Background:The objective of the present isolated spine study was to evaluate the kinematic differences between groups of normal and degenerated cervical spine specimens. Previous studies on cervical spine degeneration support the existence of the unstable phase during the degeneration process; however, there is a lack of quantitative data available to fully characterize this early stage of degeneration. Method:For this effort five degenerated and eight normal cervical spines (C2-T1) were isolated and were subject to pure bending moments of flexion, extension, axial rotation and lateral bending. The specimen quality was assessed based on the grading scale. In the present study, the degeneration was at the C5-C6 level. A four-camera motion analysis system was used to measure the overall primary and segmental motions. Finding:In the extension mode, the degenerated group demonstrated a significant larger angular rotation as well as antero-posterior displacement at the degenerated level (C5-C6). In contrast, in flexion mode, the degenerated group measured a drastic decrease in angular rotation, at the adjacent level (C6-C7). In other modes of loading as well as in other segmental levels, the degenerated group had similar segmental motion as the normal group. Interpretation:These preliminary results provide single level degeneration specific cervical spine kinematics. The finding demonstrates the influence of degeneration on the kinematics of the normal sub adjacent segment. The degenerated group observed larger translation displacement in the extension mode, which would potentially be a critical parameter in assisting early detection of cervical spine spondylosis with just a functional X-ray scan.

The Medical College of Wisconsin Department of Neurosurgery delivers subspecialty adult and pediatric neurosurgical care that is patient-centered, evidence-informed, and value-based. Medical College of Wisconsin research advances the science of neurological disease with the goal of a positive translational effect on clinical care. The department supports an environment of education and scholarship for trainees, faculty, and staff alike. The journey to become a neurosurgical center of excellence was accomplished with the leadership and foresight of the men and women who turned their dreams into reality. The establishment and rise of the department as a national force for neurosurgery and spine is an elegant example of the combination of individual leadership and foresight with synergistic institutional support.

Background: Biomechanical/anatomic limitations may limit the successful implantation, maintenance, and risk acceptance of posterior cervical plate/rod fixation for one stage decompression-fusion. A method of posterior fixation (crisscross) that resolves biomechanical deficiencies of previous facet wiring techniques and not reliant upon screw implantation has been devised. The biomechanical performance of the new method of facet fixation was compared to the traditional lateral mass plate/screw fixation method. Methods: Thirteen human cadaver spine segments (C2-T1) were tested under flexion-compression loading and four were evaluated additionally under pure-moment load. Preparations were evaluated in a sequence of surgical alterations with intact, laminectomy, lateral mass plate/screw fixation, and crisscross facet fixation using forces, displacements and kinematics. Findings: Combined loading demonstrated significantly lower bending stiffness (p < 0.05) between laminectomy compared to crisscross and lateral mass plate/screw preparations. Crisscross fixation showed a comparative tendency for increased stiffness. The increased overall motion induced by laminectomy was resolved by both fixation techniques, with crisscross fixation demonstrating a comparatively more uniform change in segmental motions. Interpretation: The crisscross technique of facet fixation offers immediate mechanical stability with resolution of increased flexural rotations induced by multi-level laminectomy. Many of the anatomic limitations and potentially deleterious variables that may be associated with multi-level screw fixation are not associated with facet wire passage, and the subsequent fixation using a pattern of wire connection crossing each facet joint exhibits a comparatively more uniform load distribution. Crisscross wire fixation is a valuable addition to the surgical armamentarium for extensive posterior cervical single-stage decompression-fixation.

Objective: The objective of this study is to determine the contribution of Chile’s 2005 child restraint legislation to the reduction in child severe traffic injuries.Methods: We analyzed motor vehicle injury data from Chile’s Ministry of Transport National Road Safety Commission from 2000 to 2012 to determine the effect of Chile’s 2005 mandatory child restraint legislation. Using time-series robust random effects models we assessed the effect of the law on two dependent variables:(1) child severe traffic injuries per vehicle fleet; and (2) child severe traffic injuries per population. The independent variable was the 2005 enactment of Chile’s mandatory child restraint legislation. We added the following control variables: Number of tickets per year per police officer; motor vehicle fleet; alcohol consumption; number of crashes; and unemployment rate. Results: There was a 23.6%[95% confidence interval (CI) 0.98–48.89, P< …

Objective: Nearside impact collisions presenting with lateral mass fractures of atlanto-axial vertebrae contralateral to the impact site represents a rare fracture pattern that does not correlate with previously described injury mechanism. We describe our clinical experience with such fractures and propose a novel description of biomechanical forces involved in this unique injury pattern. The findings serve to alert clinicians to potentially serious consequences of associated unrecognized and untreated vertebral artery injury. Material and Methods : In addition to describing our clinical experience with three of these fractures, a review of Crash Injury Research and Engineering Network (CIREN) database was conducted to further characterize such fractures. A descriptive analysis of three recent lateral mass fractures of the atlanto-axial segment is coupled with a review of the CIREN database. A total of 4047 collisions were screened for unilateral fractures of atlas or axis. Information was screened for side of impact and data regarding impact velocity, occupant injuries and use of restraints. Results: Following screening of unilateral fractures of atlas and axis for direct side impacts, 41 fractures were identified. Cross referencing these cases for occurrence contralateral to side of impact identified four such fractures. Including our recent clinical experience, seven injuries were identified: Five C1 and two C2 fractures. Velocity ranged from 14 to 43 km/h. Two associated vertebral artery injuries were identified. Conclusions: Complexity of the atlanto-axial complex is responsible for a sequence of events that define load application in side impacts. This study demonstrates the vulnerability of vertebral artery to injury under unique translational forces and supports the use or routine screening for vascular injury. Diminished sensitivity of plain radiography in identifying these injuries suggests that computerized tomography should be used in all patients wherein a similar pattern of injury is suspected.

Study Design. This study investigated the effect of neck muscle precontraction in aware occupants in whiplash. Head angulation relative to T1 and facet joint capsular ligament distractions were compared between aware and unaware occupants. Objective. To quantify changes in facet joint capsular ligament distractions between aware occupants with precontracted neck muscles and unaware occupants with reflex muscle contraction. Summary of Background Data. Clinical studies have reported that patients aware of the impending impact had decreased symptom intensity and faster recovery after whiplash. To date, no study has investigated the effects of precontracted neck musculature on localized spinal soft tissue distortions in whiplash. Methods. Aware occupants with precontracted neck muscles and unaware occupants with reflex muscle contraction in whiplash were simulated using a validated computational model. Muscle contraction attained maximum levels before impact in the aware occupant and implemented reflex delay, electromechanical delay, and finite muscle rise time in the unaware occupant. Results. Precontraction of neck muscles in aware occupants resulted in 63% decreased maximum head angles, elimination of cervical S-curvature, and up to 75% decrease in maximum facet joint capsular ligament distractions. Conclusions. Occupants aware of an impending whiplash impact with precontracted neck muscles can markedly reduce overall head-neck and spinal motions. It is our theory that this would reduce whiplash injury likelihood.

PURPOSE Arachidonic acid is avidly metabolized to a potent vasoconstrictor, 20-hydroxyeicosatetraenoic acid (20-HETE), in the cerebral circulation. 20-HETE has been reported to contribute to the acute fall in cerebral blood flow following subarachnoid hemorrhage (SAH), but its role in the development of delayed vasospasm is unknown. The present study examined whether delayed vasospasm is associated with elevations in 20-HETE in CSF in the dual hemorrhage model of SAH in dogs and if blockade of the synthesis of 20-HETE with N-(3-chloro-4-morpholin-4-yl)phenyl-N'-hydroxyimido formamide (TS-011) can reverse delayed vasospasm in this model. MATERIALS AND METHODS Delayed vasospasm was induced in 22 adult beagle dogs by dual injection of blood (0.5 mL/kg) into the cisterna magna on days 1 and 4. Sequential samples of CSF were collected before intracisternal injections of blood on days 1 and 4 and after the development of delayed vasospasm on day 7. Sequential angiograms were obtained before and after intracisternal injection of blood on days 1 and 4 and before and 1 hour after administration of TS-011 (1 mg/kg IV) on day 7. RESULTS The dogs consistently developed delayed vasospasm, and the diameter of the basilar artery fell to 68 +/- 3% (n = 15), 3 days after the second intracisternal injection of blood. The levels of 20-HETE in CSF increased from 4 +/- 2 to 39 +/- 16 pg/mL. In 9 dogs with delayed vasospasm, acute blockade of the synthesis of 20-HETE with TS011 (1 mg/kg IV) significantly increased the diameter of the basilar artery by 39%. Chronic administration of TS-011 (1 mg/kg per day) attenuated the development of delayed vasospasm, and the diameter of the basilar artery fell by 17 +/- 1% versus the 33 +/- 3% decrease in diameter seen in control animals 3 days following the second injection of blood into the cisterna magna. CONCLUSIONS These results indicate that the development of delayed vasospasm in dogs is associated with an increase in 20-HETE levels in CSF, and acute blockade of the synthesis of 20-HETE with TS-011 reverses delayed vasospasm in this model.

OBJECTIVE: Intraventricular (IVen) hemorrhage is considered a predictor of poor outcome after subarachnoid hemorrhage (SAH). This prospective study examines the feasibility and outcome of administration of IVen tissue plasminogen activator (tPA) after aneurysmal SAH.METHODS: Ten patients with SAH who received IVen tPA after the aneurysm had been secured were compared with 10 age-, sex-, and Glasgow Coma Scale score-matched control patients. The primary end point was third, and fourth ventricle clot, resolution. IVen blood-was quantified by use of the Graeb and Le Roux scales on admission and at an additional time (equal or longer for the control group) after the injection was terminated.RESULTS: Six men and four women with a mean age of 52 years in each group were evaluated. On average, 3.5 mg tPA was injected 68 +/- 51 hours after admission without ensuing complications. Although the treated group had significantly More IVen blood on admission than control subjects (mean Le Roux scale +/- standard deviation, 11 +/- 3 versus 7.6 +/- 4.2, P = 0.055, and mean Graeb scale +/- standard deviation, 8.5 +/- 2.3 in tPA versus 5.3 +/- 3, P < 0.02), it also had a significant decrease in the amount of IVen blood (mean Le Roux and Graeb scale decrease +/- standard deviation, 6.7 +/- 3.3 and 4.8 +/- 2 in tPA patients versus 0.9 +/- 3.2 and 0.5 +/- 2.6 in control subjects, P = 0.002). The tPA group had a non-statistically significantly shorter length, of stay, decreased mortality, and better Glasgow Outcome Scale and modified Rankin Scale scores at discharge. Treated survivors showed a decreased need for shunt placement (2 [22%] of 9 patients versus 5 [83%] of 6 control subjects, P = 0.04).CONCLUSION: This pilot study shows that IVen tPA administration is feasible without complications after SAH and may be associated with better outcomes. These results warrant a randomized clinical trial.

BACKGROUND:Compression fractures are common in patients with osteoporosis and cancer. In particular, vertebral compression fractures are crippling, and pose an additional risk of cord compression. Although a number of nonmedical options such as bracing and exercise programs may help these patients, the combination of constant, severe pain and spinal instability was until recently almost invariably synonymous with painful gradual deterioration and a poor quality of life. Vertebroplasty, and more recently kyphoplasty, are minimally invasive procedures that aim at limiting or reversing painful collapse of the vertebrae, while providing stability to the treated segment of the spine. As these new options are highly effective and involve minimal risk, it is important that physicians be familiar with them. OBJECTIVE:This paper reviews the demographics of vertebral compression fractures, both osteoporotic and neoplastic, the technical aspects of vertebroplasty and kyphoplasty, and current results and outcomes. RESULTS:Pain relief rates in excess of 90% have been reported with both vertebroplasty and kyphoplasty in patients with vertebral compression fractures. Procedural complication rates should be very low, in the 1%-2% range at most with proper technique. CONCLUSIONS:Until the advent of vertebroplasty, almost no effective therapeutic option could be offered to patients suffering from neoplastic or osteoporotic vertebral compression fractures, which are relatively common and often crippling. The technical feasibility of these procedures is high, the risk low, and the effectiveness high. Therefore, it is important that physicians consider vertebroplasty and kyphoplasty as viable and strong options.

BACKGROUND:Aneurysms associated with vertebrobasilar fenestrations are uncommon. We report on an unusual presentation of such aneurysm with a dedicated arterial pedicle, manifesting with significant intraventricular hemorrhage. Equally important, the aneurysm was managed in a multidisciplinary fashion, which, we think, greatly contributed to a good outcome. CASE DESCRIPTION:A 55-year-old man presented in good condition after subarachnoid and massive intraventricular hemorrhage. The aneurysm location and the extent of intraventricular hemorrhage both presented concerns regarding treatment approach. The aneurysm was first treated with transarterial coil obliteration, and intraventricular tissue plasminogen activator (tPA) infusion was given, with rapid resolution of evolving hydrocephalus. The patient had an excellent outcome. CONCLUSION:To our knowledge, this is the first report of a vertebrobasilar fenestration saccular aneurysm with a dedicated pedicle projecting toward the foramen of Magendie with significant intraventricular hemorrhage. In addition, this patient was successfully managed with endovascular obliteration and intraventricular tPA infusion.

The authors describe a case of noncommunicating syringomyelia associated with Chiari malformation Type I in a patient in whom acute symptomatic exacerbation occurred following cervical spine trauma. Surgical stabilization and realignment of the spine resulted in marked resolution of the neurological abnormalities, and subsequent magnetic resonance imaging demonstrated persistent collapse of the syrinx. The authors review the various factors in the pathogenesis of this unusual sequence of events.

Neck pain and headaches are the two most common symptoms of whiplash. The working hypothesis is that pain originates from excessive motions in the upper and lower cervical segments. The research design used an intact human cadaver head–neck complex as an experimental model. The intact head–neck preparation was fixed at the thoracic end with the head unconstrained. Retroreflective targets were placed on the mastoid process, anterior regions of the vertebral bodies, and lateral masses at every spinal level. Whiplash loading was delivered using a mini-sled pendulum device. A six-axis load cell and an accelerometer were attached to the inferior fixation of the specimen. High-speed video cameras were used to obtain the kinematics. During the initial stages of loading, a transient decoupling of the head occurs with respect to the neck exhibiting a lag of the cranium. The upper cervical spine–head undergoes local flexion concomitant with a lag of the head while the lower column is in local extension. This establishes a reverse curvature to the head–neck complex. With continuing application of whiplash loading, the inertia of the head catches up with the neck. Later, the entire head–neck complex is under an extension mode with a single extension curvature. The lower cervical facet joint kinematics demonstrates varying local compression and sliding. While the anterior- and posterior-most regions of the facet joint slide, the posterior-most region of the joint compresses more than the anterior-most region. These varying kinematics at the two ends of the facet joint result in a pinching mechanism. Excessive flexion of the posterior upper cervical regions can be correlated to headaches. The pinching mechanism of the facet joints can be correlated to neck pain. The kinematics of the soft tissue-related structures explain the mechanism of these common whiplash associated disorders.

This review presents considerations regarding major cervical spine injury, including some concepts that are presently undergoing evaluation and clarification. Correlation of certain biomechanical parameters and clinical factors associated with the causation and occurrence of traumatic cervical spine injuries assists in clarifying the pathogenesis and treatment of this diverse group of injuries. Instability of the cervical column based on clinical and mechanistic perspectives as well as the role of ligaments in determining instability is discussed. Patient variables such as pre-existing conditions (degenerative disease) and age that can influence the susceptibility or resistance to injury are reviewed. Radiological considerations of major injuries including dynamic films, CT and MRI are presented in the diagnosis and treatment of cervical trauma. Specific injury patterns of the cervical vertebral column are described including attention to the relative mechanisms of trauma. From a biomechanical perspective, quantification of injury tolerance is discussed in terms of external and human-related variables using laboratory-driven experimental models. This includes force vectors (type, magnitude, direction) responsible for injury causation, as well as potential influences of loading rate, gender, age, and type of injury.

Accepted, April 3, 2002. OBJECTIVE AND IMPORTANCE: Epithelial cysts of the central nervous system are unusual entities, with the majority reported to occur in the spinal canal. More unusual is the intracranial presentation, which shows a predilection for midline localization in the posterior fossa, brainstem, and suprasellar regions. This report discusses the differential diagnosis, pathogenesis, radiographic presentation, and therapeutic considerations of a laterally positioned cerebral convexity endodermal cyst. CLINICAL PRESENTATION: A 49-year-old right-handed man presented with approximately a 30-month history of shortand long-term memory difficulties. A magnetic resonance imaging study revealed a large, nonenhancing, extra-axial cystic lesion overlying the right lateral frontal convexity. INTERVENTION: A right frontoparietal craniotomy exposed a large extra-axial cyst with an opaque, yellowish-white membrane containing a mucoid fluid. Histological analysis disclosed a layer of unremarkable, ciliated columnar epithelium with a basement membrane that stained positive for cytokeratin, periodic acid-Schiff, and Alcian blue. No evidence of either a muscular or cartilaginous layer around the mucosa was present to further delineate neurenteric versus bronchogenic origin of the cyst. CONCLUSION: This case involved the occurrence of a solitary endodermal cyst as an extra-axial mass localized over the lateral frontal lobe. The lateral supratentorial localization of this lesion illustrates the need for consideration of the pathogenesis of this entity as well as its diagnostic differentiation from other cystic abnormalities in this region. A review of the histochemistry of endodermal, neuroepithelial, and other cerebral cysts is presented.

Study Design. Soft tissue–related injuries to the cervical spine structures were produced by use of intact entire human cadavers undergoing rear-end impacts. Radiography, computed tomography, and cryomicrotomy techniques were used to evaluate the injury. Objectives. To replicate soft tissue injuries resulting from single input of whiplash acceleration to whole human cadavers simulating vehicular rear impacts, and to assess the ability of different modes of imaging to visualize soft tissue cervical lesions. Summary of Background Data. Whiplash-associated disorders such as headache and neck pain are implicated with soft tissue abnormalities to structures of the cervical spine. To the authors' best knowledge, no previous studies have been conducted to determine whether single cycle whiplash acceleration input to intact entire human cadavers can result in these soft tissue alterations. There is also a scarcity of data on the efficacy of radiography and computed tomography in assessing these injuries. Methods. Four intact entire human cadavers underwent single whiplash acceleration (3.3 g or 4.5 g) loading by use of a whole-body sled. Pretest and posttest radiographs, computed tomography images, and sequential anatomic sections using a cryomicrotome were obtained to determine the extent of trauma to the cervical spine structures. Results. Routine radiography identified the least number of lesions (one lesion in two specimens). Although computed tomography was more effective (three lesions in two specimens), trauma was not readily apparent to all soft tissues of the cervical spine. Cryomicrotome sections identified structural alterations in all four specimens to lower cervical spine components that included stretch and tear of the ligamentum flavum, anulus disruption, anterior longitudinal ligament rupture, and zygopophysial joint compromise with tear of the capsular ligaments. Conclusions. These results clearly indicate that a single application of whiplash acceleration pulse can induce soft tissue–related and ligament-related alterations to cervical spine structures. The pathologic changes identified in this study support previous observations from human volunteers observations with regard to the location of whiplash injury and may assist in the explanation of pain arising from this injury. Although computed tomography is a better imaging modality than radiography, subtle but clinically relevant injuries may be left undiagnosed with this technique. The cryomicrotome technique offers a unique procedure to understand and compare soft tissue–related injuries to the cervical anatomy caused by whiplash loading. Recognition of these injuries may advance the general knowledge of the whiplash disorder.

Study Design. The overall, local, and segmental kinematic responses of intact human cadaver head–neck complexes undergoing an inertia-type rear-end impact were quantified. High-speed, high-resolution digital video data of individual facet joint motions during the event were statistically evaluated. Objectives. To deduce the potential for various vertebral column components to be exposed to adverse strains that could result in their participation as pain generators, and to evaluate the abnormal motions that occur during this traumatic event. Summary of Background Data. The vertebral column is known to incur a nonphysiologic curvature during the application of an inertial-type rear-end impact. No previous studies, however, have quantified the local component motions (facet joint compression and sliding) that occur as a result of rear-impact loading. Methods. Intact human cadaver head–neck complexes underwent inertia-type rear-end impact with predominant moments in the sagittal plane. High-resolution digital video was used to track the motions of individual facet joints during the event. Localized angular motion changes at each vertebral segment were analyzed to quantify the abnormal curvature changes. Facet joint motions were analyzed statistically to obtain differences between anterior and posterior strains. Results. The spine initially assumed an S-curve, with the upper spinal levels in flexion and the lower spinal levels in extension. The upper C-spine flexion occurred early in the event (approximately 60 ms) during the time the head maintained its static inertia. The lower cervical spine facet joints demonstrated statistically greater compressive motions in the dorsal aspect than in the ventral aspect, whereas the sliding anteroposterior motions were the same. Conclusions. The nonphysiologic kinematic responses during a whiplash impact may induce stresses in certain upper cervical neural structures or lower facet joints, resulting in possible compromise sufficient to elicit either neuropathic or nociceptive pain. These dynamic alterations of the upper level (occiput to C2) could impart potentially adverse forces to related neural structures, with subsequent development of a neuropathic pain process. The pinching of the lower facet joints may lead to potential for local tissue injury and nociceptive pain. [