Subject: Spine
Title: The Use Of InQu Bone Graft Extender and Bone Marrow Aspirate Concentrate In Smokers Undergoing Spinal Fusion
Authors: John B Dietze
Introduction: The incidence of non-union for spinal fusions in smokers has been shown to be significantly higher than in the non-smoking population. The use of highly osteo-inductive BMP has significant limitations, specifically it’s contraindication for use in the cervical spine and extremely high cost. The use of InQu, a biosynthetic bone graft extender, along with autologous bone marrow aspirate concentrate (BMAC) is considered as a viable alternative to supplement inter-body graft constructs.
Methods: A retrospective chart review is undertaken on 123 smokers undergoing multilevel cervical inter-body fusions (n=67) and lumbar inter-body fusions (n=56). Follow up times range from 3 to 16 months. Patients with clinically significant pain and radiographically demonstrated non-unions were identified.
Results: Of the 123 patients surveyed, 2 patients ( 1 cervical and 1 lumbar fusion) were documented to have developed non-unions. Both of these patients underwent surgical revision procedures.
Conclusions: This review suggests that the use of a combination of InQu bone graft extender and BMAC may decrease the incidence of clinically significant non-unions in smokers undergoing spinal fusion procedures. Randomized, prospective data with standardized clinical and radiographic follow-up is needed to substantiate this.
Keywords: Bone Graft, Bone Marrow Aspirate, Fusion, Non-union
Objectives: 1. Discuss issues pertaining to challenges of obtaining spinal fusion in smokers. 2. Recognize InQu bone graft extender and BMAC as a viable option to be considered in spinal fusion operations in smokers. 3. Understand the basic physiology of how these components support bone growth.
Subject: Trauma
Title: Stinger Injury in Sports- the Real Mechanism
Authors: Albert H. Capanna
Introduction: A stinger, also called a burner or nerve pinch injury, is a neurological injury suffered by athletes, mostly in high-contact sports such as ice hockey, basketball, rugby, American football, wrestling, and roller derby.
Methods: 3-D CT Reconstruction of the cervical spine was used to discover a new mechanism of the injury.
Results: The exact mechanism of the injury is not well understood, but a stinger has been thought to be due to either stretch or compression, or a combination of both, of the brachial plexus. Most often stingers are transient injuries, but they can be serious if they are persistent or recurrent. If a player has recurrent stingers, he or she should be removed from competition until fully evaluated.
Conclusions: A new mechanism of the production of “stingers” will be presented.
Keywords: Stinger, Injury, Sports, Trauma, Nerve
Objectives: Understand what a “stinger” or “burner” is in sports. Learn of the presumed mechanism of injury and two new potential mechanisms. How to diagnose and treat the injury.
Subject: Cerebrovascular
Title: The C3 Cranial Cover
Authors: Albert H. Capanna
Introduction: In an effort to avoid additional future cranial surgery a cranial cover was developed that would accommodate small and large drains and monitor and when removed would cover the cranial defect as if a drain or monitor was not left at the primary surgery.
Methods: The C3 – Cranial Cover is a protective titanium plate designed to fit over a large variety of drains while positioned over a burr hole or craniotomy hole. It fastens to the bone with only two drill-free screws, is made at a 30 degree angle. The cover is easily manipulated to flatten over the hole and maintain the natural contours of the skull once the drain is removed.
Results: Placed at primary surgery site to provide excellent protection of the brain Provides excellent cosmetic results: eliminates pulsating scalp/hair, as well as indented scalp. Protects the brain and accommodates a large variety of drains, to include larger drains that would normally not be used in conjunction with a cranial cover. Helps avoid the Syndrome of the Trephined.
Conclusions: The C3 cranial cover eliminates need for additional cosmetic surgery-important in children and the elderly and is thus cost effective. It leads to greater patient satisfaction and saves payor money.
Keywords: Cranial, Cover, Drain, Monitor
Objectives: The use of a new cranial cover to avoid the need for further surgery. Know how to use the cover and incorporate it into their practices without difficulty.
Subject: Socioeconomic
Title: EU vs USA Procedural considerations and Impact on Device and Therapy development
Authors: Sanjay N. Misra
Introduction: Innovation and advances in patient care undergo different levels of procedures and scrutiny in the European Union nations compared with the USA. This impacts on both the safety and availability to patients. Decisions to approve drugs, biologics or devices differ but share the basic consideration for safety , performance and risk /benefit for patients.
Methods: The process for the approval of endovascular therapies is discussed. Silk stents are a flow diverting device available in the EU but unavailable in the US. These silk stents underwent the EU process however not the USA regulatory process. The approach to regulatory handling when an approved device such as this is discussed as is the response to adverse events in the context of the Wright Medical Hip arthroplasty.
Results: As an available device in the case of silk stents – without clinical performance data gathered under trial conditions safety data is gathered in clinical use. Several major cerebrovascular adverse events have been observed with the silk stent in the EU and led to MHRA warnings regarding the device. For a device to be available in USA the safety data would have been required prior to clinical availability. The Wright hip arthroplasty has an approval in both EU and the USA. However post approval registry data demonstrated device failures due to materials and design flaws. A global recall of the US based company’s product was implemented as required by law. This was doable however as European countries have different requirements the process would vary for EU companies. These findings shall also impact considerations for spine arthroplasty.
Conclusions: It is clear that the abscence of performance data and expedited development thru the premarket process and rush to market may have adverse consequences for patients. Similarly the emphasis on performance data within the US regulatory framework though burdensome from a company standpoint can be negotiated if correctly followed. Similarly the EU process shares the well defined goal for patient safety in the approval of treatments and therapies.The importance of examining performance data prior to embracing a new device or treatment and its importance is reflected in the planned changes to the European Union Medical Devices Directive in 2011.
Keywords: Regulations, Innovation, Product Development
Objectives: 1. Understand the regulatory framework for EU device development 2. Explain differences in product to market procedures between the European Union and USA. 3. Understand the impact on current patient care of procedural steps in innovation
Subject: Spine
Title: Safety and Effectiveness Concerns with Dynamic Lumbar Stabilization
Authors: Sanjay N. Misra
Introduction: The use of intervertebral dynamic spinal stabilization is currently embraced as a non fusion procedure which unlike lumbar fusion does not exacerbate adjacent level disease. The reported incidence of device failures in patients has raised biomechanical questions regarding the safety and proposed efficacy of these devices.
Methods: The clinical and biomechanical data supporting the use of systems such as Dynesys is examined. Adverse events reported in the literature, for the devices currently available for clinical use in medical practice such as Dynesys , Synthes Nfix and Stabilimax devices is reviewed.
Results: Device related failures of with fracture of the rod components has resulted in concerns regarding the biomechanics of the devices. The biomechanical testing results of the Dynesys system are discussed. The biomechanical concerns are discussed in the context of the market withdrawal of both the Medtronic Agile and Synthes Nfix devices, both of which experienced significant adverse events related to the spinal construct failure, requiring reoperation with the presumed morbidity of repeat procedures. Several other devices are currently marketed due to similarity to previously approved devices. These devices are discussed as are the biomechanical concerns and potential for failure modes related to these devices.
Conclusions: Due to the need for treatments for lumbar pain there has been a rush to embrace non fusion technologies. This is underscored by the lack of biomechanical data to validate the proposed mechanism and the absence of longterm data. The occurrence of adverse events requiring retreatment due to the biomechanical concerns raised here provides a note of caution regarding the safety and effectiveness of this family of devices.
Keywords: Spine, Non fusion, Device failure
Objectives: 1. Understand the expected modes of failure of non arthroplasty dynamic systems. 2. Recognise the absence of longterm data and its causes, for several systems with device failure 3.Be able to provide patients with a realistic expectation of outcome and potential complications.
Subject: Trauma
Title: Natural History of Low-Grade Vertebral Artery Injuries
Authors: Charles V Hatchette
Introduction: Our objective is to evaluate the natural history, current treatment, and outcomes of low-grade (grades I and II) traumatic vertebral artery injuries in a level one trauma center.
Methods: This is a retrospective chart review of a prospectively maintained trauma database at Parkland Memorial Hospital from 2003-2010. It includes patients who received a CT angiogram at the time of arrival. All patients with grades I or II vertebral artery injuries were identified. These cases were reviewed for demographics, mechanism of injury, associated injuries, vascular imaging, treatment, follow-up and outcomes.
Results: Between 2003 and 2010 a change in trauma imaging protocol to the Modified Denver Screening Criteria resulted in an increase in the number of vertebral artery injuries identified. These injuries occurred more often in men. The most common mechanism of injury was motor vehicle collision. Almost all of the vertebral artery injuries that we reviewed had an associated cervical spine fracture. Medical management and imaging follow up were variable. The majority of patients were managed on either aspirin or a combination of aspirin and plavix. The most consistent follow-up imaging consisted of a CTA at 7 days after their initial injury and at variable intervals after that. By 7 months, the majority low-grade injuries completely resolved.
Conclusions: Vertebral artery injury is often identified in trauma patients. The injuries can be dynamic either progressing or improving over serial imaging. The majority of low-grade vertebral artery injuries in this series resolved within seven months. Aspirin appears to be a safe medical therapy for low-grade vertebral injuries. Imaging follow-up at three months could determine necessity for further treatment.
Keywords: Blunt Vertebral Artery Injury
Objectives: Identify current screening criteria used to detect vertebral artery injuries, define type I and type II vertebral artery injuries, and describe the current management protocol for vertebral artery injuries
Subject: Socioeconomic
Title: Of Tugboats and Computers. Ethical and Practical Pitfalls of the EMR
Authors: Howard MD Morgan
Introduction: The EMR has been hyped by the government as a way to improve care and save money.
Methods: The medical literature composed in English was reviewed on the subject of EMR. Numerous faculty members and staff at UT Southwestern were interviewed .
Results: The medical literature is mixed on the subject of the benefits of EMR. Whether or not the EMR saves money is questionable–it may actually improve some billing practices but that does not save money. There are some ethical problems with EMR besides copy and paste which is well known–for example, “keep defects secret” and “hold harmless” clauses in the contracts. The legal consequences of EMR are still to be worked out(litigated).
Conclusions: Is this a case of the emperor without clothes?
Keywords: EMR, EHR, pitfalls, ethics
Objectives: 1. Understand some of practical pitfalls of EMR. 2. Have an idea of some of ethical issues of EMR. 3. Understand that litigation will surely come and standard of care may be impacted.
Subject: Cerebrovascular
Title: The Use of CT Angiography and CT Perfusion in the Management of Patients with Steno-occlusive Disease and Vasospasm
Authors: John B. McGowan; Caleb Feliciano; Kim Rickert; Babu Welch; Christopher Eddleman; Duke S Samson; Jonathan A. White
Introduction: Significant emphasis has been given recently to noninvasive vascular imaging modalities for diagnostic and follow-up purposes in steno-occlusive disease and vasospasm secondary to subarachnoid hemorrhage. CT perfusion (CTP) and angiography (CTA) are readily available, and can provide information about cerebral vascular and capillary level perfusion related problems in minutes. The recent introduction of a 320-detector row CT also allows acquisition of multiple low contrast dose volume scans of the entire brain to provide whole brain perfusion and dynamic vascular analysis in one examination. The objective of this presentation is to illustrate cases where the combination of CT perfusion and angiography has been significant fusion (CTP) and angiography (CTA) are readily available, and can provide information about cerebral vascular and capillary level perfusion related problems in minutes. The recent introduction of a 320-detector row CT also allows acquisition of multiple low contrast dose volume scans of the entire brain to provide whole brain perfusion and dynamic vascular analysis in one examination. The objective of this presentation is to illustrate cases where the combination of CT perfusion and angiography has been significant part of the diagnostic work-up, management decision making and follow-up of cases of steno-occlusive disease and vasospasm secondary to subarachnoid hemorrhage
Methods: Case presentation of five patients treated at the University of Texas Southwestern, Dallas, between March and December, 2010, for steno-occlusive disease and subarachnoid hemorrhage/vasospasm. Clinical and radiological findings (CTA-CTP) are correlated.
Results: We noted a definitive correlation between clinical changes and CTA/CTP findings. In certain cases, subtle CTA and CTP changes may be difficult to detect. A high index of suspicion as well as clinical correlation is needed in these cases
Conclusions: Combination of CT perfusion and CT angiography is effective in selected cases of steno-occlusive disease and vasospasm in subarachnoid hemorrhage for diagnosis, follow-up and management decision making
Keywords: CT Perfusion, stroke, steno-occlusive disease
Objectives: Understand the basic CTA-CTP processes and their interpretation, along with application of these studies to patients with steno-occlusive disease and vasospasm secondary to subarachnoid hemorrhage.
Subject: Trauma
Title: Electrical Impedance Tomography: Continuous ICU imaging for head injury and hydrocephalus
Authors: Kim H Manwaring; Preston K Manwaring; Ryan Halter
Introduction: Repeat imaging by CT or MRI in the ICU environment has become routine in detection of critical changes or therapeutic targets of surgical management. Both modalities have undesirable risks including ionizing radiation, sedation requirements, or transportation limitations. Electrical Impedance Tomography (EIT) creates an axial image of the brain which, while limited in resolution, eliminates all such risks, provides continuous imaging, and is exquisitely sensitive to cerebral edema and perfusional changes. I and my colleagues at Dartmouth Thayer School of Engineering have developed a bench and swine model to investigate these strengths toward human trials for the improved management of head injury, hydrocephalus and stroke.
Methods: Methods: An external ventricular drain incorporating an ICP sensor at its tip is a central electrode in an array including 7 circumferential scalp electrodes. Impedance measurements 30 times per second of all combinations creates an impedance tomogram where the 50 kHz very low current passes transcranial among electrodes. Upon completion of bench models, 4 swine were so instrumented. Effects of hyper- and hypoventilation, mannitol, injection of IV blood, and inflation of a parenchymal 1 cm balloon were monitored in real time in anesthetized animals, followed by monitoring of circulatory arrest and termination with KCL injection.
Results: Results: The continuous axial tomogram allows immediate detection of physiologic shifts of intracranial hypertension, relief by mannitol, decreased perfusion with IVH, and loss of blood flow with circulatory arrest. Coupled with ICP, a real time compliance map of the brain is achieved. Evolving mass effect can be observed in real time.
Conclusions: Conclusions: As a method of advanced ICP monitoring, EIT is a promising imaging technology to detect deteroriation of the brain related to evolving mass effect from edema or hemorrhage. EIT can show immediate regionalized or global loss of perfusion. Axial rendering of brain compliance is a sensitive tool to improve therapeutic interventions. The method is easily adapted to the surgical and ICU environment based on the EVD as a central electrode. Sensitivity to critical changes for head injury, hydrocephalus, and stroke management appears practical.
Keywords: head trauma, ICP, continous tomographic imaging
Objectives: 1) understand the principle of electrical impedance impedance imaging 2) understand the role and promise of real time brain imaging in the ICU environment 3) recall images of the effects of ICH, mannitol, mass effect, and brain death
Subject: Spine
Title: Management Of Posterior Fossa Medulloblastoma In Adults
Authors: ihab zidan; wael foad
Introduction: Medulloblastoma is a malignant invasive embryonal tumor of the cerebellum that occurs predominantly in children with a high tendency to present metastasis at diagnosis. It is rare in adults and accounts for less than 1 % of all adult primary brain tumors. It occurs in the third and fourth decade and has subtle radiological and histological differences from childhood tumor. A hemispheric location is more common in adults and the close proximity to dura gives it a few preoperative extra-axial imaging characteristics. Classic (CM) and desmoplastic (DM) are most common histological variant (3). Some differences in the presentation, prognostic factors and outcome between adults and children and between CM and DM raised the question whether there are specific features of adult or desmoplastic medulloblastoma . Many series of adult medulloblastoma have been reported. Most of them were relatively small and collected over long intervals .
Methods: : This prospective study was carried out on consecutive 12 adult patients who had posterior fossa medulloblastoma. This study was done in Alexandria hospitals over a period of 3 years starting from March 2006 to March 2009. The male to female ratio was 2 to 1(8 males and 4 females) and their ages ranged from 19 till 51 years with mean age of 33, 8 years. Headache was the most frequent symptom (93, 5 % of patients). As regard the clinical presentation, manifestations of increased intracranial pressure was found in 10 patients (83,3%), cerebellar dysfunction in 8 patients (66,6%), cranial nerve deficits in half of the cases. The tumour was hemispheric in 10 cases (6 lateral and 4 paramedian) and vermian in 2 cases. All patients had preoperative craniospinal MRI examination. All patients had no distant or spinal metastases at the time of diagnosis. All cases underwent surgery in the form of resection of the tumour followed by postoperative craniospinal irradiation. Also two patients with recurrence and metastases received adjuvant craniospinal radiotherapy and systemic chemotherapy. Mean postoperative follow up period was 22 months, including both clinical and MRI examination.
Results: There were no operative mortality, and surgery did not provoke any permanent neurological aggravation. Postoperative MRI studies showed complete tumour resection was achieved in 9 patients (75%). After initial treatment only two patients relapsed in the posterior fossa after one and half year. Recurrence was probably related to incomplete tumor resection and long delay in initiating radiotherapy (3 months after operation). Two of the patients that received adjuvant treatment died: one from distant metastasis and one from recurrent disease. Ten patients remained alive and disease-free with Karnofsky performance status ranging 80 ñ 100.
Conclusions: Adult medulloblastoma was predominant in males and the majority of patients had hemispheric cerebellar tumors. Adults are more likely to have heterogeneous cerebellar tumours on MRI, and this is thought to be related to the greater prevalence of desmoplastic variant in adulthood. Long-term survival was not uncommon. The outcome depends on the site of the tumour with better results obtained in cases with lateral hemispherical tumour that facilitate its complete surgical resection and good irradiation planning.
Keywords: adult medulloblastoma, posterior fossa, craniospinal irradiation, desmoplastic type.
Objectives: be able to differentiate between adult and children medulloblastoama. to be able to diagnose the adult medulloblastoma based on the imaging studies. to understand the way of management of adult medulloblastoma.
Subject: Spine
Title: Occipitocervical fixation in the management of craniocervical instabilities
Authors: ihab zidan
Introduction: Introduction: The occipitocervical junction presents a unique, complex, biomechanical interface between the cranium and the upper cervical spine. Occipitocervical fixation has undergone significant evolution due to advances in operative techniques and instrumentation techniques. Objective: The purpose of this study was to evaluate clinical and radiographic results of occipitocervical fusion in patients with craniocervical instabilities and to compare these results with others reported in the literature.
Methods: This retrospective study reviewed 10 patients who underwent occipitocervical fixation for craniocervical instabilities between June 2007 and June 2010 in Alexandria hospitals. There were 7 males and 3 females and their ages ranged from 16 to 63 years with mean age of 42.1 years. As regard the clinical presentation, all patients had presented with neck pain before surgery, 8 patients (80%) with myelopathy, and 7 patients (70%) had presented with a neurological deficit either motor or sensory or both. The etiologies of occipitocervical instability in our study were trauma in three patients, rheumatoid arthritis in three patients, tumor in two patients and Down syndrome in two patients. All patients had preoperative craniocervical plain X-ray, CT and MRI examination. All patients underwent occipitocervical fixation surgery with various fixation systems and autologous bone grafts for fusion. Fusion was assessed by plain cervical X-ray films and CT scan, and the neurological outcome by Frankel grade. The mean follow-up period was 14.7 months (range, 4ñ24 months) including both clinical and radiological examination
Results: There were no operative mortalities or vascular injuries in our series. Two of our patients showed transient neurological deterioration postoperatively that had resolved within three months. We had two cases with superficial wound infection and one case with cerebrospinal fluid fistula. The mean operation time was 207 min (range 130ñ320 min) and the mean volume of blood loss was 354 ml (range 120ñ750 ml). Neck pain improved in all patients and no new instability developed at adjacent levels. Regarding the Frankel grade, five patients had shown improvement (Three patients improved from Frankel grade C to grade D, one patient from Frankel grade A to grade B and one patient from Frankel grade D to grade E), while five patients remained at the same Frankel grade. A solid fusion was achieved in nine patients out of ten (90%).
Conclusions: Occiptocervical fixation is indicated in the management of cranicervical instabilities resulting from trauma, rheumatoid arthritis, tumors and congenital anomalies of the craniocervical junction. Accurate imaging studies and proper patient selection are the keys to a successful outcome. Occipitocervical fusion procedures can be performed with low morbidity. A comprehensive knowledge of the anatomy of the occipital-cervical junction is imperative. A wide variety of stabilization techniques and instrumentation systems are currently available, each of which has its own advantages and disadvantages.
Keywords: occipitocervical, fixation, craniocervical instabilities, instrumentation
Objectives: to be able to identify the indications of occipitocervical fixation. to know the different techniques of occipitocervical fixation. to be able to assess the results of occipitocervical fusion.
Subject: Pain
Title: A Novel Device and Technique for Steering Spinal Cord Stimulation Electrode
Authors: Joel D. MacDonald
Introduction: Spinal cord stimulation is an established treatment option for patients with chronic low back and leg pain due to epidural fibrosis and arachnoiditis in the aftermath of spinal surgery. Optimal benefit and durability of this therapy are linked to precise placement of the stimulator electrode in the epidural space over the nerve cell bodies of the target stimulation field. Paddle style electrodes are commonly used for this purpose but have significant inherent design limitation. The electrodes are made of flexible plastic and iare typically inserted caudal to the target level through a small laminotomy. As the electrode is advanced, directional control declines because it is pushed into position by its tail. The farther it is inserted, the more its flexibility tends to undermine precise adjustment. A novel method and device has been developed to improve precise electrode placement.
Methods: This technique has been used in 15 patients so far, including 2 patients in whom previously place electrodes were successfully revised to new locations.
Results: This method seems to significantly improve the ability to rapidly and accurately adjust lead placement in the epidural space and thereby significantly decrease operative time. No lead placement complications have been noted and discomfort related to dural manipulation seems subjectively better. This method would not be expected to overcome other typical obstacles to lead successful placement such as dense epidural fibrosis or spinal canal stenosis.
Conclusions: This technique and device appear to facilitate rapid, safe, and accurate placement of an epidural spinal cord stimulation electrode.
Keywords: Dorsal Column Stimulation, Epidural Electrode, Surgical Technique
Objectives: Participants will be able to discuss the obstacles to optimal epidural electrode placement. Participants will be able to discuss a novel method for positioning an electrode. Participants will be able to discuss the advantages of optimal electrode placement.
Subject: Socioeconomic
Title: Neurosurgery in Vietnam
Authors: Ha Duong; Andrew S Levy
Introduction: Neurosurgery in Vietnam prestents many challenges.
Methods: Dr. Ha will present information regarding neurosurgery training, conditions and systems of care.
Results: There are approximately 300 neurosurgeons in Vietnam, but only 100 have full training and capabilities. There are three major neurosurgery centers servicing a population of 86 million. The neurosurgery department Viet Duc Hospital in Hanoi was founded in 1956 as the first neurosurgery department in Vietnam, and serves the city of 8 million people, and the surroinding region, totalling 20 million. Simple trauma and hematoma surgery can be performed at Provincial hospitals, but all complex neurosurgical patients require transfer to one of the major centers, in Hanoi, Danang, or Ho Chi Minh City.
Conclusions: Neurosurgery in Vietnam is developing, and can benefit from additional training and resources.
Keywords:
Objectives: The participants will understand the challenges facing Neurosurgeons in Vietnam. The participants will understand how they may be able to help with the development of the neurosurgery system in Vietnam. The participants will see some of the complex cases faced by neurosurgeons in Vietnam.
Subject: Functional
Title: Propofol Eliminates High Frequency Local Field Potentials
Authors: Sara Hanrahan; Talmage Egan; Bradley Greger; Paul A. House
Introduction: Propofol (2,6-di-isopropylphenol)is an intravenous sedative hypnotic whose primary effect occurs within the neocortex. It is an agonist of GABA(a) chloride channels and results in neocortical inhibition. The effects of propofol on local neocortical networks in intact animal preparations have not been well studied.
Methods: A 96 count microelectrode array was used to record action potentials and related local field potentials in three human patients and in three feline preparations. The array was implanted in the middle temporal gyrus of the human patients and recordings were performed under differing depths of anesthesia as monitored by bispectral index (BIS). The array was implanted in the frontal cortex for each feline experiment and the depth of anesthetic achieved with propofol was altered through a target controlled infusion model.
Results: In human temporal neocortex, administration of propofol resulted in a dramatic decrease in SUA firing rates concurrent with the development of large amplitude fluctuations in the LFP resembling EEG ìburstsî. Analysis of single unit action potential triggered averaged LFP (SUA-LFP) is suggestive of a fixed relationship of the SUA to the background LFP. This relationship is more easily demonstrated in the anesthetized state. In feline cortex, the administration of propofol also resulted in the development of large amplitude LFP fluctuations, resembling those seen in human, concurrent with the expected decrease in SUA firing rates. The relationship of the SUA to the LFP as seen in the SUA-LFP, however, remained phase locked across several levels of global responsiveness.
Conclusions: Propofol was shown to cause a profound decrease in single unit firing rates and alteration of LFP activity in intact human and feline neocortex. The relationship of SUA to LFP both across different levels of arousal and different depths of anesthesia appears to potentially be phaselocked. A fixed relationship of SUA to LFP activity suggests a direct mechanism to explain decreased information processing capabilities produced as anesthetic dose is increased. As LFP signal becomes slower and of increased magnitude, individual neurons become capable of firing only at rates directly modulated by the LFP. This severe entrainment of possible action potential firing rates would essentially eliminate rate dependent information encoding or processing.
Keywords: Propofol, Epilepsy, Cosciousness
Objectives: Discuss how propofol suppresses neuronal activity and how this likely relates to consciousness. Discuss how the neuronal recordings help explain why propofol is used to break status epilepticus. Discuss how propofol is clinically used to create a state of “burst suppression”.
Subject: Trauma
Title: Interrupted Pharmacologic Thromboprophylaxis Increases Venous Thromboembolism in Traumatic Brain Injury
Authors: Andrew S Levy
Introduction: Pharmacologic thromboprophylaxis (PTP) is frequently withheld, begun late, or interrupted in patients with traumatic brain injury (TBI). The purpose of this study was to determine whether late or interrupted PTP increases the risk of venous thromboembolism (VTE) following TBI.
Methods: We retrospectively studied patients with blunt TBI and stable head CT scans who were admitted to two Level I trauma centers. PTP use was analyzed as an independent risk factor for VTE using separate logistic regression models for each definition of PTP use: 1. Administration of PTP; 2. Timing of PTP [early (< 72 hours) vs. late (≥ 72 hours)]; 3. Continuous vs. interrupted use of PTP.
Results: 480 TBI patients were identified. VTE occurred in 15 patients (3.13%). VTE developed in six patients despite early PTP (5.56%), four patients with late PTP (2.72%), and five with no PTP (2.22%). Neither administration of PTP nor timing of PTP were independent predictors of developing a VTE (PTP vs. none: OR=0.36, p=0.18; early PTP vs. late PTP: OR=2.00, p=0.41). PTP was administered continuously in 188 patients (73.7%). Patients with interrupted PTP had a significant increased odds of developing VTE compared to patients with continuous PTP (OR=7.07, p=0.04). Ambulation before discharge significantly decreased the odds of developing a VTE (OR=0.19, p=0.02).
Conclusions: Interrupted administration of PTP in patients with TBI is associated with significantly increased risk of VTE. These findings underscore the importance of continuous PTP administration, and every effort should be made to avoid interruption if possible.
Keywords: Pharmacologic thromboprophylaxis, traumatic brain injury, thromboembolism, Coagulation
Objectives: Understand the issues related to PTP use in patients with TBI. Understand that interruption of PTP may increase teh risk of VTE in patients with TBI.
Subject: Trauma
Title: Abrupt Discontinuation of Statin Therapy Significantly Increases Complications and Mortality Following Traumatic Brain Injury
Authors: Andrew S Levy
Introduction: Patients aged 55 and older are commonly on statin therapy and are at higher risk for traumatic brain injury (TBI) than their younger counterparts. There is a paucity of research investigating how pre-injury statin (PIS) use and its abrupt discontinuation affects outcomes following TBI. The purpose of this study is to determine whether PIS use and abrupt statin discontinuation would significantly improve and worsen outcomes, respectively, following TBI.
Methods: Patients aged 55 and older, who were admitted to two Level 1 Trauma Centers in the Denver metro area, with a diagnosis of a blunt TBI, and whom had a hospital length of stay (LOS) greater than or equal to three days were studied. Patients were analyzed with respect to PIS use, and whether or not statins were continued after admission. The main outcome measures included hospital LOS (≤1 week vs. >1 week), in-hospital complications, and in-hospital mortality.
Results: There were 302 consecutively admitted trauma patients aged 55 and older, who were diagnosed with a blunt TBI, and whom had a hospital length of stay (LOS) greater than or equal to three days. PIS users who discontinued statin therapy after admission had over 20-times the adjusted odds of both having at least one in-hospital complication and dying in-hospital, compared to PIS users who continued statin therapy (OR=21.45, p=0.04, OR=20.97, p=0.02, respectively); no differences were seen in the adjusted odds associated with LOS. Our data did not demonstrate that PIS use in and of itself significantly changed the odds of having shorter hospital LOS, having at least one in-hospital complication or in-hospital mortality.
Conclusions: Our results suggest that the discontinuation of statin therapy in PIS users aged 55 and older suffering a blunt TBI significantly increases the odds of experiencing at least one in-hospital complication and mortality. The continuation of statin therapy in PIS users appears to be an important factor in the prevention of in-hospital mortality and complications in this population. Additional studies are needed to confirm these findings and to see if PIS in and of itself may have a beneficial effect on outcome in patients with TBI.
Keywords: Statin therapy, TBI, outcomes
Objectives: To understand the importance of continuing statin therapy for patients admitted with TBI.
Subject: Tumor
Title: Predictors Of Patient Outcome And Response To Therapy after Stereotactic Radiosurgery or Radiotherapy For Meningiomas: Emphasis on Biomarker Discovery.
Authors: Randy L. Jensen; Dennis C Shrieve
Introduction: We explore outcomes of patients with intracranial meningiomas treated with stereotactic radiotherapy (SRT) or radiosurgery (SRS) in regards to patient and treatment characteristics, tumor histology and hypoxia-related biomarker analysis.
Methods: Outcomes of 162 patients with 166 intracranial meningiomas treated with 172 treatments of either SRT (80 treatments) or SRS (92 treatments) were prospectively collected and reviewed. Median follow-up was 36 months. Patient gender, age, tumor volume, tumor grade, prior therapies, and select set of tumor hypoxia-regulated biomarkers were correlated with tumor local control and overall survival. Median tumor volumes for SRS treated patients was 2.72 cm3 (range 0.8-43.4) treated to a median dose of 1500 cGy and 12.54cm3 (range 0.5-78.85) treated to median of 5400 cGy for SRT patients. Histology was available in 78 patients, 48 WHO I, 27 WHO II, and 3 WHO III. Tissue was available for immunohistological biomarker analysis in 52 patients (20 receiving SRT and 32 SRS) for Hypoxia-inducible factor-1 (HIF-1), vascular endothelial growth factor (VEGF), glucose transporter-1 (Glut-1), and carbonic anhydrase-IX (CA-IX). We also examined this tissue for microvascular density (MVD) and proliferative index using MIB-1 staining.
Results: Ten patients received more than one treatment session; six patients for recurrent disease and 4 for separate tumors. Local control was 68/77 (88.3%) for SRT treated patients and 80/89 (89.9%) for SRS treatment. Six SRS failures and 2 SRT failures required surgery, 2 were pre-SRS mistaken for metastatic disease. There was no correlation between tumor volume and local control. The majority of treatment failures occurred in patients with WHO II tumors. In fact, tumor histology, which correlated with MIB-1 staining, was predictive of both progression-free survival (PFS) and overall survival (OS). Lower VEGF score, MIB-1 index <5 and MVD <50 are correlated with better long-term survival after SRT treatment while only MIB-1 index < 5 predicts SRS outcome. Thirty-three patients were treated with surgery before SRT, with SRT used as a salvage therapy in 13 patients as a post-op adjuvant in 20. Sixty patients were treated with surgery before SRS, with 25 treated up front and 35 as salvage therapy. There was no statistical difference in local control between adjuvant and salvage therapy in either group.
Conclusions: SRS and SRT are very successful in controlling intracranial meningioma growth. Tumor histology appears to be the best predictive marker for response to stereotactic radiation therapy but some of our other markers show promise. Our study is limited by low numbers of treatment failures and with longer follow-up more correlations may be found.
Keywords: survival, meningioma,radiation,biomarkers
Objectives: 1. Understand radiation treatment characteristics that favor local control and patient survival 2. Determine if hypoxia-regulated biomarkers predict patient outcome after radiation treatment of meningiomas 3. Review the role of tumor grade on response to radiation treatment.
Subject: Tumor
Title: Differential Scanning Calorimetry of Cerebrospinal Fluid, glioma and meningioma cells lines, and patient tumor samples: Preliminary analysis and correlation with tumor histology.
Authors: Randy L. Jensen
Introduction: Thermal stability signatures of complex molecule interaction in biological fluids can be measured using a new approach called differential scanning calorimetry (DSC). The thermal stability of plasma proteome has been described previously as a method of producing a disease-specific ìsignature,î termed thermogram, in several neoplastic and autoimmune diseases. We describe the preliminary use of DSC performed on cerebrospinal fluid (CSF) as a diagnostic tool for the identification of patients with glioblastoma multiforme (GBM). Furthermore, we use this technique on cell cultures and human tumor tissue samples to create unique ìsignaturesî for correlation with histological tumor classification.
Methods: Methods: Samples of CSF from nine patients with confirmed GBM were evaluated using DSC, and the thermogram signatures evaluated. These thermograms were compared with thermograms of CSF taken from patients with non-neoplastic conditions such as head trauma, hydrocephalus, or CSF leak. Further analysis was also performed on CSF from patients who had non-GBM neoplastic conditions such as carcinomatosis meningitis or central nervous system lymphoma or leukemia. With these established techniques we then used the same technique to examine cell lines (3 GBM and 2 meningioma) and brain tumor tissue samples (10 GBM, 5 oligodendrogliomas, 5 low grade astrocytomas, and 10 meningiomas) with confirmed histological diagnosis.
Results: The DSC thermograms of CSF of the patients with GBM were significantly different when compared with other neoplastic and non-neoplastic cases. The melting temperature of the major transition was shifted by 5∞C, which makes it easily distinguishable from control cases. DSC profiles of glioma and meningioma cell lines are distinctly different. Brain tumor sample analysis correlates with the cell line work with distinct GBM, oligodendroglioma, low-grade astrocytoma, and meningioma ìsignaturesî
Conclusions: Our results are very preliminary, but it appears that the DSC of CSF has potential utility in diagnostics and monitoring disease progression in GBM patients. DSC of processed tumor samples seems to display unique ìsignaturesî for different brain tumor histological classifications.
Keywords: Calorimetry, diagnosis, biomarker, signatures
Objectives: 1. To determine if differential scanning calorimeter of cerebrospinal fluid from patients with GBM can predict response to therapy. 2. Review if DSC of tumor samples correlates with tumor histology 3. Discuss the potential use of DSC for diagnosis of brain tumor and predict patient outcome
Subject: Tumor
Title: Predicting outcome of patients with oligodendroglioma: Hypoxia-regulated biomarker, proliferative index, and microvascular density versus UCSF low-grade scoring system
Authors: Randy L. Jensen
Introduction: Predicting outcome for patients with oligodendrogliomas and anaplastic oligodendrogliomas (AO) at present is limited to 1p/19q chromosomal deletions. Despite this important tumor marker, patient outcome and response to treatment is highly variable, especially in the case of the lower-grade oligodendroglioma. Hypoxia-Inducible Factor-1a (HIF-1a) is a transcription factor that controls many glycolytic genes including carbonic anydrase IX (CA-IX), glucose transporter-1 (Glut-1) and angiogenic proteins like Vascular endothelial growth factor (VEGF). We examine whether the expression of HIF-1 alpha and hypoxia-regulated protein expression can predict overall survival (OS) and progression-free survival (PFS) of patients with oligodendrogliomas and AO. Furthermore we correlated this data for patients with oligodendrogliomas with a previously published preoperative scoring system that has been validated in low-grade gliomas.
Methods: We prospectively collected tissue samples and followed outcomes of patients with oligodendrogliomas and anaplastic oligodendroglioma (AO). Tumor tissues were immunohistochemically stained for VEGF, CA-IX ,GLUT-1, HIF-1, MIB-1 (proliferation index) and MVD (microvascular density). These tumor markers were correlated with patient PFS and OS. We retrospectively analysed preoperative imaging and clinical data on these patients based on the UCSF scoring system (good prognostic indicators include: age < 50, KPS > 80, tumor diameter < 4 cm, non-eloquent tumor location) and correlated this to tumor immunohistochemical markers.
Results: We examined a total of 57 patients with oligodendrogliomas (ages 23-73, 27 female, 30 male) and 27 with AO (age range 29-73, 13 female, 14 male). HIF-1a, CA-IX and VEGF correlate with tumor histology. We have correlated tumor markers with an initial subset of 28 patients with oligodendrogliomas and found correlatation with the preoperative grading system. OS and PFS will be examined in relation to expression of these proteins in our final analysis.
Conclusions: Immunohistochemical markers of hypoxia-regulated proteins might add addition prognostic information for patients with oligodendrogliomas concerning OS and PFS.
Keywords: outcome, survival, oligodendroglioma, hypoxia
Objectives: 1. Determine if outcomes of patient with oligodendrogliomas can be predicted by biomarker expression 2. Compare these biomarkers against a published low grade glioma scoring system 3. Explore the role of hypoxia-regulated proteins in oligodendroglioma patient outcome
Subject: Tumor
Title: Comparison of Surgical Dissection Modalities
Authors: Chin Steven; Joel D. MacDonald
Introduction: A variety of tools exist to facilitate surgical tissue dissection. Several modalities utilize thermal properties to combine both cutting and coagulation capabilities. We compared the tissue effects of a few established devices to a novel device that employs ferromagnetic induction heating. This technology does not depend on the passage of electrical current through the patient and therefore may have unique application for neurosurgery.
Methods: Parallel incisions were randomly created in each of the three liver lobes of two adult rabbits using Bovie (monopolar) electrocautery, CO2 laser (Omni), Harmonic scalpel, Plasma (PEAK), and ferromagnetic induction heating (FM). During each incision, subjective coagulation, tissue drag, linearity, and edge uniformity were recorded. Tissue harvest was conducted immediately following surgery. Liver specimens were prepared for standard hematoxylin and Eousin staining and were independently reviewed by a surgical pathologist who was blinded to the cutting modalities. Histological effects were characterized and a schema for injury severity was developed.
Results: Each of the cutting modalities demonstrated effective coagulation capabilities but FM cutting caused less cellular damage to liver tissue than the other technologies. Subjective tissue cutting characteristics appear to be similar to the cut mode of monopolar cautery.
Conclusions: Ferromagnetic induction heating produces effective tissue cutting and capability in rabbit liver. Subjective tissue dissection characteristics appear to be comparable to monopolar electrocautery. Because this technology does not require electrical current to pass through the patient, it may have unique applications in neurosurgery.
Keywords: Monopolar cautery, Coagulation, Surgical technique
Objectives: Participants will be able to discuss histological effects of thermal tissue cutting modalities. Participants will be familiar with cellular injury due to thermal tissue dissection. Participants will be familiar with ferromagnetic induction heating for surgical dissection.
Subject: Pediatrics
Title: Thrid Ventriculostomy to Treat Obstructive Hydrocephalus in a Case of Vein of Galen Malformation
Authors: Charles V Hatchette
Introduction: Vein of Galen aneurysmal malformations are rare congenital lesions associated with high rates of mortality and morbidity. These lesions are often associated with hydrocephalus, which is most commonly treated by the placement of a ventriculoperitoneal shunt. Placing shunts in patients with VGAM is, however, known to have high complication rates, including seizures, Interventricular hemorrhage, and subdural fluid collections. The treatment of hydrocephalus by endoscopic third ventriculostomy in patients with VGAM has been suggested, and to our knowledge, however, such a treatment has never been reported for the pediatric population. Here we report the treatment of hydrocephalus in a pediatric patient with a VGAM as a treatment option in selected cases.
Methods: This is the description of a selected case of third ventriculostomy used to treat obstructive hydrocephalus in patient with a Vein of Galen Malformation
Results: This case report demonstrates the successful treatment of obstructive hydrocephalus in a selected case of Vein of Galen Malformation.
Conclusions: The pathophysiology of hydrocephalus in VGAM is multifactorial. Mechanisms include venous hypertension impeding CSF reabsorption and obstructive hydrocephalus. In the case of venous hypertension, higher venous pressure is caused by abnormally high drainage rates through the sinuses, resulting in back-pressure transmitted throughout the cortical and deep venous drainage of the brain. This increased venous pressure resists the normal flow of CSF from the subarchnoid compartment to the venous compartment. The other common mechanism of hydrocephalus is due to mass effect from the dilated vein on the cerebral aqueduct, causing obstructive hydrocephalus resulting in dilatation of the lateral and 3rd ventricles. This later etiology of hydrocephalus in these cases is seen less commonly. Ventriculoperitoneal shunts have high rates of complications in such patients, and rates as high as 70% have been reported. Endoscopic third ventriculostomy may offer some advantages over shunts in the treatment of obstructive hydrocephalus on cases of VGAM. We report this technique as an option for selected cases of hydrocephalus in VGAM, as may be demonstrated by the successful treatment in this case.
Keywords: Third Ventriculostomy, Vein of Galen Malformation
Objectives: Describe the various type of Vein of Galen Malformations, Describe the pathophysiology of Vein of Galen Malformations, Identify the different treatment options in cases of Vein of Galen Malformations
Subject: Spine
Title: Hydrostatic Comparison of Titanium Clip and Suture Repair of Durotomy
Authors: Michael Finn
Introduction: Dural tears are a frequent complications of spine surgery and can be associated with significant morbidity. Primary suture closure of durotomies is typically attempted but are associated with a 5-10% failure rate, which may be partially due to leakage through suture tracts. Non-penetrating titanium clips have been developed for vascular anastomosis and provide close tissue apposition without penetrating the tissue (Figure 1). We hypothesized that their use in closure of spinal durotomies would provide a more complete and rapid dural closure than traditional suture repair. The purpose of this study is to determine immediate hydrostatic strength of a standard durotomy closed with non-penetrating titanium clips, a monofilament suture or a braided suture.
Methods: Dural tears are a frequent complications of spine surgery and can be associated with significant morbidity. Primary suture closure of durotomies is typically attempted but are associated with a 5-10% failure rate, which may be partially due to leakage through suture tracts. Non-penetrating titanium clips have been developed for vascular anastomosis and provide close tissue apposition without penetrating the tissue (Figure 1). We hypothesized that their use in closure of spinal durotomies would provide a more complete and rapid dural closure than traditional suture repair. The purpose of this study is to determine immediate hydrostatic strength of a standard durotomy closed with non-penetrating titanium clips, a monofilament suture or a braided suture.
Results: Leakage rate increased significantly at each pressure tested for all conditions (Figure 4). There was no difference between the intact condition and the titanium clip repair at any pressure. There was significantly greater leakage than intact in both suture repair groups detected at all pressures. There was no significant difference between the suture types, although there as a trend towards greater leakage with braided compared to monofilament suture at higher pressures (p=0.110 and 0.065 at 60mmHg and 90mmHG, respectively). Clip repairs took an average of 111 seconds while suture repairs took 250 seconds, a difference which was significant.
Conclusions: The use of non-penetrating titanium dural clips provided a dural closure with immediate hydrostatic strength similar to the intact condition. Suture repairs allowed for significantly more leakage than intact and the clip repair construct. There was a trend towards greater leakage with the use of a braided suture. Dural repair with clips took approximately half as long as suture repair
Keywords: durotomy, spinal fluid leak
Objectives: The participants should be able to discuss the potential merits of durotomy clip closure.
Subject: Spine
Title: A Novel Over-the-wire System for the Decompression of Lumbar Spinal Stenosis
Authors: Ronnie I. Mimran
Introduction: Laminectomy or laminotomy with a partial resection of the posterior elements is the most common procedure for the surgical treatment of lumbar spinal stenosis. Although frequently effective for decompressing the central canal, this technique is generally less effective for decompression of the lateral recess and neural foramen. Partial or total facetectomy is required to decompress these areas, but poses the risk of immediate or delayed spinal instability. Limitations of both open and minimally invasive methods for decompression of lumbar spinal stenosis include: difficulty with rigid tools in a confined space, difficulty visualizing critical neural structures and, the inability to effectively access the impinging tissue(s) without compromising facet joint integrity. We present a flexible over-the-wire instrument system designed to address these limitations and allow for optimal access to the lateral recess and foramen.
Methods: The iO-FlexTM System (BaxanoTM Inc., San Jose, CA) is an over-the-wire technology platform that allows the surgeon to directly decompress the central canal, lateral recess and neural foramen without a facetectomy. The three step surgical technique consists of access, localization of neural tissue and decompression. Up to four neural foramen can be accessed through a single access port, thus allowing the surgeon to decompress multiple nerve roots through the same minimally invasive incision. Access is achieved through the interlaminar window using either an ipsilateral or contralateral approach. A small probe with a retracted, cannulated, guide is used to enter the epidural space. The guide tip facilitates movement through the epidural space and palpation of bony landmarks. Fluoroscopy is used to confirm probe/guide position. A guidewire is passed through the probe and exits laterally where it is secured in a distal handle. The probe is removed, leaving the wire in place. The guidewire has a proximal exchange hitch to facilitate connection to other instruments. The Neuro CheckTM device is a flexible, 4mm ribbon that contains electrical current stimulus coupled with electromyography (EMG) feedback to discern the location of neural tissue in relation to the device. Proper placement of the probe, followed by confirmation with the Neuro CheckTM device ensures safe placement of the subsequent decompression device. Once the proper location has been identified, the Neuro CheckTM device is removed and the MicroBlade ShaverTM instrument is pulled into place using the distal handle. The shaver contains small cutting blades on the dorsal surface, capable of bone and ligament excision. The ventral surface is smooth to protect surrounding tissue. A bimanual reciprocating motion is used to remove target tissue.
Results: Lateral fluoroscopic images are taken prior to bimanual reciprocation and also following bimanual reciprocation with the MicroBlade ShaverTM instrument. Comparison of these images allow the surgeon to determine when sufficient direct decompression has been achieved.
Conclusions: Current methods of addressing lumbar spinal stenosis in the lateral canal may lead to instability. Posterior element resection (>30%) can lead to increases in motion and substantial increases in intradiscal pressures, contributing to accelerated disc degeneration. Optimal decompression using traditional rigid instruments can leave the spine unstable and incomplete decompression can fail to alleviate patient symptoms. The iO-FlexTM system provides an over-the-wire flexible platform that allows the surgeon to easily reach the neural foramen, maximizing the potential for a complete decompression while minimizing the risk of instability.
Keywords: Lumbar Spinal Stenosis, Minimally-Invasive Surgery, Lumbar Decompression, Laminotomy
Objectives: 1. Discuss published peer-reviewed clinical literature related to lumbar spinal stenosis and iatrogenic instability. 2. Understand a new technique for lumbar decompression utilizing a flexible microblade shaver instrument. 3. Review clinical pre-clinical and clinical data for MIS decompression utilizing a flexible microblade shaver instrument.
Subject: Trauma
Title: Treatment of Chronic and Acute Bone Flap Infections with Antibiotic Impregnated Cranioplasty
Authors: Richard H. Schmidt
Introduction: Traditional management of infected bone flaps entails their complete removal and leaving them out for a period of three to six months to assure adequate sterilization of the affected area. This subjects the patient to at least two separate surgeries and a prolonged period of time with a cranial deflect.
Methods: We now report our experience with ten patients over a three year time period who in all cases were successfully managed with a single stage surgery using an antibiotic impregnated cranioplasty construct. Three additional patients had adequate wound healing and cranial reconstruction using just bare titanium mesh. In all cases the infected bone flap or area of osteomyelitis was excised, soft tissues adequately debrided and appropriate systemic antibiotics used, generally for 10-14 days post op.
Results: Several patients previously had chronically recurring infections with draining fistulae and one patient had such extensive scalp loss a vascularized latissumas dorsi free-flap was required at the time of surgery. The cranioplasties were performed using a base of titanium mesh coated with multiple layers of antibiotic impregnated methylmethacrylate as needed to provide the desired contour. Methacrylate powder was mixed in the OR with vancomycin or vancomycin plus meropenem depending on the microbial cultures. Follow up currently ranges from three years to ten months and complete healing has been demonstrated by clinical exam, lab data and serial imaging with contrast enhanced CT or MRI in all cases.
Conclusions: Antibiotic impregnated methylmethacrylate has been shown to elute a high local concentration of antibiotics for up to several weeks after implantation and this mechanism likely explains its success even in very difficult cases. If further experience validates these results, the management of both acute and chronic bone flap infections may be significantly improved with this method.
Keywords: osetomyelitis, bone flap infection, cranioplasty
Objectives: Describe a new method for single stage treatment of acute or chronic bone flap infections, in which debridement and permanent recontruction are done simultaneously. Describe the long term results of treating bone flap infections with antibiotic impregnated cranioplasty