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BACKGROUND CONTEXT: The enhanced recovery after surgery (ERAS) protocol is a multimodal approach which has been shown to facilitate recovery of physiological function, and reduce early post-operative pain, complications, and length of stay (LOS) in open 1–2 level TLIF. The benefit of ERAS in specifically frail patients undergoing TLIF has not been demonstrated. Frailty is clinically defined as a syndrome of physiological decline that can predispose patients undergoing surgery to poor outcomes. PURPOSE: This study primarily evaluated the benefit of an ERAS protocol in frail patients undergoing 1- or 2-level open TLIF compared to frail patients without ERAS. Secondarily, we assessed whether outcomes in frail patients with ERAS approximated those seen in nonfrail patients with ERAS. STUDY DESIGN: Retrospective consecutive patient cohort with controls propensity-matched for age, body mass index, sex, and smoking status. PATIENT SAMPLE: Consecutive patients that underwent 1- or 2-level open TLIF for degenerative disease from August, 2015 to July, 2021 by a single surgeon. ERAS was implemented in December 2018. OUTCOME MEASURES: Primary outcome measure was return of postoperative physiological function defined as the summation of first day to ambulate, first day to bowel movement, and first day to void. Additional outcome measures included LOS, daily average pain scores, opioid use, discharge disposition, 30-day readmission rate, and reoperation. METHODS: A retrospective analysis of frail patients > 65 years of age undergoing 1–2 level open TLIF post-ERAS were compared to propensity matched frail pre-ERAS patients. Frailty was assessed using the Fried phenotype classification (score > 1). Patient demographics, LOS, first-day-to-ambulate (A1), first-day-to-bowel movement (B1), first-day-to-void (V1) were collected. Return of physiological function was defined as A1+B1+V1. Primary analysis was a comparison of frail patients pre-ERAS versus post-ERAS to determine effect of ERAS on return of physiologic function with frailty. Secondary analysis was a comparison of post-ERAS frail versus post-ERAS nonfrail patients to determine if return of physiologic function in frail patients with ERAS approximates that of nonfrail patients. RESULTS: In the primary analysis, 32 frail patients were included with mean age ± standard deviation of 72.8±4.4 years, mean BMI 28.8±5.5, 65.6% were male, 15 pre-ERAS and 17 post-ERAS. Patient characteristics were similar between groups. After ERAS implementation, return of physiological function improved by a mean 3.2 days overall (post-ERAS 3.4 vs. pre-ERAS 6.7 days) (p

BACKGROUND: The enhanced recovery after surgery (ERAS) protocol is a multidisciplinary, multimodal approach which has been shown to facilitate recovery of physiological function, and reduce postoperative pain, complication rates, and length of stay without adversely affecting readmission rates. Design and implementation of ERAS protocols in the recent spine surgery literature has primarily focused on patients undergoing minimally invasive lumbar surgery. However, conventional open transforaminal lumbar interbody fusion (TLIF) remains a common procedure and to date there are no studies assessing an ERAS protocol in this patient population. PURPOSE: This study presents a single surgeon experience implementing an ERAS protocol in patients undergoing 1- or 2-level open TLIF. STUDY DESIGN/SETTING: Retrospective consecutive patient cohort with controls propensity-matched for age, body mass index, sex, and smoking status. PATIENT SAMPLE: Consecutive patients that underwent 1- or 2-level open TLIF for degenerative disease from 12/2018 – 02/2021 and controls from 12/2011–12/2017 by a single surgeon. ERAS was implemented in December 2018. OUTCOME MEASURES: Primary: length of stay; Secondary: first day to ambulate, first day to bowel movement, first day to void, daily average and maximum pain scores, opioid use, discharge disposition, 30-day readmission rate, and re-operations. METHODS: Demographic, perioperative, clinical, radiographic data were collected. Multivariate mixed-linear regression models were developed for length of stay, physiological function, pain scales, and opiate use. RESULTS: There were 114 patients included with 57 in each cohort. After propensity matching, patient characteristics were similar between groups. Operative time decreased significantly after institution of ERAS (170±44 vs. 141±37 minutes, p

Laminectomy with instrumented fusion (LF) has demonstrated better prevention of ossification of posterior longitudinal ligament (OPLL) growth compared to laminoplasty (LP). There remains uncertainty, however, as to which surgical approach is more beneficial with respect to clinical outcomes and complications. We retrospectively reviewed 273 cervical OPLL patients of more than 3 levels, from the two institutions’ databases, who underwent LF or LP between January 1998 and January 2016. Each 273 patient (85 with LF, 188 with LP) was assessed for postoperative neurologic and radiologic outcomes, complications and reoperations. The mean length of follow-up was 40.11 months. There were baseline differences between cohorts. Overall, postoperative JOA recovery rate at last follow up was significantly better in the LP group with similar improvement in visual analog neck score. Postoperative C2-7 Cobb angle was decreased compared to baseline for both LF and LP cohorts, but there was no significant difference between groups. Complications occurred in 19 (22.35%) LF patients, and 11 (5.85%) LP patients, with higher incidence of C5 palsy and instrumentation failure in the LF group. Four LF patients (4.71%) and five LP patients (2.66%) underwent reoperation during the follow up period.

Background Opioid use disorders in the United States have rapidly increased, yet little is known about the relationship between preoperative opioid duration and dose and patient outcomes after spine surgery. Likewise, the utility of preoperative opioid weaning is poorly understood. Objective The purpose of this evidence-based clinical practice guideline is to determine if duration and dose of preoperative opioids or preoperative opioid weaning is associated with patient-reported outcomes or adverse events after elective spine surgery for degenerative conditions. Methods A systematic review of the literature was performed using the National Library of Medicine/PubMed database and Embase for studies relevant to opioid use among adult patients undergoing spine surgery. Clinical studies evaluating preoperative duration, dose, and opioid weaning and outcomes were selected for review. Results A total of 41 of 845 studies met the inclusion criteria and none were Level I evidence. The use of any opioids before surgery was associated with longer postoperative opioid use, and longer duration of opioid use was associated with worse outcomes, such as higher complications, longer length of stay, higher costs, and increased utilization of resources. There is insufficient evidence to support the efficacy of opioid weaning on postoperative opioid use, improving outcome, or reducing adverse events after spine surgery. Conclusion This evidence-based clinical guideline provides Grade B recommendations that preoperative opioid use and longer duration of preoperative opioid use are associated with chronic postoperative opioid use and worse outcome after spine surgery. Insufficient evidence supports the efficacy of an opioid wean before spine surgery (Grade I).The full guidelines can be accessed at https://www.cns.org/guidelines/browse-guidelines-detail/1-preoperative-opioid-evaluation.

Preoperative malnutrition has been implicated in adverse events after elective surgery, potentially impacting patient outcomes.As a potentially modifiable risk factor, we sought to determine which assessments of nutritional status were associated with specific adverse events after spine surgery. In addition, we explored if a preoperative nutritional improvement intervention may be beneficial in lowering the rates of these adverse events.The literature search yielded 115 abstracts relevant to the PICO (patient/population, intervention, comparison, and outcomes) questions included in this chapter. The task force selected 105 articles for full text review, and 13 met criteria for inclusion in this systematic review.Malnutrition, assessed preoperatively by a serum albumin3.5 g/dL or a serum prealbumin20 mg/dL, is associated with a higher rate of surgical site infections (SSIs), other wound complications, nonunions, hospital readmissions, and other medical complications after spine surgery. A multimodal nutrition management protocol decreases albumin and electrolyte deficiencies in patients with normal preoperative nutritional status. It also improves overall complication rates but does not specifically impact SSIs.It is recommended to assess nutritional status using either serum albumin or prealbumin preoperatively in patients undergoing spine surgery.The full guidelines can be accessed at https://www.cns.org/guidelines/browse-guidelines-detail/4-preoperative-nutritional-assessment.

BACKGROUND Osteoporosis is a metabolic bone disease that commonly affects the elderly. Degenerative spinal disease that may require surgical intervention is also prevalent in this susceptible population. If undiagnosed or untreated before spine surgery, osteoporosis may result in an increased risk of postoperative adverse events. Nontreatment of osteoporosis preoperatively may be related to a poor understanding of bone physiology, a lack of standardized treatment algorithms, limited cost-effective interventions, and reluctance by spine surgeons to be the primary provider of osteoporosis management. OBJECTIVE The objective of this evidence-based review is to develop guidelines for the preoperative assessment and treatment of osteoporosis in patients undergoing spine surgery. METHODS A systematic review of the literature was performed using the National Library of Medicine/PubMed database and Embase for studies relevant to preoperative diagnostic studies that predict increased risk of osteoporosis-related postoperative adverse events and whether the preoperative treatment of low bone mineral density (BMD) in patients with osteoporosis improves outcome. RESULTS Out of 281 studies, 17 met the inclusion criteria and were included for systematic review. The task force affirmed a Grade B recommendation that preoperative osteoporosis testing with a dual-energy X-ray absorptiometry scan (T-score < -2.5), a computed tomography scan (Hounsfield units

Degenerative spine disease increases in prevalence and may become debilitating as people age. Complex spine surgery may offer relief but becomes riskier with age. Efforts to lessen the physiological impact of surgery through minimally invasive techniques and enhanced recovery programs mitigate risk only after the decision for surgery. Frailty assessments outperform traditional tools of perioperative risk stratification. The extent of frailty predicts complications after spine surgery such as reoperation for infection and 30-day mortality, as well as elements of social cost such as hospital length of stay and discharge to an advanced care facility. Symptoms of spine disease overlap with phenotypic markers of frailty; therefore, different frailty assessment tools may perform differently in patients with degenerative spine disease. Beyond frailty, however, cognitive decline and psychosocial isolation may interact with frailty and affect achievable surgical outcomes. Prehabilitation, which has reduced perioperative risk in colorectal and cardiac surgery, may benefit potential complex spine surgery patients. Typical prehabilitation includes physical exercise, nutrition supplementation, and behavioral measures that may offer symptomatic relief even in the absence of surgery. Nonetheless, the data on the efficacy of prehabilitation for spine surgery remains sparse and barriers to prehabilitation are poorly defined. This narrative review concludes that a frailty assessment-potentially supplemented by an assessment of cognition and psychosocial resources-should be part of shared decision-making for patients considering complex spine surgery. Such an assessment may suffice to prompt interventions that form a prehabilitation program. Formal prehabilitation programs will require further study to better define their place in complex spine care.

BACKGROUND There are no current recommendations for preoperative pulmonary evaluation and management of patients undergoing elective spine surgery. OBJECTIVE The aim of this guideline is to determine preoperative risk factors for perioperative and postoperative pulmonary adverse events and to determine the optimal preoperative evaluation and management of at-risk patients. METHODS A systematic review of the literature was performed using the National Library of Medicine PubMed database and the Cochrane Library for studies relevant to postoperative pulmonary adverse events in patients undergoing spine surgery. Clinical studies evaluating preoperative patient risk factors and preoperative diagnostic and treatment interventions were selected for review. RESULTS The literature search yielded 152 abstracts relevant to the PICO (patient/population, intervention, comparison, and outcomes) questions included in this chapter. The task force selected 65 articles for full-text review, and 24 were selected for inclusion in this systematic review. Twenty-three articles addressed preoperative patient risk factors. One article addressed preoperative diagnostic studies of pulmonary function. There were no studies meeting the inclusion criteria for preoperative pulmonary treatment. CONCLUSION There is substantial evidence for multiple preoperative patient factors that predict an increased risk of a postoperative pulmonary adverse event. Individuals with these risk factors (functional dependence, advanced age [≥65 yr], chronic obstructive pulmonary disease, congestive heart failure, weight loss, and obstructive sleep apnea) who are undergoing spine surgery should be counseled regarding the potential increased risk of a perioperative and postoperative pulmonary adverse events. There is insufficient evidence to support any specific preoperative diagnostic test for predicting the risk of postoperative pulmonary adverse events or any treatment intervention that reduces risk. It is suggested, however, to consider appropriate preoperative pulmonary diagnostic testing and treatment to address active pulmonary symptoms of existing or suspected disease.The full guidelines can be accessed at https://www.cns.org/guidelines/browse-guidelines-detail/5-preoperative-pulmonary-evaluation-optimization.

Osteoporosis is a metabolic bone disease that commonly affects the elderly. Degenerative spinal disease that may require surgical intervention is also prevalent in this susceptible population. If undiagnosed or untreated before spine surgery, osteoporosis may result in an increased risk of postoperative adverse events. Nontreatment of osteoporosis preoperatively may be related to a poor understanding of bone physiology, a lack of standardized treatment algorithms, limited cost-effective interventions, and reluctance by spine surgeons to be the primary provider of osteoporosis management.The objective of this evidence-based review is to develop guidelines for the preoperative assessment and treatment of osteoporosis in patients undergoing spine surgery.A systematic review of the literature was performed using the National Library of Medicine/PubMed database and Embase for studies relevant to preoperative diagnostic studies that predict increased risk of osteoporosis-related postoperative adverse events and whether the preoperative treatment of low bone mineral density (BMD) in patients with osteoporosis improves outcome.Out of 281 studies, 17 met the inclusion criteria and were included for systematic review. The task force affirmed a Grade B recommendation that preoperative osteoporosis testing with a dual-energy X-ray absorptiometry scan (T-score-2.5), a computed tomography scan (Hounsfield units97.9), and serum vitamin D3 level (20 ng/mL) predict an increased risk of osteoporosis-related adverse events after spine surgery. The task force determined a Grade B recommendation that preoperative osteoporosis treatment with teriparatide increases BMD, induces earlier and more robust fusion, and may improve select patient outcomes. There is insufficient evidence regarding preoperative treatment with bisphosphonates alone and postoperative outcome.This evidence-based clinical guideline provides a recommendation that patients with suspected osteoporosis undergo preoperative assessment and be appropriately counseled about the risk of postoperative adverse events if osteoporosis is confirmed. In addition, preoperative optimization of BMD with select treatments improves certain patient outcomes.The full guidelines can be accessed at https://www.cns.org/guidelines/browse-guidelines-detail/3-preoperative-osteoporosis-assessment.

Cervical kyphotic deformity can be a debilitating condition with symptoms ranging from mechanical neck pain, radiculopathy, and myelopathy to impaired swallowing and horizontal gaze. Surgical correction of cervical kyphosis has the potential to halt progression of neurological and clinical deterioration and even restore function. There are various operative approaches and deformity correction techniques. Choosing the optimal strategy is predicated on a fundamental understanding of spine biomechanics. Preoperative characterization of cervical malalignment, assessment of deformity rigidity, and defining postoperative clinical and radiographic objectives are paramount to formulating a surgical plan that balances clinical benefit with morbidity. This review of cervical deformity treatment provides an overview of the biomechanics of cervical kyphosis, radiographic classification, algorithm-based management, surgical techniques, and current surgical outcome studies.

Starting in the 1960s, ossification of the posterior longitudinal ligament (OPLL) became more commonly diagnosed in Japan. The disease is characterized by a gradual increase in calcification of the posterior longitudinal ligament with the eventual sequelae of cervical canal stenosis and myelopathy. Surgical interventions to relieve stenosis and neurologic symptoms are performed to decompress the cervical canal. Studies demonstrate continued ossification of the OPLL in both nonsurgical and surgically treated patients. In this review, the authors evaluate the epidemiology, pathophysiology, and literature regarding disease progression in OPLL after cervical fusion.

OBJECTIVE The purpose of this retrospective multicenter study was to compare prognostic factors for neurological recovery in patients undergoing surgery for cervical ossification of the posterior longitudinal ligament (OPLL) based on their presenting mild, moderate, or severe myelopathy. METHODS The study included 372 consecutive patients with OPLL who underwent surgery for cervical myelopathy between 2006 and 2016 in East Asian countries with a high OPLL prevalence. Baseline and postoperative clinical outcomes were assessed using the Japanese Orthopaedic Association (JOA) myelopathy score and recovery ratio. Radiographic assessment included occupying ratio, cervical range of motion, and sagittal alignment parameters. Patient myelopathy was classified as mild, moderate, or severe based on the preoperative JOA score. Linear and multivariate regression analyses were performed to identify patient and surgical factors associated with neurological recovery stratified by baseline myelopathy severity. RESULTS The mean follow-up period was 45.4 months (range 25–140 months). The mean preoperative and postoperative JOA scores and recovery ratios for the total cohort were 11.7 ± 3.0, 14.5 ± 2.7, and 55.2% ± 39.3%, respectively. In patients with mild myelopathy, only age and diabetes correlated with recovery. In patients with moderate to severe myelopathy, older age and preoperative increased signal intensity on T2-weighted imaging were significantly correlated with a lower likelihood of recovery, while female sex and anterior decompression with fusion (ADF) were associated with better recovery. CONCLUSIONS Various patient and surgical factors are correlated with likelihood of neurological recovery after surgical treatment for cervical OPLL, depending on the severity of presenting myelopathy. Older age, male sex, intramedullary high signal intensity, and posterior decompression are associated with less myelopathy improvement in patients with worse baseline function. Therefore, myelopathy-specific preoperative counseling regarding prognosis for postoperative long-term neurological improvement should include consideration of these individual and surgical factors.

Background Treatment of thoracolumbar burst fractures has traditionally involved spinal instrumentation with fusion performed with standard open surgical techniques. Novel surgical strategies, including instrumentation without fusion and percutaneous instrumentation alone, have been considered less invasive and more efficient treatments. Objective To review the current literature and determine the role of fusion in instrumented fixation, as well as the role of percutaneous instrumentation, in the treatment of patients with thoracolumbar burst fractures. Methods The task force members identified search terms/parameters and a medical librarian implemented the literature search, consistent with the literature search protocol (see Appendix I), using the National Library of Medicine PubMed database and the Cochrane Library for the period from January 1, 1946 to March 31, 2015. Results A total of 906 articles were identified and 38 were selected for full-text review. Of these articles, 12 articles met criteria for inclusion in this systematic review. Conclusion There is grade A evidence for the omission of fusion in instrumented fixation for thoracolumbar burst fractures. There is grade B evidence that percutaneous instrumentation is as effective as open instrumentation for thoracolumbar burst fractures. Question Does the addition of arthrodesis to instrumented fixation improve outcomes in patients with thoracic and lumbar burst fractures? Recommendation It is recommended that in the surgical treatment of patients with thoracolumbar burst fractures, surgeons should understand that the addition of arthrodesis to instrumented stabilization has not been shown to impact clinical or radiological outcomes, and adds to increased blood loss and operative time. Strength of Recommendation: Grade A. Question How does the use of minimally invasive techniques (including percutaneous instrumentation) affect outcomes in patients undergoing surgery for thoracic and lumbar fractures compared to conventional open techniques? Recommendation Stabilization using both open and percutaneous pedicle screws may be considered in the treatment of thoracolumbar burst fractures as the evidence suggests equivalent clinical outcomes. Strength of Recommendation: Grade B The full version of the guideline can be reviewed at: https://www.cns.org/guideline-chapters/congress-neurological-surgeons-systematic-review-evidence-based-guidelines/chapter_12.

Background Thoracic and lumbar burst fractures in neurologically intact patients are considered to be inherently stable, and responsive to nonsurgical management. There is a lack of consensus regarding the optimal conservative treatment modality. The question remains whether external bracing is necessary vs mobilization without a brace after these injuries. Objective To determine if the use of external bracing improves outcomes compared to no brace for neurologically intact patients with thoracic or lumbar burst fractures. Methods A systematic review of the literature was performed using the National Library of Medicine PubMed database and the Cochrane Library for studies relevant to thoracolumbar trauma. Clinical studies specifically comparing external bracing to no brace for neurologically intact patients with thoracic or lumbar burst fractures were selected for review. Results Three studies out of 1137 met inclusion criteria for review. One randomized controlled trial (level I) and an additional randomized controlled pilot study (level II) provided evidence that both external bracing and no brace equally improve pain and disability in neurologically intact patients with burst fractures. There was no difference in final clinical and radiographic outcomes between patients treated with an external brace vs no brace. One additional level IV retrospective study demonstrated equivalent clinical outcomes for external bracing vs no brace. Conclusion This evidence-based guideline provides a grade B recommendation that management either with or without an external brace is an option given equivalent improvement in outcomes for neurologically intact patients with thoracic and lumbar burst fractures. The decision to use an external brace is at the discretion of the treating physician, as bracing is not associated with increased adverse events compared to no brace. Question Does the use of external bracing improve outcomes in the nonoperative treatment of neurologically intact patients with thoracic and lumbar burst fractures? Recommendation The decision to use an external brace is at the discretion of the treating physician, as the nonoperative management of neurologically intact patients with thoracic and lumbar burst fractures either with or without an external brace produces equivalent improvement in outcomes. Bracing is not associated with increased adverse events compared to not bracing. Strength of Recommendation: Grade B The full version of the guideline can be reviewed at: https://www.cns.org/guideline-chapters/congress-neurological-surgeons-systematic-review-evidence-based-guidelines/chapter_8.

Question 1 Are there classification systems for fractures of the thoracolumbar spine that have been shown to be internally valid and reliable (ie, do these instruments provide consistent information between different care providers)? Recommendation 1 A classification scheme that uses readily available clinical data (eg, computed tomography scans with or without magnetic resonance imaging) to convey injury morphology, such as Thoracolumbar Injury Classification and Severity Scale or the AO Spine Thoracolumbar Spine Injury Classification System, should be used to improve characterization of traumatic thoracolumbar injuries and communication among treating physicians. Strength of Recommendation: Grade B. Question 2 In treating patients with thoracolumbar fractures, does employing a formally tested classification system for treatment decision-making affect clinical outcomes? Recommendation 2 There is insufficient evidence to recommend a universal classification system or severity score that will readily guide treatment of all injury types and thereby affect outcomes. Strength of Recommendation: Grade Insufficient The full version of the guideline can be reviewed at: https://www.cns.org/guideline-chapters/congress-neurological-surgeons-systematic-review-evidence-based-guidelines/chapter_2.

Question 1 Does routine screening for deep venous thrombosis prevent pulmonary embolism (or venous thromboembolism (VTE)-associated morbidity and mortality) in patients with thoracic and lumbar fractures? Recommendation 1 There is insufficient evidence to recommend for or against routine screening for deep venous thrombosis in preventing pulmonary embolism (or VTE-associated morbidity and mortality) in patients with thoracic and lumbar fractures. Strength of Recommendation: Grade Insufficient. Question 2 For patients with thoracic and lumbar fractures, is one regimen of VTE prophylaxis superior to others with respect to prevention of pulmonary embolism (or VTE-associated morbidity and mortality)? Recommendation 2 There is insufficient evidence to recommend a specific regimen of VTE prophylaxis to prevent pulmonary embolism (or VTE-associated morbidity and mortality) in patients with thoracic and lumbar fractures. Strength of Recommendation: Grade Insufficient. Question 3 Is there a specific treatment regimen for documented VTE that provides fewer complications than other treatments in patients with thoracic and lumbar fractures? Recommendation 3 There is insufficient evidence to recommend for or against a specific treatment regimen for documented VTE that would provide fewer complications than other treatments in patients with thoracic and lumbar fractures. Strength of Recommendation: Grade Insufficient. Recommendation 4 Based on published data from pooled (cervical and thoracolumbar) spinal cord injury populations, the use of thromboprophylaxis is recommended to reduce the risk of VTE events in patients with thoracic and lumbar fractures. Consensus Statement by the Workgroup The full version of the guideline can be reviewed at: https://www.cns.org/guideline-chapters/congress-neurological-surgeons-systematic-review-evidence-based-guidelines/chapter_7.

Spinal instrumentation often involves placing implants without direct visualization of their trajectory or proximity to adjacent neurovascular structures. Two-dimensional fluoroscopy is commonly used to navigate implant placement, but with the advent of computed tomography, followed by the invention of a mobile scanner with an open gantry, three-dimensional (3D) navigation is now widely used. This article critically appraises the available literature to assess the influence of 3D navigation on radiation exposure, accuracy of instrumentation, operative time, and patient outcomes. Also explored is the latest technological advance in 3D neuronavigation: the manufacturing of, via 3D printers, patient-specific templates that direct implant placement.

Question 1 Does the surgical treatment of burst fractures of the thoracic and lumbar spine improve clinical outcomes compared to nonoperative treatment? Recommendation 1 There is conflicting evidence to recommend for or against the use of surgical intervention to improve clinical outcomes in patients with thoracolumbar burst fracture who are neurologically intact. Therefore, it is recommended that the discretion of the treating provider be used to determine if the presenting thoracic or lumbar burst fracture in the neurologically intact patient warrants surgical intervention. Strength of Recommendation: Grade Insufficient. Question 2 Does the surgical treatment of nonburst fractures of the thoracic and lumbar spine improve clinical outcomes compared to nonoperative treatment? Recommendation 2 There is insufficient evidence to recommend for or against the use of surgical intervention for nonburst thoracic or lumbar fractures. It is recommended that the decision to pursue surgery for such fractures be at the discretion of the treating physician. Strength of Recommendation: Grade Insufficient The full version of the guideline can be reviewed at: https://www.cns.org/guideline-chapters/congress-neurological-surgeons-systematic-review-evidence-based-guidelines/chapter_1.

QUESTION Does early surgical intervention improve outcomes for patients with thoracic and lumbar fractures? RECOMMENDATIONS There is insufficient and conflicting evidence regarding the effect of timing of surgical intervention on neurological outcomes in patients with thoracic and lumbar fractures. Strength of Recommendation: Grade Insufficient It is suggested that "early" surgery be considered as an option in patients with thoracic and lumbar fractures to reduce length of stay and complications. The available literature has defined "early" surgery inconsistently, ranging from

QUESTION 1 Which neurological assessment tools have demonstrated internal reliability and validity in the management of patients with thoracic and lumbar fractures (ie, do these instruments provide consistent information between different care providers)? RECOMMENDATION 1 Numerous neurologic assessment scales (Functional Independence Measure, Sunnybrook Cord Injury Scale and Frankel Scale for Spinal Cord Injury) have demonstrated internal reliability and validity in the management of patients with thoracic and lumbar fractures. Unfortunately, other contemporaneous measurement scales (ie, American Spinal Cord Injury Association Impairment Scale) have not been specifically studied in patients with thoracic and lumbar fractures. Strength of Recommendation: Grade C. QUESTION 2 Are there any clinical findings (eg, presenting neurological grade/function) in patients with thoracic and lumbar fractures that can assist in predicting clinical outcomes? RECOMMENDATION 2 Entry American Spinal Injury Association Impairment Scale grade, sacral sensation, ankle spasticity, urethral and rectal sphincter function, and AbH motor function can be used to predict neurological function and outcome in patients with thoracic and lumbar fractures (Table I https://www.cns.org/guideline-chapters/congress-neurological-surgeons-systematic-review-evidence-based-guidelines/chapter_4_table1). Strength of Recommendation: Grade B The full version of the guideline can be reviewed at: https://www.cns.org/guideline-chapters/congress-neurological-surgeons-systematic-review-evidence-based-guidelines/chapter_4.

Question Does the choice of surgical approach (anterior, posterior, or combined anterior-posterior) improve clinical outcomes in patients with thoracic and lumbar fractures? Recommendations In the surgical treatment of patients with thoracolumbar burst fractures, physicians may use an anterior, posterior, or a combined approach as the selection of approach does not appear to impact clinical or neurological outcomes. Strength of Recommendation: Grade B With regard to radiologic outcomes in the surgical treatment of patients with thoracolumbar fractures, physicians may utilize an anterior, posterior, or combined approach because there is conflicting evidence in the comparison among approaches. Strength of Recommendation: Grade Insufficient With regard to complications in the surgical treatment of patients with thoracolumbar fractures, physicians may use an anterior, posterior, or combined approach because there is conflicting evidence in the comparison among approaches. Strength of Recommendation: Grade Insufficient The full version of the guideline can be reviewed at: https://www.cns.org/guideline-chapters/congress-neurological-surgeons-systematic-review-evidence-based-guidelines/chapter_11.

Question Does the administration of a specific pharmacologic agent (eg, methylprednisolone) improve clinical outcomes in patients with thoracic and lumbar fractures and spinal cord injury? Recommendation There is insufficient evidence to make a recommendation; however, the task force concluded, in light of previously published data and guidelines, that the complication profile should be carefully considered when deciding on the administration of methylprednisolone. Strength of recommendation: Grade Insufficient The full version of the guideline can be reviewed at: https://www.cns.org/guideline-chapters/congress-neurological-surgeons-systematic-review-evidence-based-guidelines/chapter_5.

Question Does the active maintenance of arterial blood pressure after injury affect clinical outcomes in patients with thoracic and lumbar fractures? Recommendations There is insufficient evidence to recommend for or against the use of active maintenance of arterial blood pressure after thoracolumbar spinal cord injury. Grade of Recommendation: Grade Insufficient However, in light of published data from pooled (cervical and thoracolumbar) spinal cord injury patient populations, clinicians may choose to maintain mean arterial blood pressures >85 mm Hg in an attempt to improve neurological outcomes. Consensus Statement by the Workgroup The full version of the guideline can be reviewed at: https://www.cns.org/guideline-chapters/congress-neurological-surgeons-systematic-review-evidence-based-guidelines/chapter_6.

While the incidence of postoperative infection after spine surgery is relatively uncommon, the occurrence of a surgical site infection can significantly impact individual patient outcome. Spinal deformity surgery carries a higher risk of infection compared to other spinal procedures. Posterior approach, increased number of treated levels and length of surgery, use of spinal instrumentation and grafts, and revision surgery likely contribute to greater risk of infection. Clinical presentation (symptoms, physical exam findings, diagnostic studies) and management options are reviewed in a case-based format.

Objective Traumatic high-grade cervical spinal dislocations are rare injuries, generally associated with severe neurological compromise. In particular, cervical spondyloptosis (>100% subluxation) is rarely reported. The object of our study is to present a case series describing presentation, management, and outcome in traumatic high-grade cervical spinal dislocations. Methods Retrospective analysis was performed involving two level 1 trauma centers. Patients with a high-grade traumatic cervical subluxation were selected from a database, and these patients were admitted between August 2007 and July 2011. Results Fifteen patients were identified; three had spondyloptosis. The admission American Spinal Injury Association Impairment Scale (AIS) grade varied (A = 9; B = 2; C = 1; D = 2; E = 1). Fourteen patients underwent attempted closed reduction with six (43%) failing closed reduction. High-dose methylprednisolone was administered in nine patients (60%). All patients underwent surgical stabilization: three underwent anterior only, three underwent posterior only, and nine underwent a combined anterior-posterior approach. Postoperatively, one patient improved two AIS grades, three improved one AIS grade, nine maintained their preoperative score, and two patients worsened. Conclusions In this series, 26.7% of patients had improvement in their AIS grade postoperatively, and the majority of patients (60%) maintained their preoperative AIS grade. In 57% of patients placed in traction, reduction was possible. Likely due to the severity of these injuries, there was a high incidence of complications. However, review of patient outcomes reveals that these patients can have improvement of neurological function. We recommend aggressive reduction and surgical stabilization. Our preference is either a combined anterior-posterior approach or a posterior-only approach.

Background Neurosurgical residents have traditionally been instructed on surgical techniques and procedures through an apprenticeship model. Currently, there has been research and interest in expanding the neurosurgical education model. Objective To establish a posterior cervical decompression educational curriculum with a novel cervical simulation model. Methods The Congress of Neurological Surgeons developed a simulation committee to explore and develop simulation-based models. The educational curriculum was developed to have didactic and technical components with the incorporation of simulation models. Through numerous reiterations, a posterior cervical decompression model was developed and a 2-hour education curriculum was established. Results Individual's level of training varied, with 5 postgraduate year (PGY) 2 participants, 1 PGY-3 participant, 2 PGY-5 participants, and 1 attending, with the majority being international participants (6 of 9, 67%). Didactic scores overall improved (7 of 9, 78%). The technical scores of all participants improved from 11 to 24 (mean, 14.1) to 19 to 25 (mean, 22.4). Overall, in the posterior cervical decompression simulator, there was a significant improvement in the didactic scores (P = .005) and the technical scores (P = .02). Conclusion The posterior cervical decompression simulation model appears to be a valuable tool in educating neurosurgery residents in the aspects of this procedure. The combination of a didactic and technical assessment is a useful teaching strategy in terms of educational development.

Surgical education is moving rapidly to the use of simulation for technical training of residents and maintenance or upgrading of surgical skills in clinical practice. To optimize the learning exercise, it is essential that both visual and haptic cues are presented to best present a real-world experience. Many systems attempt to achieve this goal through a total virtual interface.To demonstrate that the most critical aspect in optimizing a simulation experience is to provide the visual and haptic cues, allowing the training to fully mimic the real-world environment.Our approach has been to create a mixed-reality system consisting of a physical and a virtual component. A physical model of the head or spine is created with a 3-dimensional printer using deidentified patient data. The model is linked to a virtual radiographic system or an image guidance platform. A variety of surgical challenges can be presented in which the trainee must use the same anatomic and radiographic references required during actual surgical procedures.Using the aforementioned techniques, we have created simulators for ventriculostomy, percutaneous stereotactic lesion procedure for trigeminal neuralgia, and spinal instrumentation. The design and implementation of these platforms are presented.The system has provided the residents an opportunity to understand and appreciate the complex 3-dimensional anatomy of the 3 neurosurgical procedures simulated. The systems have also provided an opportunity to break procedures down into critical segments, allowing the user to concentrate on specific areas of deficiency.

BACKGROUND:Surgical simulators are useful in many surgical disciplines to augment residency training. Duty hour restrictions and increasing emphasis on patient safety and attending oversight have changed neurosurgical education from the traditional apprenticeship model. The Congress of Neurological Surgeons Simulation Committee has been developing neurosurgical simulators for the purpose of enhancing resident education and assessing proficiency.OBJECTIVE:To review the initial experience with an anterior cervical diskectomy and fusion (ACDF) simulator.METHODS:The first ACDF training module was implemented at the 2012 Congress of Neurological Surgeons Annual Meeting. The 90-minute curriculum included a written pretest, didactics, a practical pretest on the simulator, hands-on training, a written posttest, a practical posttest, and postcourse feedback. Didactic material covered clinical indications for ACDF, comparison with other cervical procedures, surgical anatomy and approach, principles of arthrodesis and spinal fixation, and complication management. Written pretests and posttests were administered to assess baseline knowledge and evidence of improvement after the module. Qualitative evaluation of individual performance on the practical (simulator) portion was included.RESULTS:Three neurosurgery residents, 2 senior medical students, and 1 attending neurosurgeon participated in the course. The pretest scores were an average 9.2 (range, 6-13). Posttest scores improved to 11.0 (range, 9-13; P = .03).CONCLUSION:Initial experience with the ACDF simulator suggests that it may represent a meaningful training module for residents. Simulation will be an important training modality for residents to practice surgical technique and for teachers to assess competency. Further development of an ACDF simulator and didactic curriculum will require additional verification of simulator validity and reliability.

Study Design Retrospective clinical study. Objectives Recent biomechanical studies have shown no differences in stiffness or range of motion following minimally invasive (MIS) transforaminal lumbar interbody fusion (TLIF) between unilateral pedicle and contralateral facet screw (UPFS) and bilateral pedicle screw (BPS) constructs. No studies have compared these two constructs based upon clinical outcomes. Methods Twenty-six consecutive patients who had single-level MIS TLIF were retrospectively reviewed. Outcome measures collected for patients with BPS were compared with those with UPFS. Results No associations were found between construct and length of stay ( p = 0.5), operative time ( p = 0.2), or Odom's criteria ( p = 0.7); 79% of patients in the UPFS group as compared with 71.5% in the BPS group had good or excellent outcomes. Mean follow-up was 17.7 months for the UPFS group and 20.2 months for the BPS group. There was one complication in each group, including a seroma in the BPS group and a revision operation in the UPFS group. Implant costs for the BPS group were 35% greater than the UPFS group. Conclusions The present study is the first to demonstrate that patients undergoing MIS TLIF with BPS as compared with UPFS for single-level degenerative lumbar disease had similar clinical outcomes.

Ossification of the posterior longitudinal ligament (OPLL) is a disease process characterized by progressive growth and calcification resulting in spinal canal compromise and serious neurological sequelae in advanced cases. Historically, OPLL has most commonly been treated with posterior surgical decompression. Although this procedure indirectly decompresses the spinal cord, it does not address the offending pathological entity, and further growth of the lesion may result in delayed neurological deterioration. This fact is particularly relevant because a number of long-term studies have revealed both longitudinal and transverse disease progression in individuals treated both surgically and conservatively. Despite these high rates of radiographically documented progression, however, the rate of neurological decline in patients undergoing posterior surgery with laminoplasty is low. In this article, the authors review the pathophysiology of OPLL, evidence of disease progression, and outcome data addressing conservative and surgical treatments.

BACKGROUND Spontaneous thoracic ankylosis is a progressive degenerative process that predisposes patients to potentially highly unstable traumatic injuries. Acute hyperextension fractures result in dynamic instability putting the spinal cord at risk. OBJECTIVE To describe preoperative radiographic characteristics of fractures of the ankylotic thoracic spine and relate findings to early postoperative radiographic and clinical outcomes. METHODS A single center, retrospective review was performed of 28 surgically treated patients with fractures of the ankylotic thoracic spine. Radiographic assessment included preoperative fracture angulation (FA) and fracture displacement (FD), and postoperative change in sagittal alignment. Early clinical outcomes included preoperative and postoperative American Spinal Injury Association (ASIA) grade and perioperative complications. RESULTS Seven patients (25%) presented with poor neurological grade (ASIA A-C) compared to 21 (75%) with good grade (ASIA D, E). At presentation, poor grade patients had a mean FA of 16.4° (range 0°-34.5°), and FD of 7.76 mm (range 0.8-9.2). Good grade patients had a mean FA of 18.2° (range 0°-43.3°), and FD of 4.77 mm (range 0-25.1). There was no statistically significant difference in FA or FD between groups (P = .70 and .20 respectively). All underwent posterior pedicle screw fixation for stabilization. Fifty per cent of patients presenting with ASIA C or D spinal cord injury improved 1 or more ASIA grades. There were no perioperative complications. Early postoperative sagittal alignment was maintained with a mean change of -2.6°. CONCLUSION Presenting fracture alignment does not significantly correlate with pre- or postoperative neurological status. Early posterior stabilization preserved neurological function, with neurological recovery occurring in a portion of individuals.

Anterior lumbar interbody fusion is an important staple in the armamentarium of spine surgeons. The benefits of an anterior lumbar approach include broad exposure of the disc space allowing for thorough discectomy, effective endplate preparation, appropriate sizing and placement of an optimal interbody graft, and anterior fixation if necessary. ALIF also has the advantage of protecting the neural elements and surrounding dura and, as a result, is a particularly attractive option in patients with prior posterior surgery. With the placement of broad interbody grafts or devices under compressive loads, ALIF imparts high fusion rates and provides an extremely rigid construct when supplemented with posterior spinal fixation. Therefore, ALIF is a potentially useful complement to fusion constructs that are under large biomechanical stresses such as in deformity surgery or complex reconstructive procedures. While there are potentially significant risks associated with an anterior approach, a variety of techniques are available and may be adopted by appropriately trained spine surgeons or performed with the assistance of experienced vascular, urologic, or general surgeons. Ultimately, decision to perform ALIF as opposed to other spinal fusion techniques is dictated by the patient’s underlying pathology, anatomy, and associated medical comorbidities paired with the surgeon’s preference, education, experience, and overall expertise.

BACKGROUND The evidence of or against the presence of a 'July phenomenon' in resident teaching hospitals has been inconsistent. Moreover, there are limited data on the "July phenomenon" in the field of neurosurgery. OBJECTIVE To determine whether a "July phenomenon" exists for neurosurgical mortality or complications. METHODS A search of the National Inpatient Sample database from 1998 to 2008 was performed for all admissions for International Classification of Diseases, 9th Revision codes corresponding to nontraumatic hemorrhage, central nervous system (CNS) trauma, CNS tumor, and hydrocephalus. Generalized linear mixed-model analysis was performed, adjusted for patient demographics and hospital characteristics, for the outcomes of mortality and complications for the month of July compared with all other months in teaching hospitals. RESULTS Generalized linear mixed-model analysis demonstrated that the risk of dying in the month of July vs any other month in a teaching hospital was not statistically different for any of the 4 diagnoses: nontraumatic hemorrhage (P = .071), CNS trauma category (P = .485), CNS tumor category (P = .578), hydrocephalus category (P = .1505). Moreover, the risk of any complication in the month of July vs any other month in a teaching hospital was not statistically different for any of the 4 diagnoses: nontraumatic hemorrhage (P = .529), CNS trauma category (P = .378), CNS tumor category (P = .461), and hydrocephalus category (P = .441). The same findings were true in an analysis of nonteaching hospitals performed as a control. CONCLUSION No "July phenomenon" was found for neurosurgical mortality or complications in patients with nontraumatic hemorrhage, CNS trauma, CNS tumor, or hydrocephalus.

BACKGROUND The Accreditation Council for Graduate Medical Education resident duty-hour restrictions were implemented in July 2003 based on the supposition that resident fatigue contributes to medical errors. OBJECTIVE To examine the effect of duty-hour restrictions on outcome in neurotrauma patients. METHODS The Nationwide Inpatient Sample database was analyzed for a time period with no restrictions (years 1999-2002) compared with a period with restrictions (years 2005-2008) for (1) mortality and (2) complications. We analyzed both teaching and nonteaching hospitals to account for potential differences attributed to non-resident-related factors. RESULTS There were 107,006 teaching hospital and 115,604 nonteaching hospital admissions for neurotrauma. Multivariate logistic regression demonstrated significantly more complications in the time period with restrictions in teaching hospitals. In nonteaching hospitals, there was no difference in complications. In both teaching and nonteaching hospitals, there was no difference in mortality between the 2 time periods. For teaching and nonteaching hospitals, there was no difference in hospital length of stay, but hospital charges were significantly higher in the period with restrictions. The occurrence of a complication was significantly associated with longer hospital length of stay and higher hospital charges in both time periods in both teaching and nonteaching hospitals. CONCLUSION The implementation of the Accreditation Council for Graduate Medical Education resident duty-hour restrictions was associated with increased complications and no change in mortality for neurotrauma patients in teaching hospitals. In nonteaching hospitals, there was no change in complications and mortality. The occurrence of a complication was associated with longer length of stay and higher hospital charges in both time periods in both teaching and nonteaching hospitals.

The prognosis for substantial and lasting neurological recovery after complete traumatic spinal cord injury (SCI) remains dismal. Disruption of motor and sensory pathways involving not only limb activity, but also respiratory, urinary, and autonomic function, contributes to lifelong morbidity. Obstacles impeding the spinal cord’s ability for self-repair are multifactorial. Principal among these, however, is the limited growth potential of the injured spinal cord, as well as the problematic task of functionally reconnecting supraspinal to spinal neurons, and vice versa. Exciting recent developments in preclinical SCI research, however, are bringing to light novel strategies for circumventing these barriers to spinal recovery with potential for near-future translational therapies. Contrary to traditional thought, axons within the injured adult spinal cord have the capacity to grow, if given optimal circumstances. The propensity for spontaneous axonal growth, however, is limited by the extent of the intrinsic growth potential of adult neurons, and the degree of growth inhibition mediated by the injured cord. A significant component of the inhibitory, internal milieu after injury is due to the presence of chondroitin sulfate proteoglycans (CSPGs) (2, 10). CSPGs are molecules found within the perineuronal net, which have been identified as key factors in preventing axonal growth. Under normal conditions, CSPGs likely function to stabilize mature axons and prevent aberrant growth. After injury, CSPGs are up-regulated at the glial scar that forms at the injury site, and around partially denervated neurons distal to the injury. This increase in CSPGs causes sprouting axons to dieback as they approach the injury epicenter, thereby failing to restore connectivity. Chondroitinase ABC (ChABC) is an enzyme that cleaves the inhibition-mediating sugar chains of CSPGs. In animal models, intraspinal delivery of ChABC has been shown to promote a growth-permissive environment, facilitating spontaneous axonal growth across a spinal cord injury (3, 4). Lasting neurological recovery, however, requires not only axonal growth but also the re-establishment of functional connections between relevant supraspinal and spinal neurons. Precise restoration of point-to-point neural circuitry is a therapeutic challenge that is seemingly unrealistic, particularly of complex long distance neuronal pathways. Increasing recent scientific studies reveal, however, that under ideal conditions, spinal interneurons can sprout new axons after injury. More remarkably, growing

BACKGROUND: Intermuscular approaches can expose the lumbar spine and minimize muscular trauma and injury. The segmental anatomy of the posterior lumbar musculature allows surgical access through separation of muscle groups and fascicles and provides one to develop intermuscular working channels while preserving the integrity of the muscles and their function. In addition, preservation of the accompanying neurovascular bundles minimizes blood loss, tissue atrophy, and pain. With these approaches, a variety of procedures for decompression, discectomy, interbody fusion, or pedicle screw fixation can be achieved for single or multiple levels without subperiosteal stripping or muscle transection. OBJECTIVE: A detailed description of the relevant surgical anatomy for the muscle-sparing approach to the lumbar spine.

SHAPE MEMORY ALLOYS possess distinct dynamic properties with particular applications in neurosurgery. Because of their unique physical characteristics, these materials are finding increasing application where resiliency, conformation, and actuation are needed. Nitinol, the most frequently manufactured shape memory alloy, responds to thermal and mechanical stimuli with remarkable mechanical properties such as shape memory effect, super-elasticity, and high damping capacity. Nitinol has found particular use in the biomedical community because of its excellent fatigue resistance and biocompatibility, with special interest in neurosurgical applications. The properties of nitinol and its diffusionless phase transformations contribute to these unique mechanical capabilities. The features of nitinol, particularly its shape memory effect, super-elasticity, damping capacity, as well as its biocompatibility and biomechanics are discussed herein. Current and future applications of nitinol and other shape memory alloys in endovascular, spinal, and minimally invasive neurosurgery are introduced. An understanding of the metallurgic properties of nitinol provides a foundation for further exploration of its use in neurosurgical implant design.

Intraoperative manipulation to correct scoliotic deformities relies upon spinal instrumentation for stabilization and fusion. However, novel strategies and innovative implant biotechnologies have emerged, applying natural growth and elongation of the immature spine for the treatment of scoliosis in young patients. In this work, we review the principles of growth modulation and the Hueter-Volkmann law as it applies to experimental models of scoliosis formation and correction. Current implant technologies, including shape memory alloy vertebral staples, growing rods, and vertical expandable titanium prosthetic ribs, are explored, with regards to implant design, surgical techniques, and clinical investigations. An exciting area of spinal implant technology is now becoming available to expand the surgical armamentarium for treating severe scoliotic deformity in young patients.

Study design A retrospective, case-control study was conducted to analyze postoperative outcomes in patients who received local anesthetic infusion pumps after lumbar spinal fusion procedures. Data were collected prospectively via nursing protocol and third party assessment, and analyzed retrospectively. Objective To review the safety and efficacy of continuous infusion of local anesthetic into the subfascial aspects of the wound after lumbar fusion surgery for treatment of postoperative pain, and to determine whether other outcome measures such as postoperative nausea and vomiting, ambulation and length of hospitalization were affected by the presence of the device. Summary of background data Patients who undergo lumbar spine fusion procedures frequently experience significant, debilitating pain related to their surgery. This pain may delay postoperative mobilization, increase length of hospitalization, and require prolonged use of high doses of narcotics. Use of a local anesthetic continuous-infusion pump after surgery may lead to improvements in these outcome variables. Methods After posterior lumbar spine fusion procedures, 26 consecutive patients received the ON-Q PainBuster, which infused 0.5% marcaine via an elastomeric pump into the subfascial aspects of the wound. Retrospective analysis compared each of these patients with a case-matched control patient. Data included pain scores and opiate use during the first 5 postoperative days (PODs), length of hospital stay, and complications. Variables such as age, American Society of Anesthesiologists (ASA) physical status, and surgical procedure were similar between matched cases. One patient was excluded because of active heroine abuse. Results Patients with the ON-Q PainBuster used 41.2% less narcotics on POD 1, 50.1% less on day 2, and 47.1% less on day 3 compared with the control patients. Differences in opiate usage were not statistically significant on POD 4 (45.5% less) and 5 (50.3% less). A lower average pain score was observed among patients with the ON-Q PainBuster on each POD: 39.1% less pain on POD 1, 34.0% on day 2, 45.1% on day 3, 29.5% on day 4, and 43.6% on day 5. No differences were observed in length of hospital stay or complication rate. Conclusion Patients who received the ON-Q PainBuster used less narcotic medications than case-matched patients during the first 3 PODs, and reported lower pain scores during the first 5 PODs. No complications attributable to the device were noted. These results suggest that continuous infusion of local anesthetic into the wound during the immediate postoperative period is a safe and effective technique that results in lower pain scores and narcotic use. Further data may reveal additional benefits such as lower incidence of nausea and vomiting and decreased times to mobility and functional independence.

The fundamental principle of radiosurgery is the focusing of energy within a restricted target volume. In examining the history of radiosurgery, various strategies for addressing this issue of energy containment become apparent. This is the first in a series of articles that reviews the evolution of radiosurgery through the development of instruments for beam generation and delivery for improved conformal therapy. In this first part of the series, we focus specifically on beam generation and the development of particle beams as the initial approach in radiosurgery for focused radiation treatment. We examine the physical characteristics and biological effects of particles and the unique advantage they confer for radiosurgery. We consider clinical studies and treatment of neurological diseases with particles and also assess boron neutron capture therapy as a strategy for selectively targeting neutron beams. Later in this series, we explore methods of beam delivery with the development of stereotactic radiosurgery. Finally, we introduce new concepts and applications in radiosurgery such as nanotechnology, radiation enhancement, ultrasound, near infrared, and free electron lasers. The elaboration of these efforts sets the stage for neurosurgeons to further explore new ideas, develop innovative technology, and advance the practice of radiosurgery.