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Biomedical subjects

Michael L J Apuzzo

Publications and source records attributed to Michael L J Apuzzo.

At least 37 records · Page 2Linked to original sources
PubMed2004

Analysis and evolution of head injury in football.

OBJECTIVE: To review head injury in football through historical, anatomic, and physiological analysis. METHODS: We obtained data from a thorough review of the literature. RESULTS: The reported incidence of concussion among high school football players dropped from 19% in 1983 to 4% in 1999. During the 1997 Canadian Football League season, players with a previous loss of consciousness in football were 6.15 times more likely to experience a concussion than players without a previous loss of consciousness (P < 0.05). Players with a previous concussion in football were 5.10 times more likely to experience a concussion than players without a previous concussion (P = 0.0001). With the implementation of National Operating Committee on Standards for Athletic Equipment standards, fatalities decreased by 74% and serious head injuries decreased from 4.25 per 100,000 to 0.68 per 100,000. CONCLUSION: Significant declines in both the incidence and severity of head injury have been observed. The enhanced safety records in football can be attributed to the application of more stringent tackling regulations as well as the evolving football helmet. The role of a neurosurgeon is critical in further head injury prevention and guidelines in sport.

Adolescent↗
PubMed2004

Birth and evolution of the football helmet.

OBJECTIVE: To review the advent and evolution of the football helmet through historical, physiological, and biomechanical analysis. METHODS: We obtained data from a thorough review of the literature. RESULTS: Significant correlation exists between head injuries and the advent of the football helmet in 1896, through its evolution in the early to mid-1900s, and regulatory standards for both helmet use and design and tackling rules and regulations. With the implementation of National Operating Committee on Standards for Athletic Equipment standards, fatalities decreased by 74% and serious head injuries decreased from 4.25 per 100,000 to 0.68 per 100,000. Not only is the material used important, but the protective design also proves essential in head injury prevention. Competition among leading helmet manufacturers has benefited the ultimate goal of injury prevention. However, just as significant in decreasing the incidence and severity of head injury is the implementation of newer rules and regulations in teaching, coaching, and governing tackling techniques. CONCLUSION: Helmet use in conjunction with more stringent head injury guidelines and rules has had a tremendous impact in decreasing head injury severity in football. Modifications of current testing models may further improve helmet design and hence further decrease the incidence and severity of head injury sustained while playing football.

Athletic Injuries↗
PubMed2004

Vagus nerve stimulation therapy after failed cranial surgery for intractable epilepsy: results from the vagus nerve stimulation therapy patient outcome registry.

OBJECTIVE: To determine the effectiveness of vagus nerve stimulation (VNS) therapy among patients with persistent or recurrent seizures after lobar resection, callosotomy, and other cranial operations for intractable epilepsy. METHODS: Data were obtained from the VNS therapy patient outcome registry, which was established after United States Food and Drug Administration approval of the VNS device in 1997 as a means of capturing open-label clinical data outside of protocol. The integrity of the systems for collecting and processing registry data was authenticated by an independent auditing agency. The effect of potential selection bias, however, remains uncertain. RESULTS: Two nonconsecutive cohorts were compared: patients tracked in the registry who had previously undergone cranial surgery for epilepsy (CS group, n = 921) and those who had not (non-CS group, n = 3822). For the CS group, the median reduction in seizure frequency was 42.5% after 3 months of VNS therapy, 42.9% at 6 months, 45.7% at 12 months, 52.0% at 18 months, and 50.5% at 24 months. For the non-CS group, analogous rates were 47.0%, 52.9%, 60.0%, 62.7%, and 66.7%, respectively. In the CS group, seizures were reduced by at least 50% in 55.1% of patients, at least 75% in 31.4% of patients, at least 90% in 17.3% of patients, and 100% in 5.1% of patients after 24 months of VNS therapy. Response rates were more pronounced in the non-CS group: at least 50% in 62.2% of patients, at least 75% in 43.7% of patients, at least 90% in 26.8% of patients, and 100% in 8.3% of patients. Patients in both groups experienced marked improvements in quality of life parameters. CONCLUSION: The effectiveness of VNS is maintained during prolonged stimulation, and overall seizure control continues to improve with time. Patients in whom prior cranial surgery had failed did not respond as favorably as all other patients receiving VNS therapy. Nonetheless, many of the former group improved substantially. Thus, on the basis of these open-label data, VNS therapy represents a potentially palliative treatment option for patients with refractory seizures after failed cranial surgery.

Adolescent↗
PubMed2004

An anthropomorphic phantom study of the accuracy of Cyberknife spinal radiosurgery.

OBJECTIVE: Stereotactic radiosurgery requires the highest degree of accuracy in target identification and localization. When targeting paraspinal lesions, the CyberKnife radiosurgical system (Accuray, Inc., Sunnyvale, CA) uses implanted stainless steel fiducials. The purpose of this study was to evaluate the total system for clinically relevant accuracy of this approach. METHODS: The clinically relevant accuracy of the CyberKnife depends on 1) the accuracy of beam delivery, which in turn represents a compilation of robot and camera image-tracking errors, and 2) the inherent accuracy of target localization that stems from computed tomographic imaging and treatment planning. The clinically relevant accuracy was measured at three different CyberKnife facilities using head and torso phantoms loaded with packs of radiochromic film and expressed as a displacement of the dose contours from the treatment planning. RESULTS: The mean clinically relevant error, as measured at three different CyberKnife facilities, was determined to be 0.7 +/- 0.3 mm, which did not vary with computed tomographic slice thickness in a range of 0.625 to 1.5 mm. The average treatment delivery precision was 0.3 +/- 0.1 mm. Fiducial tracking error was less than 0.3 mm for radial translations up to 14 mm and less than 0.7 mm for rotations up to 4.5 degrees. CONCLUSION: For the treatment of relatively stationary spinal lesions targeted with fiducial tracking, the CyberKnife system is capable of submillimeter accuracy.

Humans↗
PubMed2003

Radiotherapy and stereotactic radiosurgery for pituitary tumors.

Based on a review of the literature and our medical center experience, we believe that transphenoidal surgery is the procedure of choice in most patients with pituitary adenomas. Conversely, SRS is a procedure of choice for those with cavernous sinus involvement. Patients with incomplete surgical excision should be considered either for a planned stereotactic treatment or for external beam radiotherapy. The same applies to patients with recurrent tumors. We favor stereotactic treatment in patients who have tumors that are less than 35 mm in diameter and at least 3 mm from the chiasm or optic nerves. Other patients should be considered for three-dimensional conformal radiotherapy. Radiotherapy provides a good treatment alternative in those patients who either refuse surgery or have contraindications to this therapy. Contemporary radiotherapy and SRS for pituitary adenomas is safe and effective treatment. This treatment should be undertaken in medical centers with appropriate expertise and instrumentation.

Humans↗
PubMed2003

Artificial niches for human adult neural stem cells: possibility for autologous transplantation therapy.

Cellular transplantation therapy is thought to play a central role in the concept of restorative neurosurgery, which aims to restore function to the damaged nervous system. Stem cells represent a potentially renewable source of transplantable cells. However, control of the behavior of these cells, both in the process of clonogenic expansion and post-transplantation, represents formidable challenges. Stem cell behavior is thought to be directed by extracellular signals in their in vivo niches, many of which are protein or peptide based. As only one example, activation of Notch plays an important role in normal development and is the strongest known signal for stem cells to choose glial over neuronal fates. Therefore, artificial extracellular matrix proteins represent a potentially powerful tool to custom design artificial niches to strategically control stem cell behavior. We have developed a family of aECM proteins that incorporate the active domains of the DSL ligands to the Notch receptor into an elastin-based backbone. The development of our DSL-elastin artificial proteins demonstrates the design strategy and methodology for the production of bioactive artificial extracellular matrix proteins aimed at modulating stem cell behavior, and this method can be used to design other bioactive aECM proteins. In addition, we have developed a method for the isolation and characterization of adult human neural stem cells from periventricular tissue harvested from living patients. This paper reviews cellular transplantation therapy from the clinical perspective and summarizes ongoing work aimed at exploring the intriguing possibility of autologous transplantation, whereby neural stem cells can be harvested from adult patients, expanded or modified in vitro in artificial niches, and retransplanted into the original patient.

Adult↗
PubMed2003

The genesis of neurosurgery and the evolution of the neurosurgical operative environment: part I-prehistory to 2003.

Despite its singular importance, little attention has been given to the neurosurgical operative environment in the scientific and medical literature. This article focuses attention on the development of neurosurgery and the parallel emergence of its operative setting. The operative environment has, to a large extent, defined the "state of the art and science" of neurosurgery, which is now undergoing rapid reinvention. During the course of its initial invention, major milestones in the development of neurosurgery have included the definition of anatomy, consolidation of a scientific basis, and incorporation of the practicalities of anesthesia and antisepsis and later operative technical adjuvants for further refinement of action and minimalism. The progress, previously long and laborious in emergence, is currently undergoing rapid evolution. Throughout its evolution, the discipline has assimilated the most effective tools of modernity into the operative environment, leading eventually to the entity known as the operating room. In the decades leading to the present, progressive minimalization of manipulation and the emergence of more refined operative definition with increasing precision are evident, with concurrent miniaturization of attendant computerized support systems, sensors, robotic interfaces, and imaging devices. These developments over time have led to the invention of neurosurgery and the establishment of the current state-of-the-art neurosurgical operating room as we understand it, and indeed, to a broader definition of the entity itself. To remain current, each neurosurgeon should periodically reconsider his or her personal operative environment and its functional design with reference to modernity of practice as currently defined.

History, 15th Century↗
PubMed2003

The genesis of neurosurgery and the evolution of the neurosurgical operative environment: part II--concepts for future development, 2003 and beyond.

The future development of the neurosurgical operative environment is driven principally by concurrent development in science and technology. In the new millennium, these developments are taking on a Jules Verne quality, with the ability to construct and manipulate the human organism and its surroundings at the level of atoms and molecules seemingly at hand. Thus, an examination of currents in technology advancement from the neurosurgical perspective can provide insight into the evolution of the neurosurgical operative environment. In the future, the optimal design solution for the operative environment requirements of specialized neurosurgery may take the form of composites of venues that are currently mutually distinct. Advances in microfabrication technology and laser optical manipulators are expanding the scope and role of robotics, with novel opportunities for bionic integration. Assimilation of biosensor technology into the operative environment promises to provide neurosurgeons of the future with a vastly expanded set of physiological data, which will require concurrent simplification and optimization of analysis and presentation schemes to facilitate practical usefulness. Nanotechnology derivatives are shattering the maximum limits of resolution and magnification allowed by conventional microscopes. Furthermore, quantum computing and molecular electronics promise to greatly enhance computational power, allowing the emerging reality of simulation and virtual neurosurgery for rehearsal and training purposes. Progressive minimalism is evident throughout, leading ultimately to a paradigm shift as the nanoscale is approached. At the interface between the old and new technological paradigms, issues related to integration may dictate the ultimate emergence of the products of the new paradigm. Once initiated, however, history suggests that the process of change will proceed rapidly and dramatically, with the ultimate neurosurgical operative environment of the future being far more complex in functional capacity but strikingly simple in apparent form.

Forecasting↗
PubMed2003

Vagus nerve stimulation therapy for patients with persistent seizures after epilepsy surgery.

BACKGROUND: This study reports the effectiveness of vagus nerve stimulation (VNS) among patients who failed cranial surgery for intractable epilepsy. METHODS: Data were obtained from the Cyberonics VNS therapy patient outcome registry. The integrity of the systems for collecting and processing registry data was authenticated by an independent auditing agency. RESULTS: Two nonconsecutive cohorts were compared: patients who had had prior cranial surgery (CS group, n = 921) and those who had not (non-CS group, n = 3,822). For the CS group, the median reduction in seizure frequency was 42.5% after 3 months of VNS therapy, 42.9% at 6 months, 45.7% at 12 months, 52.0% at 18 months and 50.5% at 24 months. For the non-CS group, analogous rates were 47.0, 52.9, 60.0, 62.7 and 66.7%, respectively. CONCLUSION: The effectiveness of VNS is maintained during prolonged stimulation. Patients who failed prior cranial surgery did not respond quite as favorably as all other patients receiving VNS therapy.

Electric Stimulation Therapy↗
PubMed2003

Endovascular restorative neurosurgery: a novel concept for molecular and cellular therapy of the nervous system.

The amalgam of molecular biology and neurosurgery offers immense promise for neurorestoration and the management of neurodegenerative deficiencies, developmental disorders, neoplasms, stroke, and trauma. This article summarizes present strategies for and impediments to gene therapy and stem cell therapy of the central nervous system and advances the concept of a potential new approach, namely endovascular restorative neurosurgery. The objectives of gene transfer to the central nervous system are efficient transfection of host cells, selective sustained expression of the transgene, and lack of toxicity or immune excitation. The requisite elements of this process are the identification of candidate diseases, the construction of vehicles for gene transfer, regulated expression, and physical delivery. In the selection of target disorders, the underlying genetic events to be overcome, as well as their spatial and temporal distributions, must be considered. These factors determine the requirements for the physical dispersal of the transgene, the duration of transgene expression, and the quantity of transgene product needed to abrogate the disease phenotype. Vehicles for conveying the transgene to the central nervous system include viral vectors (retroviruses, lentiviruses, adenoviruses, adeno-associated viruses, and herpes simplex virus), liposomes, and genetically engineered cells, including neural stem cells. Delivery of the transgene into the brain presents several challenges, including limited and potentially risky access through the cranium, sensitivity to volumetric changes, restricted diffusion, and the blood-brain barrier. Genetic or cellular therapeutic agents may be injected directly into the brain parenchyma (via stereotaxy or craniotomy), into the cerebrospinal fluid (in the ventricles or cisterns), or into the bloodstream (intravenously or intra-arterially). The advantages of the endovascular route include the potential for widespread distribution, the ability to deliver large volumes, limited perturbation of neural tissue, and the feasibility of repeated administration.

Animals↗
PubMed2003

Virtual reality surgery: neurosurgery and the contemporary landscape.

OBJECTIVE: Virtual reality-simulated environments have been used for the training of personnel, most notably for military applications, for more than 35 years. The advantages conferred by being able to train novice personnel in a low- to no-risk simulated environment have long been appreciated by the medical community. The recent availability of affordable gigahertz-range microprocessors (once the exclusive domain of the Cray supercomputer) has made photorealistic graphical rendering and manipulation of virtual surgical substrates a reality. Concomitant advances in artificial intelligence systems and the portability of patient-specific magnetic resonance imaging, computed tomographic scanning, and angiographic image data presage the emergence of the surgical simulator as a modern surgical training adjunct. An overview of the status of surgical simulation with regard to its adaptability to current surgical training regimens is presented. METHODS: Extensive MEDLINE, Internet, and other database searches spanning the years 1960 to 2002 were conducted in an effort to delineate the status of simulated surgical environments. RESULTS: As would be expected, most articles addressing surgical simulation as their primary focus have been published in the past decade. A review of this literature demonstrates the broadest application in the field of endoscopic (and laparoscopic) procedures, most likely as a result of the reduced engineering burden with respect to incorporation of a haptic interface. CONCLUSION: The realization of ergonomically acceptable haptic interfaces remains elusive. Improvements in graphical rendering and the incorporation of artificial intelligence functions signal the certain emergence of surgical simulators as a viable supplement to the Halstedian method of surgical training.

Humans↗
PubMed2003

Fetal radiation doses for model C gamma knife radiosurgery.

OBJECTIVE: To assess fetal radiation doses in a pregnant patient undergoing gamma knife stereotactic radiosurgery (GKRS) and to quantify the components of extracranial radiation doses by means of phantom measurements. METHODS: A patient in her 25th week of pregnancy received GKRS with the Model C gamma knife for a solitary metastatic melanoma of the brain. A single isocenter with the 14-mm collimator and trunnions was used to deliver 20 Gy to the lesion defined to the 80% isodose line. Fetal radiation doses were assessed with phantom measurements before GKRS and then measured during GKRS. In addition, doses to the lateral canthi, thyroid, sternum, and pelvis were monitored with thermoluminescent dosimeters in 20 consecutive patients during their GKRS. Phantom measurements were also performed to identify extracranial radiation doses to these structures. RESULTS: Fetal radiation doses were 0.31, 0.20, and 0.15 cGy to the top, middle, and bottom of the uterus, respectively. These approximately corresponded to 0.01% of the maximum tumor dose of 25 Gy. The mean extracranial doses in 20 patients were 36.9, 5.8, 3.3, and 0.6 cGy to the lateral canthi, thyroid, sternum, and pelvis, respectively. Phantom measurements supported the results obtained from the patient measurements and further refined estimates of doses to extracranial sites. These measurements were also compared with those of a previously reported study with the use of the Model U. CONCLUSION: Measured radiation doses in a pregnant patient to extracranial sites, including those to the fetus, were very low. We think that GKRS is a safe treatment, particularly with the Model C, and could be recommended to carefully selected patients with brain metastases who are in the second and third trimester of pregnancy.

Adult↗
PubMed2003

Gamma knife radiosurgery for pituitary adenoma: early results.

OBJECTIVE: In recent years, gamma knife radiosurgery (GKRS) has emerged as an important treatment modality in the management of pituitary adenomas. Treatment results after performing GKRS and the complications of this procedure are reviewed. METHODS: Between 1994 and 2002, a total of 78 patients with pituitary adenomas underwent a total of 84 GKRS procedures in our medical center. This patient group comprised 46 men (59%) and 32 women (41%). All patients were treated for recurrent or residual disease after surgery or radiotherapy, with 83% presenting with extensive tumor involvement. The cavernous sinus was involved in 75 patients (96%), and 22 patients (28%) had hormone-secreting adenomas. This latter subset of patients included 12 prolactinomas (15%), 6 growth-hormone secreting tumors (8%), and 4 adrenocorticotropic hormone-secreting tumors (5%). The median tumor volume was 2.3 cm(3), and the median radiation dose was 15 Gy defined to the 50% isodose line. The mean and median follow-up periods were 41 and 36 months, respectively. RESULTS: GKRS was tolerated well in these patients; acute toxicity was uncommon and of no clinical significance. Late toxicity was noted in three patients (4%) and consisted of VIth cranial nerve palsy. In two patients, there was spontaneous resolution of this palsy, and in one patient, it persisted for the entire 3-year duration of follow-up. Of the 15 patients who presented with cranial nerve dysfunction, 8 (53%) experienced complete recovery and 3 (20%) showed major improvement within 12 months of therapy. Tumor volume reduction was slow, with 30% of patients showing decreased tumor volume more than 3 years after undergoing GKRS. None of the 56 patients with nonfunctioning tumors showed progression in the treated volume, and 4 (18%) of the 22 hormone-secreting tumors relapsed (P = 0.008). Of the four patients with adrenocorticotropic hormone-secreting adenomas, therapy failed in two of them. All six patients with growth hormone-producing tumors responded well to therapy. Of the 12 patients with prolactinomas 10 (83%) had normalization of hormone level and 2 patients experienced increasing prolactin level. Two patients with prolactinomas had three normal pregnancies after undergoing GKRS. CONCLUSION: GKRS is a safe and effective therapy in selected patients with pituitary adenomas. None of the patients in our study experienced injury to the optic apparatus. A radiation dose higher than 15 Gy is probably needed to improve control of hormone-secreting adenomas. Longer follow-up is required for a more complete assessment of late toxicity and treatment efficacy.

Adenoma↗
PubMed2003

Dosimetric comparison of CyberKnife with other radiosurgical modalities for an ellipsoidal target.

OBJECTIVE: To compare treatment plans obtained with the CyberKnife (CK) (Accuray, Inc., Sunnyvale, CA) with those of other commonly used radiosurgical modalities, such as the gamma knife (GK), linear accelerator multiple arcs, conformally shaped static fields, and intensity-modulated radiotherapy (IMRT). METHODS: An ellipsoidal simulated target was chosen centrally located in a three-dimensional model of a patient's head acquired with magnetic resonance or computed tomographic imaging. It was 25 mm in diameter and 35 mm long. The aims of treatment plans were 100% target volume coverage with an appropriate isodose line, minimum radiation dose to normal tissue, and clinically acceptable delivery. These plans were evaluated by use of a dose-volume histogram and other commonly used radiosurgical parameters such as target coverage, homogeneity index, and conformity index. RESULTS: All selected treatment modalities were equivalent in providing full target coverage. For dose homogeneity, all modalities except for multiple isocenter plans for GK (homogeneity index, 2.0) were similar (homogeneity index, congruent with 1.25). Dose conformity was essentially equivalent for all treatment plans except for IMRT, which had a slightly higher value (conformity index, congruent with 1.27). There was a substantial variation in the radiation dose to normal tissue between the studied modalities, particularly at the lower dose levels. CONCLUSION: CK plans seemed to be more flexible for a given target size and shape. For a target of limited volume and essentially of any shape, one could obtain similarly good conformal dosimetry with CK and GK. For a regular-shaped but other than spherical target, homogeneous dose distribution could be obtained with all selected modalities except for multiple isocenters, linear accelerator multiple arcs, or GK. Both IMRT and conformally shaped static fields offered good alternative treatment modalities to CK, GK, or linear accelerator multiple arc radiosurgery, with slightly inferior dosimetry in conformity (IMRT).

Brain Neoplasms↗
PubMed2003

Engineering of the extracellular matrix: working toward neural stem cell programming and neurorestoration--concept and progress report.

In the concept of neurorestoration, cellular and structural elements that have been lost are replaced, and their function is restored. Central to this therapeutic strategy is the transplantation of neural progenitor cells such as clonogenically expanded stem cells. Stem cells make decisions regarding fate and patterning in response to external environmental signals. The therapeutic effectiveness of neural stem cells may be facilitated by the ability to manipulate these signals in a temporal and spatially appropriate fashion. Artificial deoxyribonucleic acid and artificial protein technology combines elements of protein engineering, molecular biology, and recombinant deoxyribonucleic acid technology to produce proteins with functional domains derived from naturally occurring proteins and represents a potentially powerful tool to modulate stem cell behavior. To this end, we have developed three artificial extracellular matrix proteins that incorporate the active domain of hJagged1 and hDelta1 into an elastin backbone. hJagged1 and hDelta1 are members of the DSL family of ligands to the Notch receptor, a signaling system that is very important in development and is the strongest known signal to instruct neural progenitor cells to choose glial fates over neuronal fates. The successful cloning of the artificial genes was confirmed by test digestions with appropriate restriction enzymes as well as direct deoxyribonucleic acid sequencing. In addition, we have demonstrated that all three artificial extracellular matrix proteins express at a high level in a prokaryotic host. This report describes the concept and progress in an entirely novel and previously unreported approach to modulate neural stem cell behavior. Its future application could include in vitro processing of stem cells before transplantation, supporting and programming the cells after transplantation, as well as the development of bioactive biomaterials.

Cell Physiological Phenomena↗