Alphonse Lubansu

Results of positron emission tomography guidance and reassessment of the utility of and indications for stereotactic biopsy in children with infiltrative brainstem tumors

OBJECT Most intrinsic infiltrative brainstem lesions diagnosed in children are gliomas, and these carry a very bad prognosis. Although the utility and risk of stereotactically guided biopsy procedures in intrinsic infiltrative brainstem lesions have been widely questioned, the neuroimaging diagnosis may be inaccurate in approximately 25% of cases, and the consequences of empirical therapy should not be underestimated. Stereotactic biopsy sampling is still performed in many centers, but the reported diagnostic yield ranges from 83 to 96%. The authors integrated positron emission tomography (PET) images into the planning for stereotactic biopsy procedures to direct the biopsy needles trajectory to hypermetabolic foci of intrinsic infiltrative brainstem lesions. Their aim was to assess the benefit of the technique in terms of target selection and diagnostic yield. METHODS Twenty children with newly diagnosed intrinsic infiltrative brainstem lesions underwent a PET-guided stereotactic biopsy procedure. The PET tracer was(18)F-2-fluoro-2-deoxy-D-glucose (FDG) in six cases, (11)C-methionine in eight, and both agents were used in six. A single biopsy target was selected in the area of highest PET tracer uptake in all cases. The PET data were compared with diagnoses and outcome. RESULTS Use of PET guidance improved target selection and provided tumor diagnosis in all trajectories and in all children (high-grade glioma was diagnosed in 10, low-grade glioma in five, and nonglial tumor in five). The PET-guided trajectories provided a higher diagnostic yield than those guided by magnetic resonance imaging alone, which allowed the sampling to be reduced to a single trajectory. The PET data might also carry a prognostic value that could be useful for oncological management. CONCLUSIONS These data support the suggestion that PET guidance improves the diagnostic yield of stereotactic biopsy sampling, allows the practitioner to reduce the number of sampling procedures, and might lead to a reassessment of the utility of and indications for stereotactic biopsy in children with intrinsic infiltrative brainstem lesions.

Cerebral anaplastic pleomorphic xanthoastrocytoma with meningeal dissemination at first presentation.

IntroductionPleomorphic xanthoastrocytoma (PXA) is a rare brain glial tumour found in young patients. Most cases are reported as evolving low-grade neoplasms associated with a long survival after complete surgical resection. Some PXAs, however, can demonstrate secondary malignant transformation or progress with a short survival. Anaplastic histological features at first presentation or secondary meningeal dissemination have rarely been reported.Case reportWe describe the case of a cerebral PXA in a 7-year-old girl presenting with anaplastic histological features and craniospinal meningeal dissemination that progressed rapidly with a poor outcome.

PET imaging in the surgical management of pediatric brain tumors.

ObjectiveThe present article illustrates whether positron-emission tomography (PET) imaging may improve the surgical management of pediatric brain tumors (PBT) at different steps.Materials and methodsAmong 400 consecutive PBT treated between 1995 and 2005 at Erasme Hospital, Brussels, Belgium, we have studied with 18F-2-fluoro-2-deoxy-D-glucose (FDG)–PET and/or L-(methyl-11C)methionine (MET)–PET and integrated PET images in the diagnostic workup of 126 selected cases. The selection criteria were mainly based on the lesion appearance on magnetic resonance (MR) sequences. Cases were selected when MR imaging showed limitations for (1) assessing the evolving nature of an incidental lesion (n = 54), (2) selecting targets for contributive and accurate biopsy (n = 32), and (3) delineating tumor tissue for maximal resection (n = 40). Whenever needed, PET images were integrated in the planning of image-guided surgical procedures (frame-based stereotactic biopsies (SB), frameless navigation-based resections, or leksell gamma knife radiosurgery). Results Like in adults, PET imaging really helped the surgical management of the 126 children explored, which represented about 30% of all PBT, especially when the newly diagnosed brain lesion was (1) an incidental finding so that the choice between surgery and conservative MR follow-up was debated, and (2) so infiltrative or ill-defined on MR that the choice between biopsy and resection was hardly discussed. Integrating PET into the diagnostic workup of these two selected groups helped to (1) take a more appropriate decision in incidental lesions by detecting tumor/evolving tissue; (2) better understand complex cases by differentiating indolent and active components of the lesion; (3) improve target selection and diagnostic yield of stereotactic biopsies in gliomas; (4) illustrate the intratumoral histological heterogeneity in gliomas; (5) provide additional prognostic information; (6) reduce the number of trajectories in biopsies performed in eloquent areas such as the brainstem or the pineal region; (7) better delineate ill-defined PBT infiltrative along functional cortex than magnetic resonance imaging (MRI); (8) increase significantly, compared to using MRI alone, the number of total tumor resection and the amount of tumor tissue removed in PBT for which a total resection is a key-factor of survival; (9) target the resection on more active areas; (10) improve detection of tumor residues in the operative cavity at the early postoperative stage; (11) facilitate the decision of early second-look surgery for optimizing the radical resection; (12) improve the accuracy of the radiosurgical dosimetry planning.ConclusionsPET imaging may improve the surgical management of PBT at the diagnostic, surgical, and post-operative steps. Integration of PET in the clinical workup of PBT inaugurates a new approach in which functional data can influence the therapeutic decision process. Although metabolic information from PET are valid and relevant for the clinical purposes, further studies are needed to assess whether PET-guidance may decrease surgical morbidity and increase children survival.

Minimally invasive spinal arthrodesis in osteoporotic population using a cannulated and fenestrated augmented screw: Technical description and clinical experience

We describe a percutaneous or minimally invasive approach to apply an augmentation of pedicle fenestrated screws by injection of the PMMA bone cement through the implant and determine the safety and efficiency of this technique in a clinical series of 15 elderly osteoporotic patients. Clinical outcome and the function were assessed using respectively the Visual Analogue Scale (VAS) score and the Oswestry Disability Index (ODI). Peri- and post-operative complications were monitored during a minimum of 2 years of follow-up. Radiographic follow-up was based on plain fluoroscopic control at 3, 6 and 12 months and every year. In this approach, four steps were considered with care: optimal positioning of the screws, correct alignment of the screw heads, waiting time before the injection of cement, fluoroscopic control of the cement injection. Using these precautions, only 2 minor complications occurred. VAS scores and ODI questionnaires showed a statistically significant improvement up to 13.3 months postoperatively. No radiological complications were observed. Based on this experience, PMMA augmentation technique through the novel fenestrated screws provided an effective and long lasting fixation in osteoporotic patients. Applying this procedure through percutaneous or minimally invasive approach under fluoroscopic control seems to be safe.

A wearable inertial system to assess the cervical spine mobility: comparison with an optoelectronic-based motion capture evaluation.

In clinical settings, the cervical range of motion (ROM) is commonly used to assess cervical spine function. This study aimed at assessing cervical spine mobility based on head and thorax kinematics measured with a wearable inertial system (WS). Sequences of imposed active head movements (lateral bending, axial rotation and flexion-extension) were recorded in ten controls and 13 patients who had undergone an arthrodesis. Orientation of the head relative to the thorax was computed in terms of 3D helical angles and compared with the values obtained using an optoelectronic reference system (RS). Movement patterns from WS and RS showed excellent concurrent validity (CMC up to 1.00), but presented slight differences of bias (mean bias<2.5°) and dispersion (mean dispersion<4.2°). ROM obtained using WS also showed some differences compared to RS (mean difference<5.7°), within the range of those reported in literature. WS enabled the observation of the same significant differences between controls and patients as RS. Moreover, ROM from WS presented good test-retest repeatability (ICC between 0.63 and 0.99 and SEM<6.2°). In conclusion, WS can provide angles and ROM comparable to those obtained with RS and relevant for the cervical assessment after treatment.

Facial nerve palsy in posterior fossa arachnoid cysts: report of two cases.

Case reportTwo patients with a posterior fossa arachnoid cyst responsible for isolated facial nerve palsy are reported.DiscussionThe relationships between the cyst and the facial nerve and between the facial nerve palsy and the size variation of the cyst are discussed and documented by pre- and postoperative magnetic resonance imaging.

Objective evaluation of cervical spine mobility after surgery during free-living activity

BACKGROUND Evaluation of cervical spine mobility after surgery is mainly based on the measurement of the range of motion during imposed movements. It can thus be questionable if this assessment represents the mobility experienced during daily life. The goal of this study was to propose a new evaluation tool based on the monitoring of cervical spine movement during daily activities. METHODS The detection of cervical movement and the determination of primary motion component (lateral bending, axial rotation or flexion-extension), using two inertial sensors, were first validated in laboratory settings. Fifteen patients who underwent a cervical arthrodesis and nine healthy control subjects were monitored during their daily activity for half a day. The frequency of cervical movement was quantified according to posture, i.e. static and walking periods. The amplitude and velocity of cervical movement were evaluated using the median and cumulative distribution function. FINDINGS The movement detection and classification showed an excellent performance (sensitivity and specificity>94%). For the daily monitoring, the patients presented a movement frequency similar to controls, whereas the amplitude and velocity in patients were lower than in controls (P<0.05). The differences between patients and controls were larger for the velocity parameters (effect sizes>0.37 and >0.54 for static and walking periods respectively) than for the amplitude parameters. INTERPRETATION Body-worn inertial sensors enable the quantitative evaluation of global cervical movement. The movement amplitude and velocity during free-living conditions can be used as objective parameters to evaluate the cervical spine mobility after treatment.

AAV2 vectors mediate efficient and sustained transduction of rat embryonic ventral mesencephalon.

The success of transplantation of human embryonic mesencephalic tissue to treat parkinsonian patients is limited by the poor survival of the transplant. We show that an AAV2 vector mediates efficient expression of the egfp reporter gene in organotypic cultures of freshly explanted solid fragments of rat embryonic ventral mesencephalon (VM). We observed early and sustained transgene expression (4 days to ≥ 6 weeks). Furthermore, rAAV-infected rat embryonic VM transplanted in the adult striatum continued to express EGFP for ≥ 3 months. More than 95% of the transduced cells were neurons. Dopaminergic neurons were transduced at low frequency at earlier time points. This method of gene delivery could prove useful to achieve local, continuous secretion of neurotrophic factors at physiologically relevant doses to treat Parkinsons disease.

Recombinant AAV viral vectors serotype 1, 2, and 5 mediate differential gene transfer efficiency in rat striatal fetal grafts.

Intrastriatal grafts of fetal ganglionic eminences (GE) can reverse symptoms of striatal lesions in animal models of Huntingtons disease. On the other hand, neurotrophic factors have been shown to protect host striatal neurons from ongoing degeneration. Neurotrophic gene transfer into GE prior to grafting could combine the benefits of striatal neuron replacement and in situ delivery of neurotrophic factors. Here we evaluate the potency of recombinant adeno-associated viruses (rAAV) as vectors for gene delivery into rat embryonic (E15) GE using the eGFP reporter gene under the control of the strong cytomegalovirus (CMV) promoter. We observed a very efficient expression of the eGFP reporter gene in organotypic cultures of GE infected with rAAV serotype 1 from 4 days until at least 4 weeks postinfection. In contrast, transduction was low and absent when using serotype 2 and serotype 5 rAAV, respectively. Two months after transplantation of rAAV2/1-infected embryonic GE in adult rat striatum, more than 20% of grafted cells expressed eGFP. The majority of transduced cells in the graft were neurons as indicated by colabeling of GFP-immunoreactive cells with the NeuN marker. Our study suggests that GE transduced by rAAV-serotype 1 vectors could be an interesting tool to mediate efficient expression of a gene coding a neurotrophic factor in Huntingtons disease.

Effects of an Optimized Automated Disc Preparation on Clinical and Radiological Outcome of Minimally Invasive Transforaminal InterbodyFusion Procedure

Objective: In minimally invasive techniques for transforaminal lumbar interbody fusion (MIS TLIF) access to the disc and by consequence, the extension of the discectomy can be reduced. Insufficient disc removal and endplate violation can lead to non-unions, subsidence and pseudoarthroses. In this study, we compare the quality of disc preparation, volume of bone graft and clinical results in a group of patients who underwent MIS TLIF with discectomy and endplate preparation aided by an automated discectomy device, the enSpireTM Flex MIS Surgical Discectomy System (study group) to a control group with classical, manual instrumentation for disc preparation. Materials and methods: Twenty-seven consecutive patients were enrolled in the study group and 33 patients in the control group. All patients received similar mixture of autologous bone and cadaver allograft. Disc volume and the quantity of graft placed in the disc space was measured on the discharge CT scan and compared in a blinded, independent radiology review. Clinical outcomes assessed using the Visual Analog Scale (VAS) for leg and low back pain and the Oswestry Disability Index (ODI) were compared at 12 months postoperative. Results: The mean volume of bone graft placed and the ratio bone graft/nucleus was higher in the study group (6.21 cm3 vs. 4.39 cm3 ; p<0001 and 76.8% vs. 57.8%; p<0.0001). The mean Patient Satisfaction Index (PSI) of the EnSpire group was statistically higher than the control group (4.6 ± 0.6 vs. 3.9 ± 0.7). Conclusion: In the challenging MIS TLIF approach, we demonstrate that by using the enSpire™ Flex MIS Surgical Discectomy System, we can optimize the extension and quality of the discectomy, increase the volume of bone graft, and achieve better clinical outcomes.