A new subtype of diffuse midline glioma, H3 K27 and BRAF/FGFR1 co-altered: a clinico-radiological and histomolecular characterisation.

Diffuse midline gliomas (DMG) H3 K27-altered are incurable grade 4 gliomas and represent a major challenge in neuro-oncology. This tumour type is now classified in four subtypes by the 2021 edition of the WHO Classification of the Central Nervous System (CNS) tumours. However, the H3.3-K27M subgroup still appears clinically and molecularly heterogeneous. Recent publications reported that rare patients presenting a co-occurrence of H3.3K27M with BRAF or FGFR1 alterations tended to have a better prognosis. To better study the role of these co-driver alterations, we assembled a large paediatric and adult cohort of 29 tumours H3K27-altered with co-occurring activating mutation in BRAF or FGFR1 as well as 31 previous cases from the literature. We performed a comprehensive histological, radiological, genomic, transcriptomic and DNA methylation analysis. Interestingly, unsupervised t-distributed Stochastic Neighbour Embedding (tSNE) analysis of DNA methylation profiles regrouped BRAFV600E and all but one FGFR1MUT DMG in a unique methylation cluster, distinct from the other DMG subgroups and also from ganglioglioma (GG) or high-grade astrocytoma with piloid features (HGAP). This new DMG subtype harbours atypical radiological and histopathological profiles with calcification and/or a solid tumour component both for BRAFV600E and FGFR1MUT cases. The analyses of a H3.3-K27M BRAFV600E tumour at diagnosis and corresponding in vitro cellular model showed that mutation in H3-3A was the first event in the oncogenesis. Contrary to other DMG, these tumours occur more frequently in the thalamus (70% for BRAFV600E and 58% for FGFR1MUT) and patients have a longer overall survival with a median above three years. In conclusion, DMG, H3 K27 and BRAF/FGFR1 co-altered represent a new subtype of DMG with distinct genotype/phenotype characteristics, which deserve further attention with respect to trial interpretation and patient management.

Neurocognitive and radiological follow-up of children under 5 years of age treated for medulloblastoma according to the HIT-SKK protocol.

BACKGROUND: The HIT-SKK protocol is used for low/standard-risk medulloblastomas in young children with the aim to eliminate cranial irradiation and its neuropsychological (NP) sequelae. This therapy includes IV and intraventricular (ITV) methotrexate (MTX) potentially responsible for leukoencephalopathy (LE) and neurocognitive disorders. This study describes the risk factors and course of LE, and investigates its correlation with neurocognitive impact. METHODS: A retrospective, multicenter study was conducted in 35 children under 5 years old, with a median follow-up of 72 months (range 14 to 130). The main analysis was performed in 30 patients who received cumulative doses of MTX as per-protocol (group 1). Five patients who received higher cumulative doses of MTX were analyzed separately. All follow-up MRIs and NP assessments were centrally reviewed by experts. RESULTS: Twenty patients in group 1 developed LE, grade 2 and 3 abnormalities did not correlate with higher cumulative doses of ITV-MTX (p = 0.698). Considering the most recent NP evaluation, the Full-Scale IQ (FSIQ) and Wechsler indices were in the average to lower average range. The FSIQ was deficient in 6/17 evaluable patients. Cumulative dose of ITV-MTX was almost associated with decreased processing speed competence (p = 0.055) which was the most frequently impaired neurocognitive domain. Neuropsychological assessment scores were not statistically lower in patients with persistent grade 2 LE at the end of follow-up. CONCLUSION: This study described that the use of cumulative dose of MTX (IV and ITV) according to the HIT-SKK protocol resulted in LE that tented to decrease over time, without significant correlation with a decline in neuro-intellectual skills.

Low-grade epilepsy-associated neuroepithelial tumours with a prominent oligodendroglioma-like component: The diagnostic challenges.

AIMS: We searched for recurrent pathological features and molecular alterations in a retrospective series of 72 low-grade epilepsy-associated neuroepithelial tumours (LEATs) with a prominent oligodendroglioma-like component, in order to classify them according to the 2021 World Health Organization (WHO) classification of central nervous system (CNS) tumours. METHODS: Centralised pathological examination was performed as well as targeted molecular analysis of v-Raf murine sarcoma viral oncogene homologue B (BRAF) and fibroblast growth factor receptor 1 (FGFR1) by multiplexed digital polymerase chain reaction (mdPCR). DNA methylation profiling was performed in cases with sufficient DNA. In cases with no genetic alteration by mdPCR and sufficient material, RNA sequencing was done. RESULTS: We first reclassified our cohort into three groups: ganglioglioma (GG, n = 14), dysembryoplastic neuroepithelial tumours (DNTs, n = 19) and glioneuronal tumours/paediatric-type low-grade glioma (LGG) not otherwise specified (GNT/PLGG NOS, n = 39). mdPCR found an alteration in 38/72 cases. Subsequent RNA sequencing revealed a fusion transcript involving BRAF, FGFR1/2/3 or neurotrophic tyrosine kinase receptor type 2 [NTRK2] in 9/25 cases. DNA methylation profiling found 12/46 cases with a calibrated score ≥0.9. Unsupervised hierarchical clustering revealed two clusters: Cluster 1 was enriched with cases classified as DNT at histology, belonging to the LGG-DNT methylation class (MC), with haematopoietic progenitor cell antigen (CD34) negativity and FGRF1 alterations; Cluster 2 was enriched with cases classified at histology as GG, belonging to the LGG-GG MC MC, with BRAF V600E mutation and CD34 positivity. The tumours reclassified as GNT/PLGG NOS were equally distributed across both clusters. Interestingly, all polymorphous low-grade neuroepithelial tumour of the young belonged to Cluster 2, whereas diffuse LGG mitogen-activated protein kinase (MAPK) pathway-altered were equally distributed among the two clusters. This led us to build an algorithm to classify LEATs with a prominent oligodendroglioma-like component. CONCLUSIONS: Integrated histomolecular diagnosis of LEATs with a prominent oligodendroglioma-like component remains challenging. Because these tumours can be split into two major clusters of biological significance, the clinicopathological relevance of the four types recognised by the WHO CNS5 within this spectrum of tumours is questionable.

Pneumosinus dilatans of the sphenoid and visual loss: when should the optic nerve be decompressed?

Pneumosinus dilatans of the sphenoid sinus is a rare disorder which can be responsible for visual impairment and blindness. We present the case of an adolescent female who experienced progressive decrease in right-eye vision over 2 years. CT scan of the head showed an extensive pneumatization of the sphenoid bone extending to the lesser wing of the sphenoid and to the anterior clinoid process on the right side. MRI revealed right nerve atrophy in the optic canal and in the posterior part of the orbit. A surgical decompression of the right optic canal was performed via an intradural fronto-pterional approach. Postoperatively, her vision worsened, and at 3 years the patient was able to count fingers at 2.5 m. Our case and literature review of symptomatic sphenoidal pneumosinus dilatans confirmed that visual prognosis in such cases depended on the preoperative visual status. Early surgical decompression should be proposed whenever possible, before signs of severe visual disorders and optic atrophy.

Dysplastic gangliocytoma of the cerebellum (Lhermitte-Duclos disease) presenting as a prenatally heterotopic hamartoma.

Dysplastic gangliocytoma of the cerebellum (DGC), also called Lhermitte-Duclos disease, is a rare lesion of the posterior fossa consisting of a diffuse hypertrophy of the cerebellar cortex. DGC frequently presents in young adults and rarely in childhood. Only 3 cases have been previously described in newborns. We present an uncommon case of DGC which was diagnosed in utero. The radiological presentation prenatally and at birth was similar to a heterotopic neuroglial brain tissue. MRI aspects evolved from T1/T2 isointense signals to hypoT1 and hyperT2 signals at the age of 1 year. The girl was then operated on total removal of the lesion which was performed with no postoperative complication. Genetics did not demonstrate any germline PTEN mutation or family history suggesting Cowden disease. Two years later, the child was doing well and MRI confirmed complete resection. This case illustrates the difficulties of diagnosing intracranial lesions in foetuses and newborns. Physicians caring for pregnant women and pediatrics should be aware that neoplasm-like lesions such as DGC may present as hamartomas. Surgical resection could then be discussed whenever possible.

Fusiform dilatation of internal carotid artery after pterional but not subfrontal craniotomy in 6 patients.

PURPOSE: Our study aimed to evaluate potential risk factors for the development of FDICA after suprasellar tumor resection. MATERIALS AND METHOD: After reviewing all cases of pediatric patients who benefited from a suprasellar lesion resection in our two medical institutions, we found 6 patients with a FDICA. Surgical approach strategy (pterional or subfrontal approaches) was noted. Postoperative cranial MRI was performed in each patient 3 months after surgery and every year. When a FDICA occurred, MRI was performed 6 months after the diagnosis and 1 year later to detect any progression. RESULTS: There were 6 males with a mean age at treatment of 11 years (6 to 15). Pterional approach was performed in these 6 patients. At the 2 institutions, we have done at least 50 pterional craniotomies for suprasellar lesion resection. No FDICA was reported after subfrontal approach in 27 consecutive pediatric patients operated on from a craniopharyngioma. The delay between the surgery and the diagnosis of the FDICA was 9 months (3 to 17 months). No symptoms related to the FDICA were recorded. The mean maximal diameter of the aneurysm was 14 mm (10 to 21). ICA bifurcation was involved in 2 cases. Asymptomatic FDICA progression was noted in 2 cases but no treatment was proposed. CONCLUSION: The pathogenesis of FDICA is unclear, and might involve arterial wall necrosis caused by postoperative arachnoid fibrosis which might be worsened by the pterional approach.

Interruptions in Surgery: A Comprehensive Review.

BACKGROUND: Recent literature showed that analysis of interruptions can contribute to evaluating the care process in the operating room, and thus, understanding potential errors that may occur during surgical procedures. The aim of this comprehensive review was to summarize current knowledge on the description and impact of interruptions in surgery. MATERIAL AND METHODS: A literature search was conducted according to a set of criteria in the databases MEDLINE, BASE, Cochrane's Library, and PsycINFO. RESULTS: 41 articles were included. Two main methodological approaches were found, observational in the OR, or controlled in an experimental simulated environment. Interruptions in the OR were manifold, and several classifications were used. The severity of interruptions differed according to the category of the interruptions. Interruptions were influenced by team familiarity and the expertise of the surgical team; high team familiarity and a high level of expertise decreased the frequency of interruptions. However, our literature search lacked controlled studies carried out in the OR. Interruptions seemed to increase the workload and stress of the surgical team and impair nontechnical skills, but no clear evidence of this was advanced. CONCLUSIONS: Interruptions are probably risk factors for errors in the operating room. However, there is as yet no clear evidence of the association of interruption frequency with errors in the operating room. There is a need to define and target interruptions, which should be reduced by putting safeguards in place, thereby allowing those which could be beneficial and neglecting those with no potential consequences.

Ruptured intracranial arachnoid cysts in the subdural space: evaluation of subduro-peritoneal shunts in a pediatric population.

PURPOSE: Rupture of arachnoid cysts (AC) in the subdural space after trauma may cause a subacute/chronic subdural hematoma or a hygroma. Treatment of this complication still remains controversial, and no consensual strategy is to date clearly proposed. In this study, the authors evaluated the clinical and radiological evolution of patients treated by a subduro-peritoneal shunt for symptomatic subdural collections complicating ruptured AC. METHODS: Medical records of the 10 patients treated at our institution between January 2005 and December 2018 for a subdural collection associated with an intracranial AC were reviewed. Subduro-peritoneal shunts consisted of low-pressure valves from 2005 to 2012 (6 cases) and medium-pressure valves after 2012 (4 cases). RESULTS: A benign head trauma was retrospectively found in the history of 8 patients. The mean time to diagnosis ranged from 15 days to 5 months. Symptoms resulted mainly from intracranial hypertension. Six patients had an ipsilateral hygroma to the AC, 2 patients had a bilateral hygroma predominantly to the AC side, and 2 patients presented an ipsilateral chronic subdural hematoma. Arachnoid cysts were classified as Galassi I in 5 cases and Galassi II in 5 cases. Patients with chronic subdural hematoma were given a medium-pressure valve. Patients with subdural hygroma received a low-pressure valve in 6 cases and a medium-pressure valve in 2 cases. There were no complications during surgical procedures. All patients were rapidly free of symptoms after surgery and were discharged from hospital 1 to 4 days postoperatively. The subdural collection completely disappeared in all cases. In the long term, only 2 patients with low-pressure valves underwent shunt removal without any consequences, while a second surgical procedure was necessary to treat recurrence of intracranial hypertension in the 4 remaining cases. All the medium-pressure valves were removed without problems. The size of the AC was reduced in 3 cases, remained stable in 4 cases, and increased in 3 cases. No patients experienced recurrence of subdural collection during follow-up. CONCLUSIONS: Medium-pressure subduro-peritoneal shunts should be considered as part of the arsenal of surgical strategy in symptomatic ruptured AC in the subdural space. The procedure is simple with a very low morbidity, and it allows rapid improvement of symptoms. Although the shunt is located in the subdural space, we strongly recommend avoiding devices which may create an overdrainage and expose the patient to shunt dependency such as low-pressure shunts.

Relationships Between Expertise, Crew Familiarity and Surgical Workflow Disruptions: An Observational Study.

BACKGROUND: Teamwork is an essential factor in reducing workflow disruption (WD) in the operating room. Team familiarity (TF) has been recognized as an antecedent to surgical quality and safety. To date, no study has examined the link between team members' role and expertise, TF and WD in surgical setting. This study aimed to examine the relationships between expertise, surgeon-scrub nurse familiarity and WD. METHODS: We observed a convenience sample of 12 elective neurosurgical procedures carried out by 4 surgeons and 11 SN with different levels of expertise and different degrees of familiarity between surgeons and SN. We calculated the number of WD per unit of coding time to control for the duration of operation. We explored the type and frequency of WD, and the differences between the surgeons and SN. We examined the relationships between duration of WD, staff expertise and surgeon-scrub nurse familiarity. RESULTS: 9.91% of the coded surgical time concerned WD. The most frequent causes of WD were distractions (29.7%) and colleagues' interruptions (25.2%). This proportion was seen for SN, whereas teaching moments and colleagues' interruptions were the most frequent WD for surgeons. The WD was less high among expert surgeons and less frequent when surgeon was familiar with SN. CONCLUSIONS: The frequency of WD during surgical time can compromise surgical quality and patient safety. WD seems to decrease in teams with high levels of surgeon-scrub nurse familiarity and with development of surgical expertise. Favoring TF and giving feedback to the team about WD issues could be interesting ways to improve teamwork.

Comparison of neurogenic lower urinary tract dysfunctions in open versus closed spinal dysraphism: A prospective cross-sectional study of 318 patients.

AIMS: To compare the neurogenic lower urinary tract dysfunction (NLUTD) in patients with closed spinal dysraphism (CSD) versus patients with open spinal dysraphism (OSD) as well as their management patterns. METHODS: A prospective cross-sectional study was conducted between September 2007 and December 2015 including all spina bifida patients seen at the multidisciplinary French national referral center for spina bifida. NLUTD and its management were compared between the OSD and CSD groups. RESULTS: Three hundred and eighteen patients were included for analysis: 100 with a CSD (31.5%) and 218 with an OSD (68.6%). The prevalence of urinary incontinence did not differ significantly between the two groups (43% vs 52.8%; P = 0.11), the mean Qualiveen score was also similar (2.7 vs 2.5, P = 0.22). The voiding mechanism was clean intermittent catheterization, spontaneous voiding, suprapubic tube, and ileal conduit in 55% versus 44%; 29.8% versus 47%; 2.8% versus 3% and 11.9% versus 6% of OSD and CSD patients, respectively (P = 0.02). There were comparable prevalences of detrusor overactivity (36.5% vs 38.8%; P = 0.68) and impaired bladder compliance (34.9% vs 31.7%; P = 0.56) in both groups. Augmentation cystoplasty was more common in patients with OSD (32.1% vs 11%; P < 0.0001). CONCLUSIONS: In this prospective cohort, NLUTD were more common in OSD with a higher rate of patients requiring a surgical treatment and a lower rate of patients with preserved spontaneous voiding. However, when present, NLUTD was as severe and troublesome in patients with closed versus open spinal dysraphism.

Distinguishing surgical behavior by sequential pattern discovery.

OBJECTIVE: Each surgical procedure is unique due to patient's and also surgeon's particularities. In this study, we propose a new approach to distinguish surgical behaviors between surgical sites, levels of expertise and individual surgeons thanks to a pattern discovery method. METHODS: The developed approach aims to distinguish surgical behaviors based on shared longest frequent sequential patterns between surgical process models. To allow clustering, we propose a new metric called SLFSP. The approach is validated by comparison with a clustering method using Dynamic Time Warping as a metric to characterize the similarity between surgical process models. RESULTS: Our method outperformed the existing approach. It was able to make a perfect distinction between surgical sites (accuracy of 100%). We reached an accuracy superior to 90% and 85% for distinguishing levels of expertise and individual surgeons. CONCLUSION: Clustering based on shared longest frequent sequential patterns outperformed the previous study based on time analysis. SIGNIFICANCE: The proposed method shows the feasibility of comparing surgical process models, not only by their duration but also by their structure of activities. Furthermore, patterns may show risky behaviors, which could be an interesting information for surgical training to prevent adverse events.

Management of hydrocephalus in pediatric metastatic tumors of the posterior fossa at presentation.

PURPOSE: Presence of metastases in newly diagnosed pediatric posterior fossa tumors (PFT) is not a rare situation, but optimal treatment of associated hydrocephalus in these children has remained undetermined. METHODS: Twenty-nine children treated between January 2005 and December 2015 for a metastatic PFT associated with hydrocephalus constituted the study cohort. Patients were divided into three groups: ventriculoperitoneal shunt (VPS), endoscopic third ventriculostomy (ETV), and temporary ventricular drainage before or during tumor resection (PVD). RESULTS: There were 4 VPS, 18 ETV, and 7 PVD. The global incidence of CSF diversion failure was 52%. No case of dysfunction or dissemination of metastatic cells occurred in the VPS group. Recurrence of hydrocephalus occurred in 55% of the ETV group. Presence of multiple macroscopic metastases and CSF metastatic cells after tumor surgery was associated with ETV failure. Fifty-seven percent of the children in the PVD group were reoperated after an average time of 53 days. Specific oncologic treatment was initiated earlier in the VPS group (11 days) compared to ETV (27 days) and PVD (23 days) groups. CONCLUSIONS: ETV should be avoided in cases of multiple macroscopic metastases, and children who underwent ETV must be followed carefully when metastatic cells are present in CSF after tumor surgery. External ventricular drainage before or during surgical removal should not be considered as a final option to treat hydrocephalus. VPS remains a safe alternative in this situation and allows an early specific oncologic treatment.

Mild head injury and attention deficit hyperactivity disorder in children.

PURPOSE: Post-concussion syndrome is a well-described complication following moderate and severe head trauma but whether it occurs after mild head injury in children remains unclear. The aim of this study was to evaluate whether exposure to mild head injury with potential additional risk factors (non-surgical lesion on computed tomographic, high kinetic trauma, or Glasgow Coma Scale <15) is associated with attention deficit hyperactivity disorder (ADHD) after the head trauma. METHODS: This study was performed in an emergency department on children admitted between 2009 and 2013. It compared victims of mild head injury aged 6-16 years with matched children presenting isolated non-surgical forearm fracture (ratio1/2). ADHD was assessed using Conners' Global Index-Parent short version 3-40 months after the trauma. The patients were compared using chi-square test or Fisher's exact test, t test or u-test as appropriate with a p value set at 0.05. RESULTS: During the study period, 676 patients were admitted for mild head injury. Among them, 34 (5 %) fulfilled the inclusion criteria and were compared with 64 matched patients admitted for a forearm fracture. The groups were comparable. ADHD was observed in both groups (18 % in the mild head injury group, 11 % in the control group) with no significant differences between groups. The prevalence was high when compared to an expected frequency of 3.5-5.6 % in children aged 6-12 years in the general population. CONCLUSIONS: These results suggest that pre-existing ADHD may have contributed to injury proneness in both groups and does not argue for a specific risk of ADHD induced by mild head injury. The diagnosis of ADHD should be evoked at admission of children aged 6-16 years presenting with a trauma.

Intradiploic growing skull fracture: review of mechanisms and literature.

PURPOSE: A rare case of intradiploic growing fracture of the occipital bone is presented. Examination of this case and literature review was carried out to find significant specific features of such a rare condition. CASE: A 4-year-old boy was operated on for a huge occipital intradiploic growing skull fracture. His medical history, surgical management, and postoperative course are presented. LITERATURE REVIEW: A computer literature search using the Medline database revealed 31 well-documented cases. CONCLUSIONS: Special attention must be paid to skull fractures in childhood when occurring near CSF large spaces, especially if ventricle enlargement, suggesting that hydrocephalus is present. Surgeons should evaluate hydrocephalus before treating such lesions in order to improve surgical result and postoperative clinical evolution.

Influence of cumulative surgical experience on the outcome of poor-grade patients with ruptured intracranial aneurysm.

BACKGROUND: The expansion of endovascular techniques for intracranial aneurysms has led to a global decrease in vascular neurosurgery activity. This situation might impact neurosurgeons' level of expertise, even though they all might have to deal with this surgically challenging pathology. In that context, we wanted to assess the impact of cumulative surgical experience on the outcome of patients with poor-grade subarachnoid haemorrhage (SAH) and intracerebral haemorrhage (ICH) treated by microsurgery. METHODS: Sixty-seven patients who underwent surgery for a ruptured aneurysm with SAH and ICH, and a WFNS scale of IV/V, were included. Surgeries were performed by five surgeons, whose experience was judged by the total number of aneurysm surgeries performed. The outcome was assessed by three indicators: intraoperative rupture (IOR), early mortality, and the modified Rankin Scale at last follow-up. The time of IOR was reported on an IOR score. The correlation between surgical experience and outcome was assessed by linear regression. Nonlinear regression was used to assess the correlation of the data with a learning curve model. RESULTS: The analysis showed an influence of surgical experience on intraoperative rupture, with no effect on long-term outcome. No influence was found on early mortality. Increased surgical experience seems to reduce IOR during aneurysm dissection and clip repositioning. Intraoperative rupture data fit Wright's learning curve model. CONCLUSION: This study suggests a direct impact of cumulative experience on the course of ruptured aneurysm surgery and pleads for the use of training and simulation programmes dedicated to neurovascular surgery.

Dynamic cervical myelopathy in young adults.

PURPOSE: Non-traumatic cervical chronic joint instability in young adults is a rare and underexplored entity. We assessed the diagnostic relevance of dynamic MRI, and the clinical and radiological outcome after anterior cervical interbody fusion (ACIF) in these cases. METHODS: Six young patients (mean age 34 years) with cervical myelopathy without compression on static imaging had a dynamic MRI. Joint instability was defined by a reduction of the canal diameter on dynamic sequences. Clinical and radiological outcomes were assessed after surgery by examination, cervical X-rays, static and dynamic MRI. RESULTS: All the patients had joint instability. Four patients underwent surgery. Clinical status improved 1 year after surgery. All patients had a satisfactory fusion at 6-month follow-up and no residual compression at 1 year. CONCLUSION: Dynamic MRI can help detect a joint instability in young patients with cervical myelopathy without compression. ACIF seems to be efficient in these cases.

Two novel tumours with NTRK2 fusion in the methylation class of extraventricular neurocytomas, including one intraventricular.

We report here about two novel tumours classified as extraventricular neurocytomas (EVN) using DNA-methylation profiling, associated with NTRK2 fusions instead of the usual FGFR1 alterations so far attributed to this tumoural entity. We present the second detailed case of an intraventricular presentation in the MC EVN. Our findings broaden the spectrum of MC EVN and have implications in terms of diagnosis, therapy and terminology.

Effects of low-dose protocols in endovascular treatment of intracranial aneurysms: development of workflow task analysis during cerebral endovascular procedures.

OBJECTIVE: Reducing radiation exposure through the use of low-dose protocols during cerebral endovascular procedures is recommended, but evaluation of the impact on the procedure itself is difficult and subjective. A workflow task analysis could provide an objective comparison of two different radiation exposure protocols. SUBJECTS AND METHODS: Twenty endovascular aneurysm treatments were analyzed using a low-dose protocol (reducing radiation exposure by 20%) in 10 cases and a normal-dose protocol in the other 10 cases. The procedure was subdivided into five phases, each comprising a sequence of tasks. Each task was defined as a triplet, associating an action, an instrument, and an anatomic structure. A workflow editor was used to record tasks and phases with a tablet PC. The total duration of the entire procedure, the duration of each task, and the number of task repetitions were isolated and used as the metric. Moreover, the tasks involving x-ray use, essential for navigation and treatment phases, were separated and analyzed. RESULTS: For the microcatheter navigation and treatment phases, no statistically significant difference was found between the two radiation exposure protocols. For guide catheter navigation in cervical vessels, the total phase duration and total and mean time of tasks specifically involving x-ray use increased with age, but there was no difference between the two radiation protocols. CONCLUSION: Workflow task analysis of endovascular aneurysm treatment shows no difference between low-dose and normal-dose protocols in the guide catheter navigation, microcatheter navigation, or treatment phases.

Multi-site study of surgical practice in neurosurgery based on surgical process models.

Surgical Process Modelling (SPM) was introduced to improve understanding the different parameters that influence the performance of a Surgical Process (SP). Data acquired from SPM methodology is enormous and complex. Several analysis methods based on comparison or classification of Surgical Process Models (SPMs) have previously been proposed. Such methods compare a set of SPMs to highlight specific parameters explaining differences between populations of patients, surgeons or systems. In this study, procedures performed at three different international University hospitals were compared using SPM methodology based on a similarity metric focusing on the sequence of activities occurring during surgery. The proposed approach is based on Dynamic Time Warping (DTW) algorithm combined with a clustering algorithm. SPMs of 41 Anterior Cervical Discectomy (ACD) surgeries were acquired at three Neurosurgical departments; in France, Germany, and Canada. The proposed approach distinguished the different surgical behaviors according to the location where surgery was performed as well as between the categorized surgical experience of individual surgeons. We also propose the use of Multidimensional Scaling to induce a new space of representation of the sequences of activities. The approach was compared to a time-based approach (e.g. duration of surgeries) and has been shown to be more precise. We also discuss the integration of other criteria in order to better understand what influences the way the surgeries are performed. This first multi-site study represents an important step towards the creation of robust analysis tools for processing SPMs. It opens new perspectives for the assessment of surgical approaches, tools or systems as well as objective assessment and comparison of surgeon's expertise.

Primary gliomatosis cerebri involving gray matter in pediatrics: a distinct entity? A multicenter study of 14 cases.

BACKGROUND AND PURPOSE: Gliomatosis cerebri (GC) is a rare neoplasm including a variety of tumors, with extremely variable evolution and heterogeneity of prognosis. It may appear either de novo or after a focal glioma, involve predominantly the white or the gray matter, and concern either pediatric or adult patients. We focused on primary GC involving exclusively gray matter in a pediatric population in order better to define the presentation and outcome of this disease. PATIENTS AND METHODS: We reviewed the databases of seven Departments of Pediatric Oncology to identify pediatric cases of GC between 1990 and 2007. Patients were included if they demonstrated a diffuse infiltrative process involving gray matter in magnetic resonance imaging (MRI) and histological tissue analyses, confirming a proliferative glial disorder. RESULTS: Fourteen patients with a median age of 8 years were identified. Epilepsy was the main presenting symptom. Brain MRI showed a lesion of the temporal and insular cerebral cortex associated with tumoral infiltration of the thalami and the basal ganglia. Histological examination confirmed the diagnosis of high-grade glioma. Prognosis was always very gloomy in the short term, with a median survival of less than a year. CONCLUSION: This rare entity, whose prognosis is appalling whatever the treatment proposed, should be clearly identified within the heterogeneous group of GC in the same way as diffuse intrinsic pontine gliomas have been identified among brain stem tumors. Systematic biopsies appear essential to permit the molecular studies which will assist in guiding the choice of future targeted treatments.