Accuracy of 3D fluoro-navigated anterior transpedicular screws in the subaxial cervical spine: an experimental study on human specimens.

INTRODUCTION: Pedicle screw stabilization, the standard technique in the thoracic and lumbar spine, is increasingly used in the cervical spine. Initial studies on the use of anterior pedicle screws (ATPS) in the cervical spine have been recently published. ATPS use has theoretical advantages over posterior stabilization. We have already established a 3D-fluoroscopy navigation setup in a study of artificial bones. The aim of the current study was to evaluate the positioning quality/accuracy of ATPS introduced to human specimens. METHODS: 36 cannulated screws (3.5 mm) were implanted anteriorly into the C3-C7 segments of four spines (unfixed, frozen, cadaveric specimens) using a 3D-fluoroscopy navigation system. Placement accuracy was evaluated using a recently published classification on postoperative CT scans. Grade 1 is perfect position with pedicle wall perforation <1 mm, grade 2 is perforation <2 mm, etc., and finally grade 5 is cortical perforation of >4 mm and/or transverse foramen entry. RESULTS: 36 anterior pedicle screws were inserted into four human cervical spine specimens. Of these, seven screws were introduced to C3, five to C4 and eight each to C5, C6, and C7. Classified with the modified G&R, 21 of 36 (58.3%) were grade 1. Ten screws (27.8%) were grade 2. Grade 4 was assessed for two screws and grade 5 for three. Customary "good" positioning, combining grades 1 and 2, was thus found in 86.1%. Five screws (13.9%) did not meet this criterion (grade ≥3). CONCLUSIONS: With 86.1% of good positioning (grade 2 or better), a 3D-fluoroscopy navigation of ATPS screws into human c-spine specimens achieved a satisfying results. These are at least comparable to results presented in the literature for posteriorly introduced subaxial pedicle screws.

[Lateral ulnar collateral ligament reconstruction : A biomechanical analysis of posterolateral rotatory instability of the elbow]. / Laterale ulnare Kollateralbandplastik : Biomechanische Untersuchung zur posterolateralen Rotationsinstabilität des Ellenbogens.

BACKGROUND: Chronic posterolateral rotatory instability (PLRI) of the elbow is the result of an insufficiency of the lateral collateral ligament (LCL). Lateral ulnar collateral ligament (LUCL) reconstruction represents a well-established treatment method for PLRI. However, recurrent instability remains a problem. OBJECTIVES: The goal of this in-vitro study was to evaluate the posterolateral rotatory stability of the intact elbow, after sectioning of the LCL and after LUCL reconstruction with a triceps tendon autograft and double BicepsButton(TM) fixation. MATERIALS AND METHODS: Posterolateral rotatory stability of 6 fresh-frozen elbow specimens at a torque of 3 Nm was analyzed at 0, 45, 90 and 120° of flexion for the intact LCL, after sectioning of the LCL and after LUCL reconstruction. Moreover, cyclic loading (1000 cycles) of the intact specimens and after LUCL reconstruction was performed. RESULTS: The intact LCL and the LUCL reconstruction provided equal primary stability (0.250 ≤ p ≤ 0.888). Sectioning of the LCL significantly increased PLRI (p < 0.001). The stability of the intact specimens and after LUCL reconstruction did not differ after cyclic loading (p = 0.218). During cyclic loading, posterolateral rotation increased significantly more after LUCL reconstruction (3.2 ± 0.8°) when compared to the native LCL (2.0 ± 0.7°, p = 0.020). CONCLUSIONS: LUCL reconstruction with BicepsButton(TM) fixation provides comparable stability to the native LCL. Further clinical results are necessary to evaluate whether this technique can decrease the complication rate.

[The bare area of the proximal ulna : An anatomical study on optimizing olecranon osteotomy]. / Die Bare Area der proximalen Ulna : Eine anatomische Studie zur Optimierung der Olekranonosteotomie.

BACKGROUND: Olecranon osteotomy is an established approach for the treatment of distal humerus fractures. It should be performed through the bare area of the proximal ulna to avoid iatrogenic cartilage lesions. OBJECTIVES: The goal of this study was to analyze the anatomy of the proximal ulna with regard to the bare area and, thereby, to optimize the hitting area of the bare area when performing olecranon osteotomy. MATERIALS AND METHODS: The bare areas of 30 embalmed forearm specimens were marked with a radiopaque wire and visualized three-dimensionally with a mobile C­arm. By means of 3D reconstructions of the data sets, the following measurements were obtained: height of the bare area; span of the bare area-hitting area in transverse osteotomy; ideal angle for olecranon osteotomy to maximize the hitting area of the bare area; distance of the posterior olecranon tip to the entry point of the transverse osteotomy and the ideal osteotomy. RESULTS: The height of the bare area was 4.92 ± 0.81 mm. The hitting area of the transverse osteotomy averaged 3.73 ± 0.89 mm. The "ideal" angle for olecranon osteotomy was 30.7° ± 4.19°. The distance of the posterior olecranon tip to the entry point was 14.08 ± 2.75 mm for the transverse osteotomy and 24.21 ± 3.15 mm for the ideal osteotomy. The hitting area of the bare area in the ideal osteotomy was enhanced significantly when compared to the transverse osteotomy (p < 0.0001). CONCLUSIONS: This study provides guide values for correct osteotomy of the olecranon. Moreover, a 30° angulation of the osteotomy can significantly increase the hitting area of the bare area.

[Proximal carpal row carpectomy]. / Die Entfernung der proximalen Handwurzelreihe.

OBJECTIVE: Resection of the proximal carpal row, termed proximal row carpectomy (PRC), is performed in order to treat pathologies of the proximal carpal row or radiocarpal joint between the scaphoid and scaphoid facet. It entails the articulation of the capitate and the lunate facet. INDICATIONS: Lunate necrosis, carpal collapse, joint infection with concomitant intercarpal ligament lesions. CONTRAINDICATIONS: Severe cartilage lesions of the lunate facet and the capitate, wrist capsule laxity, rheumatoid arthritis, neuromuscular dysbalance of the wrist-covering soft tissue structures. SURGICAL TECHNIQUE: Dorsal approach to the wrist, incision of the third and fourth extensor compartments, resection and coagulation of the dorsal interosseous nerve, usage of a ligament-sparing capsule incision, identification of the proximal carpal row and inspection of cartilage of the lunate facet and capitate, mobilization and excision of the lunate, scaphoid and triquetrum, articulation of lunate facet and capitate is controlled clinically and fluoroscopically, wound closure, application of plaster slabs. POSTOPERATIVE MANAGEMENT: Immobilization of the wrist on plaster slabs for 2 weeks, removal of sutures after 14 days. RESULTS: PRC is a surgical procedure with few complications. Satisfactory range of motion and grip strength could be preserved without limiting function of the upper extremity. Postoperative osteoarthritis of capitate and lunate facet did not correlate with the good clinical outcome.

[Surgical decompression of the superficial radial nerve: Wartenberg syndrome]. / Die operative Dekompression des Ramus superficialis des Nervus radialis: Das Wartenberg-Syndrom.

OBJECTIVE: Open decompression of the superficial radial nerve is performed at the distal forearm in cases of circumscript entrapment. Broad-based entrapments can be treated by endoscopically assisted decompression. INDICATIONS: Entrapment of the nerve along its course between the brachioradialis and extensor carpi radialis longus muscles or tendons. Persistent neuropathic pain with Tinel's sign. Numbness distal to the entrapment in accordance to nerval innervation. Futile conservative treatment. Pathological electrophysiological findings. CONTRAINDICATIONS: Endogeneous neuropathy, bleeding disorders, anticoagulation medication. SURGICAL TECHNIQUE: Longitudinal skin incision at the Tinel's sign at the forearm. The subcutaneous tissue is dissected until forearm fascia is detected. The fascia is opened cautiously under direct visualization and the superficial radial nerve is identified. In cases of broad-based entrapments, endoscopically assisted decompression can be performed. The dissector with attached optical device is introduced proximally and distally. Blunt mobilization using the dissector and preparation with the Metzenbaum scissors release the superficial radial nerve sufficiently. POSTOPERATIVE MANAGEMENT: Bandaging allowing immediate motion, removal of sutures after 14 days, avoidance of excessive use for 2 weeks. RESULTS: Surgical decompression of the superficial radial nerve yields good to excellent results regarding pain reduction and sensory function.

Identification of overlengthening after replacement of the radial head with a bipolar prosthesis.

INTRODUCTION: Overlengthening of the radial column leads to insufficient functionality and increased capitellar wear. Methods to detect or prevent overlengthening have been described for monopolar prostheses. The aim of this study was to evaluate whether one such method described by Athwal et al. is also applicable for a bipolar prosthesis. MATERIALS AND METHODS: The radial heads of six fresh frozen upper extremities were resected. A bipolar radial head prosthesis was implanted in each, and the effects of sequential overlengthening on the alignment of the radiocapitellar and ulnohumeral joint line were recorded by fluoroscopic images. Digital image analysis and estimation of overlengthening followed according to the method described by Athwal et al. RESULTS: Statistical analysis of the estimated and actual differences between the native state and bipolar replacement of the radial head with stepwise overlengthening of 1.5, 3, 4.5, and 6 mm showed a specificity of 86 % but consistently underestimated the amount of overlengthening with a sensitivity of only 61 %. DISCUSSION: The method described by Athwal et al. for the identification of overlengthening by a monopolar prosthesis was not found to be reliable for ruling out or quantifying overlengthening of the tested bipolar prosthesis. However, the use of the method to detect (rule in) overlengthening may be acceptable in certain circumstances. A reliable method for postoperative quantification of overlengthening by bipolar prostheses has still to be found.

Lumbar lordosis and sacral slope in lumbar spinal stenosis: standard values and measurement accuracy.

STUDY DESIGN: Radiological study. PURPOSE: To asses standard values, intra- and interobserver reliability and reproducibility of sacral slope (SS) and lumbar lordosis (LL) and the correlation of these parameters in patients with lumbar spinal stenosis (LSS). METHODS: Anteroposterior and lateral X-rays of the lumbar spine of 102 patients with LSS were included in this retrospective, radiologic study. Measurements of SS and LL were carried out by five examiners. Intraobserver correlation and correlation between LL and SS were calculated with Pearson's r linear correlation coefficient and intraclass correlation coefficients (ICC) were calculated for inter- and intraobserver reliability. In addition, patients were examined in subgroups with respect to previous surgery and the current therapy. RESULTS: Lumbar lordosis averaged 45.6° (range 2.5°-74.9°; SD 14.2°), intraobserver correlation was between Pearson r = 0.93 and 0.98. The measurement of SS averaged 35.3° (range 13.8°-66.9°; SD 9.6°), intraobserver correlation was between Pearson r = 0.89 and 0.96. Intraobserver reliability ranged from 0.966 to 0.992 ICC in LL measurements and 0.944-0.983 ICC in SS measurements. There was an interobserver reliability ICC of 0.944 in LL and 0.990 in SS. Correlation between LL and SS averaged r = 0.79. No statistically significant differences were observed between the analyzed subgroups. CONCLUSION: Manual measurement of LL and SS in patients with LSS on lateral radiographs is easily performed with excellent intra- and interobserver reliability. Correlation between LL and SS is very high. Differences between patients with and without previous decompression were not statistically significant.

Morphology of the proximal and middle phalanx of fingers with regard to the Ascension PyroCarbon PIP total joint.

The Ascension PyroCarbon prosthesis has been used in proximal interphalangeal joint osteoarthritis. The dimensions of the intramedullary distal metadiaphyseal canal (isthmus) of the proximal phalanx and the base of the middle phalanx of cadaver fingers were investigated radiographically (n = 304) and macroscopically (n = 152). In up to 30% of the phalanges, the isthmus was smaller than the stem of the smallest proximal component size. The distal component head was always smaller than the middle phalanx base. Insertion and success of the Ascension PyroCarbon prosthesis is strongly dependent on bone morphology. A critical examination of the isthmus in radiographs is recommended in planning. If the isthmus is clearly smaller than the smallest proximal component, insertion of the prosthesis could be inadvisable. A clear mismatch between the distal component and the middle phalanx base should be avoided due to the potential risk for late subsidence and failure of the prosthesis.

Arterial supply of the distal humerus.

PURPOSE: Distal humeral fractures are rare, but severe injuries, the treatment of which is often accompanied by serious complications and its outcome strongly depends on the quality of surgical therapy. Non-union is a common entity, compromising clinical results and requiring revision surgery. Osteonecrosis is an underestimated etiologic factor in the development of non-union. The present study aims to display the distribution patterns of the arterial vessels at the distal humerus, to correlate the displayed vessels with local nutrient foramina and to disclose an endangerment of these structures by common osteosynthetic implants. METHODS: Eight plastinated fresh frozen upper extremities were digitally analyzed regarding the vascular density of the cancellous bone, by calculating the ratio of area comprised by arterial vessels and the area comprised by cancellous bone on sagittal cuts of the distal humerus. Possible differences in the vascular density of the medial epicondylar region, the lateral epicondylar region and a watershed area between the epicondyles and distal to the supracondylar region were investigated. On the basis of 200 macerated humeri, the distribution pattern of cortical nutrient foramina and their anatomic relation to properly applied common distal humerus plates were documented. RESULTS: The data show a significantly higher density of vessels per cancellous bone in the epicondylar regions than in the watershed region (p < 0.000, median 0.148 vs. 0.103). The analysis of the nutrient foramina showed distinct distribution patterns with a single foramen over the medial epicondyle (55 specimens, 27.5 %) and an area of several foramina at the posterior part of the lateral epicondyle (200 of the specimens, 100 %). In almost every specimen, the application of the osteosynthetic implants led to an overlay over the investigated nutrient foramina. DISCUSSION: Osteonecrosis and non-union are severe complications in the surgical treatment of distal humeral fractures. The biology of the bone, especially the blood supply, has to be respected as much as possible during open procedures, to optimize bony healing. This has to be considered when performing periosteal stripping or applying osteosynthetic plates over the postero-lateral and medial epicondyle. The watershed area of the distal humerus has to be considered as being prone to minor arterial blood supply and thereby non-union is possible, if the arterial vessels coming from the epicondyles are destroyed.

Biomechanical evaluation of the primary stability of pedicle screws after augmentation with an innovative bone stabilizing system.

INTRODUCTION: In today's aging population, diminished bone quality often affects the outcome of surgical treatment. This occurs especially when surgical implants must be fixed to bone, as it occurs when lumbar fusion is performed with pedicle screws. Besides Polymethylmethacrylate (PMMA) injection, several techniques have been developed to augment pedicle screws. The aim of the current study was to evaluate the primary stability of an innovative system (IlluminOss™) for the augmentation of pedicle screws in an experimental cadaveric setup. IlluminOss™ is an innovative technology featuring cement with similar biochemical characteristics to aluminum-free glass-polyalkenoate cement (GPC). MATERIALS AND METHODS: IlluminOss™ was inserted transpedicularly via a balloon/catheter system in 40 human cadaveric lumbar vertebrae. For comparability, each vertebra was treated bilaterally with pedicle screws, augmented and non-augmented. The maximum failure load during pull out test was documented by a universal material testing machine. RESULTS: The results showed significantly higher failure loads for the augmented pedicle screws (Median 555.0 ± 261.0 N, Min. 220.0 N, Max. 1,500.0 N), compared to the native screws (Median 325.0 ± 312.1 N, Min. 29.0 N, Max. 1,400.0 N). CONCLUSIONS: Based on these data, we conclude the IlluminOss™ system can be used to augment primary screw stability regarding axial traction, compared to native screws. The IlluminOss™ monomer offers ease of control for use in biological tissues. In contrast to PMMA, no relevant heat is generated during the hardening process and there is no risk of embolism. Further studies are necessary to evaluate the usefulness of the IlluminOss™ system in the in vivo augmentation of pedicle screws in the future.

Axonal branching and recovery of coordinated muscle activity after transection of the facial nerve in adult rats.

Facial nerve surgery inevitablyleads to pareses, abnormally associated movements, and pathologically altered reflexes. The reason for this "post-paralytic syndrome" is the misdirected reinnervation of targets, which consists of two major components. First, due to malfunctioning axonal guidance, a muscle gets reinnervated by a "foreign" axon, that has been misrouted along a "wrong" fascicle. Second, the supernumerary collateral branches emerging from all transected axons simultaneously innervate antagonistic muscles and cause severe impairment of coordinated activity. Since it is hardly possible to influence the first major component and improve the guidance of several thousands of axons, we concentrated on the second major component and tried to reduce the collateral axonal branching. The efficiency of various treatments was evaluated in rats by determining: (1) the degree of post-operative axonal branching as estimated by the number of double-or triple-labeled perikarya after application of crystalline DiI, Fluoro-Gold (FG), and Fast Blue (FB) to the zygomatic, buccal, and marginal mandibular branch of the facial nerve respectively; (2) the accuracy of reinnervation as estimated by the number of double-labeled perikarya innervating the whisker pad muscles before and after surgery as shown by intramuscular injections of FG and FB respectively; (3) the recovery of vibrissal motor performance, estimated by a video based motion analysis. So far, we have tried to reduce branching by alteration of the afferent trigeminal input to the axotomized facial motoneurons and by focal application of: (1) neurite outgrowth fostering ECM proteins; (2) neutralizing antibodies to NGF, BDNF, CNTF, GDNF, IGF-I, and FGF-II; (3) suspensions of olfactory ensheathing cells, Schwann cells, and bone marrow stroma cells; and (4) pieces of autologous olfactory mucosa to the transection site. Although most of these manipulations do influence peripheral nerve regeneration to some extent, only the application of autologous olfactory mucosa yielded a major improvement, i.e., better function.

Seasonal variation in Sarcocystis species infections in goats in northern Iraq.

We investigated the prevalence of sarcocystosis in 826 goats slaughtered in the winter season from November to April in northern Iraq. The prevalence of macrocysts was on average 34%, with only 20% infected animals in November, but 46% in February. The infection rate in 1-, 3- and 6-year-old goats was 4%, 48%, and 83%, respectively. The highest specificity of infection was in the oesophagus (99%) and the lowest in the diaphragm (3%). Grossly, we identified 2 forms of macroscopic sarcocysts, fat and thin, with different morphological characteristics. The prevalence of microcysts was 97% and no effects of age, sex and seasonal variations were observed. Development of microcysts in the small intestine of dogs and cats has also been investigated. The pre-patent period in experimentally infected dogs was 12-14 days and the patent period lasted 64-66 days. A dog shed about 155 million sporocysts, but no sporocysts were shed by cats that had been fed the same infected tissues, thus identifying the microcysts as Sarcocystis capracanis.

Therapeutic vaccine for acute and chronic motor neuron diseases: implications for amyotrophic lateral sclerosis.

Therapeutic vaccination with Copaxone (glatiramer acetate, Cop-1) protects motor neurons against acute and chronic degenerative conditions. In acute degeneration after facial nerve axotomy, the number of surviving motor neurons was almost two times higher in Cop-1-vaccinated mice than in nonvaccinated mice, or in mice injected with PBS emulsified in complete Freund's adjuvant (P < 0.05). In mice that express the mutant human gene Cu/Zn superoxide dismutase G93A (SOD1), and therefore simulate the chronic human motor neuron disease amyotrophic lateral sclerosis, Cop-1 vaccination prolonged life span compared to untreated matched controls, from 211 +/- 7 days (n = 15) to 263 +/- 8 days (n = 14; P < 0.0001). Our studies show that vaccination significantly improved motor activity. In line with the experimentally based concept of protective autoimmunity, these findings suggest that Cop-1 vaccination boosts the local immune response needed to combat destructive self-compounds associated with motor neuron death. Its differential action in CNS autoimmune diseases and neurodegenerative disorders, depending on the regimen used, allows its use as a therapy for either condition. Daily administration of Cop-1 is an approved treatment for multiple sclerosis. The protocol for non-autoimmune neurodegenerative diseases such as amyotrophic lateral sclerosis, remains to be established by future studies.

Motoneuron adaptability to new motor tasks following two types of facial-facial anastomosis in cats.

The ability of the facial motor system to adapt to a new motor function was studied in alert cats after unilateral transection, 180 degrees rotation and suture of the zygomatic nerve, or transection and cross-anastomosis of the proximal stump of the buccal nerve to the distal stump of the zygomatic nerve. These procedures induced reinnervation of the orbicularis oculi (OO) muscle by different OO- or mouth-related facial motoneurons. Eyelid movements and the electromyographic activity of the OO muscle were recorded up to 1 year following the two types of anastomosis. Animals with a zygomatic nerve rotation recovered spontaneous and reflex responses, but with evident deficits in eyelid kinematics, i.e. the proper regional distribution of OO motor units was disorganized by zygomatic nerve rotation and resuture, producing a permanent defect in eyelid motor performance. Following buccal-zygomatic anastomosis, the electrical activity of the OO muscle was recovered after 6-7 weeks, but air puff-, flash- and tone-evoked reflex blinks never reached the control values on the operated side. Electromyographic OO activities and lid movements corresponding to licking and deglutition activities were observed on the operated side in buccal-zygomatic anastomosed animals up to 1 year following surgery. Mouth-related facial motoneurons did not readapt their discharges to the kinetic, timing and oscillatory properties of OO muscle fibres. A significant hyper-reflexia was observed following both types of nerve repair in response to air puffs, but not to light flashes or tones. In conclusion, adult mammal facial premotor circuits maintain their motor programmes when motoneurons are induced to reinnervate a foreign muscle, or even a new set of muscle fibres.

Focal application of neutralizing antibodies to soluble neurotrophic factors reduces collateral axonal branching after peripheral nerve lesion.

A major reason for the insufficient recovery of function after motor nerve injury are the numerous axonal branches which often re-innervate muscles with completely different functions. We hypothesized that a neutralization of diffusable neurotrophic factors at the lesion site in rats could reduce the branching of transected axons. Following analysis of local protein expression by immunocytochemistry and by in situ hybridization, we transected the facial nerve trunk of adult rats and inserted both ends into a silicon tube containing (i) collagen gel with neutralizing concentrations of antibodies to NGF, BDNF, bFGF, IGF-I, CNTF and GDNF; (ii) five-fold higher concentrations of the antibodies and (iii) combination of antibodies. Two months later, retrograde labelling was used to estimate the portion of motoneurons the axons of which had branched and projected into three major branches of the facial trunk. After control entubulation in collagen gel containing non-immune mouse IgG 85% of all motoneurons projecting along the zygomatic branch sprouted and sent at least one twin axon to the buccal and/or marginal-mandibular branches of the facial nerve. Neutralizing concentrations of anti-NGF, anti-BDNF and anti-IGF-I significantly reduced sprouting. The most pronounced effect was achieved after application of anti-BDNF, which reduced the portion of branched neurons to 18%. All effects after a single application of antibodies were concentration-dependent and superior to those observed after combined treatment. This first report on improved quality of reinnervation by antibody-therapy implies that, in rats, the post-transectional collateral axonal branching can be reduced without obvious harmful effects on neuronal survival and axonal elongation.

Transplantation of olfactory ensheathing cells stimulates the collateral sprouting from axotomized adult rat facial motoneurons.

Axon regrowth after CNS and PNS injury is only the first step toward complete functional recovery which depends largely on the specificity of the newly formed nerve-target projections. Since most of the studies involving the application of glial cells to the lesioned nervous system have focused primarily on the extent of neurite outgrowth, little is known regarding their effects on the accompanying processes of axonal sprouting and pathfinding. In this study, we analyzed the effects of transplanted olfactory ensheathing cells (OECs) on axonal sprouting of adult facial neurons by using triple fluorescent retrograde tracing and biometrical analysis of whisking behavior. We found that 2 months after facial nerve axotomy and immediate implantation of OECs in between both nerve stumps fixed in a silicon tube, the total number of labeled neurons was increased by about 100%, compared to animals with simple facial nerve suture or entubulation in an empty conduit. This change in the number of axon sprouts was not random. The highest increase in axon number was observed in the marginal mandibular branch, whereas no changes were detected in the zygomatic branch. This increased sprouting did not improve the whisking behavior as measured by biometric video analysis. Our results demonstrate that OECs are potent inducers of axonal sprouting in vivo. Hence OEC-filled nerve conduits may be a powerful tool to enforce regeneration of a peripheral nerve under adverse conditions, e.g., after long delay between injury and surgical repair. In mixed nerves, increased axonal sprouting will improve specificity since inappropriate nerve-target connections are pruned off during preferential motor innervation. In pure motor nerves, however, OEC-mediated axonal sprouting may result in polyneuronal innveration of target muscles.

Exogenous antigen containing perivascular phagocytes induce a non-encephalitogenic extravasation of primed lymphocytes.

Recent evidence suggests that T-lymphocyte extravasation and CNS-parenchymal infiltration during autoimmune disease might be regulated by antigen-presenting (ED2(+)) cerebral/spinal perivascular phagocytes (CPP/SPP). Since the massive erythrocytic and leukocytic infiltrates in the CNS of rats with experimental allergic encephalomyelitis do not allow a precise differentiation between CPP/SPP and the invading cells in the Virchow-Robin space, we developed a new immune-response model whereby the extravasation of T-lymphocytes was not followed by other blood cells. Adult Lewis rats were sensitized to horseradish peroxidase (HRP). Subsequent intracerebroventricular (i.c.v.) injections of HRP and/or Fluoro-Emerald (FE) served to: (1) challenge the primed T-lymphocytes and (2) label the CPP/SPP for additional immunocytochemical analysis. We found that 24 h and 3 days after single, double, or triple antigen boosting T-lymphocytes (R73(+), W3/25(+), OX50(+)) entered the Virchow-Robin space but did not break through the astrocytic glia limitans. Instead they adhered to HRP-containing activated CPP/SPP (mabs OX-6(+), SILK6(+), CD40(+), CD80(+), CD86(+)). This selective contact was mediated neither by cell adhesion molecules (P-selectin, ICAM-1, VCAM-1), nor promoted by chemokine receptors (CCR1, CCR5) or chemokines (monocyte chemoattractant protein (MCP)-1, MIP-1alpha, MIP-1beta, RANTES). This non-inflammatory, but antigen-dependent lymphocyte extravasation provides optimal conditions to further study the CNS immune response.

Hypoglossal and reticular interneurons involved in oro-facial coordination in the rat.

Chewing, swallowing, breathing, and vocalization in mammals require precise coordination of tongue movements with concomitant activities of the mimetic muscles. The neuroanatomic basis for this oro-facial coordination is not yet fully understood. After the stereotaxic microinjection of retrograde and anterograde neuronal tracers (biotin-dextran, Fluoro-Ruby, Fluoro-Emerald, and Fluoro-Gold) into the facial and hypoglossal nuclei of the rat, we report here a direct bilateral projection of hypoglossal internuclear interneurons onto facial motoneurons. We also confirm the existence of a small pool of neurons in the dorsal part of the brainstem reticular formation that project ipsilaterally to both facial and hypoglossal nuclei. For precise tracer injections, both motor nuclei were located and identified by the electrical antidromic activation of their constituent motoneurons. Injections of retrograde tracers into the facial nucleus consistently labeled neurons in the hypoglossal nucleus. These neurons prevalently lay in the ipsilateral side, were small in size, and, like classic intrinsic hypoglossal local-circuit interneurons, had several thin dendrites. Reverse experiments - injections of anterograde tracers into the hypoglossal nucleus - labeled fine varicose nerve fiber terminals in the facial nucleus. These fiber terminals were concentrated in the intermediate subdivision of the facial nucleus, with a strong ipsilateral prevalence. Double injections of different tracers into the facial and the hypoglossal nuclei revealed a small, but constant, number of double-labeled neurons located predominantly ipsilateral in the caudal brainstem reticular formation. Hypoglossal internuclear interneurons projecting to the facial nucleus, as well as those neurons of the parvocellular reticular formation that project to both facial and hypoglossal nuclei, could be involved in oro-facial coordination.

Evaluation of muscle re-innervation employing pre- and post-axotomy injections of fluorescent retrograde tracers.

In experimental studies on peripheral nerve repair, the possibility to objectively compare original and post-operative innervation is of decisive importance for the selection of the proper nerve-reconstruction strategy. Herewith we report serious drawbacks encountered with the standard method of pre- and post-operative intramuscular injections of widely used retrograde neuronal tracers. Labeling of rat facial motoneurons by injection of Fast-Blue (FB; Group 1), Dil (Group 2), or Fluoro-Gold (FG; Group 3) into the whisker pad muscles was followed by transection and suture of the facial nerve. Two months later, the same rats received Dil (Group 1), FG (Group 2), and FB (Group 3) injections with the same parameters as the pre-operative injections. By quantitative evaluation of single- and double-retrogradely labeled perikarya of facial motoneurons, we tried to estimate the accuracy of re-innervation. Observations through a "UV-filter" (for FB-labeled perikarya) and a "rhodamine-filter" (for Dil-labeled perikarya) in Group 1 revealed an unexpected axotomy-triggered leakage of FB which compromised the counts. After pre-operative Dil labeling, nerve suture, and post-operative FG labeling (Group 2), Dil created an extracellular deposit in the whisker pad. Thus, the uptake of pre-operative tracer by sprouts of re-growing axons compromised counts of retrogradely labeled motoneurons. Employing the "UV-filter" in Group 3 (FG-, FB-, FG+FB-labeled perikarya), the emission of FB obscured that of FG and also compromised cell counts. The use of filter sets constructed ad hoc for detection of FG and FB rendered possible an objective comparison.

Superior muscle reinnervation after autologous nerve graft or poly-L-lactide-epsilon-caprolactone (PLC) tube implantation in comparison to silicone tube repair.

Recovery after peripheral nerve injury depends not only on the amount of reinnervation, but also on its accuracy. The rat sciatic nerve was subjected to an 8 mm long gap lesion repaired either by autograft (AG, n = 6) or tubulization with impermeable silicone tube (SIL, n = 6) or permeable tube of poly-L-lactide-epsilon-caprolactone (PLC, n = 8). Recordings of the compound muscle action potential (CMAP) from gastrocnemius (mGC), tibialis anterior (mTA) and plantar (mPL) muscles were performed 90 days after injury to assess the amount of muscle reinnervation. The CMAP amplitude achieved in mGC, mTA and mPL was similar in after nerve autograft (39%, 42%, 22% of control values) and PLC tube implantation (37%, 36%, 24%) but lower with SIL tube (29%, 30%, 14%). The nerve fascicles projecting into each of these muscles were then transected and retrograde tracers (Fluoro Gold, Fast Blue, DiI) were applied to quantify the percentage of motoneurons with single or multiple branches to different targets. The total number of labeled motoneurons for the three muscles did not differ in autografted rats (1186 +/- 56; mean +/- SEM) with respect to controls (1238 +/- 82), but was reduced with PLC tube (802 +/- 101) and SIL tube (935 +/- 213). The percentage of neurons with multiple projections was lower after autograft and PLC tube (6%) than with SIL tube (10%). Considering the higher CMAP amplitude and lower number of neurons with multiple projections, PLC nerve conduits seem superior to SIL tubes and a suitable alternative to autografts for the repair of long gaps.