Neurosurgery residency and fellowship education in the United States: 2 decades of system development by the One Neurosurgery Summit organizations

The purpose of this report is to chronicle a 2-decade period of educational innovation and improvement, as well as governance reform, across the specialty of neurological surgery. Neurological surgery educational and professional governance systems have evolved substantially over the past 2 decades with the goal of improving training outcomes, patient safety, and the quality of US neurosurgical care. Innovations during this period have included the following: creating a consensus national curriculum; standardizing the length and structure of neurosurgical training; introducing educational outcomes milestones and required case minimums; establishing national skills, safety, and professionalism courses; systematically accrediting subspecialty fellowships; expanding professional development for educators; promoting training in research; and coordinating policy and strategy through the cooperation of national stakeholder organizations. A series of education summits held between 2007 and 2009 restructured some aspects of neurosurgical residency training. Since 2010, ongoing meetings of the One Neurosurgery Summit have provided strategic coordination for specialty definition, neurosurgical education, public policy, and governance. The Summit now includes leadership representatives from the Society of Neurological Surgeons, the American Association of Neurological Surgeons, the Congress of Neurological Surgeons, the American Board of Neurological Surgery, the Review Committee for Neurological Surgery of the Accreditation Council for Graduate Medical Education, the American Academy of Neurological Surgery, and the AANS/CNS Joint Washington Committee. Together, these organizations have increased the effectiveness and efficiency of the specialty of neurosurgery in advancing educational best practices, aligning policymaking, and coordinating strategic planning in order to meet the highest standards of professionalism and promote public health.

Cannabinoids in the Treatment of Back Pain

Marijuana is increasingly utilized for the treatment of multiple medical problems, including back pain, in the United States. Although there is strong preclinical evidence supporting the promise of cannabinoids in the treatment of back pain, there is a paucity of clinical data supporting their use in clinical practice. Opioids are an important medication for the treatment of acute and chronic back pain, but utilization of opioid-based regimens have likely contributed to the growing opioid epidemic. The significant risk of morbidity, mortality, and dependence secondary to opioid medications have increased the interest in nonopioid medications, including cannabinoid-based pain regimens, in treating back pain. This review will provide an overview on the pharmacology, drug delivery methods, clinical evidence, and safety considerations critical to understanding the potential role of cannabinoids in the treatment of back pain.

Chronicling the philanthropic arm of neurological surgery: a review of the growth and development of the Neurosurgery Research & Education Foundation

OBJECTIVE

The Neurosurgery Research & Education Foundation (NREF), previously known as the Research Foundation of the American Association of Neurological Surgeons (AANS), was established in 1980 to encourage and facilitate innovation through financial support to young neurosurgeons in the process of honing their competencies in neurosciences and neurological surgery. This article provides a historical overview of NREF, its mission, and charitable contributions and the ever-expanding avenues for neurosurgeons, neurosurgical residents and fellows, and medical students to supplement clinical training and to further neurosurgical research advances.

METHODS

Data were collected from the historical archives of the AANS and NREF website. Available data included tabulated revenue, geographic and institutional records of funding, changes in funding for fellowships and awards, advertising methods, and sources of funding.

RESULTS

Since 1984, NREF has invested more than $23 million into the future of neurosurgery. To date, NREF has provided more than 500 fellowship opportunities which have funded neurosurgeons' education and research efforts at all stages of training and practice.

CONCLUSIONS

NREF is designed to serve as the vehicle through which the neurosurgical community fosters the continued excellence in the care of patients with neurosurgical diseases.

A review of Big Data analytics and potential for implementation in the delivery of global neurosurgery

Global access to neurosurgical care is still a work in progress, with many patients in low-income countries not able to access potentially lifesaving neurosurgical procedures. “Big Data” is an increasingly popular data collection and analytical technique predicated on collecting large amounts of data across multiple data sources and types for future analysis. The potential applications of Big Data to global outreach neurosurgery are myriad: from assessing the overall burden of neurosurgical disease to planning cost-effective improvements in access to neurosurgical care, and collecting data on conditions which are rare in developed countries. Although some global neurosurgical outreach programs have intelligently implemented Big Data principles in their global neurosurgery initiatives already, there is still significant progress that remains to be made. Big Data has the potential to drive the efficient improvement of access to neurosurgical care across low- and medium-income countries.

Novel placement of cortical bone trajectory screws in previously instrumented pedicles for adjacent-segment lumbar disease using CT image-guided navigation

OBJECT

Symptomatic adjacent-segment lumbar disease (ASLD) after lumbar fusion often requires subsequent surgical intervention. The authors report utilizing cortical bone trajectory (CBT) pedicle screw fixation with intraoperative CT (O-arm) image-guided navigation to stabilize spinal levels in patients with symptomatic ASLD. This unique technique results in the placement of 2 screws in the same pedicle (1 traditional pedicle trajectory and 1 CBT) and obviates the need to remove preexisting instrumentation.

METHODS

The records of 5 consecutive patients who underwent lumbar spinal fusion with CBT and posterior interbody grafting for ASLD were retrospectively reviewed. All patients underwent screw trajectory planning with the O-arm in conjunction with the StealthStation navigation system. Basic demographics, operative details, and radiographic and clinical outcomes were obtained.

RESULTS

The average patient age was 69.4 years (range 58-82 years). Four of the 5 surgeries were performed with the Minimal Access Spinal Technologies (MAST) Midline Lumbar Fusion (MIDLF) system. The average operative duration was 218 minutes (range 175-315 minutes). In the entire cohort, 5.5-mm cortical screws were placed in previously instrumented pedicles. The average hospital stay was 2.8 days (range 2-3 days) and there were no surgical complications. All patients had more than 6 months of radiographic and clinical follow-up (range 10-15 months). At last follow-up, all patients reported improved symptoms from their preoperative state. Radiographic follow-up showed Lenke fusion grades of A or B.

CONCLUSIONS

The authors present a novel fusion technique that uses CBT pedicle screw fixation in a previously instrumented pedicle with intraoperative O-arm guided navigation. This method obviates the need for hardware removal. This cohort of patients experienced good clinical results. Computed tomography navigation was critical for accurate CBT screw placement at levels where previous traditional pedicle screws were already placed for symptomatic ASLD.

Review of 31 cases of anterior thoracolumbar fixation with the anterior thoracolumbar locking plate system

Anterior fixation devices for the thoracolumbar spine have gained wide acceptance as viable alternatives to long-segment posterior fixation in cases of thoracolumbar spine trauma. This review was undertaken to evaluate the safety and efficacy of the Synthes anterior thoracolumbar locking plate (ATLP) system. Over a 3-year period, 31 patients with unstable traumatic fractures of the thoracolumbar spine underwent corpectomy, placement of a structural bone graft, and anterior fixation in which the Synthes ATLP system was used. Long-term follow-up data were obtained in 29 patients. Two patients were lost to follow up, one at 4 months and the other at 1 year. In the remaining patients, the average length of follow up was 20 months. In all patients radiographic evidence of solid bone fusion was demonstrated on follow-up plain x-ray films, and there were no signs or symptoms of pseudarthrosis. No patient suffered neurological deterioration as a result of surgery, and there was relatively little morbidity associated with this plating system. To date, none of the patients in this study has developed any delayed complications related to the fixation device. In one patient, who had sustained a severe flexion injury, loosening of the anterior fixation device occurred, and the patient developed progressive kyphosis, which required a posterior stabilization procedure. These results appear slightly better than those obtained in published studies in which other anterior plating systems were used, indicating that this system is safe and effective in the treatment of unstable fractures of the thoracolumbar spine.

A review of surgical intervention in the setting of traumatic central cord syndrome

BACKGROUND CONTEXT

Surgical treatment in the setting of central cord syndrome (CCS) has become safer since Schneider's original description. It is generally accepted that a decompressive surgical intervention is a valid treatment option in a patient with CCS and radiographic evidence of spinal cord compression. The optimal timing of surgical intervention for CCS remains controversial.

PURPOSE

To review a single institution's experience managing CCS, with particular emphasis on surgical versus medical management, timing of surgery, neurologic outcomes, hospital length of stay, and complications.

STUDY DESIGN

Retrospective review.

PATIENT SAMPLE

One hundred twenty-six patients diagnosed with CCS were treated at Wake Forest University Baptist Medical Center between June 1985 and September 2006.

OUTCOME MEASURES

Neurological outcomes were measured using the Frankel grading scale. Other outcome measures included hospital and intensive care unit (ICU) length of stay and complication profiles.

METHODS

A retrospective chart review was performed on patients admitted to Wake Forest University Baptist Medical Center with the diagnosis of traumatic central cord injury from June 1985 to September 2006 with institutional review board approval. Neurologic status was recorded on presentation and at maximum follow-up using the Frankel classification. The surgical cohort was stratified into three subgroups with regard to the timing of surgical intervention after injury: surgery less than 24 hours after injury, surgery greater than 24 hours after injury but during the initial admission, and delayed operative intervention on a second hospital admission. Other variables collected included ICU and hospital length of stay and complication profiles. Data analyses were performed using SPSS (SPSS, Chicago, IL, USA) and Excel 2002 (Microsoft, Seattle, WA, USA).

RESULTS

A total of 126 patients treated for CCS were reviewed. Sixty-seven patients received surgery compared with 59 patients managed nonoperatively. Of those managed operatively, 16 patients received surgery within 24 hours of the time of injury. There were 34 patients who received surgery greater than 24 hours after the time of injury but during their initial admission with a mean time to surgery of 6.4 days (5-52 days). There were 17 patients who received their operation on a second hospital admission with a mean time interval of 137 days between injury and surgery (3-209). Mean follow-up was 32 months (1-210 months). An improvement in Frankel grade was seen in the overall operative cohort compared with those patients who received medical management alone. No statistically significant difference in neurologic outcome using Frankel grades was identified between the surgical subgroups with regard to timing of surgery. A trend toward decreased length of stay was seen in the surgical subgroup that received surgery during their initial admission. No statistically significant difference was identified between complication rates for the operative and nonoperative groups; however, a trend toward fewer complications and deaths was seen in those who received surgery in the first 24 hours or during the initial hospitalization.

CONCLUSIONS

Surgical treatment in the setting of CCS has become safer since Schneider's original description. Acknowledging its numerous limitations, this retrospective study supports surgical intervention in the setting of CCS as a safe effective management option. Improved Frankel grades were identified in those patients managed surgically compared with those receiving medical management alone. The data further shed light on the safety and potential benefits of early operative intervention for acute CCS compared with delayed surgical treatment. A prospective randomized controlled trial is needed to definitively compare surgical versus medical management and/or early versus delayed surgical treatment in the setting of traumatic CCS.

Characterization of a CNS penetrant, selective M1 muscarinic receptor agonist, 77-LH-28-1

BACKGROUND AND PURPOSE

M1 muscarinic ACh receptors (mAChRs) represent an attractive drug target for the treatment of cognitive deficits associated with diseases such as Alzheimer's disease and schizophrenia. However, the discovery of subtype-selective mAChR agonists has been hampered by the high degree of conservation of the orthosteric ACh-binding site among mAChR subtypes. The advent of functional screening assays has enabled the identification of agonists such as AC-42 (4-n-butyl-1-[4-(2-methylphenyl)-4-oxo-1-butyl]-piperidine), which bind to an allosteric site and selectively activate the M(1) mAChR subtype. However, studies with this compound have been limited to recombinantly expressed mAChRs.

EXPERIMENTAL APPROACH

In this study, we have compared the pharmacological profile of AC-42 and a close structural analogue, 77-LH-28-1 (1-[3-(4-butyl-1-piperidinyl)propyl]-3,4-dihydro-2(1H)-quinolinone) at human recombinant, and rat native, mAChRs by calcium mobilization, inositol phosphate accumulation and both in vitro and in vivo electrophysiology.

KEY RESULTS

Calcium mobilization and inositol phosphate accumulation assays revealed that both AC-42 and 77-LH-28-1 display high selectivity to activate the M1 mAChR over other mAChR subtypes. Furthermore, 77-LH-28-1, but not AC-42, acted as an agonist at rat hippocampal M1 receptors, as demonstrated by its ability to increase cell firing and initiate gamma frequency network oscillations. Finally, 77-LH-28-1 stimulated cell firing in the rat hippocampus in vivo following subcutaneous administration.

CONCLUSIONS AND IMPLICATIONS

These data suggest that 77-LH-28-1 is a potent, selective, bioavailable and brain-penetrant agonist at the M1 mAChR and therefore that it represents a better tool than AC-42, with which to study the pharmacology of the M1 mAChR.

Cervical osteomyelitis: a brief review

Object

The authors conducted a literature-based review of the etiology, diagnosis, and treatment of cervical vertebral osteomyelitis (CVO).

Methods

A Medline (PubMed) search using the key words “cervical vertebral osteomyelitis” yielded 256 articles. These were further screened for relevance, yielding 15 articles. Each publication was reviewed, and several others not identified in the PubMed search were screened and included in the review according to relevance. Each article was identified as involving either the epidemiology/etiology, diagnosis, or treatment of CVO. Separate categories were created for case reports and general reviews.

Conclusions

Cervical vertebral osteomyelitis has a spectrum of origins, which include spontaneous, postoperative, traumatic, and hematogenously spread causes. The majority of patients have medical risk factors and comorbidities that include diabetes, trauma, drug abuse, and infectious processes in extraspinal areas. The diagnosis of CVO can be accomplished in most cases by using plain x-ray films and computerized tomography scans. Nevertheless, preferential use of magnetic resonance imaging in cases in which there is a neurological deficit is helpful in identifying epidural compressive processes. Treatment for CVO can be successfully initiated with intravenous antibiotic therapy. Nevertheless, in cases in which there is a neurological deficit, spinal deformity and/or progressive lysis, or intractable pain, the earliest feasible surgical intervention with debridement and fusion is warranted.

Postoperative Level 1 anticoagulation therapy and spinal surgery: practical guidelines for management

OBJECT

The authors conducted a review of the literature to establish reasonable practical guidelines for the management of complications in patients who have undergone recent spinal surgery and who require Level 1 anticoagulation therapy.

METHODS

A MEDLINE (PubMed) literature search was performed using the key words "postoperative anticoagulation," "spinal surgery," and "postoperative epidural hematoma," for articles published between 1990 and 2004. The search yielded 148 articles, which were then further screened for relevance and classified according to level-of-evidence guidelines established by the American Association of Neurological Surgeons/Congress of Neurological Surgeons joint committee for spinal cord injury. A total of 12 relevant articles were reviewed. There were no relevant articles meeting Class 1 standards of evidence, two met Class 2 evidence standards (one was a nonrandomized cohort study, the other was case-controlled), and the remaining 10 articles contained Class 3 evidence.

CONCLUSIONS

There are insufficient data to establish evidence-based guidelines for the use of Level 1 heparin or an equivalent anticoagulation protocol in patients who have recently undergone spinal surgery. Nevertheless, a search of the limited peer-reviewed literature on the subject indicates that there is an anecdotally high risk of complications in patients who have undergone spinal surgery and in whom a Level 1 or equivalent heparin protocol is administered. It therefore seems most prudent to arrange for placement of a vena cava filter in patients who have undergone spinal surgery and in whom a pulmonary embolus is found postoperatively. In patients who undergo spinal surgery and who require heparinization therapy for myocardial ischemia or infarction, the use of frequent neurological examinations in conjunction with anticoagulation therapy seems to be the only reasonable option.

Segmental Lumbar Lordosis

OBJECTIVES

Obliteration of end-plate landmarks by interbody fusion has made the traditional measurement of segmental lumbar lordosis nearly impossible. Because the L4-L5 and L5-S1 levels are most likely to be subjected to fusion procedures or arthroplasty and contribute to more than half of normal lumbar lordosis, it is crucial to identify a reproducible and accurate means of measuring segmental lordosis at these levels.

METHODS

Twelve spinal surgeons measured lordosis at L4-L5 and L5-S1 on 10 separate radiographs using three techniques for L4-L5 and four techniques for L5-S1. With use of identical radiographs, measurements first were made using a manual method and then were repeated with a computer-assisted method. Measurements were analyzed for both intraobserver and interobserver error.

RESULTS

The individual data demonstrated an intraobserver variance of 9.56 and a standard deviation of 3.092 for computerized measurements compared with 7.742 and 2.782 for manual measurements. The interobserver variance was 4.107 with a standard deviation of 2.027 for the computerized group compared with 4.221 and 2.055 for manual measurements. When analyzed as a group to evaluate interobserver error, the pooled data yielded variance of 19.235 for the computerized group and 19.117 for the manual measurements.

CONCLUSIONS

Variance calculations identified the Cobb technique and the posterior vertebral body technique as the least variable measurement techniques for the L4-L5 and L5-S1 levels, respectively; however, there was no statistical significance. In direct comparison, the manual and computer-assisted techniques were found to be statistically equivalent with similar degrees of variance. We believe that the anterior vertebral technique, which did not demonstrate a significant difference from other techniques, will prove to be the most reliable method of assessing segmental lumbar lordosis in patients before surgery, after interbody fusion, and after motion-sparing disc arthroplasty.

Posterior lumbar interbody fusion using recombinant human bone morphogenetic protein type 2 with cylindrical interbody cages

BACKGROUND CONTEXT

In a large series of human patients undergoing open anterior lumbar interbody fusion with a tapered titanium fusion cage, recombinant human bone morphogenetic protein type 2 (rhBMP-2) on an absorbable collagen sponge carrier has been shown to decrease operative time and blood loss, to promote osteoinduction and fusion and to be a safe and effective substitute for iliac crest harvesting.

PURPOSE

The purpose of the study was to determine the clinical and radiographic outcomes in patients treated for single-level degenerative lumbar disc disease with a posterior interbody fusion, using stand-alone cylindrical threaded titanium fusion cages with either autogenous bone graft or rhBMP-2 and an absorbable collagen sponge carrier.

STUDY DESIGN/SETTING

A prospective, randomized, nonblinded, 2-year pilot study at 14 investigational sites.

PATIENT SAMPLE

Between March 1999 and December 1999, 67 patients with symptomatic, single-level degenerative lumbar disc disease of at least 6 months' duration underwent a single-level posterior lumbar interbody fusion using two paired cylindrical threaded titanium fusion devices. Patients were randomly assigned to one of two groups: one (n=34 patients) received rhBMP-2 on a collagen sponge carrier; the other (n=33 patients) autogenous iliac crest bone graft.

OUTCOME MEASURES

Clinical outcomes were measured using low back and leg pain numerical rating scales, the Short Form (SF)-36, Oswestry Low Back Pain Disability Questionnaire and work status. Plain radiographs and computed tomographic scans were used to evaluate fusion at 6, 12 and 24 months after surgery.

METHODS

In this prospective nonblinded study, 67 patients were randomly assigned to one of two groups who underwent interbody fusion using two cylindrical threaded fusion cages: the investigational group (34 patients), who received rhBMP-2 on an absorbable collagen sponge, and a control group (33 patients), who received autogenous iliac crest bone graft. Clinical data were collected and analyzed by a commercial entity.

RESULTS

The mean operative time and blood loss for the investigational rhBMP-2 group was 2.6 hours and 322.8 ml, respectively. For the autograft control group, these values were 3.0 hours and 372.7 ml. The differences were not significant. Although not statistically different, at 24 months, the investigational group's fusion rate of 92.3% was higher than the control's at 77.8%. At all postoperative intervals, the mean Oswestry, back and leg pain scores and physical components of the SF-36 improved in both treatment groups compared with preoperative scores, but no significant differences were found between groups. A statistically significant difference in the change in back pain was found at 24 months for the investigational group. In the control group, two adverse events related to harvesting of the iliac crest graft occurred in two patients (6.1%).

CONCLUSIONS

This small multicenter, randomized, nonblinded trial showed few statistically significant differences between the study groups. Both groups showed comparable improvements on outcome scores. Overall results show that the use of rhBMP-2 can eliminate the need for harvesting iliac crest graft and may be an equivalent replacement for autograft for use in successful posterior lumbar interbody fusions. Further studies of the use of rhBMP-2 in posterior lumbar interbody fusion cage procedures are needed.

Posterior lumbar interbody fusion in the treatment of symptomatic spinal stenosis

Lumbar spinal stenosis is often the result of advanced degeneration of motion segments of the lumbar spine. Loss of disc height, facet displacement and hypertrophy, spondylosis, and spondylolisthesis, as well as buckling of the ligamentum flavum and annulus fibrosus, all contribute to impingement on the spinal canal and intervertebral foramen in lumbar stenosis. There is a subgroup of patients with spinal stenosis in whom the spine is unstable preoperatively or becomes destabilized following decompression who would benefit from an initial fusion procedure. Posterior lumbar interbody fusion (PLIF) addresses several aspects of the multifactorial pathophysiology responsible for spinal stenosis and may arrest the degenerative changes at the fused level. Fusion, in particular PLIF, should be considered in complex cases of lumbar spinal stenosis, most notably in patients with postlaminectomy stenosis or stenosis associated with spondylolisthesis.

Posterior lumbar interbody fusion with bioabsorbable spacers and local autograft in a series of 27 patients

Object

The goal of this prospective study was to review a series of 27 patients who underwent bilateral posterior lumbar interbody fusion with instrumented pedicle fixation and two HYDROSORB (known generically as 70:30 poly[L-lactide-co-D,L-lactide]) rectangular cages packed with locally harvested autograft at a total of 48 levels, and to assess the safety and efficacy of this novel technique. This analysis, conducted at a mean of 26 months of follow up, is the first report of a long-term evaluation of this technique. Fusion rates and clinical outcomes are presented.

Methods

A prospective clinical and radiographic review of findings in 27 consecutive patients was performed. Fusion rates and clinical outcome were assessed at 6-month intervals up to the 32-month follow-up end point. Two patients with four corresponding fusion levels were lost to follow up.

Radiographic evidence of satisfactory fusion was achieved in 42 (95.5%) of 44 levels fused. Satisfactory fusion at all levels was achieved in 23 (92%) of 25 patients. Two patients required repeated operations for treatment of symptomatic pseudarthrosis during the study period. The likelihood of all levels attaining fusion in a given patient decreased as the number of levels treated increased, which is consistent with previously published studies. Nonetheless, fusion rates per treated level were similar for patients in whom one to three levels were treated. No significant surgical complication occurred.

Conclusions

Posterior lumbar interbody fusion in which the HYDROSORB bioabsorbable implant packed with locally harvested autograft and segmental internal fixation are used appears to be an interbody fusion alternative whose efficacy is comparable with previously reported procedures.

Spinal pseudomeningoceles and cerebrospinal fluid fistulas

Spinal pseudomeningoceles and cerebrospinal fluid (CSF) fistulas are rare extradural collections of CSF that result following a breach in the dural-arachnoid layer. They may occur due to an incidental durotomy, during intradural surgery, or from trauma or congenital abnormality. The majority are iatrogenic and occur in the posterior lumbar region following surgery. Although they are often asymptomatic, they may cause low-back pain, headaches, and even nerve root entrapment. Leakage of CSF from the wound may cause a fistulous tract, which is a conduit for infection and should be repaired immediately. Diagnosis can be confirmed on clinical examination or imaging studies including magnetic resonance imaging, computerized tomography myelography, and radionuclide myelography. Treatment must be specific to each patient because the timing, size, symptoms, and location of the dural breach all affect the choice of therapy. Nonsurgical methods may be used, but more frequently operative repair is required. In this article, the authors review the diagnosis and treatment of spinal pseudomeningoceles and CSF fistulas.

Novel bioabsorbable interbody fusion spacer–assisted fusion for correction of spinal deformity

Object

The authors report the cases of 12 patients with medically refractory mechanical low-back pain and intermittent radicular symptoms in whom radiography demonstrated evidence of multilevel lumbosacral degenerative kyphotic and scoliotic deformity and spondylolisthesis.

Methods

These patients underwent multilevel posterior lumbar interbody fusion in which Macropore bioabsorbable spacers were placed. Each patient underwent at least 1 year of clinical and radiographic follow up.

Conclusions

This series illustrates the novel use of bioabsorbable interbody spacers and fusion technique for correction of spinal deformity due to advanced degenerative kyphoscoliosis and spondylolisthesis.

Applications of a resorbable interbody spacer in posterior lumbar interbody fusion

Polyhydroxy acids are a promising class of resorbable materials with potential applications in spinal surgery. One such polymer, MacroPore (MacroPore Biosurgery, Inc.), offers a balance of strength, predictable degradation, lack of stimulus of foreign body reaction, and biocompatibility with neural tissue. MacroPore can be formed into an array of shapes and can be manufactured, sterilized, and stored using conventional techniques. Limited clinical experience has been gained with resorbable implants used as load-sharing devices in a posterior lumbar interbody fusion construct.

Applications of a resorbable interbody spacer via a posterior lumbar interbody fusion technique

Polyhydroxyacids are a promising class of bioresorbable materials withpotential applications in spinal surgery. One such polymer, MacroPore (MacroPore Biosurgery Inc, San Diego, Calif), offers a balance of strength, predictable degradation, lack of stimulus of foreign body reaction, and biocompatibility with neural tissue. MacroPore can be formed into an array of shapes and can be manufactured, sterilized, and stored with conventional techniques. Limited clinical experience has been gained with bioresorbable implants that are used as load-sharing devices in a posterior lumbar interbody fusion construct.

Design and synthesis of novel 2,3-dihydro-1H-isoindoles with high affinity and selectivity for the dopamine D3 receptor

Starting from the tetrahydroisoquinoline SB-277011 1, a novel series of 5-substituted-2,3-dihydro-1H-isoindoles has been designed. Subsequent optimisation resulted in identification of 19, which has high affinity for the dopamine D3 receptor (pKi 8.3) and > or = 100-fold selectivity over other aminergic receptors. In rat studies 19 was brain penetrant with an excellent pharmacokinetic profile (oral bioavailability 77%, t1/2 5.2h).

Predictors of successful extubation in neurosurgical patients

A respiratory therapist-driven weaning protocol incorporating daily screens, spontaneous breathing trials (SBT), and prompts to caregivers has been associated with superior outcomes in mechanically ventilated medical patients. To determine the effectiveness of this approach in neurosurgical (NSY) patients, we conducted a randomized controlled trial involving 100 patients over a 14-mo period. All had daily screens of weaning parameters. If these were passed, a 2-h SBT was performed in the Intervention group. Study physicians communicated positive SBT results, and the decision to extubate was made by the primary NSY team. Patients in the Intervention (n = 49) and Control (n = 51) groups had similar demographic characteristics, illness severity, and neurologic injuries. Among all patients, 87 (45 in the Control and 42 in the Intervention group) passed at least one daily screen. Forty (82%) patients in the Intervention group passed SBT, but a median of 2 d passed before attempted extubation, primarily because of concerns about the patient's sensorium (84%). Of 167 successful SBT, 126 (75%) did not lead to attempted extubation on the same day. The median time of mechanical ventilation was 6 d in both study groups, and there were no differences in outcomes. Overall complications included death (36%), reintubation (16%), and pneumonia (9%). Tracheostomies were created in 29% of patients. Multivariate analysis showed that Glasgow Coma Scale (GCS) score (p < 0.0001) and partial pressure of arterial oxygen/fraction of inspired oxygen ratio (p < 0.0001) were associated with extubation success. The odds of successful extubation increased by 39% with each GCS score increment. A GCS score > or = 8 at extubation was associated with success in 75% of cases, versus 33% for a GCS score < 8 (p < 0.0001). Implementation of a weaning protocol based on traditional respiratory physiologic parameters had practical limitations in NSY patients, owing to concerns about neurologic impairment. Whether protocols combining respiratory parameters with neurologic measures lead to superior outcomes in this population requires further investigation.

Novel 2,3,4,5-tetrahydro-1H-3-benzazepines with high affinity and selectivity for the dopamine D3 receptor

Starting from the dopamine D3 receptor antagonist SB-277011 1, a series of 2,3,4,5-tetrahydro-1H-3-benzazepines has been identified with high affinity for the dopamine D3 receptor and selectivity over the D2 receptor. The 3-acetamido-2-fluorocinnamide derivative 20 gave high D3 receptor affinity (pKi 8.4) with 130-fold selectivity over the 2, receptor.

Pharmacological actions of a novel, high-affinity, and selective human dopamine D(3) receptor antagonist, SB-277011-A

SB-277011-A (trans-N-[4-[2-(6-cyano-1,2,3, 4-tetrahydroisoquinolin-2-yl)ethyl]cyclohexyl]-4-quinolininecarboxamide), is a brain-penetrant, high-affinity, and selective dopamine D(3) receptor antagonist. Radioligand-binding experiments in Chinese hamster ovary (CHO) cells transfected with human dopamine D(3) or D(2 long) (hD(3), hD(2)) receptors showed SB-277011-A to have high affinity for the hD(3) receptor (pK(i) = 7.95) with 100-fold selectivity over the hD(2) receptor and over 66 other receptors, enzymes, and ion channels. Similar radioligand-binding data for SB-277011-A were obtained from CHO cells transfected with rat dopamine D(3) or D(2). In the microphysiometer functional assay, SB-277011-A antagonized quinpirole-induced increases in acidification in CHO cells overexpressing the hD(3) receptor (pK(b) = 8.3) and was 80-fold selective over hD(2) receptors. Central nervous system penetration studies showed that SB-277011-A readily entered the brain. In in vivo microdialysis studies, SB-277011-A (2. 8 mg/kg p.o.) reversed the quinelorane-induced reduction of dopamine efflux in the nucleus accumbens but not striatum, a regional selectivity consistent with the distribution of the dopamine D(3) receptor in rat brain. SB-277011-A (2-42.3 mg/kg p.o.) did not affect spontaneous locomotion, or stimulant-induced hyperlocomotion. SB-277011-A (4.1-42.2 mg/kg p.o.) did not reverse prepulse inhibition deficits in apomorphine- or quinpirole-treated rats, but did significantly reverse the prepulse inhibition deficit in isolation-reared rats at a dose of 3 mg/kg p.o. SB-277011-A (2.5-78. 8 mg/kg p.o.) was noncataleptogenic and did not raise plasma prolactin levels. Thus, dopamine D(3) receptor blockade produces few of the behavioral effects characteristic of nonselective dopamine receptor antagonists. The effect of SB-277011-A on isolation-induced prepulse inhibition deficit suggests that blockade of dopamine D(3) receptors may benefit the treatment of schizophrenia.

Design and synthesis of trans-N-[4-[2-(6-cyano-1,2,3, 4-tetrahydroisoquinolin-2-yl)ethyl]cyclohexyl]-4-quinolinecarboxamide (SB-277011): A potent and selective dopamine D(3) receptor antagonist with high oral bioavailability and CNS penetration in the rat

A selective dopamine D(3) receptor antagonist offers the potential for an effective antipsychotic therapy, free of the serious side effects of currently available drugs. Using clearance and brain penetration studies as a screen, a series of 1,2,3, 4-tetrahydroisoquinolines, exemplified by 13, was identified with high D(3) affinity and selectivity against the D(2) receptor. Following examination of molecular models, the flexible butyl linker present in 13 was replaced by a more conformationally constrained cyclohexylethyl linker, leading to compounds with improved oral bioavailability and selectivity over other receptors. Subsequent optimization of this new series to improve the cytochrome P450 inhibitory profile and CNS penetration gave trans-N-[4-[2-(6-cyano-1, 2,3, 4-tetrahydroisoquinolin-2-yl)ethyl]cyclohexyl]-4-quinolinecarbo xamide (24, SB-277011). This compound is a potent and selective dopamine D(3) receptor antagonist with high oral bioavailability and brain penetration in the rat and represents an excellent new chemical tool for the investigation of the role of the dopamine D(3) receptor in the CNS.

Novel 1,2,3,4-tetrahydroisoquinolines with high affinity and selectivity for the dopamine D3 receptor

Using clearance and brain penetration studies as a screen, tetrahydroisoquinoline 3 was identified as a lead having low clearance in rats (CLb 20 ml/min/kg). Introduction of a 7-CF3SO2O- substituent into the tetrahydroisoquinoline, followed by replacement of the biphenylamido group of 3 by a 3-indolylpropenamido group gave 31, having high D3 receptor affinity (pKi 8.4) and 150 fold selectivity over the D2 receptor.

A clinical comparison of one- and two-screw odontoid fixation

OBJECT

The optimal treatment of Type II odontoid fractures is controversial. Various therapies have been used, including nonrigid immobilization, halo orthosis, posterior atlantoaxial arthrodesis, and odontoid screw fixation. Of these, odontoid screw fixation is the only treatment modality that provides immediate stabilization and preserves normal motion at C1-2. It has been suggested in cadaveric biomechanical studies that there is no advantage to using more than one screw for anterior odontoid fixation. The authors compared the clinical safety and efficacy of one- and two-screw anterior odontoid fixation.

METHODS

The authors retrospectively reviewed the medical records and radiographs of 42 consecutive patients who had undergone fixation for treatment of odontoid fractures at a single institution between 1989 and 1995. The group treated with a single screw consisted of 20 patients (11 males and nine females) with an average age of 54 years. The union rate in this group, as determined by postoperative dynamic radiographs, was 81%. The group treated with two screws consisted of 22 patients (13 men and nine women) with an average age of 64 years, whose union rate was 85%.

CONCLUSIONS

Anterior odontoid screw fixation is a safe and efficacious treatment for odontoid fractures. In the authors' experience there was no significant difference in the successful union rates achieved with either the one- or two-screw fixation techniques (81% and 85%, respectively; chi(2) = 0.09, p = 0.76).

Novel C-2 substituted carbapenem derivatives. Part IV. Synthesis and biological activity of five membered heteroaromatic derivatives

The synthesis, antibacterial activity, and stability to human dehydropeptidase-1 (DHP-1) of a novel series of (5R,6S)-6-[(1R)-1-hydroxyethyl]-2-heterocyclylcarbapen-2-em-3-carb oxylates are described. Of the compounds investigated 1,5-disubstituted pyrazol-3-yl and 3-substituted isoxazol-5-yl derivatives have the best combination of antibacterial activity and stability to DHP-1. They are particularly active against community-acquired respiratory tract pathogens and have stabilities to DHP-1 superior to that of meropenem.

Revision of anterior cervical pseudoarthrosis with anterior allograft fusion and plating

Anterior cervical discectomy and fusion is an efficacious procedure used to treat a variety of cervical spinal disorders, including spondylosis, myelopathy, herniated discs, trauma, and degenerative disc disease. Pseudarthrosis, or failure of fusion, may be the most common complication of spinal fusion procedures. Nineteen consecutive patients with symptomatic pseudarthrosis following failed anterior cervical fusions were treated with anterior cervical revision using iliac crest allografts and either the Cervical Spine Locking Plate system (10 patients) or the Trapezial Osteosynthetic Plate system (nine patients). The mean age of the nine men and 10 women undergoing treatment was 49.1 years (range 25-72 years). Eleven patients (57.9%) exhibited pseudarthrosis at one level, six (31.5%) at two levels, and two (10.5%) at three levels. The indications for revision were intractable neck pain with radiculopathy (17 patients) or myelopathy (two patients), with evidence of pseudarthrosis on plain cervical radiography as well as computerized tomography (CT) or single-photon emission computerized tomography (SPECT) scanning, or both. All eight patients evaluated with SPECT showed increased focal uptake consistent with pseudarthrosis, which was subsequently confirmed intraoperatively in all eight. The average follow-up period was 22.4 months (range 12-42 months). Solid osseous fusion was achieved over all 28 levels in all 18 patients available for follow-up review (100%). One patient died 4 months postoperatively from myocardial infarction related to preexisting coronary artery disease. There were no intraoperative complications; postoperatively, two patients (10.5%) experienced transient hoarseness. Anterior revision of failed cervical fusions using allograft interbody fusion material and anterior plating is a safe and efficacious procedure. In this series, the use of allografts avoided donor site morbidity without adversely affecting fusion rates. Rigid internal fixation was achieved by means of anterior plating without increasing surgical morbidity rates. The SPECT imaging technique has the potential to reliably confirm the diagnosis of pseudarthrosis.

Arteriovenous fistula as a complication of C1-2 transarticular screw fixation. Case report and review of the literature

A case is reported of a vertebral artery-to-epidural venous plexus fistula as a complication of posterior atlantoaxial facet screw fixation. The use of transarticular screws to stabilize the C1-2 joint has become an increasingly popular fixation technique, most notably for atlantoaxial instability due to trauma or rheumatoid disease. Despite the fact that this approach is technically challenging, there have been few reports of complications associated with C1-2 transarticular fixation. Although damage to the vertebral artery is a documented hazard of transarticular fixation at this level, a symptomatic arteriovenous fistula resulting from the procedure has not been described previously. The etiology, presentation, and treatment of this unusual complication are discussed.

Structure-activity relationships within a series of C(7)-substitutedoxyiminocephalosporins containing the C(3)-methylaminopyridiniumthiomethyl substituent. Synthesis and biological properties of BRL 57342 and some close analogues

(6R,7R)-7-[2-(2-Amino-4-thiazolyl)-2-[(Z)-[(S)-carboxy(3,4- dihydroxyphenyl)methyl]oxyimino]acetamido]-3-(1-methylaminopyri dinium-4-thiomethyl)ceph-3-em-4-carboxylate sodium salt (BRL 57342, 1f) combines excellent in vitro antibacterial potency against Gram-positive and Gram-negative bacteria, including P. aeruginosa and Acinetobacter spp., with excellent stability to extended spectrum beta-lactamases. This potency is reflected in in vivo efficacy studies.

Predictors of hospital mortality in older patients with subdural hematoma

OBJECTIVE

To identify presenting characteristics of older patients with subdural hematoma who are unlikely to survive hospitalization.

DESIGN

A retrospective cohort.

PATIENTS

All patients > or = 65 years of age hospitalized at a tertiary care center from 1985-1990 with the primary diagnosis of subdural hematoma.

MEASUREMENTS

Chart review was performed to characterize presenting clinical characteristics, hospital course, and outcome at the time of hospital discharge.

MAIN RESULTS

Of the 157 eligible patients, 42% (66/157) were > or = 80 years of age. Although 30% of patients had no recorded trauma, 54% experienced a fall before hospitalization. Twenty-six percent (47/157) of patients had been on antithrombotic therapy (14 on coumadin, two on heparin, 31 on antiplatelet agents, one on both coumadin and an antiplatelet agent). Sixty percent of patients had no focal neurologic findings, and the mean Glasgow Coma Score was 12.3 (+/- 3.6). The hematoma was considered chronic in 49% (77/157) of cases, based on time from antecedent trauma or on neuroimaging criteria. Midline shift by neuroimaging was present in 69%. Overall hospital mortality was 31% (48/157). Using logistic regression to control for other factors, level of consciousness (Glasgow Coma Score < = 7) (OR = 10.4), age > or = 80 (OR = 3.7), duration of hematoma considered acute (OR = 2.7), and craniotomy (OR = 2.6) were significantly associated with hospital mortality. Presence of focal symptoms, previous antithrombotic medication use, nature of trauma, comorbidity score, and presence of midline shift were not associated with hospital mortality.

CONCLUSIONS

Among older patients with subdural hematoma, level of consciousness, extreme old age, duration of the hematoma, and nature of the intervention were significantly associated with hospital mortality. These factors should help physicians in clinical decision making and formulation of advance directives for geriatric patients with subdural hematoma.

Synthesis and biological properties of some 3-[(N-substituted-amino)pyridinium-4-thiomethyl]-7-[2-(2-amino-thiazol- 4-yl)-2-(Z)-(methoxyimino)acetamido]ceph-3-em-4-carboxylates

The synthesis and antibacterial activity of a series of beta-lactamase stable, broad spectrum 7-[2-(2-amino-thiazol-4-yl)-2-(Z)-(methoxyimino)acetamido]-cephalo sporins, characterised by a C-3-[N-(substituted-amino)pyridinium-4-thiomethyl] group, is described. Gram-positive and Gram-negative bacteria including extended spectrum beta-lactamase-producing strains were most susceptible to the N-amino- and N-methylamino derivatives (3a) and (3b); with the exception of Pseudomonas aeruginosa, (3b) was more active in vitro and in vivo than cefpirome or ceftazidime.

Synthesis and biological activity of 3-(N-substituted pyridinium-4-thiomethyl)-7 alpha-formamido cephalosporins

The synthesis and antibacterial activity of a series of 3-(1-substituted pyridinium-4-thiomethyl)-7 alpha-formamido cephalosporins is described. All the derivatives showed good potency and stability to bacterial beta-lactamases. The antibacterial efficacy seen with the N-alkyl pyridinium substituents was enhanced by the introduction of a catecholic side chain at C-7 and by preparation of N-(substituted amino)pyridinium derivatives.

A simple test phantom for stereotactic computed tomography

An easy-to-use phantom has been constructed for checking the accuracy of a stereotactic computed tomography localization system. This phantom has been used on a commercially available stereotactic radiosurgery system. With this system, the phantom reference point, whose location is established by means of a precision measuring implement, can be localized by a computed tomography (CT) scanner with a standard deviation of measurement that is less than 0.3 mm in three orthogonal axes.

Thoracic disk herniation

Symptomatic thoracic disk herniation is unlikely to be encountered with significant frequency in clinical practice. Subtle manifestations required a high index of suspicion if the work-up is to be efficient. In the appropriate candidate, magnetic resonance imaging is the best screening tool, and it may be the only diagnostic study required. In the symptomatic patient with neurologic dysfunction or persistent pain refractory to nonsurgical therapy, surgical diskectomy is a safe and effective treatment with limited morbidity.

Fixation of fractures of the lower cervical spine using methylmethacrylate and wire: technique and results in 99 patients

Surgical stabilization of traumatic fracture-dislocations of the lower cervical spine with wire and methylmethacrylate remains a controversial procedure. Yet, the resultant immediate fixation with minimal patient morbidity seems to indicate that this method provides an ideal stabilization construct. We describe and report the outcome of a technique of posterior cervical fixation with methylmethacrylate and wire for stabilization of traumatic fractures of the lower cervical spine. Over a 12-year period, 124 fracture-dislocations of the lower cervical spine in 99 patients (mean age, 32 years; range, 15-76 years) were treated at this institution using a posterior methylmethacrylate and wire technique. Eighty-two patients had a posterior element fracture; 28 had a vertebral compression with posterior ligamentous injury; and 14 had a ligamentous injury alone. Thirty-six patients were neurologically intact upon admission, while the rest had radiculopathy or partial or complete myelopathy. Ninety-one patients were available for follow-up [mean, 18.6 months; range, 1-100 months (8.33 years)]. Eighty-eight patients (97%) had a stable fixation and 77 (85%) had resumed preoperative activity or were working but with a residual deficit. Complications included fixation failure requiring a second operation in 3 patients, nonlethal pulmonary embolism in 2 patients, lethal pulmonary embolism in 1 patient, and a superficial wound infection in 3 patients (none affected the underlying fixation construct). These results indicate that this technique is a safe, simple, and effective method for stabilizing the lower cervical spine that allows rapid patient mobility with minimal morbidity.