conclusions: Long-segment cervical or cervicothoracic constructs that anchor into C2 may have similar complication rates but lower revision rates for proximal ASD than constructs that anchor into the subaxial spine.

Background: Data exist of the benefits of antifibrinolytics such as tranexamic acid (TXA) in general spine surgery. However, there are limited data of its use in oncological spine patients., Methods: A systematic review was conducted using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. PubMed, Cochrane, OVID, and Embase databases were searched. Search terms: " tranexamic acid" , " aprotinin ," " aminocaproic acid ," " spine surgery ," " spine tumors ," and " spine oncology ." Included studies were full text publications written in English with patients treated with either agent or who had surgery for oncological spine disease (OSD)., Results: Seven hundred results were reviewed form the different databases, seven were selected. A total of 408 patients underwent spine surgery for OSD and received antifibrinolytics. There was a male predominance (55.2%) and mean age ranged from 43 to 62 years. The most common tumor operated was metastatic renal cancer, followed by breast and lung. Most studies administered TXA as a bolus followed by an infusion during surgery. Median blood loss was of 667 mL (253.3-1480 mL). Patients with TXA required 1-2 units less of transfusion and had 56-63 mL less of postoperative drainage versus no TXA. The median incidence of deep venous thrombosis (DVT) was 2.95% (0-7.9%) and for pulmonary embolism (PE) was 4.25% (0-14.3%). The use of TXA reduced intraoperative blood loss, transfusions and reduced postoperative surgical drainage output compared to no TXA use in patients with OSD., Conclusion: In this review, we found that TXA may diminish intraoperative blood loss, the need for transfusion and postoperative drainage from surgical drains when used in OSD without major increase in rates of DVT or PE., Competing Interests: There are no conflicts of interest., (Copyright: © 2022 Surgical Neurology International.)

Purpose: To determine whether the published literature supports the current practice of utilizing antibiotics postoperatively in spine surgery., Methods: A systematic review from PubMed and Cochrane Central Register of Controlled trials databases was performed. Search terms used: "Antibiotic Prophylaxis"[Mesh], antibiotic*, antibacterial*, "Spine"[Mesh], "Surgical Procedures, Operative"[Mesh]. Only comparative, clinical studies were included. Those studies with surgical site infection (SSI) criteria that were not similar to the CDC definition were excluded. A meta-analysis for overall SSI was performed. A subgroup analysis was also performed to analyze the outcomes specifically on instrumented groups of patients. A random-effects model was used to calculate risk ratios (RR). Forest plots were used to display RR and 95% confidence intervals (CI)., Results: Thirteen studies were included (four Randomized-Controlled Trials, three prospective cohorts, and six retrospective). Three different perioperative strategies were used in the selected studies: Group 1: preoperative antibiotic administration (PreopAbx) versus PreopAbx and any type of postoperative antibiotic administration (Pre + postopAbx) (n = 6 studies; 7849 patients); Group 2: Pre + postopAbx ≤ 24 h versus Pre + postopAbx > 24 h (n = 6; 1982); and Group 3: Pre + postopAbx ≤ 48 h versus. Pre + postopAbx ≤ 72 h (n = 1; 502). The meta-analysis performed on Groups 1 and 2 did not show significant effects (RR = 1.27, 95% CI = 0.77, 2.09, and RR = 0.97, 95% CI = 0.64, 1.46, respectively)., Conclusion: A meta-analysis and comprehensive review of the literature show that the routine use of postoperative antibiotics in spine surgery may not be effective in preventing surgical site infections., (© 2022. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Background: Multidisciplinary spine conferences (MSCs) are a strategy for discussing diagnostic and treatment aspects of patient care. Although they are becoming more common in hospitals, literature investigating how they impact patient care and outcomes is scarce. The aim of this study is to examine the impact of MSCs on surgical management and outcomes in elective spine surgical care., Methods: A systematic review of the literature was conducted to evaluate the impact of MSCs on patient management and outcomes. PubMed and Cochrane databases were searched using combinations and variations of search terms "Spine Conferences," "Multidisciplinary," and "Spine Team.", Results: The literature search yielded 435 articles, of which 120 were selected for full-text review. Four articles (N = 529 patients) were included. Surgical plans were discussed in 211 patients. The decision was altered to conservative treatment in 70 patients (33.17%) and a different surgical strategy in 34 patients (16.11%). The differences were significant in 2 studies (P < 0.05). A 51% reduction in 30-day complications rates was observed when MSC was implemented in patients with adult complex scoliosis. Other spinal disorders showed a 30-day complication rate between 0% and 14% after MSC., Conclusions: To our knowledge, this is the first systematic review of outcomes of MSCs in elective spine surgery and it confirms that MSCs impact management plan and outcomes. Consistent MSCs that include surgeons and nonsurgeons have the potential to enhance communication between specialists, standardize treatments, improve patient care, and encourage teamwork. More analysis is warranted to determine if patient outcomes are improved with these measures., (Copyright © 2022 Elsevier Inc. All rights reserved.)

Background: Burst fractures of the fifth lumbar vertebra (L5) are rare injuries and typically occur because of high-energy axial compressive load. Their unique anatomy and biomechanical characteristics distinguish them from other lumbar spine injuries. To the best of our knowledge, the treatment strategies for L5 burst fractures have not been thoroughly described. The aims of this case series and systematic review were to highlight the treatment strategies and outcomes of the L5 burst fractures., Methods: We performed a retrospective case series of 8 patients treated for burst L5 fractures in our institution between 2005 and 2020. Additionally, a systematic review via PubMed and Cochrane Library databases according to PRISMA guidelines was performed to review L5 burst fractures treatment strategies. Only Articles in English with full text available were included. The references of the selected studies were checked to find all possible related articles. Treatment strategies were conservative, posterior segmental instrumentation and fixation (PSIF), PSIF with anterior corpectomy (AC), and PSIF with posterior corpectomy (PC). Outcomes measures included neurological status, radiological regional alignment, and complications., Results: A total of 1449 publications were found, and 29 articles were finally selected for analysis. Of those, 15 were retrospective case reports, and 14 were retrospective case series. One hundred and sixty-nine patients were found in the review. The author's eight cases were added to the found in the literature for a methodological quality assessment. There were 52 (29%) patients managed non-operative, and 125 (71%) underwent surgery. One-hundred-two patients were neurologically intact, of whom 46 were managed non-operative. Canal compromise in intact patients ranged between 20 and 90%. Posterior segmental fixation and instrumentation with decompression was the preferred surgical strategy in patients with neurological deficits. Patients with combined anterior column restoration and anterior approach showed vertebral height and lordosis restoration. A 79% of the operative treated group reported neurological improvement. Patients with pre-operative neurological deficit managed non-operative reported the highest rate of complications (33.3%)., Conclusion: In the setting of L5 burst fractures, neurological injuries have a promising prognosis after surgery and are not correlated with the degree of canal stenosis. The compromise of the L5 vertebra affects the sagittal balance and its restoration can be achieved with an anterior corpectomy. Nonoperative management can be considered in cases of reasonable alignment, and no neurologic deficit., (Copyright © 2022 Elsevier Ltd. All rights reserved.)

Objective: Distance learning has become increasingly important to expand access to neurosurgical spine education. However, emerging online spine education initiatives have largely focused on residents, fellows, and surgeons in practice. We aimed to assess the utility of online neurosurgical spine education for medical students regarding career interests, knowledge, and technical skills., Methods: A survey assessing the demographics and effects of virtual spine education programming on the interests, knowledge, and technical skills was sent to attendees of several virtual spine lectures. The ratings were quantified using 7-point Likert scales., Results: A total of 36 responses were obtained, of which 15 (41.7%) were from first- or second-year medical students and 18 (50.0%) were from international students. Most respondents were interested in neurosurgery (n = 30; 80.3%), with smaller numbers interested in radiology (n = 3; 8.3%) and orthopedic surgery (n = 2; 5.6%). The rating of utility ranged from 5.69 ± 1.14 to 6.50 ± 0.81 for career, 5.83 ± 0.94 to 6.14 ± 0.80 for knowledge, and 5.22 ± 1.31 to 5.83 ± 1.06 for clinical skills. Of the 36 respondents, 26 (72.2%) preferred virtual neurosurgical spine education via intermixed lectures and interactive sessions. The most common themes regarding the utility of virtual spine education were radiology by 18 (50.0%), anatomy by 12 (33.3%), and case-based teaching by 8 (22.2%) respondents., Conclusions: Virtual distance learning for neurosurgical spine education is beneficial for students by enabling career exploration and learning content and clinical skills. Although the overall benefit was lowest for clinical skills, virtual programming could serve as an adjunct to traditional in-person exposure. Distance learning could also provide an avenue to reduce disparities in medical student neurosurgical spine education locally and globally., (Copyright © 2021 Elsevier Inc. All rights reserved.)

Background: Dropped head syndrome (DHS) is uncommon and involves severe weakness of neck-extensor muscles resulting in a progressive reducible cervical kyphosis. The first-line management consists of medical treatment targeted at diagnosing underlying pathologies. However, the surgical management of DHS has not been well studied., Methods: Here, we systematically reviewed the PubMed and Cochrane databases for DHS using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. All relevant articles up to March 31, 2022, were analyzed. The patient had to be ≥18 years with DHS and had to have undergone surgery with outcomes data available. Outcomes measurements included neurological status, rate of failure (RF), horizontal gaze, and complications., Results: A total of 22 articles selected for this study identified 54 patients who averaged 68.9 years of age. Cervical arthrodesis without thoracic extension was performed in seven patients with a RF of 71%. Cervicothoracic arthrodesis was performed in 46 patients with an RF of 13%. The most chosen upper level of fusion was C2 in 63% of cases, and the occiput was included only in 13% of patients. All patients neurologically stabilized or improved, while 75% of undergoing anterior procedures exhibited postoperative dysphagia and/or airway-related complications., Conclusion: The early surgery for patients with DHS who demonstrate neurological compromise or progressive deformity is safe and effective and leads to excellent outcomes., Competing Interests: There are no conflicts of interest., (Copyright: © 2022 Surgical Neurology International.)

Introduction: Patients with Ehlers-Danlos syndrome (EDS) are at elevated risk for soft tissue complications when undergoing decompression with or without fusion of the craniocervical junction. We have previously shown that muscle flap closure can decrease reoperative rates. This study investigated whether myofascial flap closure improved clinical outcomes after simple or complex surgery of the craniocervical junction in EDS patients specifically., Methods: We performed a retrospective chart review of EDS patients who had undergone surgery for Chiari malformation at the Weill Cornell Medical Center between 2013 and 2020. Postoperative complications were recorded, including infection, wound dehiscence, seroma, hematoma, hardware removal, cerebrospinal fluid (CSF) leak, reoperation, and pseudomeningocele. Patients were stratified by type of closure and type of surgery. Fisher exact test was used for statistical comparison., Results: Between 2013 and 2020, 62 EDS patients who had surgery of the cervicocranial junction were reviewed. Of these, 31 patients had complex surgery with myofascial flap closure and 22 had simple surgery with traditional closure. The mean age at the time of surgery was 21.3 years. There were no significant differences in wound complications or reoperation rates between the simple surgery and complex surgery groups. In addition, there were no significant differences in complications between complex surgery with flap closure and simple surgery with traditional closure. Our CSF cutaneous fistula rate was 0%, considerably lower than rates reported in the literature, and, in one case, a patient developed a postoperative pseudomeningocele secondary to a dural leak, but the myofascial flap closure prevented its progression., Conclusions: Patients with EDS undergoing surgery of the cervicocranial junction may benefit from myofascial flap closure. Flap closure reduced complications after complex surgery of the craniocervical junction to the level of simple surgery. Our CSF leak rate was exceptionally low and only one patient experienced pseudomeningocele. Myofascial flaps are safe to perform in the EDS cohort and prevented CSF cutaneous fistula formation., Competing Interests: Conflicts of interest and source of funding: none declared., (Copyright © 2022 Wolters Kluwer Health, Inc. All rights reserved.)

Background: Intracranial hypotension (IH) manifests with orthostatic headaches secondary to cerebrospinal fluid (CSF) hypovolemia. Common iatrogenic etiologies include lumbar punctures and spinal surgery. Although much rarer, structural defects such as osteophytes and herniated calcified discs can violate dural integrity, resulting in CSF leak., Observations: The authors reported the case of a 32-year-old woman who presented with progressively worsening orthostatic headaches. During an extensive examination, magnetic resonance imaging of her thoracic spine revealed a cervicothoracic ventral epidural collection of CSF, prompting a dynamic computed tomography myelogram, which not only helped to confirm severe cerebral hypotension but also suggested underlying pathology of a dorsally projecting disc osteophyte complex at T2-3. Conservative and medical management failed to alleviate symptoms, and a permanent surgical cure was eventually sought. The patient underwent a transdural thoracic discectomy with dural repair, which resulted in resolution of her symptoms., Lessons: Clear guidelines regarding the management strategy of IH secondary to disc osteophyte complexes are yet to be established. A thorough literature review noted only 24 reported cases between 1998 and 2019, in which 13 patients received surgery. There is a 46% symptom resolution rate with conservative management, lower than that for iatrogenic etiologies. For patients in whom conservative management failed, surgical intervention proved effective in resolving symptoms, with a success rate of 92.3%.

Background: Spinal metastases are present in approximately 20% of patients with cancer, giving a risk for neurologic dysfunction and instability. In already frail patients, surgeons strive to improve quality of life. Our goal was to review a 10-year trend in the surgical management of spinal metastases., Methods: A scoping review was performed systematically using PubMed to assess trends in surgical treatment for spinal metastases. The search terms used were: metastas∗, "neoplasm metastasis"[Mesh], "Spine"[Mesh], spine, spinal, "vertebral column," "vertebral body," laser, robot, radiofrequency, screws, fixation, "separation surgery," corpectomy, vertebrectomy, spondylectomy, vertebroplasty, kyphoplasty, surgery, "open surgery," "mini open surgery," "minimally invasive surgery," endoscopy, thoracoscopy, corpectom∗, vertebrectom∗, spondylectom∗, "en bloc," and MIS. The variables of interest were neurologic improvement, tumor recurrence, reoperation, and overall survival., Results: A total of 2132 articles were found within the primary query. Fifty-six studies were selected for final review. The results were organized into main surgical practices: decompression, mechanical stabilization, and pain management. For separation surgery, clinical outcomes were overall 1-year survival, 40.7%-78.4%; recurrence rate, 4.3%-22%; reoperation, 5%; and complications, 5.4%-14%. For corpectomy, clinical outcomes were overall 1-year survival, 30%-92%; reoperation, 1.1%-50%; and recurrence rate, of 1.1%-28%. Complications and reoperations with spinal instrumentation were 0%-13.6% and 0%-15%, respectively. Cement augmentation achieved pain reduction rates of 56%-100%, neurologic improvement/stability 84%-100%, and complication rates 6%-56%. Laser achieved local tumor control rate of 71%-82% at 1 year follow-up, reoperation rate of 15%-31%, and complication rate of 5%-26%., Conclusions: Minimally invasive techniques for decompression and stabilization seem to be the preferred method to surgically treat metastatic spine disease, with good outcomes. More research with high level of evidence is required to support the long-term outcomes of these approaches., (Copyright © 2021 Elsevier Inc. All rights reserved.)

Objective: There is no consensus regarding the best surgical strategy at the lumbosacral junction (LSJ) in long constructs for adult spinal deformity (ASD). The use of interbody fusion (IF) has been advocated to increase fusion rates, with additional pelvic fixation (PF) typically recommended. The actual benefit of IF even when extending to the pelvis, however, has not been vigorously analyzed. The goal of this work was to better understand the role of IF, specifically with respect to arthrodesis, when extending long constructs to the ilium., Methods: A systematic review of the PubMed and Cochrane databases was performed to identify the relevant studies in English, addressing the management of LSJ in long constructs (defined as ≥ 5 levels) in ASD. The search terms used were as follows: "Lumbosacral Junction," "Long Constructs," "Long Fusion to the Sacrum," "Sacropelvic Fixation," "Interbody Fusion," and "Iliac Screw." The authors excluded technical notes, case reports, literature reviews, and cadaveric studies; pediatric populations; pathologies different from ASD; studies not using conventional techniques; and studies focused only on alignment of different levels., Results: The PRISMA protocol was used. The authors found 12 retrospective clinical studies with a total of 1216 patients who were sorted into 3 different categories: group 1, using PF or not (n = 6); group 2, using PF with or without IF (n = 5); and group 3, from 1 study comparing anterior lumbar interbody fusion versus transforaminal lumbar interbody fusion. Five studies in group 1 and 4 in group 2 had pseudarthrosis rate as primary outcome and were selected for a quantitative analysis. Forest plots were used to display the risk ratio, and funnel plots were used to look at the risk of publication bias. The summary risk ratios were 0.36 (0.23-0.57, p < 0.001) and 1.03 (0.54-1.96, p = 0.94) for the PF and IF, respectively; there is a protective effect of overall pseudarthrosis for using PF in long constructs for ASD surgeries, but not for using IF., Conclusions: The long-held contention that L5/S1 IF is always advantageous in long-construct deformity surgery is not supported by the current literature. Based on the findings from this systematic review and meta-analysis, PF with or without additional L5/S1 interbody grafting demonstrates similar overall construct pseudarthrosis rates. The added risk and costs associated with IF, therefore, should be more closely considered on a case-by-case basis.

Coronavirus disease 2019 (COVID-19) has disrupted lives and indelibly impacted the practice of medicine since emerging as a pandemic in March 2020. For neurosurgery departments throughout the United States, the pandemic has created unique challenges across subspecialties in devising methods of triage, workflow, and operating room safety. Located in New York City, at the early epicenter of the COVID-19 crisis, the Weill Cornell Medicine Department of Neurological Surgery was disrupted and challenged in many ways, requiring adaptations in clinical operations, workforce management, research, and education. Through our department's collective experience, we offer a glimpse at how our faculty and administrators overcame obstacles, and transformed in the process, at the height of the COVID-19 pandemic., (Copyright © 2020 Elsevier Inc. All rights reserved.)

Background: Fascia lata remains a popular and robust graft to repair osteodural defects in endoscopic neurosurgery. Classically, this graft is obtained via a large incision in the thigh that is prone to pain and muscle herniation after surgery., Objective: To present a novel technique for harvesting fat and fascia lata graft and reapproximating the edges via an endoscopic approach through the thigh using an "outside-in" technique to prevent muscle herniation., Methods: Initially our technique was performed in cadavers and includes the following: small 2 cm incision in the lateral thigh to accommodate the endoscope, use of blunt dissection and endoscopic tools to obtain the graft, and reapproximation of the fascia via an outside-in technique using conventional sutures with endoscopic visualization to retrieve the sutures beneath the skin and tie them. We then applied the technique to a patient undergoing transsphenoidal tumor resection., Results: This technique was trialed in 3 cadaver specimens (6 limbs) and was used successfully in a patient with excellent cosmetic results seen in follow-up., Conclusion: Endoscopic retrieval of fascia lata is feasible via a very small incision. Reapproximation of the cut fascial edges to minimize muscle herniation can quickly and easily be performed with an outside-in technique detailed here. Additional case series may help to solidify the endoscopic retrieval as a preferred technique for fascia lata graft., (Copyright © 2020 by the Congress of Neurological Surgeons.)

Background: Advances in surgical technology and adjuvant therapies along with an aging and increasingly morbid U.S. population have led to an increase in complex spine surgery. With this increase comes an elevated risk of complications, including those related to the surgical wound, with some studies demonstrating wound complication incidences approaching 45 percent. The authors hypothesize that immediate muscle flap closure improves outcomes in high-risk patients., Methods: Three hundred one consecutive index cases of spinal wound closure using local muscle flaps performed by the senior author at a single institution between 2006 and 2018 were reviewed. The primary outcome was major wound complication (reoperation and/or readmission because of surgical-site infection, late infection, dehiscence, seroma, or hematoma). Logistic regression analysis was performed to identify predictors of this endpoint., Results: Major wound complications occurred in 6.6 percent of patients (reoperation, 3.6 percent; readmission, 3.0 percent), with a 6.0 percent infection rate and five cases requiring instrumentation removal because of infection. Risk factors identified included radiotherapy (OR, 5.9; p = 0.004), age 65 years or older (OR, 2.8; p = 0.046), and prior spine surgery (OR, 4.3; p = 0.027). The incidence of major wound complication increased dramatically with each additional risk factor. Mean drain dwell duration was 21.1 ± 10.0 days and not associated with major wound complications, including infection (OR, 1.04; p = 0.112)., Conclusions: Immediate local muscle flap closure following complex spine surgery on high-risk patients is associated with an acceptable rate of wound complications and, as these data demonstrate, is safe and effective. Consideration should be given to immediate muscle flap closure in appropriately selected patients., Clinical Question/level of Evidence: Risk, III.

Background: The coronavirus identified in 2019 (COVID-19) pandemic effectively ended all major spine educational conferences in the first half of 2020. In response, the authors formed a "virtual" case-based conference series directed at delivering spine education to health care providers around the world. We herein share the technical logistics, early participant feedback, and future direction of this initiative., Methods: The Virtual Global Spine Conference (VGSC) was created in April 2020 by a multiinstitutional team of spinal neurosurgeons and a neuroradiologist. Biweekly virtual meetings were established wherein invited national and international spine care providers would deliver case-based presentations on spine and spine surgery-related conditions via teleconferencing. Promotion was coordinated through social media platforms such as Twitter., Results: VGSC recruited more than 1000 surgeons, trainees, and other specialists, with 50-100 new registrants per week thereafter. An early survey to the participants, with 168 responders, indicated that 92% viewed the content as highly valuable to their practice and 94% would continue participating post COVID-19. Participants from the United States (29%), Middle East (16%), and Europe (12%) comprised the majority of the audience. Approximately 52% were neurosurgeons, 18% orthopedic surgeons, and 6% neuroradiologists. A majority of participants were physicians (55%) and residents/fellows (21%)., Conclusions: The early success of the VGSC reflects a strong interest in spine education despite the COVID-19 pandemic and social distancing guidelines. There is widespread opinion, backed by our own survey results, that many clinicians and trainees want to see "virtual" education continue post COVID-19., (Copyright © 2020 Elsevier Inc. All rights reserved.)

Introduction: The benefits of decompression and fusion for patients with craniocervical instability are well described. However, complications such as wound breakdown and need for unplanned reoperation frequently occur. Recent studies have shown advantages of myofascial flap closure for various spinal procedures. This study investigated whether closure with myofascial flaps after surgery for craniocervical instability decreases complications with further subgroup analysis of patients with Ehlers-Danlos syndrome (EDS)., Methods: A retrospective review of patients presenting to Weill Cornell Medical Center from 2010 to 2017 for craniocervical surgery was performed. All patients who underwent craniocervical surgery, regardless of plastic surgical involvement, were included in the study. Data including patient demographics, comorbidities, EDS diagnosis, surgical history, complications, and follow-up information were collected and analyzed., Results: Data from 57 patients were analyzed. Eighteen patients (31.6%) had craniocervical surgery without myofascial flap closure, whereas 39 (68.4%) had surgery with flap closure. In the nonflap group, 9 patients required unplanned reoperation (50%). In the flap group, there were 5 patients requiring unplanned reoperation (15%). For reoperation, the Fisher exact test 2-tailed P value is 0.0096. Of those 57 patients, 24 had EDS: 5 (20.8%) had no flap closure, whereas 19 (79.2%) had flap closure. In the no-flap group, 3 patients required unplanned reoperation (60%). In the flap group, 5 patients required unplanned reoperation (21%). For reoperation, the Fisher exact test 2-tailed P value is 0.1265., Conclusions: Patients undergoing surgery for craniocervical instability may benefit from myofascial flap closure even if they have EDS. Mobilizing well-vascularized tissue can decrease rates of reoperation.

Objective: Patients who undergo decompression surgery for Chiari malformation frequently require occipitocervical fixation. This is typically performed with occipital plates, which may cause intracranial injuries due to multiple fixation points. We undertook this study to assess the feasibility of occipital condyle (OC) screw placement as an alternative method of occipitocervical fixation in this patient population., Methods: Using a cadaveric model with navigational assistance, we performed the complete surgical procedure for occipitocervical fixation with OC screws. We then performed a morphometric analysis using measurements from computed tomography scans of 49 patients (32 adult, 17 pediatric) who had undergone occipitocervical fusion with instrumentation following decompression surgery for Chiari malformation. Bilateral morphometric data were analyzed for the adult and pediatric subgroups separately, as well as for the overall group., Results: The surgical procedure was successfully performed in the cadaveric model, demonstrating the feasibility of the proposed method. Ninety-eight OCs were studied in the morphometric analysis, and 80 (81.6%) met our eligibility criteria for OC screw placement. However, in 14.1% of adult OCs and 26.5% of pediatric OCs studied, placement of condylar screws would have been challenging or unsafe, according to our criteria., Conclusions: Our findings suggest that OC screws provide a useful option for occipitocervical fixation in a substantial proportion of patients with Chiari malformation. However, rigorous preoperative analysis would be essential to identify appropriate candidates for this technique and exclude those in whom it should not be attempted. Additional study is warranted., (Copyright © 2020 Elsevier Inc. All rights reserved.)

Arachnoid web of the spine (AWS) is a rare and subtle lesion that can have severe neurological consequences. Patients typically present with progressive myelopathic symptoms and have no more than a slight indentation of spinal cord on imaging, commonly referred to as the "scalpel sign." A unique feature associated with this lesion is the extent of (and sometimes the rapidity of) the recovery that occurs following treatment. In this operative video, we highlight the treatment of a 32-yr-old male with a history of lumbar spondylosis, who, over a 2 wk period, developed progressive spasticity and weakness of the entire left lower extremity and left foot numbness. Magnetic resonance imaging revealed a T4-T5 "scalpel sign" and spinal cord compression on computed topography myelogram, which was subsequently taken to the operating theater. The major steps in this video include the following: A) a summary of the patient's presentation and preoperative imaging, B) the technical steps in the surgical lysis of the AWS, and C) his postoperative course. The patient tolerated the procedure well, demonstrating a rapid improvement in symptoms postoperative day 1. At the time of most recent follow-up (4 mo), the patient remains neurologically intact with a full return to his neurologic baseline. Surgical lysis of AWS demonstrated to be a curative procedure with rapid neurological recovery, showing no signs of recurrence or regression. Consent was given by the patient for the use of deidentified images and the intraoperative video for educational purposes at the time consent was obtained for the surgical procedure, in accordance with our institution's policy., (Copyright © 2019 by the Congress of Neurological Surgeons.)

Compared to the thoracolumbar spine, the literature on cervical spine alignment is scarce. While a consistent number of articles have been published, few analyze the ideal surgical approaches for each type of deformity and the optimal amount of correction to achieve. This paper provides a comprehensive review of current literature on cervical spinal deformities (with or without myelopathy) and their surgical management; it is our goal to create a framework on which surgical planning can be made. A general assessment of the actually utilized parameters and correlation between the cervical and thoracolumbar spine alignment is presented. Moreover, we provide an analysis of cervical surgical approaches (anterior, posterior, or combined), techniques (laminoplasty, laminectomy and fusion, anterior cervical discectomy and fusion, corpectomy), and their indications. Finally, a complete evaluation of outcomes and postoperative health-related quality of life (HRQOL) measures based on questionnaires (NDI, VAS, SF-36, mJOA) is discussed. Several prospective studies would be useful in understanding how cervical alignment may be important in the assessment and treatment of cervical deformities with or without myelopathy. In particular, future works should concentrate on the correlation between cervical alignment parameters, disability scores, and myelopathy outcomes. We propose, via comprehensive literature review, a guide of practical key points on surgical techniques, cervical alignment, and symptom improvement goals surgeons should aim to achieve for each patient., (Copyright © 2019. Published by Elsevier B.V.)

Context: Multiple angles of the craniocervical junction (CCJ) are associated with pathological conditions and surgical outcomes, including the clivo-axial angle (CXA), clival slope (CS), and sagittal axis (XS). However, there are varying normative ranges reported and a paucity of data analyzing the effects of imaging modality, age, and gender on these angles., Setting and Design: A retrospective review of computed tomographic (CT) and magnetic resonance imaging (MRI) scans in fifty adults without CCJ pathology from 2014 to 2019., Methods: Age, gender, indication, and hours between scans were recorded. Two-blinded observers measured all angles. Analysis between angles from the same patient was performed using the Wilcoxon signed-rank test. Multivariable linear regression was used to test for associations between average angles and age or gender., Results: Average age and time between scans were 41.3 and 14.3 h, respectively, with 94% performed due to trauma. On CT, average CXA, CS, and XS were 162.1°, 118.4°, and 81.3°, respectively. On MRI, they were 159.8°, 117.2°, 85.3°, respectively. There were statistically significant differences between CXA and XS ( P < 0.01) based on imaging modality. On CT, there was a significant increase in XS by 1.93°° and decrease in CS by 1.88°° and on MRI, there was a significant increase in CXA by 1.93°° and decrease in CS by 2.75°° corresponding with a 10-year advancement of age. Gender did not have an effect., Conclusion: There are significant differences in angular measurements of the CCJ between CT and MRI from the same patient, as well as changes in normative values based on age., Competing Interests: There are no conflicts of interest., (Copyright: © 2020 Journal of Craniovertebral Junction and Spine.)

Osteoporosis is a skeletal condition characterized by low bone mineral density (BMD). Common in older patients undergoing spinal fusion, it is a significant risk factor for instrumentation failure and related complications. The objective of this review is to articulate clear suggestions for screening and medical/surgical management strategies in patients with osteoporosis. A thorough review of the literature was conducted using PubMed. Varied search terms were applied to yield published manuscripts on osteoporosis and spine surgery. Biomechanical studies and studies conducted in animal models were excluded. Screening should be considered in those that present with multiple risk factors for low BMD. Dual-energy x-ray absorptiometry (DEXA) remains the gold standard, but Hounsfield Units (HU) have emerged as a powerful complement to DEXA. While both bisphosphonates and teriparatide have been investigated in the perioperative setting and have a positive impact on outcomes, teriparatide maintains an advantage in comparative studies. Surgical treatment need not be postponed. Standard surgical modifications such as using multiple points of fixation, varied fixation equipment, anterior/posterior instrumentation, and modified screw design/trajectories should all be considered. However, recent clinical studies focus on cement augmentation and expandable pedicle screws. All have been shown to improve bone-screw interface strength, but extravasation remains a risk of cement augmentation, and hydroxyapatite cement (HAC), while an emerging alternative to polymethyl methacrylate (PMMA), is not as well investigated in the setting of osteoporosis. Furthermore, research on expandable pedicle screws is limited. To conclude, optimizing spine surgery outcomes in the osteoporotic patient is possible with a thorough preoperative workup, medical management, and a tailoring of the surgical technique. This is especially important when performing complex spinal instrumentation., (Copyright © 2019. Published by Elsevier B.V.)

Objective: An arachnoid web of the spine (AWS) is a rare and oftentimes challenging lesion to diagnose, given its subtle radiographic findings. However, when left untreated, this lesion can have devastating effects on a patient's neurological function. To date, only limited case reports and series have been published on this topic. In this study, the authors sought to better describe this lesion, performing a systematic literature review and including 2 cases from their institution's experience., Methods: A systematic literature search was performed in September 2018 that queried Ovid MEDLINE (1946-2018), PubMed (1946-2018), Wiley Cochrane Library: Central Register of Controlled Trials (1898-2018), and Thompson Reuters Web of Science: Citation Index (1900-2018), per PRISMA guidelines. Inclusion criteria specified all studies and case reports of patients with an AWS in which any relevant surgery types were considered and applied. Studies on arachnoid cysts and nonhuman populations, and those that did not report patient treatments or outcomes were excluded from the focus review., Results: A total of 19 records and 2 patients treated by the senior authors were included in the systematic review, providing a total of 43 patients with AWS. The mean age was 52 years (range 28-77 years), and the majority of patients were male (72%, 31/43). A syrinx was present in 67% (29/43) of the cases. All AWSs were located in the thoracic spine, and all but 2 (95%) were located dorsally (1 ventrally and 1 circumferentially). Weakness was the most frequently reported symptom (67%, 29/43), followed by numbness and/or sensory loss (65%, 28/43). Symptoms predominated in the lower extremities (81%, 35/43). It was found that nearly half (47%, 20/43) of patients had been experiencing symptoms for 1 year or longer before surgical intervention was performed, and 35% (15/43) of reports stated that symptoms were progressive in nature. The most commonly used surgical technique was a laminectomy with intradural excision of the arachnoid web (86%, 36/42). Following surgery, 91% (39/43) of patients had reported improvement in their neurological symptoms. The mean follow-up was 9.2 months (range 0-51 months)., Conclusions: AWS of the spine can be a debilitating disease of the spine with no more than an indentation of the spinal cord found on advanced imaging studies. The authors found this lesion to be reported in twice as many males than females, to be associated with a syrinx more than two-thirds of the time, and to only have been reported in the thoracic spine; over 90% of patients experienced improvement in their neurological function following surgery.

Purpose: Occipitocervical instrumentation is infrequently required for stabilization of the axial and subaxial cervical spine in very young children. However, when it is necessary, unique surgical considerations arise in children when compared with similar procedures in adults., Methods: The authors reviewed literature describing fusion of the occipitocervical junction (OCJ) in toddlers and share their experience with eight cases of young children (age less than or equal to 4 years) receiving occiput to axial or subaxial spine instrumentation and fixation. Diagnoses and indications included severe or secondary Chiari malformation, skeletal dysplastic syndromes, Klippel-Feil syndrome, Pierre Robin syndrome, Gordon syndrome, hemivertebra and atlantal occipitalization, basilar impression, and iatrogenic causes., Results: All patients underwent occipital bone to cervical spine instrumentation and fixation at different levels. Constructs extended from the occiput to C2 and T1 utilizing various permutations of titanium rods, autologous rib autografts, Mersilene sutures, and combinations of autografts with bone matrix materials. All patients were placed in rigid cervical bracing or halo fixation postoperatively. No postoperative neurological deficits or intraoperative vascular injuries occurred., Conclusion: Instrumented arthrodesis can be a treatment option in very young children to address the non-traumatic craniocervical instability while reducing the need for prolonged external halo vest immobilization. Factors affecting fusion are addressed with respect to preoperative, intraoperative, and postoperative decision-making that may be unique to the toddler population.

OBJECTIVEThere are limited data regarding the implications of revision posterior surgery in the setting of previous cervical arthroplasty (CA). The purpose of this study was to analyze segmental biomechanics in human cadaveric specimens with and without CA, in the context of graded posterior resection.METHODSFourteen human cadaveric cervical spines (C3-T1 or C2-7) were divided into arthroplasty (ProDisc-C, n = 7) and control (intact disc, n = 7) groups. Both groups underwent sequential posterior element resections: unilateral foraminotomy, laminoplasty, and finally laminectomy. Specimens were studied sequentially in two different loading apparatuses during the induction of flexion-extension, lateral bending, and axial rotation.RESULTSRange of motion (ROM) after artificial disc insertion was reduced relative to that in the control group during axial rotation and lateral bending (13% and 28%, respectively; p < 0.05) but was similar during flexion and extension. With sequential resections, ROM increased by a similar magnitude following foraminotomy and laminoplasty in both groups. Laminectomy had a much greater effect: mean (aggregate) ROM during flexion-extension, lateral bending, and axial rotation was increased by a magnitude of 52% following laminectomy in the setting of CA, compared to an 8% increase without arthroplasty. In particular, laminectomy in the setting of CA introduced significant instability in flexion-extension, characterized by a 90% increase in ROM from laminoplasty to laminectomy, compared to a 16% increase in ROM from laminoplasty to laminectomy without arthroplasty (p < 0.05).CONCLUSIONSForaminotomy and laminoplasty did not result in significant instability in the setting of CA, compared to controls. Laminectomy alone, however, resulted in a significant change in biomechanics, allowing for significantly increased flexion and extension. Laminectomy alone should be used with caution in the setting of previous CA.

Purpose: To provide the reader with a comprehensive but concise understanding of congenital scoliosis METHODS: We have undertaken to summarize available literature on the pathophysiology, epidemiology, and management of congenital scoliosis., Results: Congenital scoliosis represents 10% of pediatric spine deformity and is a developmental error in segmentation, formation, or a combination of both leading to curvature of the spine. Treatment options are complicated by balancing growth potential with curve severity. Often associated abnormalities of cardiac, genitourinary, or intraspinal systems are concurrent and should be evaluated as part of the diagnostic work-up. Management balances the risk of progression, growth potential, lung development/function, and associated risks. Surgical treatment options involve growth-permitting systems or fusions., Conclusion: Congenital scoliosis is a complex spinal problem associated with many other anomalous findings. Treatment options are diverse but enable optimization of management and care of these children.

Objectives: Patients with neoplastic disease involving the spine either from primary or metastatic disease present a unique challenge given these patients' frequent poor nutritional status at the time of surgery, the delivery of early post-operative chemotherapy or radiation, and placement of large amounts of hardware and avascular bone graft into a wound bed that is atrophic, previously operated or irradiated. As a result, wound morbidity has traditionally been high in this cohort of patients. Herein we review the outcomes of patients at our institution who underwent local muscle flap closure following spinal tumor extirpation., Patients and Methods: Between 2007 and 2017, 55 patients with oncologic disease of the spine underwent 60 spine surgeries and concomitant muscle flap reconstruction. Charts were retrospectively reviewed for diagnosis and indications for surgery, as well as risk factors for poor wound healing including diabetes, steroid use, body mass index (BMI), history of pre-operative chemo and or radiation therapy, preoperative albumin and hemoglobin levels. Outcomes were postoperative wound related complications including surgical site infection, wound dehiscence and/or need for reoperation., Results: 60 reconstructions were included in 55 patients. Median follow up was 253 days. Paraspinous muscle flaps were used in all cases. There were 2 major complications (3.3%) related to wound infections which required reoperation and 10 minor wound complications (16.7%), of which 9 were subcutaneous seromas aspirated in the office, that did not require return to the operating room. Median postoperative stay in the hospital was 10 days. Closed suction drains placed at the end of the reconstruction were removed at a median of 17.5 days. Regression analysis found patient BMI to be a significant risk predictor for wound related post-operative complications., Conclusions: Post-operative wound specific complications that required return to the operating room were uncommon despite the high-risk profile of this subset of patients. These data indicate that muscle flap closure should be routinely practiced in this high-risk cohort of patients., (Copyright © 2018 Elsevier B.V. All rights reserved.)

MINI: We assessed 90-day readmission and evaluated risk factors associated with readmission after lumbar spinal fusion surgery in New York State. The overall 90-day readmission rate was 24.8%. Age, sex, race, insurance, procedure, number of operated spinal levels, health service area, and comorbidities are major risk factors for 90-day readmission., Study Design: Retrospective cohort study., Objective: The aim of this study was to assess 90-day readmission and evaluate risk factors associated with readmission after lumbar fusion in New York State., Summary of Background Data: Readmission is becoming an important metric for quality and efficiency of health care. Readmission and its predictors following spine surgery are overall poorly understood and limited evidence is available specifically in lumbar fusion., Methods: The New York Statewide Planning and Research Cooperative System (SPARCS) was utilized to capture patients undergoing lumbar fusion from 2005 to 2014. Temporal trend of 90-day readmission was assessed using Cochran-Armitage test. Logistic regression was used to examine predictors associated with 90-day readmission., Results: There were 86,869 patients included in this cohort study. The overall 90-day readmission rate was 24.8%. On a multivariable analysis model, age (odds ratio [OR] comparing ≥75 versus <35 years: 1.24, 95% confidence interval [CI]: 1.13-1.35), sex (OR female to male: 1.19, 95% CI: 1.15-1.23), race (OR African-American to white: 1.60, 95% CI: 1.52-1.69), insurance (OR Medicaid to Medicare: 1.42, 95% CI: 1.33-1.53), procedure (OR comparing thoracolumbar fusion, combined [International Classification of Disease, Ninth Revision, ICD-9: 81.04] to posterior lumbar interbody fusion/transforaminal lumbar spinal fusion [ICD-9: 81.08]: 2.10, 95% CI: 1.49-2.97), number of operated spinal levels (OR comparing four to eight vertebrae to two to three vertebrae: 2.39, 95% CI: 2.07-2.77), health service area ([HSA]; OR comparing Finger Lakes to New York-Pennsylvania border: 0.67, 95% CI: 0.61-0.73), and comorbidity, i.e., coronary artery disease (OR: 1.26, 95% CI: 1.19-1.33) were significantly associated with 90-day readmission. Directions of the odds ratios for these factors were consistent after stratification by procedure type., Conclusion: Age, sex, race, insurance, procedure, number of operated spinal levels, HSA, and comorbidities are major risk factors for 90-day readmission. Our study allows risk calculation to determine high-risk patients before undergoing spinal fusion surgery to prevent early readmission, improve quality of care, and reduce health care expenditures., Level of Evidence: 3.

Adolescent idiopathic scoliosis (AIS) is a 3D spinal deformity affecting children between the ages of 11 and 18, without an identifiable etiology. The authors here reviewed the available literature to provide spine surgeons with a summary and update on current management options. Smaller thoracic and thoracolumbar curves can be managed conservatively with observation or bracing, but corrective surgery may be indicated for rapidly growing or larger curves. The authors summarize the atypical features to look for in patients who may warrant further investigation with MRI during diagnosis and review the fundamental principles of the surgical management of AIS. Patients with AIS can be managed very well with a combination of conservative and surgical options. Outcomes for these children are excellent with sustained longer-term results.

Study Design: Review of the articles., Objective: The objective of this study was to review all articles related to spinal instability to determine a consensus statement for a contemporary, practical definition applicable to thoracolumbar injuries., Summary of Background Data: Traumatic fractures of the thoracolumbar spine are common. These injuries can result in neurological deficits, disability, deformity, pain, and represent a great economic burden to society. The determination of spinal instability is an important task for spine surgeons, as treatment strategies rely heavily on this assessment. However, a clinically applicable definition of spinal stability remains elusive., Materials and Methods: A review of the Medline database between 1930 and 2014 was performed limited to papers in English. Spinal instability, thoracolumbar, and spinal stability were used as search terms. Case reports were excluded. We reviewed listed references from pertinent search results and located relevant manuscripts from these lists as well., Results: The search produced a total of 694 published articles. Twenty-five articles were eligible after abstract screening and underwent full review. A definition for spinal instability was described in only 4 of them. Definitions were primarily based on biomechanical and classification studies. No definitive parameters were outlined to define stability., Conclusions: Thirty-six years after White and Panjabi's original definition of instability, and many classification schemes later, there remains no practical and meaningful definition for spinal instability in thoracolumbar trauma. Surgeon expertise and experience remains an important factor in stability determination. We propose that, at an initial assessment, a distinction should be made between immediate and delayed instability. This designation should better guide surgeons in decision making and patient counseling.