Effects of an immunomodulatory therapy and chondroitinase after spinal cord hemisection injury.

BACKGROUND: Individually, immunomodulatory therapy and chondroitinases have demonstrated neuroprotective and potential neuroregenerative effects following spinal cord injury. OBJECTIVE: To investigate the therapeutic potential of combined immunomodulatory and chondroitin sulfate-glycosaminoglycan degradation therapy in spinal cord injury. METHODS: A combined immunomodulatory treatment using (1) liposome-encapsulated clodronate (selectively depletes peripheral macrophages), and (2) rolipram (a selective type 4 phosphodiesterase inhibitor), along with the chondroitin sulfate proteoglycan-glycosaminoglycan-degrading enzyme, chondroitinase ABC (ChABC), was assessed for its potential to promote axonal regrowth and improve locomotor recovery following midthoracic spinal cord hemisection injury in adult rats. RESULTS: We demonstrate that combined treatment with liposomal clodronate, rolipram, and ChABC attenuates macrophage accumulation at the site of injury, reduces axonal die-back of injured dorsal column axons, and produces the greatest improvement in locomotor recovery at 6 weeks postinjury compared with controls and noncombined therapy. Anterograde and retrograde tracing revealed that delivery of clodronate, rolipram, and ChABC did not promote substantial axonal regeneration through the site of injury, although the treatment did limit the extent of axonal die-back. Histological assessments revealed that combined treatment with clodronate/rolipram and/or ChABC resulted in a significant reduction in lesion size and cystic cavitation in comparison with injured controls. Combined clodronate, rolipram, and ChABC treatment reduced the accumulation of macrophages within the injured spinal cord 7 weeks after injury. CONCLUSION: The present data suggest that delivery of an immunomodulatory therapy consisting of clodronate and rolipram, in combination with ChABC, reduces axonal injury and enhances neuroprotection, plasticity, and hindlimb functional recovery after hemisection spinal cord injury in adult rats.

Occipitocervical fusion in an infant with atlantooccipital dislocation.

BACKGROUND: For children who survive traumatic atlantooccipital dislocation (AOD), early surgical stabilization and arthrodesis of the occipitoatlantoaxial complex is typically performed. Because of the unique and crowded anatomy of the occipitocervical junction, the creation of a fusion construct that is both safe and biomechanically sound is extremely challenging, especially in infants. We present a technical report of a patient with infantile type I AOD with gross instability, who underwent surgical stabilization consisting of occiput to C2 arthrodesis using autologous rib, augmented with bone morphogenic protein 2 (BMP-2), Mersilene suture, and Ethibond suture as "cross-connectors." CASE DESCRIPTION: The patient is a 12-month-old female infant who was involved in a high-speed motor vehicle accident and sustained a type I AOD. Definitive surgical stabilization consisting of arthrodesis from the occiput to C2 using autologous rib augmented with BMP-2, Mersilene suture, and Ethibond suture as cross-connectors was performed. There were no intraoperative complications. A follow-up cervical spine computed tomography obtained 12 weeks postoperatively demonstrated excellent occipitocervical alignment, with evidence of modest bony fusion from the occiput to C2. Neurologic examination demonstrated modest, but progressive, improvement, with partial resolution of bilateral sixth nerve palsies, and improvement in upper- and lower-extremity muscle strength and tone. CONCLUSION: Significant surgical challenges exist regarding occipitocervical fusion in infants with AOD and gross instability. This case report illustrates the successful application of BMP-2-augmented occipitocervical fusion using autologous rib, in combination with Mersilene and Ethibond suture, in the treatment of an infant with type I AOD with gross instability.

Convection-enhanced delivery of therapeutic agents into the brain.

CED of therapeutic agents remains a promising strategy for treating malignant gliomas and non-neoplastic neurological diseases. Although initial clinical trials have failed to show survival benefit for new agents delivered via this approach, multiple earlier stage trials have addressed only a fraction of the myriad of technical and technological issues that surround this novel approach. Development of CED has been limited by the fact that both new technologies and novel therapeutic agents are being developed simultaneously.New trials are being planned to investigate agents that can be coinfused with radiographic tracers, as well as novel catheters that avoid problems with backflow and potentially will provide more reliable drug distribution.

Oncomodulin affords limited regeneration to injured sensory axons in vitro and in vivo.

Oncomodulin, an ~12 kDa Ca(2+)-binding protein secreted from activated macrophages, has been shown to promote axonal regeneration from retinal ganglion cells (RGCs) following optic nerve injury. However, to date, the axonal growth-promoting capacity of oncomodulin in other models of 'regenerative failure' has not been evaluated. We assessed the capability of preconditioning treatment with oncomodulin to promote sensory axonal regeneration in an in vitro spot model of regenerative failure, and across the dorsal root zone (DREZ) after root crush injury. Neither the direct exposure of adult rat DRGs to oncomodulin, nor preconditioning of DRGs by intraganglionic injection of oncomodulin, stimulated axonal outgrowth in the in vitro proteoglycan spot gradient assay. However, direct exposure of unconditioned DRGs to both oncomodulin and db-cAMP in vitro, as well as preconditioning of DRGs with the combined treatment in vivo, resulted in significant, albeit modest, neurite extension across the inhibitory proteoglycan barrier. We next quantified axon regeneration through the C8 DREZ in adult rats after oncomodulin and/or db-cAMP preconditioning and chondroitinase (ChABC) injection into the DREZ immediately following a root crush injury. Axonal regeneration across the DREZ was not observed in control animals, or after injection of ChABC-alone. Treatment with oncomodulin- or db-cAMP-alone resulted in extremely sparse regeneration. However, significant, but meager, sensory axon regeneration across the DREZ was observed using the oncomodulin/ db-cAMP combination (p<0.001), supporting findings from previous studies suggesting that cAMP is necessary for the growth-promoting effects of oncomodulin. Although our results support a role for oncomodulin in macrophage-induced axonal regeneration, the effects of oncomodulin/db-cAMP on sensory regeneration were extremely limited in comparison to previous studies in the same injury model using zymosan.

A combination immunomodulatory treatment promotes neuroprotection and locomotor recovery after contusion SCI.

The present study assessed the ability of a combined immunomodulatory treatment using (1) selective depletion of peripheral macrophages with liposomal-encapsulated clodronate, and (2) rolipram, a type 4 phosphodiesterase (PDE4) inhibitor, to promote neuroprotection and improve locomotor recovery following experimental contusion SCI. We demonstrate that delivery of either liposomal clodronate or rolipram alone promotes neuroprotection, enhances myelinated tissue sparing, and improves hindlimb functional recovery. Combined treatment with liposomal clodronate and rolipram produced the greatest improvement in locomotor recovery (inter-limb coordination, paw placement, and toe clearance), at 4 weeks post-injury (2.9 points). Retrograde tracing revealed substantial axonal sparing and/or sprouting from several brainstem motor nuclei, and hindlimb motor cortex. The combined treatment with these two drugs promoted the greatest amount of axonal sparing (3- to 4-fold increase compared to controls). Histological assessments revealed that combined treatment with clodronate/ rolipram resulted in a significant reduction in lesion volume (51%) and lesion area at the injury epicenter (45%), and significantly increased the extent of myelinated tissue sparing. Immunohistochemical studies showed a qualitative reduction in the accumulation of ED-1(+) macrophages within the injured spinal cord 5 weeks after injury. Our results demonstrate robust neuroprotection and improved hindlimb locomotor function using a combined immunomodulatory treatment strategy consisting of liposomal clodronate and rolipram. The present data suggest that clinical trials with acute delivery of combination immunomodulatory therapies may be warranted. This article is part of a Special Issue entitled "Interaction between repair, disease, & inflammation."

Dorsal approaches to intradural extramedullary tumors of the craniovertebral junction.

Tumors of the craniovertebral junction (CVJ) pose significant challenges to cranial and spine surgeons. Familiarity with the complex anatomy and avoidance of injury to neurologic and vascular structures are essential to success. Multiple surgical approaches to address lesions at the CVJ have been promoted, including ventral and dorsal-based trajectories. However, optimal selection of the surgical vector to manage the pathology requires a firm understanding of the limitations and advantages of each approach. The selection of the best surgical trajectory must include several factors, such as obtaining the optimal exposure of the region of interest, avoiding injury to critical neurologic or vascular structures, identification of normal anatomical landmarks, the familiarity and comfort level of the surgeon to the approach, and the need for fixation. This review article focuses on dorsal approaches to the CVJ and the advantages and limitations in managing intradural extramedullary tumors.

Effective lordosis: analysis of sagittal spinal canal alignment in cervical spondylotic myelopathy.

OBJECT: Analysis of cervical sagittal deformity in patients with cervical spondylotic myelopathy (CSM) requires a thorough clinical and radiographic evaluation to select the most appropriate surgical approach. Angular radiographic measurements, which are commonly used to define sagittal deformity, may not be the most appropriate to use for surgical planning. The authors present a simple straight-line method to measure effective spinal canal lordosis and analyze its reliability. Furthermore, comparisons of this measurement to traditional angular measurements of sagittal cervical alignment are made in regards to surgical planning in patients with CSM. METHODS: Twenty preoperative lateral cervical digital radiographs of patients with CSM were analyzed by 3 independent observers on 3 separate occasions using a software measurement program. Sagittal measurements included C2-7 angles utilizing the Cobb and posterior tangent methods, as well as a straight-line method to measure effective spinal canal lordosis from the dorsal-caudal aspect of the C2-7 vertebral bodies. Analysis of variance for repeated measures or Cohen 3-way (kappa) correlation coefficient analysis was performed as appropriate to calculate the intra- and interobserver reliability for each parameter. Discrepancies in angular and effective lordosis measurements were analyzed. RESULTS: Intra- and interobserver reliability was excellent (intraclass coefficient > 0.75, kappa > 0.90) utilizing all 3 techniques. Four discrepancies between angular and effective lordotic measurements occurred in which images with a lordotic angular measurement did not have lordosis within the ventral spinal canal. These discrepancies were caused by either spondylolisthesis or dorsally projecting osteophytes in all cases. CONCLUSIONS: Although they are reliable, traditional methods used to make angular measurements of sagittal cervical spine alignment do not take into account ventral obstructions to the spinal cord. The effective lordosis measurement method provides a simple and reliable means of determining clinically significant lordosis because it accounts for both overall alignment of the cervical spine as well as impinging structures ventral to the spinal cord. This method should be considered for use in the treatment of patients with CSM.

Solitary Nocardia farcinica brain abscess in an immunocompetent adult mimicking metastatic brain tumor: rapid diagnosis by pyrosequencing and successful treatment.

BACKGROUND: Nocardia brain abscess carries a higher morbidity and mortality rate than other bacterial cerebral abscesses, with reported mortality rates of 55% and 20% in immunocompromised and immunocompetent patients, respectively. To prevent a delay in diagnosis and treatment, an aggressive therapeutic approach is required. In the present study, a rapid and accurate molecular diagnostic approach using pyrosequencing (PS), a semiautomated molecular genotyping method of nucleotide sequencing-by-synthesis, was performed. CASE DESCRIPTION: A 53-year-old man developed word-finding difficulties, followed by confusion and disorientation. On examination, the patient had a mixed aphasia; the receptive component was greater than the expressive component. The remainder of his neurologic examination findings was normal. Gadolinium-enhanced magnetic resonance imaging of the brain revealed a 2.0-cm multilobular, partially cystic, peripheral-enhancing mass in the posterior left temporal-parietal region with significant vasogenic edema and localized mass effect. A detailed laboratory investigation revealed that this patient was immunocompetent. An awake left posterior temporal-parietal craniotomy with cortical motor and speech mapping, using frameless stereotactic image guidance and intraoperative real-time ultrasound, was performed. Frozen section was consistent with cerebral abscess and methenamine silver staining revealed many beaded, thin-branching gram-positive bacilli. Colonies suspicious for Nocardia sp were seen within 2 days, and PCR followed by pyrosequencing (PS) identified Nocardia farcinica. CONCLUSIONS: We report a nocardial cerebral abscess mimicking a metastatic brain tumor, and we demonstrate that PS technology can be used for the accurate and rapid identification of N farcinica isolated from a brain abscess -- facilitating a rapid diagnosis and successful, durable treatment.

Dural repair reduces connective tissue scar invasion and cystic cavity formation after acute spinal cord laceration injury in adult rats.

This study examined whether duraplasty after acute cervical laceration spinal cord injury (SCI) in a rat model could (1) improve cerebrospinal fluid (CSF) circulation adjacent to the injury; (2) minimize connective tissue scarring; and (3) reduce post-traumatic inflammation and cystic cavitation. Following a transverse dural/arachnoid incision and C5-6 dorsal spinal hemisection, a 5-mm2 cadaveric dura mater allograft was placed over the lesion and fixed with fibrin glue (n=12). Control animals received an identical dural/arachnoid incision and cervical dorsal hemisection without dural repair (n=12). At 1, 5, and 10 weeks post-injury, plain film myelograms were obtained to characterize CSF circulation, and stereological methods were used to compare the extent of tissue sparing between the two groups. Immunohistochemical studies were performed to assess the degree of inflammation (ED-1), connective tissue scarring (laminin and type IV collagen), and reactive astrogliosis (GFAP). Our results indicate that dural allograft can improve CSF flow adjacent to the site of injury, which may be due to reduced meningeal fibrosis/scarring at the lesion site. Stereological analysis demonstrated that duraplasty resulted in a significant reduction in lesion volume at each time-point (p<0.01) associated with a nearly complete attenuation of post-traumatic cystic cavitation (p<0.001). Immunofluorescence studies demonstrated that duraplasty reduced the infiltration of ED-1-positive macrophages/microglia into and surrounding the lesion site, which may be responsible for the marked reduction in secondary injury following duraplasty. We conclude that duraplasty following acute spinal cord laceration may (1) improve CSF flow by limiting meningeal fibrosis; (2) reduce connective tissue scar formation; and (3) attenuate macrophage accumulation and progressive secondary injury.

Functional and electrophysiological changes after graded traumatic spinal cord injury in adult rat.

A graded contusion spinal cord injury (SCI) was created in the adult rat spinal cord using the Infinite Horizons (IH) impactor to study the correlation between injury severity and anatomical, behavioral, and electrophysiological outcomes. Adult Fisher rats were equally divided into five groups and received contusion injuries at the ninth thoracic level (T9) with 100, 125, 150, 175, or 200 kdyn impact forces, respectively. Transcranial magnetic motor-evoked potentials (tcMMEPs) and BBB open-field locomotor analyses were performed weekly for 4 weeks postinjury. Our results demonstrated that hindlimb locomotor function decreased in accordance with an increase in injury severity. The locomotor deficits were proportional to the amount of damage to the ventral and lateral white matter (WM). Locomotor function was strongly correlated to the amount of spared WM, which contains the reticulospinal and propriospinal tracts. Normal tcMMEP latencies were recorded in control, all of 100-kdyn-injured and half of 125-kdyn-injured animals. Delayed latency responses were recorded in some of 125-kdyn-injured and all of 150-kdyn-injured animals. No tcMMEP responses were recorded in 175- and 200-kdyn-injured animals. Comparison of tcMMEP responses with areas of WM loss or demyelination identified the medial ventrolateral funiculus (VLF) as the location of the tcMMEP pathway. Immunohistochemical and electromicroscopic (EM) analyses showed the presence of demyelinated axons in WM tracts surrounding the lesion cavities at 28 days postinjury. These data support the notion that widespread WM damage in the ventral and lateral funiculi may be a major cause for locomotor deficits and lack of tcMMEP responses after SCI.

A neuroprotective role of glial cell line-derived neurotrophic factor following moderate spinal cord contusion injury.

The present study investigated neuroprotective effects of glial cell line-derived neurotrophic factor (GDNF), a distant member of the transforming growth factor-beta (TGF-beta) superfamily, following moderate contusive spinal cord injury (SCI) in adult rats. A T11 spinal cord contusion injury was made using an Infinite Horizon impactor (IH; impact force=150 kDyn) and recombinant human GDNF at two concentrations (rhGDNF; 1 or 5 microg/microl), or saline vehicle was delivered intrathecally for 28 days using an Alzet miniosmotic pump. We demonstrated that, at 7 weeks postinjury, GDNF infusion significantly reduced the total lesion volume by 34-42% (assessed stereologically) and increased the percentage of white matter sparing by 10-13% (measured at the injury epicenter), as compared to the vehicle infusion. Retrograde tracing revealed that GDNF infusion resulted in a significant increase in the number of FluoroGold (FG)-labeled neurons in propriospinal regions as well as in two supraspinal regions, that is, the medullary and pontine reticular formation, and the lateral vestibular nucleus. Immunofluorescent staining confirmed that the spared white matter contained neurofilament-positive axons. However, transcranial magnetic motor-evoked potential (tcMMEP) assessment revealed no significant difference in onset latency and amplitude between the GDNF- and vehicle-infused groups. These results suggest that GDNF has a strong neuroprotective effect on white matter sparing and the sparing of a subset of proprio- and supraspinal axons following injury. However, a return of tcMMEPs requires the sparing and/or myelination of axons in a defined region of the white matter which was either not spared or remyelinated at this level of injury severity.

Dural closure, cord approximation, and clot removal: enhancement of tissue sparing in a novel laceration spinal cord injury model.

OBJECT: Laceration-induced spinal cord injury (SCI) results in the invasion of a connective tissue scar, progressive damage to the spinal cord due to complex secondary injury mechanisms, and axonal dieback of descending motor pathways. The authors propose that preparation of the spinal cord for repair strategies should include hematoma removal and dural closure, resulting in apposition of the severed ends of the spinal cord. Such procedures may reduce the size of the postinjury spinal cord cyst as well as limit scar formation. METHODS: Using a novel device, the Vibraknife, the authors created a dorsal hemisection of the spinal cord at C-6 in the adult rat. In Group 1 (eight rats), the dura mater was repaired with apposition of the two stumps of the spinal cord to reduce the lesion gap. In Group 2 (10 rats), the dura was not closed and the two cord stumps were not approximated. All rats were killed at 4 weeks postinjury, and the spinal cords from each group were removed and examined using histological, stereological, and immunohistochemical methods. In Group 1 rats a significant reduction of the total lesion volume and connective tissue scar was observed compared with those in Group 2 (Student t-test, p < 0.05). Approximation of the stumps did not promote the regeneration of corticospinal tract fibers or sensory axons through the lesion site. CONCLUSIONS: Apposition of the severed ends of the spinal cord by dural closure reduces the lesion gap, cystic cavitation, and connective tissue scar formation. These outcomes may collectively reduce secondary tissue damage at the injury site and shorten the length of the lesion gap, which will facilitate transplantation-mediated axonal regeneration after laceration-induced SCI.

Glial cell line-derived neurotrophic factor-enriched bridging transplants promote propriospinal axonal regeneration and enhance myelination after spinal cord injury.

Glial cell line-derived neurotrophic factor (GDNF), a distant member of the transforming growth factor-beta (TGF-beta) family, is widely expressed in the developing and adult central nervous system (CNS). At present, limited information is available regarding the effects of GDNF in the repair of spinal cord injury (SCI). In the present study, mini-guidance channels containing either: (1) Matrigel (MG, a basement membrane component), (2) Schwann cells (SCs, 120 x 10(6)/ml) in MG (SC-MG), (3) recombinant human GDNF (rhGDNF, 3 microg/microl) in MG (GDNF-MG), and (4) a combination of all three components (GDNF-SC-MG) were grafted into a T9 hemisection-gap lesion in adult rats to examine the effects of GDNF on axonal regeneration and myelination following SCI. Thirty days post-transplantation, limited axonal growth was observed within guidance channels containing MG-alone (MG). When SCs were added to the channels (SC-MG group), consistent axonal ingrowth containing both myelinated and unmyelinated axons was observed, confirming our previous findings. The addition of GDNF-alone without SCs (GDNF-MG) resulted in substantial ingrowth of unmyelinated axons, suggesting that GDNF has a direct neurite-growth promoting effect on these axons. Implantation of channels containing both GDNF and SCs (GDNF-SC-MG) produced a significant and synergistic increase in axonal regeneration and myelination. In addition, GDNF reduced the extent of reactive gliosis, infiltration of activated macrophages/microglia, and cystic cavitation at the graft-host interfaces. Retrograde tracing revealed that grafts of SC-seeded channels containing GDNF promoted a significant increase in the number of propriospinal neurons which had regenerated their axons into the grafts, as compared to SC-MG-seeded channels. These results indicate that GDNF may play a novel therapeutic role in promoting propriospinal axonal regeneration, enhancing myelin formation, and improving graft-host interfaces after SCI.

Identification of regenerative tissue cables using in vivo MRI after spinal cord hemisection and schwann cell bridging transplantation.

The purpose of this study was to examine the feasibility of a non-invasive in vivo magnetic resonance imaging (MRI) procedure, performed at 1.5 T, to detect regenerative tissue cables in a rat spinal cord hemisection and Schwann cell (SC) bridging transplantation paradigm. Two months after implantation of a SC-seeded guidance channel (1.25 mm in diameter and 3.0 mm in length) into a T8 spinal cord hemisection-gap lesion, axial fast-spin echo (FSE) T2-weighted MR imaging (T2WI) was performed. Axial T2WI through the graft identified a circular area of low intensity surrounded by high-intensity signal within the guidance channel lumen. Correlative histological assessments of Toluidine blue-stained sections confirmed that the low-intensity signal represented a tissue cable, which, in most cases, contained a substantial number of myelinated axons oriented along the rostro-caudal axis of the spinal cord. The percentage of guidance channel cross-sectional area occupied by the tissue cable, expressed as the tissue cable index (TCI), was also determined from histological sections. Linear regression analysis of the TCI plotted relative to the number of myelinated axons revealed a strong positive correlation (r(2) = 0.85) between these two outcome measures. In addition, the sensitivity of MRI to detect regenerative tissue cables within guidance channels was 86%. These results demonstrate that (1). 1.5 T MR imaging performed 2 months after spinal cord hemisection and SC bridging transplantation is sensitive in detecting low-intensity regenerative tissue cables, and (2). the TCI strongly correlates with the extent of axonal regeneration into implanted SC-seeded guidance channels.