Naturally occurring autoantibodies against beta-amyloid: investigating their role in transgenic animal and in vitro models of Alzheimer's disease.

Alzheimer's disease (AD) is a neurodegenerative disorder primarily affecting regions of the brain responsible for higher cognitive functions. Immunization against ß-amyloid (Aß) in animal models of AD has been shown to be effective on the molecular level but also on the behavioral level. Recently, we reported naturally occurring autoantibodies against Aß (NAbs-Aß) being reduced in Alzheimer's disease patients. Here, we further investigated their physiological role: in epitope mapping studies, NAbs-Aß recognized the mid-/C-terminal end of Aß and preferentially bound to oligomers but failed to bind to monomers/fibrils. NAbs-Aß were able to interfere with Aß peptide toxicity, but NAbs-Aß did not readily clear senile plaques although early fleecy-like plaques were reduced. Administration of NAbs-Aß in transgenic mice improved the object location memory significantly, almost reaching performance levels of wild-type control mice. These findings suggest a novel physiological mechanism involving NAbs-Aß to dispose of proteins or peptides that are prone to forming toxic aggregates.

Posterior C1-2 fusion with C1 lateral mass and C2 isthmic screws: accuracy of screw position, alignment and patient outcome.

BACKGROUND: Transarticular screw fixation is seen as the "gold standard" in instrumented fusion of C1 and C2. However, drawbacks are the necessity of a reduction before instrumentation and a risk of vertebral artery injury. Therefore, C1 lateral mass and C2 isthmic screws are an alternative. The present study assessed the feasibility of C1-2 stabilization with C1 lateral mass and C2 isthmic screws and evaluated quality of life. METHOD: All data of 35 consecutive patients treated from May 2006 to September 2009 were collected. Patients had C1 lateral mass and C2 isthmic screws. RESULTS: Twenty patients were operated on for traumatic instabilities, six for neoplastic instabilities, five for infectious instabilities and two each for degenerative and congenital instabilities. Sixty-six of 70 C1 screws had an ideal position, while four were placed suboptimal without the need for revision. Twelve of 68 C2 screws were not ideal but acceptable; one screw needed a surgical revision. There was one non-surgery related case of neurological deterioration after multilevel instrumentation. No vascular injuries occurred. Realignment was correct in all patients. After a median follow-up of 12 months, patients showed a reduction of pain, disability and improvements in EQ-5D items. SF36 data compared with a normative population and a historical cohort showed lower levels of function in all domains. CONCLUSION: C1-C2 instrumented fusion with lateral mass and isthmic screws is a safe procedure. Sufficient screw position and alignment was possible in all cases. Therefore, at our institution transarticular screws were abandoned in favor of C1 lateral mass and C2 isthmic screws.

Role of macrophage migration inhibitory factor in primary glioblastoma multiforme cells.

Macrophage migration inhibitory factor (MIF) is a protein that is overexpressed in many tumors, such as colon and prostate cancer, melanoma, and glioblastoma multiforme (GBM). In its function as a cytokine, MIF induces angiogenesis, promotes cell cycle progression, and inhibits apoptosis. Recently, the molecular signal transduction has been specified: MIF has been found to be a ligand to the CD74/CD44-receptor complex and to activate the ERK1/2 MAPK cascade. In addition MIF binds to the chemokine receptors CXCR2 and CXCR4. This effects an integrin-dependent leukocyte arrest and mediates leukocyte chemotaxis. Recent work has described a clearer role of MIF in GBM tumor cell lines. The current study used human primary GBM cells. We show that inhibition of MIF with ISO-1, an inhibitor of the D-dopachrome tautomerase site of MIF, reduced the growth rate of primary GBM cells in a dose-dependent manner, and in addition ISO-1 increased protein expression of MIF and its receptors CD74, CXCR2, and CXCR4 in vitro but decreased expression of CD44. Furthermore, hypoxia as cell stressor increases the protein expression of MIF in primary GBM cells. These results underscore the importance of MIF in GBM and show that MIF and its receptors may be a promising target for the treatment of malignant gliomas.

Robotic technology in spine surgery: current applications and future developments.

Medical robotics incrementally appears compelling in nowadays surgical work. The research regarding an ideal interaction between physician and computer assistance has reached a first summit with the implementation of commercially available robots (Intuitive Surgical's® da Vinci®). Moreover, neurosurgery--and herein spine surgery--seems an ideal candidate for computer assisted surgery. After the adoption of pure navigational support from brain surgery to spine surgery a meanwhile commercially available miniature robot (Mazor Surgical Technologies' The Spine Assist®) assists in drilling thoracic and lumbar pedicle screws. Pilot studies on efficacy, implementation into neurosurgical operating room work flow proved the accuracy of the system and we shortly outline them. Current applications are promising, and future possible developments seem far beyond imagination. But still, medical robotics is in its infancy. Many of its advantages and disadvantages must be delicately sorted out as the patients safety is of highest priority. Medical robots may achieve a physician's supplement but not substitute.

Pedicle screw-based dynamic stabilization of the thoracolumbar spine with the Cosmic-system: a prospective observation.

OBJECT: The objective of the study was to generate prospective data to assess the clinical results after dynamic stabilization with the Cosmic system (Ulrich Medical). PATIENTS AND METHODS: Between April 2006 and December 2007, 103 consecutive patients were treated with Cosmic for painful degenerative segmental instability +/- spinal stenosis. The preoperative workup included radiological (MRI and myelography/CT) and clinical parameters (general/neurological examination, visual analogue scale (VAS), Oswestry disability index (ODI), SF-36, Karnofsky (KPS)). At pre-defined intervals (at discharge, 6 weeks, 3 months, 6 months, 12 months, and yearly) the patients were reevaluated (X-ray/flexion/extension, neurological status, VAS, ODI, SF-36, KPS, and patient satisfaction). Data were collected in a prospective observational design. RESULTS: Data collection was completed in 100 of 103 operated patients (mean follow-up, 15 +/- 0.6 months). Dynamic stabilization was performed as first-tier surgery in 43 cases and as second-tier therapy in 60 cases. Additional decompression was performed in 83 cases. Dynamic stabilization led to significant reduction of back pain-related disability (ODI pre-op, 51 +/- 1%; post-op, 21 +/- 1%) and improvement of pain (VAS pre-op, 65 +/- 1; post-op, 21 +/- 2), mental/physical health (norm-based SF-36: mental pre-op, 44; post-op, 48; physical pre-op, 41; post-op, 46), and mobility (KPS pre-op, 70 +/- 1; post-op, 82 +/- 31). Early reoperation was necessary in 12 patients (n = 3 symptomatic misplaced screws, n = 8 CSF pseudocele, rebleeding, or impaired wound healing, n = 1 misjudged instability/stenosis in adjacent segment). Reoperations within the follow-up period were necessary in another 10 patients due to secondary screw loosening (n = 2), persistent stenosis/disk protrusion in an instrumented segment (n = 3), symptomatic degeneration of an adjacent segment (n = 6), or osteoporotic fracture of an adjacent vertebra (n = 1), respectively. Patient satisfaction rate was 91%. CONCLUSIONS: Dynamic stabilization with Cosmic achieved significant improvement of pain, related disability, mental/physical health, and mobility, respectively, and a high rate of satisfied patients. A reoperation rate of 10% during follow-up seems relatively high at first glance. Comparable data, however, are scarce, and a prospective randomized trial (spondylodesis vs. dynamic stabilization) is warranted based on these results.

Safety and efficacy of a new percutaneously implantable interspinous process device.

BACKGROUND: Lumbar spinal stenosis is a degenerative disease of the elderly population. Although microsurgical decompression has shown good long-term results, percutaneous techniques could provide an alternative in the presence of significant comorbidities. METHOD: Eighty-seven interspinous process decompression devices (In-space; Synthes, Umkirch, Germany) were implanted percutaneously in up to three segments of 50 patients. Outcome was assessed directly after surgery, at 6-8 weeks, and at average follow-up of 1 year (11.8 ± 6 months). Assessment included complications, pain and spinal claudication, neurodeficit, time to recurrence of symptoms, and time to second surgery. Subgroups with additional low back pain at presentation and mild spondylolisthesis were analyzed separately. FINDINGS: Intraoperative complications were rare (one misplacement and two cases of failed implantation); average operation time was 16.4 ± 12.2 min per segment. Initial response was very good with 72% good or excellent relief of symptoms. After a 1-year follow-up, 42% reported of lasting relief from spinal claudication. Thirteen percent of these complained about lasting or new-onset low back pain. A second surgery had been performed in 22%. Subgroup analysis was performed for patients presenting with additional low back pain and spondylolisthesis patients. No significant differences could be noted between subgroups. CONCLUSIONS: The In-space is a percutaneous treatment option of claudication in patients with lumbar spinal stenosis. Compared with microsurgical decompression surgery, recurrence rate within 1 year is, however, high and the device seems not suitable for the treatment of low back pain. Therefore, the authors suggest that the device should presently be used primarily in controlled clinical trials in order to get more information concerning the optimal indication.

Treatment of painful osteoporotic compression and burst fractures using kyphoplasty: a prospective observational design.

OBJECT: The aim of this study was to test the hypothesis that kyphoplasty is an effective treatment in painful osteoporotic vertebral fractures, even with involvement of the posterior cortical wall. METHODS: Between December 2001 and May 2004, 74 consecutive patients were treated with kyphoplasty for 118 painful osteoporotic compression (38%) or burst (62%) fractures. Additional decompression of the spinal canal was performed in six patients, internal fixation in three. Data were collected in a prospective observational design until May 2005. The preoperative workup included neuroimaging (plain x-ray films, densitometry, short tau inversion recovery magnetic resonance imaging, and computed tomography scanning) and clinical parameters (general and neurological examinations, visual analog scale [VAS], Karnofsky Performance Scale [KPS], and 36-Item Short Form Health Survey [SF]-36). At predefined time intervals (at discharge and 6 weeks and 3, 6, 12, and 24 months posttherapy) the patients were evaluated (x-ray films, neurological status, VAS, KPS, and SF-36). Kyphoplasty led to a significant reduction in kyphotic deformity (mean +/- standard error of the mean, sagittal index: preoperative 10 +/- 1 degrees, postoperative 5 +/- 1 degrees), and an improvement in pain (VAS: preoperative 70 +/- 3, postoperative 23 +/- 2), activity (KPS score: preoperative 51 +/- 3, postoperative 71 +/- 2), and mental and physical health (SF-36, mental status: preoperative 43, postoperative 58; SF-36, physical status: preoperative 24, postoperative 35). No secondary narrowing of the spinal canal by the retropulsed posterior wall was observed after the procedure. Clinical improvement was durable (mean follow up 15 +/- 1.1 months), although the VAS score secondarily increased slightly. All patients, who suffered from a compression-induced motor deficit, recovered completely during the follow-up interval. The main procedural complications consisted of one symptomatic extravertebral cement leakage (permanent monoparesis) requiring open revision, two nerve root contusions (transient radiculopathy), and one wound infection. CONCLUSIONS: Kyphoplasty is effective in the treatment of painful osteoporotic vertebral compression and burst fractures, at least under medium-term conditions. The potential complication of procedure-related secondary narrowing of the spinal canal by the retropulsed posterior wall in burst fractures appears to be more of a theoretical than an actual risk.

Skull base chordomas: management and results.

Growth patterns of skull base chordomas are related to important neurovascular structures. Local invasiveness results in "clinically malignant" behavior. A high rate of transient neurological deficits occurs following radical surgery. At our institution, the principle of radical removal is not followed at any price. This study compared the results of our management with recent series. Eleven patients, five females and six males aged 24-65 years (mean 41 years), underwent removal of skull base chordoma with size one <3 cm, five 3-5 cm, and five >5 cm. Mostly, standard operative approaches were chosen. All patients underwent postoperative radiotherapy. Resection was subtotal/partial in seven patients and total in four with no mortality. Neurological deterioration occurred due to transient cranial nerve deficits in six patients. Temporary surgical morbidity (including cranial nerve deficits) was observed in seven patients. Median Karnofsky performance status score improved compared to preoperative (80), early postoperative (70), and latest assessment (90) (median 36 months). Five patients underwent reoperation due to tumor recurrence after 4-48 months (mean 24 months). Most patients undergoing removal of skull base chordomas suffer from transient neurological deficits which are mainly nonsignificant as the patients return to preoperative functional status. The apparently high rate of incomplete tumor resection (64%) reflects the infiltrative behavior and relationship with neurovascular structures. The operative strategy should not be excessively aggressive at any price, but rather take into account the options of radiotherapy and observation of residual tumor.

Norepinephrine in the rat cortex before and after occlusion of chronic arteriovenous fistulae: a microdialysis study in an animal model of cerebral arteriovenous malformations.

OBJECTIVE: In an animal model, we tested the hypothesis that intracerebral, extracellular norepinephrine (NE) influences cerebral blood flow (CBF) in the presence of cerebral arteriovenous malformations (AVMs). METHODS: A microdialysis (MD) probe was implanted into the cortices of Sprague-Dawley rats 3 months after the creation of extracranial arteriovenous fistulae (AVFs; n = 19), carotid ligation (n = 10), and cervical vessel preparation (sham operations; n = 8). Ipsilateral regional cortical oxygen saturation (microspectrophotometry) and regional cerebral blood flow (laser Doppler flowmetry) were scanned with simultaneous MD sampling for NE (high-performance liquid chromatography). Local CBF and cortical capillary oxygen saturation (SO2) were recorded continuously with serial MD sampling after fistula occlusion for 100 minutes. The scanning protocol was repeated after 120 minutes. Values were compared by analysis of variance and Duncan's test (P < 0.05; values expressed as mean +/- standard deviation). RESULTS: NE was highest in sham-operated animals and lowest after carotid ligation as compared with before and after the creation of the AVFs (sham operations, 5.9 +/- 2.3 nmol/L; common carotid artery ligation, 2.4 +/- 1 nmol/L; before creation of AVF, 4.1 +/- 1.9 nmol/L; after creation of AVF, 4.1 +/- 2.3 nmol/L). Regional cortical oxygen saturation differed significantly between all groups; regional cerebral blood flow was lower only in sham-operated animals (sham operations, 210 +/- 75 laser Doppler units [LDU], 71 +/- 13% SO2; common carotid artery ligation, 250 +/- 82 LDU, 62 +/- 19% SO2; before creation of AVF, 249 +/- 96 LDU, 65 +/- 14% SO2; after creation of AVF, 256 +/- 82 LDU, 74 +/- 10% SO2). After fistula occlusion, a sustained CBF increase for 100 minutes up to 40% above baseline (i.e., regional cerebral blood flow and regional cortical oxygen saturation before occlusion) was observed. SO2 increased to 16% after 120 minutes. Peaks of NE concentrations occurred 40 minutes and 100 minutes after fistula occlusion. CONCLUSION: The model seems to be valid for the simulation of events that occur before and after the obliteration of human cerebral AVMs in most cases, but not in those prone to hyperperfusion syndromes. The results provide evidence that cerebral sympathetic nervous system activity can be monitored by in vivo MD and that NE may play a role in CBF control before and after the obliteration of AVFs.

A staged treatment algorithm for spinal infections.

BACKGROUND AND STUDY AIM: Spinal pyogenic infections occur frequently in today's neurosurgical routine. Conservative therapy often proves to be insufficient against an aggressive disease that affects patients who tend to be elderly and debilitated with complex comorbidity. Treatment, or lack of treatment, carries risks of persistent disability, sepsis, and death. In this study, we propose a tailored and staged algorithm for treating such spinal infections and present results of this approach. PATIENTS AND METHODS: We retrospectively analyzed 52 patients (33 male, 19 female; median age: 68 years) who had undergone cervical, thoracic, or lumbar surgery for spinal infections according to the proposed staged treatment algorithm. RESULTS: Most of the 52 patients were severely disabled (35% with quadri- or paraparesis, 31% with sepsis and catecholamine dependency, 17% with a single motor deficit, and 10% with meningitis). We surgically treated multilevel and multisegmental spinal infections via 23 nonstabilizing and 57 stabilizing ventral or dorsal approaches to the cervical, thoracic, or lumbar spine. The mean follow-up time was 24 months. Overall mortality was 19%. Surgery-related complications occurred in 11.5% of patients; recurrence of infection occurred in 3.8%. Motor function improved in 61.7%; bladder and sphincter dysfunction remitted completely in 50.0%. CONCLUSIONS: Depending on the patient's health status and neurological condition, surgery in complex spinal infections provides a good outcome in most cases. Nevertheless, indication must be individualized; for this, the proposed algorithm seems to be an excellent tool. We find that surgery should be discussed as a treatment of first choice for today's often complex spinal infections.

Accuracy of robot-assisted placement of lumbar and sacral pedicle screws: a prospective randomized comparison to conventional freehand screw implantation.

STUDY DESIGN: Single-center prospective randomized controlled study. OBJECTIVE: To evaluate the accuracy of robot-assisted (RO) implantation of lumbar/sacral pedicle screws in comparison with the freehand (FH) conventional technique. SUMMARY OF BACKGROUND DATA: SpineAssist is a miniature robot for the implantation of thoracic, lumbar, and sacral pedicle screws. The system, studied in cadaver and cohort studies, revealed a high accuracy, so far. A direct comparison of the robot assistance with the FH technique is missing. METHODS: Patients requiring mono- or bisegmental lumbar or lumbosacral stabilization were randomized in a 1:1 ratio to FH or RO pedicle screw implantation. Instrumentation was performed using fluoroscopic guidance (FH) or robot assistance. The primary end point screw position was assessed by a postoperative computed tomography, and screw position was classified (A: no cortical violation; B: cortical breach <2 mm; C: ≥2 mm to <4 mm; D: ≥4 mm to <6 mm; E: ≥6 mm). Secondary end points as radiation exposure, duration of surgery/planning, and hospital stay were assessed. RESULTS: A total of 298 pedicle screws were implanted in 60 patients (FH, 152; RO, 146). Ninety-three percent had good positions (A or B) in FH, and 85% in RO. Preparation time in the operating room (OR), overall OR time, and intraoperative radiation time were not different for both groups. Surgical time for screw placement was significantly shorter for FH (84 minutes) than for RO (95 minutes). Ten RO screws required an intraoperative conversion to the FH. One FH screw needed a secondary revision. CONCLUSION: In this study, the accuracy of the conventional FH technique was superior to the RO technique. Most malpositioned screws of the RO group showed a lateral deviation. Attachment of the robot to the spine seems a vulnerable aspect potentially leading to screw malposition as well as slipping of the implantation cannula at the screw entrance point.

Dynamic Autoregulation Testing Does Not Indicate Changes of Cerebral Blood Flow Before and After Resection of Small- and Medium-Sized Cerebral AVM.

This study tested the hypothesis that dynamic cerebral autoregulation (AR) remains intact before and after the excision of human arteriovenous malformations (AVM). In 12 patients (six female and six male; mean age, 34 years) harboring cerebral AVMs (AVM group), and 15 patients (nine female/six male; mean age, 49 years) with deep-seated lesions (e.g., small frontobasal meningiomas) approached by transsylvian dissection (control group), we continuously assessed cerebral blood flow (CBF) using a thermo-diffusion technique, and mean arterial blood pressure (MABP). AR was estimated post-hoc using correlation-coefficient autoregulatory-index (Mx) analysis. Measurements were compared according to groups (AVM/control) and times (pre/post), referred to as conditions before and after AVM resection and transsylvian dissection, respectively. All values are given as mean ± SD. The correlation index Mx was without significant difference among the study groups, indicating unimpaired autoregulatory function. Intragroup comparisons related to AVM nidus size (small- (≤3 cm) and medium-sized (3-6 cm)) did not show significant influence on autoregulation. The study shows that in patients harboring small- and medium-sized AVMs, dynamic autoregulatory function as estimated by correlation-coefficient index analysis seems to be intact in the surrounding cerebrovascular bed perioperatively.

Evidence for a predominant intrinsic sympathetic control of cerebral blood flow alterations in an animal model of cerebral arteriovenous malformation.

In terms of neurogenic cerebral blood flow (CBF) control, the activity of the sympathetic nervous system (SNS) has a regulating effect. The impact of a manipulation of both the peripheral (via the perivascular sympathetic net) and central components (via the intracortical noradrenergic terminals originating from the locus coeruleus) on CBF-and especially on hyperperfusion syndromes-is unclear. To test the specific patterns following such alterations, cortical oxygen saturation (rSO2), regional CBF (rCBF), and cortical interstitial norepinephrine (NE) concentrations were measured. Twelve weeks after either the creation of an extracranial AV fistula or sham operation, 80 male Sprague-Dawley rats underwent one of the following procedures: (1) no SNS manipulation, (2) peripheral SNS inhibition via bilateral sympathectomy, (3) central SNS inhibition via the neurotoxin DSP-4, or (4) complete SNS inhibition. Norepinephrine concentrations were lowest after complete inhibition (NE [nmol]: pre, 1.8 ± 1.2; post, 2.4 ± 1.8) and highest following peripheral inhibition (NE [nmol]: pre, 3.6 ± 1.9; post, 6.6 ± 4.4). Following fistula occlusion, rCBF (laser Doppler unit [LDU]) and rSO2 (%SO2) increases were highest after complete inhibition (pre: 204 ± 14 LDU, 34 ± 3%SO2; post: 228 ± 18 LDU, 39 ± 3%SO2) and lowest after peripheral inhibition (pre: 221 ± 18 LDU, 41 ± 2%SO2; post: 226 ± 14 LDU, 47 ± 2%SO2). Thus, a complete inhibition down-regulates SNS activity and provokes a cortical hyperperfusion condition. With this, the hitherto unknown predominant role of the intrinsic component could be demonstrated for the first time in vivo.

Clinical acceptance and accuracy assessment of spinal implants guided with SpineAssist surgical robot: retrospective study.

STUDY DESIGN: Retrospective, multicenter study of robotically-guided spinal implant insertions. Clinical acceptance of the implants was assessed by intraoperative radiograph, and when available, postoperative computed tomography (CT) scans were used to determine placement accuracy. OBJECTIVE: To verify the clinical acceptance and accuracy of robotically-guided spinal implants and compare to those of unguided free-hand procedures. SUMMARY OF BACKGROUND DATA: SpineAssist surgical robot has been used to guide implants and guide-wires to predefined locations in the spine. SpineAssist which, to the best of the authors' knowledge, is currently the sole robot providing surgical assistance in positioning tools in the spine, guided over 840 cases in 14 hospitals, between June 2005 and June 2009. METHODS: Clinical acceptance of 3271 pedicle screws and guide-wires inserted in 635 reported cases was assessed by intraoperative fluoroscopy, where placement accuracy of 646 pedicle screws inserted in 139 patients was measured using postoperative CT scans. RESULTS: Screw placements were found to be clinically acceptable in 98% of the cases when intraoperatively assessed by fluoroscopic images. Measurements derived from postoperative CT scans demonstrated that 98.3% of the screws fell within the safe zone, where 89.3% were completely within the pedicle and 9% breached the pedicle by up to 2 mm. The remaining 1.4% of the screws breached between 2 and 4 mm, while only 2 screws (0.3%) deviated by more than 4 mm from the pedicle wall. Neurologic deficits were observed in 4 cases yet, following revisions, no permanent nerve damage was encountered, in contrast to the 0.6% to 5% of neurologic damage reported in the literature. CONCLUSION: SpineAssist offers enhanced performance in spinal surgery when compared to free-hand surgeries, by increasing placement accuracy and reducing neurologic risks. In addition, 49% of the cases reported herein used a percutaneous approach, highlighting the contribution of SpineAssist in procedures without anatomic landmarks.

Genome-wide association study of intracranial aneurysm identifies three new risk loci.

Saccular intracranial aneurysms are balloon-like dilations of the intracranial arterial wall; their hemorrhage commonly results in severe neurologic impairment and death. We report a second genome-wide association study with discovery and replication cohorts from Europe and Japan comprising 5,891 cases and 14,181 controls with approximately 832,000 genotyped and imputed SNPs across discovery cohorts. We identified three new loci showing strong evidence for association with intracranial aneurysms in the combined dataset, including intervals near RBBP8 on 18q11.2 (odds ratio (OR) = 1.22, P = 1.1 x 10(-12)), STARD13-KL on 13q13.1 (OR = 1.20, P = 2.5 x 10(-9)) and a gene-rich region on 10q24.32 (OR = 1.29, P = 1.2 x 10(-9)). We also confirmed prior associations near SOX17 (8q11.23-q12.1; OR = 1.28, P = 1.3 x 10(-12)) and CDKN2A-CDKN2B (9p21.3; OR = 1.31, P = 1.5 x 10(-22)). It is noteworthy that several putative risk genes play a role in cell-cycle progression, potentially affecting the proliferation and senescence of progenitor-cell populations that are responsible for vascular formation and repair.

Endoscopy-assisted approaches for anterior column reconstruction after pedicle screw fixation of acute traumatic thoracic and lumbar fractures.

OBJECTIVE: Surgical treatment of thoracic and lumbar vertebral body fractures combines instrumentation to stabilize the fracture and an anterior reconstruction to promote fusion of the fractured spine. The aim of the present study was to show that minimally invasive thoracoscopic or endoscopy-assisted approaches to the thoracic and lumbar spine are feasible for anterior column reconstruction. METHODS: This prospective, single-center study included 83 consecutive patients harboring 100 acute thoracic and lumbar vertebral fractures. Patients' neurological status; preoperative, postoperative, and follow-up radiographic data; and surgical data were obtained. RESULTS: Fractures ranged from T5 to L5. All fractures underwent posterior pedicle screw fixation followed by a thoracoscopic or endoscopy-assisted anterior approach for anterior column reconstruction to promote fusion. Ventral graft position was correct in 45 patients and acceptable in 37 patients; one patient required a surgical repositioning. Initial correction of kyphosis was 9 degrees; during follow-up (23 +/- 11 mo), the mean loss of correction was 6 degrees. In 84 minimally invasive approaches, five conversions to an open approach were necessary. Complications included one case of L1 nerve root injury, two cases of transient neurological worsening, one case of posterior wound infection, and one case of pleural empyema. CONCLUSION: The minimally invasive endoscopic approach for anterior column reconstruction is a feasible strategy in the treatment of unstable thoracic and lumbar fractures. Fracture type and the material of the anterior graft can affect long-term maintenance of correction.

Norepinephrine and cerebral blood flow regulation in patients with arteriovenous malformations.

OBJECTIVE: To test the hypothesis that the sympathetic nervous system plays a role in cerebral blood flow regulation in patients with arteriovenous malformations (AVM). METHODS: Cortical interstitial norepinephrine was measured by means of microdialysis, regional cerebral blood flow was measured by a thermal diffusion technique, and regional oxygen saturation (SO2) was measured by microspectrophotometry in 12 patients harboring cerebral AVMs (AVM group) and in 15 patients with deep-seated nonvascular lesions (control group) before and after resection. Measurements were compared according to groups and times of measurements. All values are given as means +/- standard deviation. RESULTS: Cortical regional SO2 increased significantly (P < 0.05) in both groups after surgery (AVM group: presurgery 52.4 +/- 12.5% SO2, postsurgery 71.4 +/- 7.4% SO2; control group: presurgery 57.1 +/- 8.4% SO2, postsurgery 69.9 +/- 8.7% SO2), whereas regional cerebral blood flow increased only in the AVM group (AVM group: presurgery 18.9 +/- 6.6 ml/100 g/min, postsurgery 26.2 +/- 6.9 ml/100 g/min; control group: presurgery 20.1 +/- 7.6 ml/100 g/min, postsurgery 19.4 +/- 7.8 ml/100 g/min). Norepinephrine concentrations were significantly lower in the AVM group as compared with the control group before surgery. Although there was no significant difference between pre- and postsurgery conditions in the AVM group, the norepinephrine level of the control group was significantly lower after surgery (AVM group: presurgery 3.3 +/- 1.2 nmol/L, postsurgery 2.9 +/- 1.7 nmol/L; control group: presurgery 5.4 +/- 1.4 nmol/L, postsurgery 4.2 +/- 1.1 nmol/L). CONCLUSION: Chronically lowered perfusion pressure seems to induce the hypothesized adaptive down-regulation of sympathetic nervous system activity, yet protective up-regulation after a sudden elevation of cerebral perfusion pressure after AVM excision could not be shown in this study.

Frequent recurrence and progression in pilocytic astrocytoma in adults.

BACKGROUND: Most pilocytic astrocytomas (piloA) are benign growths (World Health Organization [WHO] grade 1) of the deep midline structures, the brainstem, and the cerebellum. To the authors' knowledge, the literature contains only scarce data regarding piloA in adults. METHODS: Between 1995 and 2005, 44 patients (26 women and 18 men) underwent surgery for a primary or recurrent piloA at the authors' institution. All patients were aged > 16 years (mean +/- standard deviation: 31 +/- 14 years) at the time of their first surgery. The histopathologic diagnoses were reviewed, and relevant clinical information was obtained through a chart review and telephone interviews. The mean follow-up was 76 +/- 59 months (range, 1-227 months). RESULTS: There were 20 patients (45%) with supratentorial lobar piloA (including 10 temporal/temporomesial tumors, 5 parietal tumors, 3 insular tumors, 1 frontal tumor, and 1 occipital tumors), 12 patients with cerebellar piloA, 7 patients with brainstem piloA, 2 patients with opticochiasmatic PiloA, 1 patient with intramedullary piloA, and 2 patients with piloA of the basal ganglia. All but 1 patient with a lobar tumor presented with epilepsy. In 6 of 44 patients (14%), increased proliferative activity was revealed. WHO grade 3 primary anaplastic piloA was diagnosed in 2 patients (5%), and WHO grade 3 secondary anaplastic piloA was diagnosed in 4 patients (9%). Tumor recurrence or disease progression was observed in 13 of 44 patients (30%). Eight of 44 patients (18%) died from their disease. Histologic grading and extent of surgical resection proved to be important predictors of survival. CONCLUSIONS: PiloA in adult patients, surprisingly, often was not a benign disease. The degree of surgical resection was found to be of major importance for the patient's further clinical course; therefore, an aggressive surgical resection should be attempted whenever possible.

Minimally invasive transmuscular pedicle screw fixation of the thoracic and lumbar spine.

OBJECTIVE: This study assessed the feasibility and safety of percutaneous posterior pedicle screw fixation for instabilities of the thoracic and lumbar spine, using standard instruments designed for the open approach and fluoroscopy. METHODS: All patients who underwent percutaneous posterior pedicle screw fixation of the thoracic and lumbar spine were studied retrospectively. Charts and operative notes were analyzed for epidemiological data, underlying spinal pathological features, and indications for stabilization, stabilized segments, number of implanted pedicle screws, surgical time, and complications. Postoperative computed tomographic scans were analyzed for screw position. RESULTS: From May 2002 through May 2005, 115 internal fixators were implanted percutaneously in 104 patients. A total of 488 pedicle screws were implanted, stabilizing 1 to 5 spinal motion segments. Median surgical time was 93 minutes. On postoperative computed tomographic scans, 87% of screw positions were rated good, 10% were rated acceptable, and 3% were rated unacceptable. A total of 11 revisions were necessary, 9 for misplaced screws and 2 for loosening of anchor bolts. Only two of the patients experienced new clinical symptoms (i.e., radicular pain) because of screw misplacement. No patients experienced new neurological deficits or other surgery-related morbidity. CONCLUSION: This study shows that percutaneous internal pedicle screw fixation using standard instruments is feasible and safe for posterior stabilization of the thoracic and lumbar spine. It is a straightforward alternative for open approaches or minimally invasive ones using navigation in conjunction with customized instruments. Accuracy of screw placement is similar to that reported for other techniques.