Clinically relevant glioblastoma patient-derived xenograft models to guide drug development and identify molecular signatures.

Glioblastoma (GBM) heterogeneity, aggressiveness and infiltrative growth drastically limit success of current standard of care drugs and efficacy of various new therapeutic approaches. There is a need for new therapies and models reflecting the complex biology of these tumors to analyze the molecular mechanisms of tumor formation and resistance, as well as to identify new therapeutic targets. We established and screened a panel of 26 patient-derived subcutaneous (s.c.) xenograft (PDX) GBM models on immunodeficient mice, of which 15 were also established as orthotopic models. Sensitivity toward a drug panel, selected for their different modes of action, was determined. Best treatment responses were observed for standard of care temozolomide, irinotecan and bevacizumab. Matching orthotopic models frequently show reduced sensitivity, as the blood-brain barrier limits crossing of the drugs to the GBM. Molecular characterization of 23 PDX identified all of them as IDH-wt (R132) with frequent mutations in EGFR, TP53, FAT1, and within the PI3K/Akt/mTOR pathway. Their expression profiles resemble proposed molecular GBM subtypes mesenchymal, proneural and classical, with pronounced clustering for gene sets related to angiogenesis and MAPK signaling. Subsequent gene set enrichment analysis identified hallmark gene sets of hypoxia and mTORC1 signaling as enriched in temozolomide resistant PDX. In models sensitive for mTOR inhibitor everolimus, hypoxia-related gene sets reactive oxygen species pathway and angiogenesis were enriched. Our results highlight how our platform of s.c. GBM PDX can reflect the complex, heterogeneous biology of GBM. Combined with transcriptome analyses, it is a valuable tool in identification of molecular signatures correlating with monitored responses. Available matching orthotopic PDX models can be used to assess the impact of the tumor microenvironment and blood-brain barrier on efficacy. Our GBM PDX panel therefore represents a valuable platform for screening regarding molecular markers and pharmacologically active drugs, as well as optimizing delivery of active drugs to the tumor.

The genomic and transcriptional landscape of primary central nervous system lymphoma.

Primary lymphomas of the central nervous system (PCNSL) are mainly diffuse large B-cell lymphomas (DLBCLs) confined to the central nervous system (CNS). Molecular drivers of PCNSL have not been fully elucidated. Here, we profile and compare the whole-genome and transcriptome landscape of 51 CNS lymphomas (CNSL) to 39 follicular lymphoma and 36 DLBCL cases outside the CNS. We find recurrent mutations in JAK-STAT, NFkB, and B-cell receptor signaling pathways, including hallmark mutations in MYD88 L265P (67%) and CD79B (63%), and CDKN2A deletions (83%). PCNSLs exhibit significantly more focal deletions of HLA-D (6p21) locus as a potential mechanism of immune evasion. Mutational signatures correlating with DNA replication and mitosis are significantly enriched in PCNSL. TERT gene expression is significantly higher in PCNSL compared to activated B-cell (ABC)-DLBCL. Transcriptome analysis clearly distinguishes PCNSL and systemic DLBCL into distinct molecular subtypes. Epstein-Barr virus (EBV)+ CNSL cases lack recurrent mutational hotspots apart from IG and HLA-DRB loci. We show that PCNSL can be clearly distinguished from DLBCL, having distinct expression profiles, IG expression and translocation patterns, as well as specific combinations of genetic alterations.

Molecular characterization of CNS paragangliomas identifies cauda equina paragangliomas as a distinct tumor entity.

Paragangliomas/pheochromocytomas are rare neuroendocrine tumors that arise from the adrenal gland or ganglia at various sites throughout the body. They display a remarkable diversity of driver alterations and are associated with germline mutations in up to 40% of the cases. Comprehensive molecular profiling of abdomino-thoracic paragangliomas revealed four molecularly defined and clinically relevant subtypes. Paragangliomas of the cauda equina region are considered to belong to one of the defined molecular subtypes, but a systematic molecular analysis has not yet been performed. In this study, we analyzed genome-wide DNA methylation profiles of 57 cauda equina paragangliomas and show that these tumors are epigenetically distinct from non-spinal paragangliomas and other tumors. In contrast to paragangliomas of other sites, chromosomal imbalances are widely lacking in cauda equina paragangliomas. Furthermore, RNA and DNA exome sequencing revealed that frequent genetic alterations found in non-spinal paragangliomas-including the prognostically relevant SDH mutations-are absent in cauda equina paragangliomas. Histologically, cauda equina paragangliomas show frequently gangliocytic differentiation and strong immunoreactivity to pan-cytokeratin and cytokeratin 18, which is not common in paragangliomas of other sites. None of our cases had a familial paraganglioma syndrome. Tumors rarely recurred (9%) or presented with multiple lesions within the spinal compartment (7%), but did not metastasize outside the CNS. In summary, we show that cauda equina paragangliomas represent a distinct, sporadic tumor entity defined by a unique clinical and morpho-molecular profile.

Intradural spinal tumors in adults-update on management and outcome.

Among spinal tumors that occur intradurally, meningiomas, nerve sheath tumors, ependymomas, and astrocytomas are the most common. While a spinal MRI is the state of the art to diagnose intradural spinal tumors, in some cases CT scans, angiography, CSF analyses, and neurophysiological examination can be valuable. The management of these lesions depends not only on the histopathological diagnosis but also on the clinical presentation and the anatomical location, allowing either radical resection as with most extramedullary lesions or less invasive strategies as with intramedullary lesions. Although intramedullary lesions are rare and sometimes difficult to manage, well-planned treatment can achieve excellent outcome without treatment-related deficits. Technical advances in imaging, neuromonitoring, minimally invasive approaches, and radiotherapy have improved the outcome of intradural spinal tumors. However, the outcome in malignant intramedullary tumors remains poor. While surgery is the mainstay treatment for many of these lesions, radiation and chemotherapy are of growing importance in recurrent and multilocular disease. We reviewed the literature on this topic to provide an overview of spinal cord tumors, treatment strategies, and outcomes. Typical cases of extra- and intramedullary tumors are presented to illustrate management options and outcomes.

Clinical Use of Navigation in Lateral Skull Base Surgery: Results of a Multispecialty National Survey among Skull Base Surgeons in Germany.

Objective To analyze the current clinical use of navigation at the lateral skull base among skull base surgeons in Germany. Methods A web-based questionnaire was provided to surgeons being head of the department and member of one of the following scientific societies: German Society of Head and Neck Surgery, Maxillo-Facial Surgery, Neurosurgery, and German Skull Base Society. Replies were recorded anonymously. The questionnaire included the estimated case load per year and percent of surgery performed with navigation (middle and posterior fossa), type of navigation, estimates of intraoperative inaccuracy, and reasons for not using navigation. Results Eighty nine out of 99 replies met requirements for final analysis. Overall, 37% of skull base surgeons use navigation on a regular basis (15% use no navigation). Optical tracking is more frequently used than magnetic tracking (71 vs 19). At the middle fossa, ENT surgeons split into routine users ( n = 10/36) and rare users ( n = 16/36), the latter stating navigation inaccuracy as a major reason for neglecting navigation. Neurosurgeons use navigation at the middle fossa significantly more often and criticize navigation inaccuracy less. At the posterior fossa, navigation is used less frequently by both ENT and neurosurgeons with similar rates of estimated inaccuracy. Conclusions A moderate use of navigation at the lateral skull base was demonstrated. Insufficient accuracy causes ENT surgeons to frequently omit navigation at the middle fossa (not neurosurgeons) and posterior fossa (also neurosurgeons). Higher intraoperative navigation accuracy is needed to enhance the use of navigation at the lateral skull base.

Rehabilitation after Clipping of Cerebral Aneurysms without Acute Subarachnoid Hemorrhage: Outcome Analysis of 100 Consecutive Cases.

BACKGROUND: Discharge to rehabilitation is reported in large studies as one important outcome parameter based on hospital codes. Because neurologic outcome scores (e.g., the modified Rankin Scale [mRS]) are missing in International Classification of Diseases (ICD) databases, rehabilitation indirectly serves as a kind of surrogate parameter for overall outcome. Reported fractions of patients with rehabilitation, however, largely differ between studies and seem high for patients with aneurysm clipping. Variances in rehabilitation fractions seem to largely differ between treatments (clipping versus coiling) for unruptured intracranial aneurysms, so we analyzed our patients for percentage of and potential factors predicting rehabilitation. PATIENTS: From July 2007 to September 2013, 100 consecutive patients with at least one cerebral aneurysm underwent aneurysm clipping. Aneurysms were classified as incidental, associated, pretreated (coil compaction after subarachnoid hemorrhage), and symptomatic (oculomotor nerve compression, microemboli), and they were assigned to their anatomical location. Complications (infection, hemorrhage, cerebrospinal fluid fistula, transient and permanent neurologic deficit, reoperation) and outcome (mRS at 6 months; clip occlusion rate by postoperative digital subtraction angiography) as well as frequency and type of rehabilitation were analyzed and correlated retrospectively. Multiple aneurysms clipped in one procedure were not counted separately regarding complications or outcome (i.e., one patient, one outcome). RESULTS: The overall complication rate was 17% including 10% early and 3% permanent neurologic deficits and 7% reoperations. There were no deaths. Overall, 98% of patients had a good outcome (mRS 0-2). Clip occlusion rate was 97.9%. Multivariate logistic regression analysis identified aneurysm location as the only significant independent factor for risk of complication (p < 0.001) and complication as the only significant independent risk factor for rehabilitation (p = 0.003). Rehabilitation was indicated or requested by the patient as early neurologic rehabilitation (5%), inpatient follow-up (15%), and outpatient follow-up (15%). The long-term care rate was 2%. CONCLUSION: Microsurgery of unruptured and not acutely ruptured aneurysms (including post-coil and associated aneurysms) has a low rate of rehabilitation with a low risk of a permanent neurologic deficit, long-term care, or early neurologic rehabilitation. The rate of rehabilitation is well below reported risks from studies based on ICD-based health care analysis. Rehabilitation per se is not a good indicator for outcome.

Optimized Screw Trajectory for Lumbar Cortical Bone Trajectory Pedicle Screws Based on Clinical Outcome: Evidence Favoring the Buttress Effect Theory.

BACKGROUND: Cortical bone trajectory (CBT) is a relatively new technique for pedicle screw insertion in the field of spine surgery. Previous studies have demonstrated the significantly better pullout and toggle characteristics the new method offers, and it appears to have certain advantages over the widely used traditional trajectory. The mechanism of the pullout and toggle characteristics still remains unknown. PURPOSE: To report the medium- to long-term follow-up findings of patients who underwent posterior lumbar interbody fusion or posterior lumbar fusion (PLIF/PLF) at our institution and to discuss the ideal screw trajectory when using this technique. STUDY DESIGN: Retrospective radiologic study. METHODS: Fifty-five patients who underwent PLIF/PLF for lumbar spondylosis using the new technique between January 2011 and January 2016 were included. Clinical outcome was assessed using the Japanese Orthopaedic Association scores for low back pain and visual analog scale scores. Screw loosening was evaluated via the presence of a translucent zone surrounding the pedicle screw using plain X-radiography (Xp). The screw trajectory was evaluated by measuring the rostral range (RR) and the lateral range score (LRS). The RR is the angle between the line drawn along the distal end plate of the vertebra and the line drawn along the screw on the lateral view. The LRS is the score given depending on the position of the tip of the screw seen on the Xp taken in the anteroposterior (AP) view. The pedicle ring is equally divided into the medial third (zone A), central third (zone B), and the lateral third (zone C) by four vertical lines. A score of 0 to 3 points is given depending on the position of the tip of the screw: 0, outside the pedicle ring; 1, zone A; 2, zone B; and 3, zone C. RESULTS: Bone fusion was recorded in 49 patients (49/55 patients). The total number of screws with a visible translucent zone on Xp was 26 (26/242 screws). When the screws are inserted at a more acute angle in the lateral view (low RR) or when the screws are directed more medially (low LRS), the risk of developing a translucent zone around the pedicle screw increased. CONCLUSION: With CBT, the pedicle screws are inserted from the pars interarticularis that is rich in cortical bone, strong enough to withstand the substantial forces usually encountered in the region. Our clinical data suggest that the optimal screw trajectory is one where the screw is inserted at an angle > 22.55 degrees (high RR) on the lateral view Xp and where the tip of the screw is directed toward the lateral third of the pedicle on the AP Xp. We believe the naturally occurring buttress effect that exists in the vertebra may give CBT a mechanical and anatomical advantage over the traditional screw trajectory.

Technical accuracy of the integration of an external ultrasonography system into a navigation platform: effects of ultrasonography probe registration and target detection.

BACKGROUND: Intraoperative navigated ultrasonography has reached clinical acceptance, while published data for the accuracy of some systems are missing. We technically quantified and optimised the accuracy of the integration of an external ultrasonography system into a BrainLab navigation system. METHODS: A high-end ultrasonography system (Elegra; Siemens, Erlangen, Germany) was linked to a navigation system (Vector Vision; BrainLab, Munich, Germany). In vitro accuracy and precision was calculated from differences between a real world target (high-precision crosshair phantom) and the ultrasonography image of this target in the navigation coordinate system. The influence of the intrinsic component of the calibration phantom (for ultrasonography probe registration), type of target definition (manual versus automatic) and orientation of the ultrasound probe in relation to the navigation tracking device on accuracy and precision were analysed in different settings (100 measurements for each setting) resembling clinically relevant scenarios in the neurosurgical operating theatre. RESULTS: Line-of-sight angles of 45°, 62° and 90° for the optical tracking of the navigated ultrasonography probe and a distance of 1.8 m revealed best accuracy and precision. Technical accuracy of the integration of ultrasonography into a standard navigation system is high [Euclidean error: median, 0.79 mm; mean, 0.89 ± 0.42 mm for 62° angle; median range: 1.16-1.46 mm; mean range (±SD): 1.22 ± 0.32 mm to 1.46 ± 0.55 mm for grouped analysis of all angles tested]. Software-based automatic target definition improved precision significantly (p < 0.001). CONCLUSIONS: Integration of an external ultrasonography system into the BrainLab navigation is accurate and precise. By modifying registration (and measurement conditions) via software modification, the in vitro accuracy and precision is improved and requirements for a clinical application are fully met.

The evolution of the anaplastic cerebellar liponeurocytoma: case report and review of the literature.

Cerebellar liponeurocytoma, first recognized as a distinct entity in the revised WHO classification of Tumors of the Central Nervous System in 2000, is a rare tumor with characteristic histological features and predominant location in the cerebellum. The proliferative index is usually low, and previous reports supported a favorable prognosis. We report a case of a second recurrence of a cerebellar liponeurocytoma with increased proliferative and mitotic activity in which extensive immunohistochemical characterization and genetic profiling were performed. The tumor specimen was characterized in terms of genetic changes frequently associated with gliomas and medulloblastomas. Considering the low number of reported cases, the prognosis of cerebellar liponeurocytoma seems difficult to assess. Our case suggests the existence of different histological grades of cerebellar liponeurocytoma and its possible progression towards a dedifferentiated, malignant phenotype, which has not yet been adequately taken into consideration in the current WHO classification.

Dysplasia of C-1 and craniocervical instability in patients with Shprintzen-Goldberg syndrome. Case report and review of the literature.

Shprintzen-Goldberg syndrome is a rare connective tissue disorder characterized by marfanoid habitus and additional dysmorphic stigmata. Craniocervical anomalies occur in fewer than 30% of cases. Serious vertebral instability can also occur, albeit rarely. The authors report on the first patient treated with surgical fusion at the craniocervical junction because of a C-1 dysplasia and severe instability. The skeletal and cardiovascular anomalies that can pose additional problems for surgical treatment and perioperative care are discussed in detail.

Surgical treatment for ulnar nerve entrapment at the elbow.

The outcomes of 81 operations were assessed for the treatment of ulnar nerve entrapment at the elbow performed on 55 males (bilateral operations in one) and 25 females during the period from January 1995 to December 2000. Before operation, neurophysiological examination was performed in all patients. Simple ulnar nerve decompression or anterior transposition of the ulnar nerve (subcutaneous or intramuscular) was performed with or without the operating microscope. Nine patients were lost to follow up. The outcome was excellent or good in 63 of 72 cases, no change in eight cases, and poor in one case. The outcomes of procedures performed with the operating microscope tended to be superior.

Autologous stem cells (adipose) and fibrin glue used to treat widespread traumatic calvarial defects: case report.

This is a report of a 7-year-old girl suffering from widespread calvarial defects after severe head injury with multifragment calvarial fractures, decompressive craniectomy for refractory intracranial hypertension and replantation of cryopreserved skull fragments. Chronic infection resulted in an unstable skull with marked bony defects. Two years after the initial injury the calvarial defects were repaired. Due to the limited amount of autologous cancellous bone available from the iliac crest, autologous adipose derived stem cells were processed simultaneously and applied to the calvarial defects in a single operative procedure. The stem cells were kept in place using autologous fibrin glue. Mechanical fixation was achieved by two large, resorbable macroporous sheets acting as a soft tissue barrier at the same time. The postoperative course was uneventful and CT-scans showed new bone formation and near complete calvarial continuity three months after the reconstruction.

Early decompressive craniectomy and duraplasty for refractory intracranial hypertension in children: results of a pilot study.

INTRODUCTION: Severe traumatic brain injury (TBI) in childhood is associated with a high mortality and morbidity. Decompressive craniectomy has regained therapeutic interest during past years; however, treatment guidelines consider it a last resort treatment strategy for use only after failure of conservative therapy. PATIENTS: We report on the clinical course of six children treated with decompressive craniectomy after TBI at a pediatric intensive care unit. The standard protocol of intensive care treatment included continuous intracranial pressure (ICP) monitoring, sedation and muscle relaxation, normothermia, mild hyperventilation and catecholamines to maintain an adequate cerebral perfusion pressure. Decompressive craniectomy including dura opening was initiated in cases of a sustained increase in ICP > 20 mmHg for > 30 min despite maximally intensified conservative therapy (optimized sedation and ventilation, barbiturates or mannitol). RESULTS: In all cases, the ICP normalized immediately after craniectomy. At discharge, three children were without disability, two children had a mild arm-focused hemiparesis (one with a verbal impairment), and one child had a spastic hemiparesis and verbal impairment. This spastic hemiparesis improved within 6 months follow-up (no motor deficit, increased muscle tone), and all others remained unchanged. CONCLUSION: These observational pilot data indicate feasibility and efficacy of decompressive craniectomy in malignant ICP rise secondary to TBI. Further controlled trials are necessary to evaluate the indication and standardization of early decompressive craniectomy as a 'second tier' standard therapy in pediatric severe head injury.

Risk factors for outcome and complications of dorsal foraminotomy in cervical disc herniation.

BACKGROUND: Dorsal foraminotomy is a standard operative procedure for lateral cervical disc herniation. Factors associated with surgical complications and clinical outcome in dorsal foraminotomy of cervical disc herniation were evaluated in a retrospective cohort study. METHOD: Thirty-nine patients were operated upon for unilateral, monosegmental, mediolateral cervical disc herniation (+/- associated spondylosis) from 1997 to 1999. Preoperative radiologic imaging and surgical reports were analyzed. Motor disfunction, neck irritation, and radicular pain were evaluated. Outcome was ranked according to modified Odom's criteria at 6 weeks and 1 year postoperatively. RESULTS: Six weeks after injury 7 of 39 patients (18%) showed neck irritation. No new neurologic deficit was seen. All patients with preoperative paresis improved; two had early relapses of a medial soft disc prolapse (2/39). Residual radicular pain was seen in 3 of 39 patients (8%) within 30 days postoperatively, necessitating surgical revision. Factors of surgical failure were associated spondylosis (2/3) and residual mediolateral disc protrusion (1/3). In one patient with associated spondylosis, local pain due to a symptomatic fracture of the lateral process of D1 resolved after revision. Duration of preoperative radicular pain was identified as a risk factor for unfavorable outcome. CONCLUSION: In lateral cervical disc herniation, associated spondylosis or medial disc protrusion poses a significant risk of surgical failure and complications of dorsal foraminotomy. Reducing the radicular failure rate by enlarging the bony decompression may lead to local failure. In well-selected patients with a lateral cervical free disc fragment, dorsolateral foraminotomy is successful and safe.

Endoscopic surgical anatomy of the paediatric third ventricle studied using virtual neuroendoscopy based on 3-D ultrasonography.

INTRODUCTION: Endoscopic treatment for occlusive hydrocephalus requires knowledge of individual ventricular and vascular anatomies of the ventricular system. METHODS: We studied the feasibility of virtual neuroendoscopy (VNE) based on 3-D ultrasonography (3-D US) for the identification of parenchymal and vascular anatomical landmarks of the third ventricle and its impact on the surgical planning of endoscopic third ventriculostomy (ETV) in paediatric patients. 3-D US was performed through the anterior fontanel in four infants with hydrocephalus. RESULTS: Virtual neuroendoscopy revealed the size of the foramen of Monro, anatomical landmarks of the floor of the third ventricle crucial for correct fenestration during ETV, but not the premesencephalic cistern. The basilar bifurcation was identified in relation to the floor of the third ventricle by VNE (power-Doppler ultrasonography) and confirmed intraoperatively after ETV. CONCLUSION: 3-D US-based VNE reveals detailed anatomical information on the ventricular system including the foramen of Monro and the floor of the third ventricle. Within the premesencephalic cistern vascular anatomy can be visualized, but not non-vascular structures.

Monitoring of brain tissue oxygenation during aneurysm surgery: prediction of procedure-related ischemic events.

OBJECT: The aim of this study was to evaluate the feasibility of monitoring brain tissue oxygenation (PO2) during aneurysm surgery for the detection of procedure-related ischemia. METHODS: Between 1997 and 1998, PO2 was monitored prospectively in a cohort of 40 patients (42 recordings) during aneurysm surgery in the anterior circulation within the vascular territory of the aneurysm-bearing artery. The position of the probe used to measure oxygenation levels was verified on computerized tomography (CT) scanning on the 1st postoperative day. Because of the mislocation of one probe and the malfunction of another, data from only 38 patients (40 recordings) were suitable for analysis. Relative changes from baseline to absolute nadir values of intraoperative PO2 were correlated with simultaneously recorded somatosensory evoked potentials (SSEPs), and cardiovascular and ventilatory parameters. The frequency of ischemic events was evaluated with the aid of CT on the 1st postoperative day as a substitute parameter for intraoperative ischemia. Clinical outcome was evaluated 30 days postoperatively based on the Glasgow Outcome Scale. Except for three, all patients underwent surgery for treatment of a symptomatic aneurysm. Mean baseline PO2 was 23.9 mm Hg (range 2-67.2 mm Hg) before clip application. A relative decrease in PO2 (20% decrease in value compared with baseline) occurred in 12 patients and was a sensitive indicator for the risk of ischemia during temporary arterial occlusion, but was less predictive of nonocclusive ischemia (sensitivity 0.5; positive predictive value [PPV] 0.42; p > 0.05). Results of receiver operating characteristic analysis demonstrated a postclipping PO2 nadir of 15 mm Hg as a dichotomizing threshold for the prediction of ischemia. This threshold rendered an improved sensitivity (0.9) and PPV (0.56) for procedure-related ischemia (p = 0.0003). The results of utility analysis revealed this monitoring parameter to be clinically diagnostic. Only PO2 monitoring, and not SSEP at the tibial nerve, was predictive of ischemia within the anterior cerebral artery territory. CONCLUSIONS: Using 15 mm Hg as a dichotomizing threshold, intraoperative PO2 monitoring enables one to identify patients at risk for procedure-related ischemia during aneurysm surgery and surpasses SSEP monitoring. This newly defined threshold based on intraoperative PO2 monitoring provides a basis for studies on treatments for procedure-related ischemia during aneurysm surgery.

Virtual endoscopy of the cerebral ventricles based on 3-D ultrasonography.

Virtual endoscopy enables preoperative surgical planning based on "surgeons' view" information in the individual patient. In neurosurgery, magnetic resonance (MR) images are mainly used for planning of virtual neuroendoscopy (VNE). We studied the feasibility of three-dimensional (3-D) ultrasonography as the imaging modality for VNE in pediatric patients with hydrocephalus. 3-D ultrasonography data sets were obtained through the open anterior fontanelle and analyzed using perspective volume rendering, with delineation of the ventricular system for anatomical details in relation to standard ultrasonography and intraoperative anatomy, during endoscopy in two infants with hydrocephalus. VNE clarified anatomical variants seen on standard ultrasonography images, anticipated ventricular dysmorphia seen during neuroendosopy and enabled a realistic impression of an endoscopic inspection into the ventricular system of the two infants studied. Based on 3-D ultrasonography, VE enables detailed information on ventricular anatomy in pediatric patients for planning of endoscopic interventions.