Long-term results following titanium cranioplasty of large skull defects

Object

Decompressive craniectomy is an established procedure to lower intracranial pressure. Therefore, cranioplasty remains a necessity in neurosurgery as well. If the patient's own bone flap is not available, the surgeon can choose between various alloplast grafts. A review of the literature proves that 4–13.8% of polymethylmethacrylate plates and 2.6–10% of hydroxyapatite-based implants require replacement. In this retrospective study of large skull defects, the authors compared computer-assisted design/computer-assisted modeled (CAD/CAM) titanium implants for cranioplasty with other frequently used materials described in literature.

Methods

Twenty-six patients underwent cranioplasty with CAD/CAM titanium implants (mean diameter 112 mm). With the aid of visual analog scales, the patients' pain and cosmesis were evaluated 6–12 years (mean 8.1 years) after insertion of the implants.

Results

None of the implants had to be removed. Of all patients, 68% declared their outcomes as excellent, 24% as good, 0.8% as fair, and 0% as poor. There was no resulting pain in 84% of the patients, and 88% were satisfied with the cosmetic result, noting > 75 mm on the visual analog scale of cosmesis. All patients would have chosen cranioplasty again, stating an improvement in their quality of life by the calvarial reconstruction. Nevertheless, follow-up images obtained in 4 patients undergoing removal of meningiomas was only suboptimal.

Conclusions

With the aid of CAD technology, all currently used alloplastic materials are suited even for large skull defect cranioplasty. Analysis of the authors' data and the literature shows that cranioplasty with CAD/CAM titanium implants provides the lowest rate of complications, reasonable costs, and acceptable postoperative imaging. Polymethylmethacrylate is suited for primary cranioplasty or for long-term follow-up imaging of tumors. Titanium implants seem to be the material of choice for secondary cranioplasty of large skull defects resulting from decompressive craniectomy after trauma or infarction. Expensive HA-based ceramics show no obvious advantage over titanium or PMMA.

Anterior cervical discectomy and fusion: comparison of titanium and polyetheretherketone cages

BACKGROUND

Titanium (TTN) cages have a higher modulus of elasticity when compared with polyetheretherketone (PEEK) cages. This suggests that TTN-cages could show more frequent cage subsidence after anterior cervical discectomy and fusion (ACDF) and therefore might lead to a higher loss of correction. We compared the long term results of stand-alone PEEK- and TTN-cages in a comparable patient collective that was operated under identical operative settings.

METHODS

From 2002 to 2007 154 patients underwent single-level ACDF for degenerative disc disease (DDD). Clinical and radiological outcome were assessed in 86 eligible patients after a mean of 28.4 months. 44 patients received a TTN- and 42 patients a PEEK-cage.

RESULTS

Solid arthrodesis was found in 93.2% of the TTN-group and 88.1% of the PEEK-group. Cage subsidence was observed in 20.5% of the TTN- and 14.3% of the PEEK-group. A significant segmental lordotic correction was achieved by both cage-types. Even though a loss of correction was found at the last follow-up in both groups, it did not reach the level of statistical significance. Statistical analysis of these results revealed no differences between the TTN- and PEEK-group.When assessed with the neck disability index (NDI), the visual analogue scale (VAS) of neck and arm pain and Odom's criteria the clinical data showed no significant differences between the groups.

CONCLUSIONS

Clinical and radiological outcomes of ACDF with TTN- or PEEK-cages do not appear to be influenced by the chosen synthetic graft. The modulus of elasticity represents only one of many physical properties of a cage. Design, shape, size, surface architecture of a cage as well as bone density, endplate preparation and applied distraction during surgery need to be considered as further important factors.

Comparison between anterior and posterior decompression with instrumentation for cervical spondylotic myelopathy: sagittal alignment and clinical outcome

Object

A variety of anterior, posterior, and combined approaches exist to decompress the spinal cord, restore sagittal alignment, and avoid kyphosis, but the optimal surgical strategy remains controversial. The authors compared the anterior and posterior approach used to treat multilevel cervical spondylotic myelopathy (CSM), focusing on sagittal alignment and clinical outcome.

Methods

The authors studied 48 patients with CSM who underwent multilevel decompressive surgery using an anterior or posterior approach with instrumentation (24 patients in each group), depending on preoperative sagittal alignment and direction of spinal cord compression. In the anterior group, a 1–2-level corpectomy was followed by placement of an expandable titanium cage. In the posterior group, a multilevel laminectomy and posterior instrumentation using lateral mass screws was performed. Postoperative radiography and clinical examinations were performed after 1 week, 12 months, and at last follow-up (range 15–112 months, mean 33 months). The radiological outcome was evaluated using measurement of the cervical and segmental lordosis.

Results

Both the posterior multilevel laminectomy (with instrumentation) and the anterior cervical corpectomy (with instrumentation) improved clinical outcome. The anterior group had a significantly lower preoperative cervical and segmental lordosis than the posterior group. The cervical and segmental lordosis improved in the anterior group by 8.8 and 6.2°, respectively, and declined in the posterior group by 6.5 and 3.8°, respectively. The loss of correction was higher in the anterior than in the posterior group (−2.0 vs −0.7°, respectively) at last follow-up.

Conclusions

. These results demonstrate that both anterior and posterior decompression (with instrumentation) are effective procedures to improve the neurological outcome of patients with CSM. However, sagittal alignment may be better restored using the anterior approach, but harbors a higher rate of loss of correction. In cases involving a preexisting cervical kyphosis, an anterior or combined approach might be necessary to restore the lordotic cervical alignment.

The influence of cage positioning and cage type on cage migration and fusion rates in patients with monosegmental posterior lumbar interbody fusion and posterior fixation

In posterior lumbar interbody fusion, cage migrations and lower fusion rates compared to autologous bone graft used in the anterior lumbar interbody fusion procedure are documented. Anatomical and biomechanical data have shown that the cage positioning and cage type seem to play an important role. Therefore, the aim of the present study was to evaluate the impact of cage positioning and cage type on cage migration and fusion. We created a grid system for the endplates to analyze different cage positions. To analyze the influence of the cage type, we compared "closed" box titanium cages with "open" box titanium cages. This study included 40 patients with 80 implanted cages. After pedicle screw fixation, 23 patients were treated with a "closed box" cage and 17 patients with an "open box" cage. The follow-up period averaged 25 months. Twenty cages (25%) showed a migration into one vertebral endplate of <3 mm and four cages (5%) showed a migration of > or =3 mm. Cage migration was highest in the medio-medial position (84.6%), followed by the postero-lateral (42.9%), and the postero-medial (16%) cage position. Closed box cages had a significantly higher migration rate than open box cages, but fusion rates did not differ. In conclusion, cage positioning and cage type influence cage migration. The medio-medial cage position showed the highest migration rate. Regarding the cage type, open box cages seem to be associated with lower migration rates compared to closed box cages. However, the cage type did not influence bone fusion.

Application of titanium and polyetheretherketone cages in the treatment of pyogenic spondylodiscitis

OBJECTIVE

Surgical treatment of a pyogenic spondylodiscitis (PSD) involves a fixation and debridement of the affected segment combined with a specific antibiotic therapy. To achieve a proper stability and to avoid pseudarthrosis and kyphotic malposition many surgeons favour the interposition of an anterior graft. Besides autologous bone grafts titanium (TTN) cages have gained acceptance in the treatment of PSD. Polyetheretherketone (PEEK) cages have a more favourable modulus of elasticity than TTN. We compared both cage types. Primary endpoints were the rate of reinfection and radiological results.

METHODS

From 2004 to 2013 51 patients underwent surgery for PSD with fixation and TTN or PEEK cage-implantation. While lumbar patients underwent a partial discectomy by the posterior approach, discs of the cervical and thoracic patients had been totally removed from anterior. Clinical and radiological parameters were assessed in 37 eligible patients after a mean of 20.4 months. 21 patients received a PEEK- and 16 patients a TTN-cage.

RESULTS

A reinfection after surgery and 3 months of antibiotic therapy was not observed. Solid arthrodesis was found in 90.5% of the PEEK-group and 100% of the TTN-group. A segmental correction could be achieved in both groups. Nonetheless, a cage subsidence was observed in 70.3% of all cases. Comparison of radiological results revealed no differences between both groups.

CONCLUSIONS

A debridement and fixation with anterior column support in combination with an antibiotic therapy appear to be the key points for successful treatment of PSD. The application of TTN- or PEEK-cages does not appear to influence the radiological outcome or risk of reinfection, neither does the extent of disc removal in this clinical subset.

The analysis of segmental mobility with different lumbar radiographs in symptomatic patients with a spondylolisthesis

PURPOSE

Lumbar flexion-extension radiographs in standing position (SFE) are the most commonly used imaging method to evaluate segmental mobility. Many surgeons use SFE to disclose abnormal vertebral motion and base their decision for surgical fusion on its results. We tested the hypothesis that imaging in standing and recumbent position (SRP) reveals a higher sagittal translation (ST) and sagittal rotation (SR) in symptomatic patients than with SFE.

MATERIALS AND METHODS

We analysed images of 100 symptomatic patients with a low-grade spondylolisthesis that underwent surgical fusion. To determine the ST and SR in SRP, we compared the images taken in the recumbent position in the CT with images taken in the standing position during the routine plain radiography.

RESULTS

The measurement of ST revealed an absolute value of 2.3 ± 1.5 mm in SFE and 4.0 ± 2.0 mm in SRP and differed significantly (p = 0.001). The analysis of the relative value showed an ST of 5.9 ± 3.9% in SFE and 7.8 ± 5.4% in SRP (p = 0.008). The assessment of ST in flexion and in a recumbent position (FRP) revealed the highest ST (4.6 ± 2.5 mm or 9.2 ± 5.7%). Comparison of SR showed the highest rotation in SFE (6.1° ± 3.8°), however, compared to SRP (5.4° ± 3.3°), it missed the level of significance (p = 0.051).

CONCLUSIONS

For evaluation of ST in symptomatic patients with spondylolisthesis SRP appears to be more suitable than SFE, while a pathological SR is better revealed in SFE. The analysis of SRP might offer a complementary method to detect or exclude pathological mobility in more cases.

The SCIentinel study--prospective multicenter study to define the spinal cord injury-induced immune depression syndrome (SCI-IDS)--study protocol and interim feasibility data

Background

Infections are the leading cause of death in the acute phase following spinal cord injury and qualify as independent risk factor for poor neurological outcome (“disease modifying factor”). The enhanced susceptibility for infections is not stringently explained by the increased risk of aspiration in tetraplegic patients, neurogenic bladder dysfunction, or by high-dose methylprednisolone treatment. Experimental and clinical pilot data suggest that spinal cord injury disrupts the balanced interplay between the central nervous system and the immune system. The primary hypothesis is that the Spinal Cord Injury-induced Immune Depression Syndrome (SCI-IDS) is 'neurogenic’ including deactivation of adaptive and innate immunity with decreased HLA-DR expression on monocytes as a key surrogate parameter. Secondary hypotheses are that the Immune Depression Syndrome is i) injury level- and ii) severity-dependent, iii) triggers transient lymphopenia, and iv) causes qualitative functional leukocyte deficits, which may endure the post-acute phase after spinal cord injury.

Methods/Design

SCIentinel is a prospective, international, multicenter study aiming to recruit about 118 patients with acute spinal cord injury or control patients with acute vertebral fracture without neurological deficits scheduled for spinal surgery. The assessment points are: i) <31 hours, ii) 31–55 hours, iii) 7 days, iv) 14 days, and v) 10 weeks post-trauma. Assessment includes infections, concomitant injury, medication and neurological classification using American Spinal Injury Association impairment scale (AIS) and neurological level. Laboratory analyses comprise haematological profiling, immunophenotyping, including HLA-DR expression on monocytes, cytokines and gene expression of immune modulators. We provide an administrative interim analysis of the recruitment schedule of the trial.

Discussion

The objectives are to characterize the dysfunction of the innate and adaptive immune system after spinal cord injury and to explore its proposed 'neurogenic’ origin by analyzing its correlation with lesion height and severity. The trial protocol considers difficulties of enrolment in an acute setting, and loss to follow up. The administrative interim analysis confirmed the feasibility of the protocol. Better understanding of the SCI-IDS is crucial to reduce co-morbidities and thereby to attenuate the impact of disease modifying factors to protect neurological “outcome at risk”. This putatively results in improved spinal cord injury medical care.

Trial registration

DRKS-ID: DRKS00000122 (German Clinical Trials Registry)

Adequacy of herniated disc tissue as a cell source for nucleus pulposus regeneration

OBJECT

The object of this study was to characterize the regenerative potential of cells isolated from herniated disc tissue obtained during microdiscectomy. The acquired data could help to evaluate the feasibility of these cells for autologous disc cell transplantation.

METHODS

From each of 5 patients (mean age 45 years), tissue from the nucleus pulposus compartment as well as from herniated disc was obtained separately during microdiscectomy of symptomatic herniated lumbar discs. Cells were isolated, and in vitro cell expansion for cells from herniated disc tissue was accomplished using human serum and fibroblast growth factor-2. For 3D culture, expanded cells were loaded in a fibrin-hyaluronan solution on polyglycolic acid scaffolds for 2 weeks. The formation of disc tissue was documented by histological staining of the extracellular matrix as well as by gene expression analysis of typical disc marker genes.

RESULTS

Cells isolated from herniated disc tissue showed significant signs of dedifferentiation and degeneration in comparison with cells from tissue of the nucleus compartment. With in vitro cell expansion, further dedifferentiation with distinct suppression of major matrix molecules, such as aggrecan and Type II collagen, was observed. Unlike in previous reports of cells from the nucleus compartment, the cells from herniated disc tissue showed only a weak redifferentiation process in 3D culture. However, propidium iodide/fluorescein diacetate staining documented that 3D assembly of these cells in polyglycolic acid scaffolds allows prolonged culture and high viability.

CONCLUSIONS

Study results suggested a very limited regenerative potential for cells harvested from herniated disc tissue. Further research on 2 major aspects in patient selection is suggested before conducting reasonable clinical trials in this matter: 1) diagnostic strategies to predict the regenerative potential of harvested cells at a radiological or cell biology level, and 2) clinical assessment strategies to elucidate the metabolic state of the targeted disc.

Arachnoid cysts of the middle cranial fossa accompanied by subdural effusions--experience with 60 consecutive cases

BACKGROUND

Subdural effusions (SDEs) can complicate arachnoid cysts of the middle cranial fossa (ACMFs). While there is a consensus that at least in adults asymptomatic ACMFs should not be operated, those with concomitant subdural and/or intracystic effusions are clinically apparent in the majority of cases and should be surgically treated. But it remains unclear, which surgical procedure is best.

METHODS

Since 1980, 60 out of 343 patients with an ACMF presented with accompanying SDEs. Four categories of SDEs were differentiated radiologically. This collective was controlled in a follow-up study up to 60 months after conservative or operative treatment by clinical and radiological means.

RESULTS

In 54 of the 60 patients, we saw an indication for surgical treatment. Twenty-nine patients received a burr hole, 13 cases were treated by craniotomy, seven by endoscopical means, three patients underwent shunting and two combined procedures. Six patients were treated conservatively. An excellent final clinical outcome was observed in 55 cases. While craniotomy succeeded best to reduce the cyst volume in postoperative CT, the final clinical outcome did not differ significantly compared with burr hole trepanation.

CONCLUSIONS

Patients with small effusions can be treated conservatively in selected cases. Based on our experience, we prefer a differentiated therapy. As first procedure, burr hole and subdural drainage were performed, leaving the cyst alone, seeming sufficient for the majority of cases. Craniotomy or endoscopical means should be reserved as treatment of choice for special cases, depending on category and acuteness of SDE and size/localisation of the ACMF.

The short- and mid-term effect of dynamic interspinous distraction in the treatment of recurrent lumbar facet joint pain

Owing to failure to achieve positive long-term effects, the currently performed treatment methods for lumbar facet joint syndrome (LFJS) are still under debate. Interspinous distraction devices unload the facet joints. Thus, these devices might be an alternative surgical treatment method for LFJS. The aim of this study was to evaluate the clinical and radiological outcome of an interspinous distraction device for the treatment of LFJS. Subjects had verified single level LFJS at level L4-5. They received percutaneous facet joint denervation (PFJD). If pain persisted, they were offered implantation of an interspinous device (Coflex) and/or repeat PFJD. Clinical and radiological outcome was determined before and after PFJD or surgery up to 2 years afterwards in all cases. Forty-one patients with LFJS at L4-5 underwent PFJD. Twenty patients with persisting pain underwent a subsequent surgery for implantation of an interspinous device. Five patients with recurrent pain at 6-12 months opted for an additional PFJD. Three obese patients (body weight > 100 kg) had persistent pain at 3 months after surgery and received additionally dorsal semi-dynamic stabilization. The clinical outcome improved significantly in the surgically treated patients; however, it did not differ compared with patients receiving PFJD only after 24 months.Radiological evaluation revealed a restricted range of motion (ROM) of the operated and an elevated ROM of the adjacent segment. Surgical or device-related complications were not observed. In conclusions, the implantation of an interspinous Coflex device in case of recurrent facet joint pain succeeds to improve facet joint pain in clinical shortand mid-term settings. However, it does not exceed the outcome of denervated patients.

Intraoperative neurophysiological monitoring of extracranial-intracranial bypass procedures

OBJECT

Intraoperative neurophysiological monitoring (IONM) represents an established tool in neurosurgery to increase patient safety. Its application, however, is controversial. Its use has been described as helpful in avoiding neurological deterioration during intracranial aneurysm surgery. Its impact on extracranial-intracranial (EC-IC) bypass surgery involving parent artery occlusion for the treatment of complex aneurysms has not yet been studied. The authors therefore sought to evaluate the effects of IONM on patient safety, the surgeon's intraoperative strategies, and functional outcome of patients after cerebral bypass surgery. Intraoperative neurophysiological monitoring results were compared with those of intraoperative blood flow monitoring to assess bypass graft perfusion.

METHODS

Compound motor action potentials (CMAPs) were generated using transcranial electrical stimulation in patients undergoing EC-IC bypass surgery. Preoperative and postoperative motor function was analyzed. To assess graft function, intraoperative flowmetry and indocyanine green fluorescence angiography were performed. Special care was taken to compare the relevance of electrophysiological and blood flow monitoring in the detection of critical intraoperative ischemic episodes.

RESULTS

The study included 31 patients with 31 aneurysms and 1 bilateral occlusion of the internal carotid arteries, undergoing 32 EC-IC bypass surgeries in which radial artery or saphenous vein grafts were used. In 11 cases, 15 CMAP events were observed, helping the surgeon to determine the source of deterioration and to react to it: 14 were reversible and only 1 showed no recovery. In all cases, blood flow monitoring showed good perfusion of the bypass grafts. There were no false-negative results in this series. New postoperative motor deficits were transient in 1 case, permanent in 1 case, and not present in all other cases.

CONCLUSIONS

Intraoperative neurophysiological monitoring is a helpful tool for continuous functional monitoring of patients undergoing large-caliber vessel EC-IC bypass surgery. The authors' results suggest that continuous neurophysiological monitoring during EC-IC bypass surgery has relevant advantages over flow-oriented monitoring techniques such as intraoperative flowmetry or indocyanine green-based angiography.

Empty polyetheretherketone (PEEK) cages in anterior cervical diskectomy and fusion (ACDF) show slow radiographic fusion that reduces clinical improvement: results from the prospective multicenter "PIERCE-PEEK" study

Background

Anterior cervical diskectomy and fusion (ACDF) is a well-established surgical treatment for radiculopathy and myelopathy. Previous studies showed that empty PEEK cages have lower radiographic fusion rates, but the clinical relevance remains unclear. This paper’s aim is to provide high-quality evidence on the outcomes of ACDF with empty PEEK cages and on the relevance of radiographic fusion for clinical outcomes.

Methods

This large prospective multicenter clinical trial performed single-level ACDF with empty PEEK cages on patients with cervical radiculopathy or myelopathy. The main clinical outcomes were VAS (0–10) for pain and NDI (0–100) for functioning. Radiographic fusion was evaluated by two investigators for three different aspects.

Results

The median (range) improvement of the VAS pain score was: 3 (1–6) at 6 months, 3 (2–8) at 12 months, and 4 (2–8) at 18 months. The median (range) improvement of the NDI score was: 12 (2–34) at 6 months, 18 (4–46) at 12 months, and 22 (2–44) at 18 months. Complete radiographic fusion was reached by 126 patients (43%) at 6 months, 214 patients (73%) at 12 months, and 241 patients (83%) at 18 months. Radiographic fusion was a highly significant (p < 0.001) predictor of the improvement of VAS and NDI scores.

Conclusion

This study provides strong evidence that ACDF is effective treatment, but the overall rate of radiographic fusion with empty PEEK cages is slow and insufficient. Lack of complete radiographic fusion leads to less improvement of pain and disability. We recommend against using empty uncoated pure PEEK cages in ACDF.

Trial registration

ISRCTN42774128. Retrospectively registered 14 April 2009.

Proliferation, Migration, and ECM Formation Potential of Human Annulus Fibrosus Cells Is Independent of Degeneration Status

OBJECTIVE

The objective was to evaluate the proliferating, migratory and extracellular matrix (ECM) forming potential of annulus fibrosus cells derived from early (edAFC) or advanced (adAFC) degenerative tissue and their usability as a possible cell source for regenerative approaches for AF closure.

DESIGN

EdAFC (n = 5 Pfirrman score of 2-3) and adAFC (n = 5 Pfirrman score of 4-5) were isolated from tissue of patients undergoing spine stabilizing surgery. Cell migration on stimulation with human serum (HS), platelet-rich plasma (PRP), and transforming growth factor β-3 (TGFB3) was assessed by migration assay and proliferation was assessed on stimulation with HS. Induction of ECM synthesis was evaluated by gene expression analysis of AF-related genes in three-dimensional scaffold cultures that have been stimulated with 5% PRP or 10 ng/mL TGFB3 and histologically by collagen type I, type II, alcian blue, and safranin-O staining.

RESULTS

EdAFC and adAFC were significantly attracted by 10% HS and 5% PRP. Additionally, both cell groups proliferated under stimulation with HS. Stimulation with 10 ng/mL TGFB3 showed significant induction of gene expression of collagen type II and aggrecan, while 5% PRP decreased the expression of collagen type I. Both cell groups showed formation of AF-like ECM after stimulation with TGFB3, whereas stimulation with PRP did not.

CONCLUSIONS

Our study demonstrated that AF cells retain their potential for proliferation, migration, and ECM formation independent of the degeneration status of the tissue. Proliferation, migration, and ECM synthesis of the endogenous AF cells can be supported by different supplements. Hence, endogenous AF cells might be a suitable cell source for a regenerative repair approaches.

A 3D environment for anulus fibrosus regeneration

OBJECT

Biological repair strategies for the treatment of degenerated intervertebral discs are of growing interest. In addition to the development of nucleus pulposus implants to restore disc height and relieve pain, there is growing demand for an appropriate method for reconstructing the anulus fibrosus (AF). The aim of this pilot study was to evaluate the applicability of a resorbable 3D polymer of pure polyglycolic acid (PGA) combined with hyaluronan for the use in cell-free and cell-based regeneration and repair of the AF.

METHODS

Adult human AF cells were expanded in vitro using human serum and rearranged three dimensionally in hyaluronan-PGA scaffolds that were stabilized with fibrin for in vitro analyses. The capacity of dedifferentiated AF cells to redifferentiate was evaluated after 2 weeks of culture, using propidium iodide/fluorescein diacetate staining, gene expression analysis of typical marker genes, and histological staining of proteoglycans.

RESULTS

The propidium iodide/fluorescein diacetate staining demonstrated that vital human AF cells were evenly distributed within the construct. The induction of typical AF marker genes such as collagen Types I-III indicated the initiation of AF redifferentiation by 3D assembly in hyaluronan-PGA. Histological analysis of the constructs showed initial formation of an AF-like matrix comprising proteoglycans.

CONCLUSIONS

The results suggest that the 3D arrangement of human AF cells in resorbable hyaluronan-PGA scaffolds cultured in the presence of human serum is an excellent system for AF cell redifferentiation.

Polymethylmethacrylate-assisted ventral discectomy: rate of pseudarthrosis and clinical outcome with a minimum follow-up of 5 years

Background

Polymethylmethacrylate (PMMA) assisted ventral discectomy has been criticized for high rates of graft migration and pseudarthrosis when compared with various other fusion procedures for the treatment of cervical degenerative disc disease (DDD), therefore rendering it not the preferred choice of treatment today. Recently however spine surgery has been developing towards preservation rather than restriction of motion, indicating that fusion might not be necessary for clinical success. This study presents a long term comparison of clinical and radiological data from patients with pseudarthrosis and solid arthrodesis after PMMA assisted ventral discectomy was performed.

Methods

From 1986 to 2004 416 patients underwent ventral discectomy and PMMA interposition for DDD. The clinical and radiological outcome was assessed for 50 of 127 eligible patients after a mean of 8.1 years. Based on postoperative radiographs the patients were dichotomized in those with a pseudarthrosis (group A) and those with solid arthrodesis (group B).

Results

Pseudarthrosis with movement of more than 2 of the operated segment was noted in 17 cases (group A). In 33 cases no movement of the vertebral segment could be detected (group B). The analysis of the clinical data assessed through the neck disability index (NDI), the visual analogue scale (VAS) of neck and arm pain and Odom's criteria did not show any significant differences between the groups.

Patients from group B showed a trend to higher adjacent segment degeneration (ASD) than group A (p = 0.06). This correlated with the age of the patients.

Conclusions

PMMA assisted discectomy shows a high rate of pseudarthrosis. But the clinical long-term success does not seem to be negatively affected by this.

Chemokine CCL25 Induces Migration and Extracellular Matrix Production of Anulus Fibrosus-Derived Cells

Intervertebral disc degeneration is a major source of back pain. For intervertebral disc regeneration after herniation a fast closure of anulus fibrosus (AF) defects is crucial. Here, the use of the C-C motif chemokine ligand 25 (CCL)25 in comparison to differentiation factors such as transforming growth factor (TGF)β3, bone morphogenetic protein (BMP)2, BMP7, BMP12, and BMP14 (all in concentrations of 10, 50 and 100 ng/mL) was tested in an in vitro micro mass pellet model with isolated and cultivated human AF-cells (n = 3) to induce and enhance AF-matrix formation. The pellets were differentiated (serum-free) with supplementation of the factors. After 28 days all used factors induced proteoglycan production (safranin O staining) and collagen type I production (immunohistochemical staining) in at least one of the tested concentrations. Histomorphometric scoring revealed that TGFβ3 delivered the strongest induction of proteoglycan production in all three concentrations. Furthermore, it was the only factor able to facilitate collagen type II production, even higher than in native tissue samples. CCL25 was also able to induce proteoglycan and collagen type I production comparable to several BMPs. CCL25 could additionally induce migration of AF-cells in a chemotaxis assay and therefore possibly aid in regeneration processes after disc herniation by recruiting AF-cells.

The value of intraoperative neurophysiological monitoring for microsurgical removal of conus medullaris lipomas: a 12-year retrospective cohort study

Background

Lipomas in the lower spinal canal can lead to progressive neurological deficits, so they may have to be surgically removed. Intraoperative neurophysiological monitoring serves to minimize the morbidity of the surgical procedure. However, so far there are no evidence-based recommendations which type of monitoring procedure or combination of procedures to choose.

Methods

The aim of this study was to evaluate the feasibility and value of various intraoperative monitoring techniques: motor and sensory evoked potentials (MEP, SEP), free-running and triggered electromyography (EMG). Thirty cases of spinal lipomas of the Conus medullaris (dorsal Type A: 20.0%; caudal Type B: 33.3%; transitional Type C: 46.7%) were retrospectively evaluated over a 12-year period.

Results

The patients were mostly pediatric and suffered from persistent pain (73.3%), pareses (56.7%), sensory deficits (43.4%), and/or urogenital dysfunctions (60.0%). SEPs were successfully evoked in 66.7% of cases, MEPs in 86.7% of cases, and EMGs in 100%. MEP alterations correlated with direct mechanical maneuvers in the operating site. SEP changes correlated mostly with physiological events, such as rinsing/cooling of the operating site. Spike-, burst- or tonic train-activity was found in the free-running EMG that occurred only with certain manipulation patterns. Irreversible MEP changes and signal loss in the triggered EMG correlated with post-operative deficits.

Conclusions

The results of this study showed, that intraoperative monitoring could be considered a helpful tool during lipoma tumor surgery near the Conus medullaris. Most reliable results were obtained from transcranial MEPs, free-running EMGs, and triggered EMGs. That’s why the authors favor a routine set-up consisting of at least these three techniques, as this enables mapping at the beginning of the operation, continuous functional testing during surgery, and prognosis of the post-operative symptomology.

Vestibular ganglion neurons survive hair cell defects in jerker, shaker, and Varitint-waddler mutants and downregulate calretinin expression

Bipolar neurons (BNs) in the vestibular ganglion (VG) connect vestibular hair cells with the central nervous system (CNS). Disturbed function and cell loss in central vestibular target areas or in the vestibular periphery involve BNs either retro- or anterogradely. However, the impact of central vestibular disturbances or hair cell defects on the maintenance of BNs is poorly understood. In the present study the volume of the VG, the size and total number of BNs, and the number of BNs expressing the calcium-binding protein calretinin (Calr) were quantified stereologically in the cerebellar mutants purkinje cell degeneration (pcd/pcd), weaver (wv/wv), and Lurcher (Lc/+), and in the vestibular mutants jerker (je/je), shaker-1 (sh/sh), and Varitint-waddler (Va/+). In all the different mutant mice investigated the total number of BNs did not differ from that of wildtypes. In contrast, the number of Calr-positive BNs was significantly reduced in je/je (23%) and sh/sh (33%) mutants. Reduced cell size was apparent in sh/sh mutants and the volume of the VG significantly decreased in je/je mice. Calr was virtually absent from calyx endings in the vestibular periphery of je/je, sh/sh, and Va/+ mutants, whereas in wildtypes and cerebellar mutants many calyces displayed intense Calr labeling. These results imply that the survival of BNs is apparently unaffected by the peripheral and central target defects found in the mutants investigated. Whether the decrease in Calr expression may reflect biochemical adaptations in response to input disturbances or a specific loss of large BNs is discussed.

Effect of degeneration on gene expression of chondrogenic and inflammatory marker genes of intervertebral disc cells: a preliminary study

AIM

New techniques for biological repair in the treatment of degenerative disc disease (DDD) have been developed recently. The question arises whether it is possible to find a predictive marker to identify a patient population which could benefit from this new treatment option. Standard magnetic resonance imaging (MRI) fails to differentiate between pathologic painful and asymptomatic aging discs. Neurological symptoms contribute to identifying the pathological level. In this preliminary translational research study we analysed the gene expression of structure proteins and inflammatory mediators as well as histological features of lumbar intervertebral discs in symptomatic patients with various signs of degeneration in the MRI.

METHODS

Specimens of intervertebral disc tissue were obtained from 20 patients undergoing lumbar nucleotomy. Preoperatively, a group selection based on four pre-defined MRI-criteria was performed: Group 1 (mild signs of degeneration), group 2 (moderate), group 3 (moderate-severe), group 4 (severe).

RESULTS

An increase of the expression of structural proteins and inflammatory markers could be observed in MRI-groups 2 and 3. Gene expression of collagen type I and II and aggrecan went along with levels of cyclooxygenase-2 (COX-2) and (fibroblast growth factor-2) FGF-2 expression. Histological examination showed signs of granulation tissue in only 35% of cases, but no differences between the groups.

CONCLUSION

Our findings implicate that the gene expression of structural proteins might correlate with the appearance of inflammatory mediators in symptomatic patients with moderate disc changes in the MRI in this preliminary clinical subset. The assessment of cell activity and protein expression in a larger number of patients could be next step to support and supplement the present data.

The spinal cord injury-induced immune deficiency syndrome: results of the SCIentinel study

Infections are prevalent after spinal cord injury (SCI), constitute the main cause of death and are a rehabilitation confounder associated with impaired recovery. We hypothesize that SCI causes an acquired lesion-dependent (neurogenic) immune suppression as an underlying mechanism to facilitate infections. The international prospective multicentre cohort study (SCIentinel; protocol registration DRKS00000122; n = 111 patients) was designed to distinguish neurogenic from general trauma-related effects on the immune system. Therefore, SCI patient groups differing by neurological level, i.e. high SCI [thoracic (Th)4 or higher]; low SCI (Th5 or lower) and severity (complete SCI; incomplete SCI), were compared with a reference group of vertebral fracture (VF) patients without SCI. The primary outcome was quantitative monocytic Human Leukocyte Antigen-DR expression (mHLA-DR, synonym MHC II), a validated marker for immune suppression in critically ill patients associated with infection susceptibility. mHLA-DR was assessed from Day 1 to 10 weeks after injury by applying standardized flow cytometry procedures. Secondary outcomes were leucocyte subpopulation counts, serum immunoglobulin levels and clinically defined infections. Linear mixed models with multiple imputation were applied to evaluate group differences of logarithmic-transformed parameters. Mean quantitative mHLA-DR [ln (antibodies/cell)] levels at the primary end point 84 h after injury indicated an immune suppressive state below the normative values of 9.62 in all groups, which further differed in its dimension by neurological level: high SCI [8.95 (98.3% confidence interval, CI: 8.63; 9.26), n = 41], low SCI [9.05 (98.3% CI: 8.73; 9.36), n = 29], and VF without SCI [9.25 (98.3% CI: 8.97; 9.53), n = 41, P = 0.003]. Post hoc analysis accounting for SCI severity revealed the strongest mHLA-DR decrease [8.79 (95% CI: 8.50; 9.08)] in the complete, high SCI group, further demonstrating delayed mHLA-DR recovery [9.08 (95% CI: 8.82; 9.38)] and showing a difference from the VF controls of -0.43 (95% CI: -0.66; -0.20) at 14 days. Complete, high SCI patients also revealed constantly lower serum immunoglobulin G [-0.27 (95% CI: -0.45; -0.10)] and immunoglobulin A [-0.25 (95% CI: -0.49; -0.01)] levels [ln (g/l × 1000)] up to 10 weeks after injury. Low mHLA-DR levels in the range of borderline immunoparalysis (below 9.21) were positively associated with the occurrence and earlier onset of infections, which is consistent with results from studies on stroke or major surgery. Spinal cord injured patients can acquire a secondary, neurogenic immune deficiency syndrome characterized by reduced mHLA-DR expression and relative hypogammaglobulinaemia (combined cellular and humoral immune deficiency). mHLA-DR expression provides a basis to stratify infection-risk in patients with SCI.

Bone grafting and substitutes in spine surgery

The increase of spinal procedures over the last decades has made the long-term problems, such as pseudarthrosis, apparent. This demands optimized strategies, techniques and technologies. Modern fixation systems have been developed as an adjunct to spinal fusion, and several generations of different synthetic cages have proved to be reasonable alternatives to autologous bone or allografts. The development of recombinant bone morphogenetic proteins (BMPs) is of promise, because of their great osteoinductive capabilities. While spine surgeons are familiar with autologous and synthetic grafts as well as allografts, these comparably new evolving growth-factor-based technologies are of high interest. This was a selective literature review. Alternatives to autologous grafts include allograft bone, synthetic cages and growth-factor based bone substitutes, BMPs being the most-studied among them. Autologous iliac crest alone provides all of the required capabilities of an ideal bone graft, i.e. osteoconduction, osteoinduction, osteogenesis, but each of the alternatives can produce excellent results in a number of indications. If combined, these alternatives can cumulatively provide all required graft capabilities. Nevertheless, all of the available grafts have specific characteristics and can feature certain complications. Alternatives to autologous grafts circumvent donor-site morbidity and are available in a larger amount than autologous bone for extensive surgery. New technologies offer excellent possibilities of new bone formation, but there are also severe risks and high costs to be considered. The indication for bone grafting must be clearly defined, the graft selection should be individually adapted, and the risks, efforts and costs of the selected fusion procedure should be carefully considered.