bluuebunny/crossref_metadata_2025 huggingface dataset:
Pediatric spinal deformities
Authors: Wiggins Gregory C. , Shaffrey Christopher I. , Abel Mark F. , Menezes Arnold H.
Published: January 2008

Pediatric spinal deformity results from multiple conditions including congenital anomalies, neuromuscular disorders, skeletal dysplasia, and developmental disorders (idiopathic). Pediatric spinal deformities can be progressive and cause pulmonary compromise, neurological deficits, and cardiovascular compromise. The classification and treatment of these disorders have evolved since surgical treatment was popularized when Harrington distraction instrumentation was introduced.

The advent of anterior-spine instrumentation systems has challenged the concepts of length of fusion needed to arrest curvature progression. Segmental fixation revolutionized the surgical treatment of these deformities. More recently, pedicle screw–augmented segmental fixation has been introduced and promises once again to shift the standard of surgical therapy. Recent advances in thoracoscopic surgery have made this technique applicable to scoliosis surgery.

Not only has surgical treatment progressed but also the classification of different forms of pediatric deformity continues to evolve. Recently, Lenke and associates proposed a new classification for adolescent idiopathic scoliosis. This classification attempts to address some of the shortcomings of the King classification system.

In this article the authors review the literature on pediatric spinal deformities and highlight recent insights into classification, treatment, and surgery-related complications.
Atlantooccipital dislocation in children: presentation, diagnosis, and management
Authors: Steinmetz Michael P. , Lechner Roseanna M. , Anderson James S.
Published: January 2008

Atlantooccipital dislocation (AOD) injuries are highly unstable, and usually result in significant neurological injury and death. Recently the postinjury survival period has increased. In a review of the literature the authors found 41 cases in which survival was greater than 48 hours. This is likely due to improved on-scene resuscitation, spinal immobilization, transportation, new diagnostic techniques, and a higher index of suspicion.

Diagnosis is usually made with plain cervical radiographs, but there are shortcomings associated with this modality in the pediatric population. Diagnosis is aided by high-resolution computerized tomography and magnetic resonance imaging. Infants and toddlers may undergo orthotic immobilization alone, whereas older children usually undergo early occipital cervical fusion. Those with incomplete AOD may be managed successfully with orthotic immobilization.
Evaluation of factors predicting accurate resection of high-grade gliomas by using frameless image-guided stereotactic guidance
Authors: Benveniste Ronald , Germano Isabelle M.
Published: January 2008

Object

Frameless image-guided stereotaxy is often used in the resection of high-grade gliomas. The authors of several studies, however, have suggested that brain shift may occur intraoperatively and result in inaccurate resection. To determine the usefulness of frameless stereotactic image-guided surgery of high-grade gliomas, the authors correlated factors predictive of brain shift, such as tumor size, periventricular location, and patient age (as an indicator of brain atrophy) with the extent of resection.

Methods

Inclusion criteria included the following: 1) stereotactic volumetric craniotomy for resection of tumor; 2) histologically proven high-grade glioma; 3) preoperative magnetic resonance (MR) imaging demonstration of an enhancing portion of tumor; 4) postoperative MR imaging within 48 hours to assess the extent of resection; and 5) preoperative intention to perform gross-total resection of the enhancing tumor. Fifty-four patients met these criteria between September 1997 and November 2002. Accurate resection was considered to be indicated by a lack of nodular enhancement on postoperative Gd-enhanced MR images obtained within 48 hours of surgery.

Frameless stereotactic image-guided surgery resulted in the successful resection of 46 (85%) of 54 high-grade gliomas. Accurate resection was significantly more likely with tumors less than 30 ml in volume than with those greater than 30 ml (93 and 58%, respectively [p < 0.05]). In addition, small periventricular tumors were associated with significant less successful resection compared with nonperiventricular tumor (77 and 96%, respectively [p = 0.5]). Patient age did not affect the likelihood of successful resection.

Conclusions

Frameless image-guided stereotactic techniques can be reliably used for accurate resection of high-grade gliomas when the tumor is less than 30 ml in volume and not adjacent to the ventricular system. In cases involving tumors larger in volume or located near the ventricles, intraoperative ultrasonography or MR imaging updates should be considered.
Coregistered intraoperative ultrasonography in resection of malignant glioma
Authors: Nikas Dimitrios C. , Hartov Alexander , Lunn Karen , Rick Kyle , Paulsen Keith , Roberts David W.
Published: January 2008

Object

The authors present their experience with coregistration of preoperative imaging data to intraoperative ultrasonography in the resection of high-grade gliomas, focusing on methodology and clinical observation.

Methods

Images were obtained preoperatively and coregistered to intraoperative hand-held ultrasound images by merging the respective imaging coordinate systems. After patient registration and imaging calibration, the authors computed the location on the magnetic resonance (MR) space of each pixel on an ultrasound image acquired in the operating room. The data were retrospectively reviewed in 11 patients with high-grade gliomas who underwent ultrasonography-assisted resection at our institution between June 2000 and December 2002.

Satisfactory coregistration of intraoperative ultrasound and preoperative MR images was accomplished in all cases. Ultrasound and MR image data were closely congruent. Preoperative setup and intraoperative use of the system were unencumbering.

Conclusions

Based on these preliminary results, intraoperative ultrasonography is an attractive neuronavigational alternative, by which a less expensive and constraining imaging technique is used to acquire updated information. Optimal intraoperative guidance can be provided by the integration of this with other imaging studies.
Cerebral Revascularization
Authors: Nussbaum Eric S.
Published: January 2008

Despite decades of critical analysis, the precise indications for cerebral revascularization remain poorly defined. It is clear that some patients undergoing therapeutic carotid artery (CA) sacrifice for the management of unclippable intracranial aneurysms or skull base neoplasms will require revascularization to prevent or reduce the risk of cerebral infarction.4,11 Nevertheless, the decisions of when to perform this procedure and what type of bypass to undertake in these cases remain debated. The question of whether revascularization should be conducted in cases involving ischemic disease is even more controversial.1–3,5,8

This issue of Neurosurgical Focus is devoted to the topic of cerebral revascularization, assembling a collection of articles from noted experts in this field. The papers address many of the challenging and important issues yet to be defined in this controversial area.
Thyrocervical trunk–external carotid artery bypass for positional cerebral ischemia due to common carotid artery occlusion
Authors: Melgar Miguel A. , Weinand Martin E.
Published: January 2008

Medically refractory positional cerebral ischemia and concomitant orthostatic hypotension associated with chronic common carotid artery (CCA) occlusion are rare. The authors detail their experience with three cases treated exclusively by an extracranial bypass in which the thyrocervical trunk was used as the donor vessel. Postoperatively grafts were patent and symptoms resolved in all three patients, although orthostatic hypotension remained. Postural cerebral ischemia due to CCA occlusion can be treated by extracranial bypass surgery. The thyrocervical trunk is a suitable donor for reconstruction of the external carotid artery in these cases.
Noninvasive intracranial compliance and pressure based on dynamic magnetic resonance imaging of blood flow and cerebrospinal fluid flow: review of principles, implementation, and other noninvasive approaches
Authors: Raksin Patricia B. , Alperin Noam , Sivaramakrishnan Anusha , Surapaneni Sushma , Lichtor Terry
Published: January 2008

Current techniques for intracranial pressure (ICP) measurement are invasive. All require a surgical procedure for placement of a pressure probe in the central nervous system and, as such, are associated with risk and morbidity. These considerations have driven investigators to develop noninvasive techniques for pressure estimation. A recently developed magnetic resonance (MR) imaging–based method to measure intracranial compliance and pressure is described. In this method the small changes in intracranial volume and ICP that occur naturally with each cardiac cycle are considered. The pressure change during the cardiac cycle is derived from the cerebrospinal fluid (CSF) pressure gradient waveform calculated from the CSF velocities. The intracranial volume change is determined by the instantaneous differences between arterial blood inflow, venous blood outflow, and CSF volumetric flow rates into and out of the cranial vault. Elastance (the inverse of compliance) is derived from the ratio of the measured pressure and volume changes. A mean ICP value is then derived based on a linear relationship that exists between intracranial elastance and ICP. The method has been validated in baboons, flow phantoms, and computer simulations. To date studies in humans demonstrate good measurement reproducibility and reliability. Several other noninvasive approaches for ICP measurement, mostly nonimaging based, are also reviewed. Magnetic resonance imaging–based ICP measurement may prove valuable in the diagnosis and serial evaluation of patients with a variety of disorders associated with alterations in ICP.
The role of stereotactic radiosurgery for low-grade astrocytomas
Authors: Hadjipanayis Costas G. , Kondziolka Douglas , Flickinger John C. , Lunsford L. Dade
Published: January 2008

Object

This study was conducted to examine the role of radiosurgery in the management of patients with recurrent or unresectable low-grade astrocytomas.

Methods

During a 13-year interval, 49 patients underwent stereotactic radiosurgery as part of multimodal treatment of their recurrent or unresectable low-grade astrocytomas. Thirty-seven of these patients (median age 14 years) harbored pilocytic astrocytomas and 12 patients harbored World Health Organization (WHO) Grade II fibrillary astrocytomas (median age 25 years). Tumors involved the brainstem in 22 cases, cerebellum in four, thalamus in six, temporal lobe in five, frontal lobe in four, and parietal lobe in three, as well as the hypothalamus, corpus callosum, insular cortex, optic tract, and third ventricle in one patient each. Each diagnosis was confirmed with the aid of stereotactic biopsy sampling in 17 patients, open biopsy sampling in five, partial resection in 13, and near-total resection in 14. Multimodal treatment included fractionated radiotherapy in 14 patients, stereotactic intracavitary irradiation in five, chemotherapy in two, cyst drainage in eight, ventriculoperitoneal shunt placement in five, and additional cytoreductive surgery in five. Tumor volumes ranged from 0.42 to 45.1 cm3. The median radiosurgical dose to the tumor margin was 15 Gy (range 9.6–22.5 Gy).

After radiosurgery, serial neuroimaging demonstrated complete tumor resolution in 11 patients, reduced tumor volume in 12, stable tumor volume in 10, and delayed tumor progression in 16. No procedure-related death was encountered. Forty-five of 49 patients are alive at a median follow-up period of 32 months after radiosurgery and 63 months after diagnosis. Sixteen patients participated in follow-up review for more than 60 months. Three patients died of local tumor progression.

Conclusions

Stereotactic radiosurgery is a potential alternative or adjunctive intervention in the management of selected patients with pilocytic or WHO Grade II fibrillary astrocytomas, usually performed for small-volume tumors in an attempt to avoid larger-field fractionated radiotherapy.
Foramen magnum meningiomas: concepts, classifications, and nuances
Authors: Boulton Melfort R. , Cusimano Michael D.
Published: January 2008

Foramen magnum meningiomas represent a common histological tumor in a rare and eloquent location. The authors review the clinical presentation, relevant anatomical details of the foramen magnum region, neuroimaging features, the posterior and posterolateral surgical approaches for resection, and outcomes. Based the experiences of the senior author (M.D.C.) and a review of the literature, they introduce the concept of a “surgical corridor,” discuss the classification of these tumors, and the nuances of care for patients with these challenging lesions.
Tuberculum sellae meningiomas
Authors: Chi John H. , McDermott Michael W.
Published: January 2008

Tuberculum sellae meningiomas are a classic tumor of the anterior fossa that present in patients with gradual visual deterioration secondary to optic apparatus compression. If untreated, complete blindness can occur. Treatment involves tumor removal and decompression of the optic chiasm via several operative approaches. Gross-total resection (Simpson Grade I or II) is the goal of treatment and can usually be accomplished safely. Special excision-related considerations include appreciation of arachnoid planes separating the tumor from neural tissue, adequate drilling of osseous elements for optimal exposure, and intraoperative preservation of the vascular supply to the optic apparatus. The authors reviewed their experience at the University of California, San Francisco, in cases of tuberculum sellae meningiomas treated between 1992 and 2002. In most patients, improvement of vision can be achieved with minimal postoperative complications and morbidity.
Magnetic resonance spectroscopy of atypical diffuse pontine masses
Authors: Krieger Mark D. , Blüml Stefan , McComb J. Gordon
Published: January 2008

Object

Diffuse pontine gliomas in children carry a dismal prognosis, with a mean survival of less than 1 year despite therapy. The diagnosis is based on the characteristic changes demonstrated on traditional magnetic resonance (MR) imaging. A few typically MR imaging–appearing pontine masses, however, do not behave in the expected fashion, which calls the original diagnosis into question.

Methods

The authors conducted a retrospective review of data obtained in 42 children (age 6 months–13 years) in whom diffuse pontine glioma had been diagnosed at their institution. Five of these patients (12%) survived longer than expected (> 8 months). There were no differences in these patients in terms of demographics, presentation, traditional imaging findings, or treatment compared with the group as a whole. Magnetic resonance spectroscopy, however, demonstrated two distinct patterns not seen in typical diffuse pontine gliomas. In two patients elevated lipid and lactate levels were shown, with decreased levels of choline, myoinositol, and n-acetyl-aspartate (NAA). In the other patients strikingly elevated choline/creatinine ratios and myoinositol levels were observed in comparison with typical pontine tumors.

Conclusions

These MR spectroscopy patterns demonstrated in this retrospective study seem to convey prognostic information and may lead to an expansion of this diagnostic tool.
Neurological manifestation of sacral tumors
Authors: Payer Michael
Published: January 2008

An extensive analysis of the existing literature concerning sacral tumors was conducted to characterize their clinical manifestations. Although certain specific manifestations can be attributed to some of the tumor types, a more general pattern of clinical presentation of an expansive sacral lesion can be elaborated. Local pain with or without pseudoradicular or radicular radiation is the most frequent initial symptom and is usually followed by the manifestation of a lumbosacral sensorimotor deficit; bladder/bowel and/or sexual dysfunction appear throughout the natural course of disease.
Embolization of sacral tumors
Authors: Gottfried Oren N. , Schmidt Meic H. , Stevens Edwin A.
Published: January 2008

The management of sacral tumors is challenging because of difficulties in accessing the lesion, the high rate of local recurrence, extensive vascularity causing significant intraoperative blood loss, resistance to radiation therapy, and risk of malignant transformation. Although surgery is the main treatment for many sacral tumors, embolization is a valuable primary and adjunctive therapy. Patients with benign lesions, including aneurysmal bone cysts and giant cell tumors, have responded to embolization with resolution of their symptoms and with ossification of their lesions. Embolization is used as a primary therapy for metastatic lesions and results in neurological improvement, reduced tumor size, and decreased spinal canal compromise. It is also used as an adjuvant therapy to reduce intraoperative blood loss and to aid in the resection of benign, malignant, and metastatic sacral lesions. It is important to note that embolization techniques are a valuable resource in the treatment of sacral tumors, and, overall, embolization should always be considered in patients with sacral tumors.
Surgical techniques for total sacrectomy and spinopelvic reconstruction
Authors: Zhang Ho-Yeol , Thongtrangan Issada , Balabhadra Raju S. V. , Murovic Judith A. , Kim Daniel H.
Published: January 2008

The surgical management of sacral tumors requires partial or total sacrectomy and spinopelvic reconstruction. These lesions present a great surgical challenge, because most spine surgeons are unfamiliar with the techniques required for these procedures. The authors describe a step-by-step operative technique and provide several illustrations.

Total sacrectomy is performed by sequential anterior and posterior approaches that involve a rectus abdominis pull-through pedicle flap reconstruction. The anterior procedure is an intraperitoneal approach used to expose the anterior aspect of the tumor, to ligate the main tumor vessels, and to conduct an anterior partial sacrectomy. After this, the rectus abdominis myocutaneous flap, based on the inferior epigastric vessel, is prepared, and a posterior sacrectomy is performed, dividing all sacral nerve roots in the thecal sac. After complete en bloc extirpation of the sacrum with tumor, spinopelvic reconstruction and closure with a myocutaneous flap are performed. Spinopelvic reconstruction is undertaken using a modified Galveston technique or double iliac screw fixation combined with posterior lumbar segmental fixation. These provide a long lever arm within the ilium to counteract the forces exerted by the lumbar spine.

Understanding the nature of the disease as well as the biomechanics of the lumbosacral pelvic area and spinopelvic fixation will help surgeons select the appropriate treatment for sacral tumors.
Radiosurgery and radiotherapy for sacral tumors
Authors: Gibbs Iris C. , Chang Steven D.
Published: January 2008

Sacral tumors represent a small subset of spinal lesions and typically include chordomas, metastases, other primary bone tumors, and benign schwannomas. Resection is the standard treatment for many sacral tumors, but many types of sacral lesions have the potential for recurrence after excision. In these cases, adjuvant radiotherapy is often beneficial. Although conventional radiotherapy plays an important role in the management of spinal lesions, the radiation doses required for adequate local control of many sacral lesions generally exceed the tolerance doses of normal tissues, thus limiting its definitive role in the management of sacral tumors. Recent advances in the field of stereotactic radio-surgery have allowed precise targeting of the sacrum. In this report the authors review the use of these two forms of radiation treatment and their role in managing sacral tumors.
Complications of revision spinal surgery
Authors: Eichholz Kurt M. , Ryken Timothy C.
Published: January 2008

Surgical treatment for symptomatic cervical and lumbar spondylosis has become prevalent in recent years. With this increased intervention, increasing numbers of patients experience persistent symptoms and require revision spinal surgery. Although many aspects of the workup and operation are similar for both primary and revision surgery, there are special considerations that must be examined when determining if a patient is a candidate for revision surgery.

Preoperative workup should include evaluation for spinal instability. Intraoperatively, scar tissue may complicate the procedure, and care must be taken to avoid incidental durotomy. The prognosis for a revision surgery can be predicted best by the patient's outcome after the primary surgery. As with any surgical procedure, patient selection is imperative for successful outcome.
Revision surgery for chiari malformation decompression
Authors: Mazzola Catherine A. , Fried Arno H.
Published: January 2008

Chiari malformations comprise four different hindbrain anomalies originally described by Hans Chiari, a professor of pathology at the German University in Prague. There are four basic Chiari malformations. The reasons for revision of Chiari malformation decompression may be for conservative or inadequate initial decompression or the development of postoperative complications. Another reason involves cases of both hindbrain herniation and syringomyelia in patients who have undergone adequate posterior fossa decompression without resolution of symptoms, signs, or radiological appearance of their syrinx cavity. Additionally, symptom recurrence has been reported in association with various types of dural grafts. Reoperation or revision surgery for patients with Chiari malformations is common and may not be due to technical error or inadequate decompression. The types of revision surgeries, their indications, and initial presentations will be reviewed.
Laminoplasty for the treatment of failed anterior cervical spine surgery
Authors: Wang Michael Y. , Green Barth A.
Published: January 2008

Object

Cervical stenotic myelopathy can be treated via anterior or posterior approaches. In anterior cervical decompression and fusion (ACDF), because the risks and likelihood of pseudarthrosis increase with the number of treated segments, attempts are typically made to limit the number of treated levels. Thus, postoperative recurrence of myelopathy following ACDF may occur because stenotic levels were not treated or because adjacent segments have degenerated. Revision decompressive surgery via an anterior approach is one solution; however, if the stenosis involves multiple levels a posterior decompressive laminoplasty can be performed as an alternative.

Methods

Twenty-four cases treated over an 8-year period were identified and data were retrospectively reviewed. In 15 cases posterior decompressive surgery was necessary because of progressive spinal degeneration and stenosis (five cases following initial treatment for radiculopathy, seven after initial treatment for spondylotic myelopathy, and three due to spreading of an ossified posterior longitudinal ligament). In nine cases revision surgery was undertaken because the initial decompression was inadequate.

The mean follow-up period after the second surgery was 16 months. Improvements in myelopathy were seen in 83% of patients (mean improvement of 1.25 points on the Nurick Scale). Preoperative severe gait disorders were associated with poor recovery. Complications included two cases of transient C-5 nerve root palsy and two cases of new persistent axial neck pain.

Conclusions

Laminoplasty is a straightforward and effective treatment for failed ACDF due to inadequate decompression or progressive degeneration of the spinal column, avoiding reentry through scar tissue. In terms of myeolpathic pain, the recovery rate is comparable with that related to revision ACDF.
Reliability assessment of computerized tomography scanning measurements in intracerebral hematoma
Authors: Bhattathiri Parameswaran S. , Gregson Barbara , Manjunath Prasad Kuskoor S. , Mitchell Patrick , Soh Calvin , Mitra Dipayan , Gholkar Anil , Mendelow Alexander D.
Published: January 2008

Object

As one of the aspects of the International Surgical Trial in Intracerebral Haemorrhage (STICH), prerandomization computerized tomography (CT) scans were collected. In the present study the authors determined the inter-and intraobserver variability of various parameters pertinent to CT scans obtained in patients with intracerebral hematomas (ICHs).

Methods

A protocol was devised to analyze CT scans in a uniform and systematic manner. Each observer evaluated the same set of scans twice, with a minimum 2-month interval between assessments. In addition to noting the side and the sites of involvement, the observers measured the scale present on the scan itself and the length, breadth, height, and depth of the spontaneous ICH as well as the midline shift. The intraclass correlation was very high (κ 0.8–1) for the measurements of volume, depth, and midline shift. Good interobserver agreement (κ 0.8–1) was demonstrated with regard to involvement of basal ganglia or thalamus, presence of intraventricular extension, and the side of the hematoma. Agreement was substantial (κ 0.61–0.8) with regard to identifying primary involvement of particular lobes. Agreement was moderate (κ 0.41–0.6) on the presence or absence of hydrocephalus. When comparing the first and the second sets of readings, the intraobserver agreement was good (80–100%).

Conclusions

The study quantifies the degree of inter- and intraobserver agreement regarding evaluation of CT scans in patients with ICH when conducted in accordance with a set protocol.
Principles and techniques of en bloc vertebrectomy for bone tumors of the thoracolumbar spine: an overview
Authors: Bohinski Robert J. , Rhines Laurence D.
Published: January 2008

Oncological principles for en bloc resection of bone tumors were initially developed for tumors of the long bone by orthopedic surgical oncologists. Recently, spine surgeons have adopted these principles for the treatment of vertebral column tumors. The goal of en bloc resection is to establish a surgical margin that can be designated marginal or wide. In this article, the principles of surgical oncology for bone tumors of the spine are briefly reviewed and the different surgical approaches used to remove these tumors in an en bloc fashion are described in detail.
Vertebral body replacement with an expandable cage for reconstruction after spinal tumor resection
Authors: Thongtrangan Issada , Balabhadra Raju S. V. , Le Hoang , Park Jon , Kim Daniel H.
Published: January 2008

Object

The authors report their clinical experience with expandable cages used to stabilize the spine after verte-brectomy. The objectives of surgical treatment for spine tumors include a decrease in pain, decompression of the neural elements, mechanical stabilization of the spine, and wide resection to gain local control of certain primary tumors. Most of the lesions occur in the anterior column or vertebral body (VB). Anterior column defects following resection of VBs require surgical restoration of anterior column support. Recently, various expandable cages have been developed and used clinically for VB replacement (VBR).

Methods

Between January 2001 and June 2003, the authors treated 15 patients who presented with primary spinal tumors and metastatic lesions from remote sites. All patients underwent vertebrectomy, VBR with an expandable cage, and anterior instrumentation with or without posterior instrumentation, depending on the stability of the involved segment. The correction of kyphotic angle was achieved at an average of 20°. Pain scores according to the visual analog scale decreased from 8.4 to 5.2 at the last follow-up review. Patients whose Frankel neurological grade was below D attained at least a one-grade improvement after surgery. All patients achieved immediate stability postsurgery and there were no significant complications related to the expandable cage.

Conclusions

The advantage of the expandable cage is that it is easy to use because it permits optimal fit and correction of the deformity by in vivo expansion of the device. These results are promising, but long-term follow up is required.
Is there an upper limit of intracranial pressure in patients with severe head injury if cerebral perfusion pressure is maintained?
Authors: Young Jeffrey S. , Blow Osbert , Turrentine Florence , Claridge Jeffrey A. , Schulman Andrew
Published: January 2008

Authors of recent studies have championed the importance of maintaining cerebral perfusion pressure (CPP) to prevent secondary brain injury following traumatic head injury. Data from these studies have provided little information regarding outcome following severe head injury in patients with an intracranial pressure (ICP) greater than 40 mm Hg, however, in July 1997 the authors instituted a protocol for the management of severe head injury in patients with a Glasgow Coma Scale score lower than 9. The protocol was focused on resuscitation from acidosis, maintenance of a CPP greater than 60 mm Hg through whatever means necessary as well as elevation of the head of the bed, mannitol infusion, and ventriculostomy with cerebrospinal fluid drainage for control of ICP. Since the institution of this protocol, nine patients had a sustained ICP greater than 40 mm Hg for 2 or more hours, and five of these had an ICP greater than 75 mm Hg on insertion of the ICP monitor and later experienced herniation and expired within 24 hours. Because of the severe nature of the injuries demonstrated on computerized tomography scans and their physical examinations, these patients were not aggressively treated under this protocol. The authors vigorously attempted to maintain a CPP greater than 60 mm Hg with intensive fluid resuscitation and the administration of pressor agents in the four remaining patients who had developed an ICP higher than 40 mm Hg after placement of the ICP monitor. Two patients had an episodic ICP greater than 40 mm Hg for more than 36 hours, the third patient had an episodic ICP greater than of 50 mm Hg for more than 36 hours, and the fourth patient had an episodic ICP greater than 50 mm Hg for more than 48 hours. On discharge, all four patients were able to perform normal activities of daily living with minimal assistance and experience ongoing improvement.

Data from this preliminary study indicate that intense, aggressive management of CPP can lead to good neurological outcomes despite extremely high ICP. Aggressive CPP therapy should be performed and maintained even though apparently lethal ICP levels may be present. Further study is needed to support these encouraging results.
What is the optimal cerebral perfusion pressure in children suffering from traumatic coma?
Authors: Chambers Iain R. , Kirkham Fenella J.
Published: January 2008

Head injury is a major cause of death and disability in children. Despite advances in resuscitation, emergency care, intensive care monitoring, and clinical practices, there are few data demonstrating the predictive value of certain physiological variables regarding outcome in this patient population. Mean arterial blood pressure (MABP), intracranial pressure (ICP), and cerebral perfusion pressure (CPP = MABP − ICP) are routinely monitored in patients in many neurological intensive care units throughout the world, but there is little evidence indicating that advances in care have been matched with corresponding improvements in outcome.

Nonetheless, there is evidence that hypotension immediately following head injury is predictive of early death, and many patients with these features die with clinical signs of brain herniation caused by intracranial hypertension. Furthermore, available data indicate that a minimal and a mean CPP measured during intensive care are good predictors of outcome in survivors, but a target threshold to improve outcome has yet to be defined.

Some medical management strategies can have detrimental effects, and there is now a good case for undertaking a controlled trial of immediate or delayed craniectomy. Independent outcome in children following severe head injury is associated with higher levels of CPP. The ability to tolerate different levels of CPP may be related to age, and therefore any such surgical trial would need a carefully defined protocol so that the potential benefit of such a treatment is maximized.
What is the optimal threshold for cerebral perfusion pressure following traumatic brain injury?
Authors: Vespa Paul
Published: January 2008

Intensive care of the patient with traumatic brain injury centers on control of intracranial pressure and cerebral perfusion pressure (CPP). The optimal CPP by definition delivers an adequate supply of blood and oxygen to meet the metabolic demands of brain tissue. A great deal of controversy exists regarding the optimal CPP value, with disparate studies providing conflicting evidence for the use of supraphysiological CPP values. No study that accurately assesses the efficacy of normal CPP compared with elevated CPP has been performed, but several studies demonstrate that a CPP threshold exists on an individual basis for patients with TBI. The use of brain monitors of cerebral metabolism and oxygen supply may assist the clinician in the selection of the optimal CPP for an individual patient.
Evolution of posterior cervical and occipitocervical fusion and instrumentation
Authors: Vender John R. , Rekito Andy J. , Harrison Steven J. , McDonnell Dennis E.
Published: January 2008

The past several decades have been the setting for a remarkable evolution of spinal instrumentation technology. The advancements that have been made have allowed previously complex disorders of the cervical spine, the atlantoaxial articulation, and the occipitocervical junction to be managed more effectively with direct methods of internal fixation and arthrodesis. This has resulted in improvements in patient outcomes and fusion success rates. The improved strength of instrumentation constructs allows minimal, if any, external bracing, obviating the need for a halo orthosis in many cases. In this paper the authors review key events that have occurred in neuroimaging, biomechanical testing, and the development of fusion and instrumentation constructs.
Evolution of the lateral extracavitary approach to the spine
Authors: Lifshutz Jason , Lidar Zvi , Maiman Dennis
Published: January 2008

The development of alternative approaches to spine disorders marked an evolutionary change in the methods by which surgeons address diseases that affect the ventral portion of the spine. From the advent of spinal surgery until quite recently, physicians used posterior approaches almost exclusively for the treatment of all pathological processes. Surgeons subsequently became frustrated and disenchanted with outcomes of patients with anterior vertebral body disease when these procedures were applied. This sentiment is best reflected in the surgical thought related to Pott disease. In this paper, the authors chart the development of an influential approach to the spine that is designed to address these issues: the lateral extracavitary approach. They trace its origins to early precursor procedures and follow its use in current practice for the treatment of a variety of spinal disorders. They also examine its applications, role, and continued importance in the age of minimally invasive surgery.
Minimally invasive spinal surgery: a historical perspective
Authors: Thongtrangan Issada , Le Hoang , Park Jon , Kim Daniel H.
Published: January 2008

The concept of minimally invasive spinal surgery embodies the goal of achieving clinical outcomes comparable to those of conventional open surgery, while minimizing the risk of iatrogenic injury that may be incurred during the exposure process. The development of microscopy, laser technology, endoscopy, and video and image guidance systems provided the foundation on which minimally invasive spinal surgery is based. Minimally invasive treatments have been undertaken in all areas of the spinal axis since the 20th century. Lumbar disc disease has been treated using chemonucleolysis, percutaneous discectomy, laser discectomy, intradiscal thermoablation, and minimally invasive microdiscectomy techniques. The initial use of thoracoscopy for thoracic discs and tumor biopsies has expanded to include deformity correction, sympathectomy, vertebrectomy with reconstruction and instrumentation, and resection of paraspinal neurogenic tumors. Laparoscopic techniques, such as those used for appendectomy or cholecystectomy by general surgeons, have evolved into procedures performed by spinal surgeons for anterior lumbar discectomy and fusion. Image-guided systems have been adapted to facilitate pedicle screw placement with increased accuracy. Over the past decade, minimally invasive treatment of cervical spinal disorders has become feasible by applying technologies similar to those developed for the thoracic and lumbar spine. Endoscope-assisted transoral surgery, cervical lam-inectomy, discectomy, and foraminotomy all represent the continual evolution of minimally invasive spinal surgery. Further improvement in optics and imaging resources, development of biological agents, and introduction of instrumentation systems designed for minimally invasive procedures will inevitably lead to further applications in minimally invasive spine surgery.
History of spinal cord localization
Authors: Naderi Sait , Türe Uğur , Pait T. Glenn
Published: January 2008

The first reference to spinal cord injury is recorded in the Edwin Smith papyrus. Little was known of the function of the cord before Galen's experiments conducted in the second century AD. Galen described the protective coverings of the spinal cord: the bone, posterior longitudinal ligament, dura mater, and pia mater. He gave a detailed account of the gross anatomy of the spinal cord. During the medieval period (AD 700–1500) almost nothing of note was added to Galen's account of spinal cord structure. The first significant work on the spinal cord was that of Blasius in 1666. He was the first to differentiate the gray and white matter of the cord and demonstrated for the first time the origin of the anterior and posterior spinal nerve roots. The elucidation of the various tracts in the spinal cord actually began with demonstrations of pyramidal decussation by Mistichelli (1709) and Pourfoir du Petit (1710). Huber (1739) recorded the first detailed account of spinal roots and the denticulate ligaments. In 1809, Rolando described the substantia gelati-nosa. The microtome, invented in 1824 by Stilling, proved to be one of the fundamental tools for the study of spinal cord anatomy. Stilling's technique involved slicing frozen or alcohol-hardened spinal cord into very thin sections and examining them unstained by using the naked eye or a microscope. With improvements in histological and experimental techniques, modern studies of spinal cord anatomy and function were initiated by Brown-Séquard. In 1846, he gave the first demonstration of the decussation of the sensory tracts. The location and direction of fiber tracts were uncovered by the experimental studies of Burdach (1826), Türck (1849), Clarke (1851), Lissauer (1855), Goll (1860), Flechsig (1876), and Gowers (1880). Bastian (1890) demonstrated that in complete transverse lesions of the spinal cord, reflexes below the level of the lesion are lost and muscle tone is abolished. Flatau (1894) observed the laminar nature of spinal pathways.

The 20th century ushered in a new era in the evaluation of spinal cord function and localization; however, the total understanding of this remarkable organ remains elusive. Perhaps the next century will provide the answers to today's questions about spinal cord localization.
Medieval management of spinal injuries: parallels between Theodoric of Bologna and contemporary spine surgeons
Authors: Deshaies Eric M. , DiRisio Darryl , Popp A. John
Published: January 2008

In recent decades there have been revolutionary technological advances in the management of traumatic spinal column injuries. Despite these advances, the basic principles of reduction and stabilization of vertebral fractures and dislocations remain similar to those proposed by ancient and medieval physicians. Theodoric of Bologna, in his text Chiurgica de Theodoric (ca. AD 1267), described an extracorporeal approach to the management of traumatic spinal column misalignments. Surprisingly, his techniques are still used in many instances by contemporary spine surgeons, despite the availability of a more advanced technological armamentarium than that existent in medieval times.
The use of high-resolution magnetic resonance imaging for monitoring interbody fusion and bioabsorbable cages: an ex vivo pilot study
Authors: Krijnen Matthijs R. , Smit Theo H. , Strijkers Gustav J. , Nicolay Klaas , Pouwels Petra J. W. , Wuisman Paul I. J. M.
Published: January 2008

Object

Interbody fusion is a gradual process of graft resorption and tissue formation, ideally resulting in a bone bridge between two adjacent vertebral bodies. Initially, fibrous tissue and cartilage are formed, which subsequently are replaced by bone through the process of endochondral ossification. When cages and/or their contents are made of resorbable polymers like lactic or glycolic acids, there is a simultaneous process of implant degradation, which is eventually accompanied by reactions in the surrounding tissues. The purpose of this study was to explore the use of high-resolution magnetic resonance (MR) imaging for monitoring tissue differentiation, spinal fusion, cage degradation, and eventually tissue reactions as a function of time.

Methods

Lumbar vertebral segments obtained in 14 goats with 3, 6, and 12 months of follow up (three, four, and seven animals, respectively) were available from a study of the feasibility of poly(L,D-lactic acid) cages for spinal fusion. Plain x-ray films, MR images, and histological sections were used to evaluate spinal fusion and cage resorption. The first follow-up tests revealed that MR imaging noninvasively provided three-dimensional information on cage placement, cage degradation and bone formation, and that it has potential to differentiate between the various soft tissues.

Conclusions

Although the magnetic field strength and thus the resolution used were higher than normal in clinical practice, MR imaging appears to be a promising modality for the noninvasive clinical follow up of patients who undergo fusion with resorbable cages. Tissue reactions were not encountered in this study, and thus could not be evaluated.
In vivo evaluation of bioresorbable polylactide implants for cervical graft containment in an ovine spinal fusion model
Authors: Cornwall G. Bryan , Ames Christopher P. , Crawford Neil R. , Chamberlain Robert H. , Rubino Anthony M. , Seim Howard B. , Turner A. Simon
Published: January 2008

Object

An in vivo study was conducted in an ovine model to investigate the biomechanical changes after the animals underwent single-level anterior cervical discectomy followed by fusion in which autologous tricortical graft was used and implantation of cervical plates for which bioresorbable polymer screws and plates were used. The specific aims of the study were to evaluate whether implant failure or screw backout would occur over time and to measure the change in stiffness at the treated level at various postoperative time periods (3, 6, and 12 months).

Methods

A total of 58 x-ray films were evaluated over the 12-month survival period. No screw breakage or displacement was observed in any animal during the temporal radiographic analysis. Radiographically confirmed fusion appeared to be complete at all time periods longer than 6 months. The biomechanical testing demonstrated dramatic reductions in range of motion at the fusion level in the animals allowed to survive for 6 and 12 months, indicating complete fusion after 6 months.

Conclusions

The bioresorbable polymer cervical graft containment system appears to provide a safe and effective alternative for cervical fusion, and warrants further clinical evaluation for its use in single-level anterior cervical discectomy and fusion without postoperative orthosis.
Early findings in a pilot study of anterior cervical fusion in which bioabsorbable interbody spacers were used
Authors: Vaccaro Alexander R. , Robbins Matthew M. , Madigan Luke , Albert Todd J. , Smith William , Hilibrand Alan S.
Published: January 2008

Object

In this pilot study the authors assessed the efficacy of bioabsorbable interbody spacers in the treatment of cervical degenerative disease. Metallic cages or interbody spacers have been widely used in the treatment of degenerative and traumatic cervical disease. Bioabsorbable technology has been used to develop a resorbable cage that can eliminate the complications and drawbacks seen with the use of traditional metallic implants. In general clinical practice bioabsorbable implants have shown the ability to degrade safely while demonstrating optimal imaging characteristics as a result of their radiolucency, and these devices eliminate stress shielding by their gradual dissolution.

Methods

This study is a retrospective evaluation of charts and x-ray films obtained in the first eight patients who underwent an anterior cervical decompression and fusion procedure with placement of a bioabsorbable interbody spacer and anterior cervical plate. All patients were treated in one surgeon's practice and had a minimum follow-up period of at least 6 months. At a follow-up interval of approximately 7 months, five patients exhibited an excellent result and three had a good result; no patient was noted to have a satisfactory or poor outcome according to the Odom criteria at their most recent follow-up visit. Seventeen (94%) of 18 grafted levels appeared to be solidly fused. One patient experienced a perisurgical complication consisting of a symptomatic hematoma, which was successfully drained.

Conclusions

Bioabsorbable interbody spacers appear to be a safe and effective interbody implant in terms of clinical outcome and radiographically confirmed healing.
Hyponatremia in the neurosurgical patient: diagnosis and management
Authors: Cole Chad D. , Gottfried Oren N. , Liu James K. , Couldwell William T.
Published: January 2008

Hyponatremia is frequently encountered in patients who have undergone neurosurgery for intracranial processes. Making an accurate diagnosis between the syndrome of inappropriate secretion of antidiuretic hormone (SIADH) and cerebral salt wasting (CSW) in patients in whom hyponatremia develops is important because treatment differs greatly between the conditions. The SIADH is a volume-expanded condition, whereas CSW is a volume-contracted state that involves renal loss of sodium. Treatment for patients with SIADH is fluid restriction and treatment for patients with CSW is generally salt and water replacement. In this review, the authors discuss the differential diagnosis of hyponatremia, distinguish SIADH from CSW, and highlight the diagnosis and management of hyponatremia, which is commonly encountered in patients who have undergone neurosurgery, specifically those with traumatic brain injury, aneurysmal subarachnoid hemorrhage, recent transsphenoidal surgery for pituitary tumors, and postoperative cranial vault reconstruction for craniosynostosis.