The role of SEEG in the presurgical decision-making process in MRI-normal mesial temporal lobe epilepsy.

OBJECTIVES: In patients with mesial temporal lobe epilepsy (mTLE) and normal MRI, anterior temporal lobectomy sparing the hippocampus might be considered because of the risk of post-operative memory deficit. However, it is unclear whether some patients with normal MRI and non-invasive EEG and semiological pattern highly suggestive of mesial temporal seizures demonstrate a seizure onset network sparing the hippocampus, potentially warranting surgery. METHODS: A retrospective study of 17 patients with mTLE epilepsy and normal MRI who underwent SEEG. Only patients whose non-invasive presurgical data suggested an unilateral mesial temporal epileptogenic zone (EZ), as defined by combination of ictal semiology and ictal EEG during scalp video-EEG, were included. SEEG data were analyzed using both visual and quantitative approaches. Two EZ organization were defined: (i) EZ involved the hippocampus at the onset of the ictal discharge (HIP group): (ii) patients in whom a delay>1sec was observed between the seizure onset and the involvement of the hippocampus (nHIP group). Non-invasive clinical and functional imaging data, as well as post-operative outcomes, were compared across groups. RESULTS: Eleven patients were included in HIP group and 6 in the nHIP group. In the nHIP group, the maximal epileptogenicity was in the amygdala in five patients and in the entorhinal cortex in one. The hippocampus normalized interictal spiking activity was not different between groups. None of the patients characteristics collected during the non-invasive presurgical workup was associated with the SEEG-based organization of the EZ. Twelve patients underwent a surgical resection, including temporal cortectomy sparing hippocampus in six. Seizure and neuropsychological post-operative outcomes were similar. CONCLUSION: In patients with MRI-normal mTLE, SEEG should be included in the surgical decision-making process because seizure organization cannot be predicted from non-invasive investigations. When hippocampus is not included in the EZ, temporal resection sparing the hippocampus can be considered.

Supraorbital transciliary approach as primary route to fronto-basal high grade glioma resection with 5-Aminolevulinic Acid use: Technical note.

BACKGROUND: Gliomas are diffuse intra-axial lesions, which can be accessed by multiple surgical corridors for a same location depending on the surgeon's preference. 5-Aminolevulinic Acid use facilitates the extend of resection in case of high-grade gliomas, especially when differentiating normal brain from tumor periphery is challenging. METHODS: Complete resection of glioblastoma via a supraorbital transciliary approach with 5-Aminolevulinic Acid use was performed without any complications, as demonstrated on postoperative MRI. RESULTS: Patient was discharged on the third postoperative day. Wound follow-up shows good cosmetic result. Patient underwent concomitant chemo-radiation (Temozolomide- 60Gy) and adjuvant chemotherapy (Temozolomide). No tumor recurrence was noted at six months follow-up. CONCLUSION: In selected cases, supraorbital transciliary approach could be proposed as primary approach as it provides the advantage of full control over all the vasculo-nervous structures at skull base without the necessity of protective brain retractor use while the 5-Aminolevulinic Acid use allows a gross total resection.

Cerebral arterio-venous malformations hemodynamics changes in hereditary hemorrhagic telangiectasia - case report.

BACKGROUND: Spontaneous obliteration of cerebral arteriovenous malformations (AVMs) is a rare phenomenon. Hereditary Hemorrhagic Telangiectasia (HHT) is a predisposal genetic condition for AVMs development in all organs. CASE ILLUSTRATION: We report the case of a 34 years old woman with HHT family history. After radiosurgical treatment of a symptomatic evolving cerebellar AVM, late control subtracted digital angiography (DSA) demonstrated the complete obliteration of this AVM but also spontaneous obliteration of 3 fronto-parietal AVMs without any hemorrhagic sign on MRI. CONCLUSION: To our knowledge, this is the first report of spontaneous obliteration of multiple and unruptured AVMs in a HTT case.

Radiotherapy of non-tumoral refractory neurological pathologies.

Intracranial radiotherapy has been improved, primarily because of the development of stereotactic approaches. While intracranial stereotactic body radiotherapy is mainly indicated for treatment of benign or malignant tumors, this procedure is also effective in the management of other neurological pathologies; it is delivered using GammaKnife® and linear accelerators. Thus, brain arteriovenous malformations in patients who are likely to experience permanent neurological sequelae can be managed by single session intracranial stereotactic body radiotherapy, or radiosurgery, in specific situations, with an advantageous benefit/risk ratio. Radiosurgery can be recommended for patients with disabling symptoms, which are poorly controlled by medication, such as trigeminal neuralgia, and tremors, whether they are essential or secondary to Parkinson's disease. This literature review aims at defining the place of intracranial stereotactic body radiotherapy in the management of patients suffering from non-tumoral refractory neurological pathologies. It is clear that the multidisciplinary collaboration of experienced teams from Neurosurgery, Neurology, Neuroradiology, Radiation Oncology and Medical Physics is needed for the procedures using high precision radiotherapy techniques, which deliver high doses to locations near functional brain areas.

Anatomo-radiological correlation between diffusion tensor imaging and histologic analyses of glial tumors: a preliminary study.

BACKGROUND AND PURPOSE: The challenge of the neurosurgical management of gliomas lies in achieving a maximal resection without persistent functional deficit. Diffusion tensor imaging (DTI) allows non-invasive identification of white matter tracts and their interactions with the tumor. Previous DTI validation studies were compared with intraoperative cortical stimulation, but none was performed based on the tumor anatomopathological analysis. This preliminary study evaluates the correlation between the preoperative subcortical DTI tractography and histology in terms of fiber direction as well as potential tumor-related fiber disruption. METHODS: Eleven patients harboring glial tumors underwent preoperative DTI images. Correlations were performed between the visual color-coded anisotropy (FA) map analysis and the tumor histology after "en bloc" resection. Thirty-one tumor areas were classified according to the degree of tumor infiltration, the destruction of myelin fibers and neurofilaments, the presence of organized white matter fibers, and their orientation in space. RESULTS: After histologic comparison, the DTI sensitivity and specificity to predict disrupted fiber tracts were respectively of 89% and 90%. The positive and negative predicted values of DTI were 80% and 95%. The DTI data were in line with the histologic myelin fiber orientation in 90% of patients. In our series, the prevalence of destructed fiber was 31%. Glioblastoma WHO grade IV harbored a higher proportion of destructed white matter tracts. Lower WHO grades were associated with higher preservation of subcortical fiber tracts. CONCLUSION: This DTI/histology study of "en bloc"-resected gliomas reported a high and reproducible concordance of the visual color-coded FA map with the histologic examination to predict subcortical fiber tract disruption. Our series brought consistency to the DTI data that could be performed routinely for glioma surgery to predict the tumor grade and the postoperative clinical outcomes.

Follow-Up MRI for Small Brain AVMs Treated by Radiosurgery: Is Gadolinium Really Necessary?

BACKGROUND AND PURPOSE: Follow-up MR imaging of brain AVMs currently relies on contrast-enhanced sequences. Noncontrast techniques, including arterial spin-labeling and TOF, may have value in detecting a residual nidus after radiosurgery. The aim of this study was to compare noncontrast with contrast-enhanced MR imaging for the differentiation of residual-versus-obliterated brain AVMs in radiosurgically treated patients. MATERIALS AND METHODS: Twenty-eight consecutive patients with small brain AVMs (<20 mm) treated by radiosurgery were followed with the same MR imaging protocol. Three neuroradiologists, blinded to the results, independently reviewed the following: 1) postcontrast images alone (4D contrast-enhanced MRA and postcontrast 3D T1 gradient recalled-echo), 2) arterial spin-labeling and TOF images alone, and 3) all MR images combined. The primary end point was the detection of residual brain AVMs using a 5-point scale, with DSA as the reference standard. RESULTS: The highest interobserver agreement was for arterial spin-labeling/TOF (κ = 0.81; 95% confidence interval, 0.66-0.93). Regarding brain AVM detection, arterial spin-labeling/TOF had higher sensitivity (sensitivity, 85%; specificity, 100%; 95% CI, 62-97) than contrast-enhanced MR imaging (sensitivity, 55%; specificity, 100%; 95% CI, 27-73) and all MR images combined (sensitivity, 75%; specificity, 100%; 95% CI, 51-91) (P = .008). All nidus obliterations on DSA were detected on MR imaging. In 6 patients, a residual brain AVM present on DSA was only detected with arterial spin-labeling/TOF, including 3 based solely on arterial spin-labeling images. CONCLUSIONS: In this study of radiosurgically treated patients with small brain AVMs, arterial spin-labeling/TOF was found to be superior to gadolinium-enhanced MR imaging in detecting residual AVMs.

High-field intraoperative MRI in glioma surgery: A prospective study with volumetric analysis of extent of resection and functional outcome.

BACKGROUND: High-field intraoperative MRI (IoMRI) is a useful tool to improve the extent of glioma resection (EOR). OBJECTIVE: To compare the interest of 1.5T IoMRI in glioma surgery between enhancing and non-enhancing tumors, based on volumetric analysis. METHODS: A prospective single-center study included consecutive adult patients undergoing glioma surgery with IoMRI. Volumetric evaluation was based on FLAIR hypersignal after gadolinium injection in non-enhancing tumors and T1 hypersignal after gadolinium injection in enhancing tumors. Endpoints comprised: residual tumor volume (RTV), EOR, workflow and clinical outcome on Karnofsky performance score (KPS). RESULTS: Fifty-three surgeries were performed from July 2014 to January 2016. Thirty-four patients underwent one IoMRI, and 19 two IoMRIs. In non-enhancing tumors, intraoperative RTV on 1st IoMRI T2/FLAIR was higher than in enhancing tumors on T1 sequences (7.25cm3 vs. 0.74cm3, respectively; P=0.008), whereas the RTV on 2nd IoMRIs and final RTV were no longer significantly different. After IoMRI, 72% of patients underwent additional resection. In non-enhancing tumors, EOR increased from 77.3% on 1st IoMRI to 97.4% on last MRI (P<0.001). Taking all tumors together, final RTV values were: median=0cm3, mean=3.9cm3. Mean final EOR was 94%. In 25% of patients, KPS was reduced during early postoperative course; at 3 and 6 months postoperatively, median KPS was 90. CONCLUSION: Intraoperative MRI guidance significantly enhanced the extent of glioma resection, especially for non- or minimally enhancing tumors, while preserving patient autonomy.

Intraoperative MRI for the management of brain lesions adjacent to eloquent areas.

BACKGROUND: The aim of our study was to report the usefulness of intraoperative MRI guidance in the resection of brain lesions adjacent to eloquent areas. PATIENTS AND METHODS: A single center prospective series of gliomas amenable to optimized resection with intraoperative MRI between September 2014 and December 2015. RESULTS: The study included 56 patients. The median duration of the first intraoperative MRI was 38min, interquartile range (IQR 30-46). Fourteen patients (40%) underwent a second intraoperative MRI, which had a median duration of 26min (IQR, 18-30). The median total operative time was 265min (IQR, 242-337). After the first intraoperative MRI, the median residual glioma volume of the 35 gliomas adjacent to eloquent areas was 7.04cm3 (IQR, 2.22-13.8), which did not significantly differ from the other gliomas (P=0.07). After the second intraoperative MRI, the median residual glioma volume was 3.86cm3 (IQR, 0.82-6.99), which did not significantly differ from the other patients (P=0.700). On the postoperative MRI, the median extent of the glioma resections adjacent to eloquent areas was 99.78% (IQR, 88.9-100), which was not significantly different from the rest of the population (P=0.290). At 6 months after surgery, the median Karnofsky Performance Score was 90, and 2.8% of the patients presented a permanent new neurological deficit. CONCLUSION: Our results suggest that intraoperative MRI is an effective and safe technique to improve the extent of brain lesion resections close to eloquent areas.

Resection of cavernous angioma located in eloquent areas using functional cortical and subcortical mapping under awake conditions. Outcomes in a 50-case multicentre series.

INTRODUCTION: Surgical resection of supratentorial cavernous angiomas located in eloquent areas poses a significant risk to the patient of postoperative neurological impairment and justifies intraoperative functional monitoring. METHODS: Multicentre retrospective series of adult patients with cavernous angiomas located within eloquent areas and treated with functional-based surgical resection according to functional boundaries under intraoperative functional cortico-subcortical monitoring under awake conditions. RESULTS: Fifty patients (18 males, mean 36.3±10.8 year-old) underwent surgical resection with intraoperative cortico-subcortical functional mapping using direct electrostimulation under awake conditions for a cavernous angioma located in eloquent areas with a mean postoperative follow-up of 21.0±21.2 months. At presentation, the cavernous angioma had previously resulted in severe impairment (neurological deficit in 34%, seizures in 70%, uncontrolled seizures in 34%, reduced Karnofsky Performance Status score of 70 or less in 24%, inability to work in 52%). Functional-based surgical resection allowed complete removal of the cavernous angioma in 98% and of the haemosiderin rim in 82%. Postoperative seizures and other complications were rare, and similarly so across all centres included in this series. Postoperatively, we found functional improvement in 84% of patients (reduced Karnofsky Performance Status score of 70 or less in 6%, uncontrolled seizures in 16%, and inability to work in 11%). CONCLUSION: Functional-based surgical resection aids the safe and complete resection of cavernous angiomas located in eloquent areas while minimizing the surgical risks. Functional mapping has to be considered in such challenging cases.

Radionecrosis after stereotactic radiotherapy for brain metastases.

INTRODUCTION: Radionecrosis (RN) represents the main complication of stereotactic radiotherapy (SRT) for brain metastases. It may be observed in up to 34% of cases at 24 months after treatment and associated with significant morbidity in 10-17%. AREAS COVERED: Our aim is to discuss the results of original studies on RN related to SRT for brain metastases. Expert commentary: Although the development of RN is unpredictable, larger volume of the lesion, prior whole brain irradiation, and higher dose of radiation represent the major risk factors. RN appears on MRI as contrast-enhancing necrotic lesions, surrounded by edema, occurring at least 3 months after SRT, localized within fields of irradiation. No firm criteria are established. Surgery can provide symptomatic relief but is associated with a risk of complications. Corticosteroids are considered the standard of care treatment, despite limited efficacy and many adverse effects. Bevacizumab represents another interesting option that needs to be validated.

[Global brain metastases management strategy: a multidisciplinary-based approach]. / Stratégie globale de prise en charge des métastases cérébrales: une approche multidisciplinaire.

Brain metastases management has evolved over the last fifteen years and may use varying strategies, including more or less aggressive treatments, sometimes combined, leading to an improvement in patient's survival and quality of life. The therapeutic decision is subject to a multidisciplinary analysis, taking into account established prognostic factors including patient's general condition, extracerebral disease status and clinical and radiological presentation of lesions. In this article, we propose a management strategy based on the state of current knowledge and available therapeutic resources.

[Stereotactic radiotherapy in brain metastases]. / Radiothérapie en conditions stéréotaxiques des métastases cérébrales.

Stereotactic radiotherapy of brain metastases is increasingly proposed after polydisciplinary debates among experts. Its definition and modalities of prescription, indications and clinical interest regarding the balance between efficacy versus toxicity need to be discussed. Stereotactic radiotherapy is a 'high precision' irradiation technique (within 1mm), using different machines (with invasive contention or frameless, photons X or gamma) delivering high doses (4 to 25Gy) in a limited number of fractions (usually 1 to 5, ten maximum) with a high dose gradient. Dose prescription will depend on materials, dose constraints to organs at risk varying with fractionation. Stereotactic radiotherapy may be proposed: (1) in combination with whole brain radiotherapy with the goal of increasing (modestly) overall survival of patients with a good performance status, 1 to 3 brain metastases and a controlled extracranial disease; (2) for recurrence of 1-3 brain metastases after whole brain radiotherapy; (3) after complete resection of a large and/or symptomatic brain metastases; (4) after diagnosis of 3-5 asymptomatic new or progressing brain metastases during systemic therapy, with the aim of delaying whole brain radiotherapy (avoiding its potential neurotoxicity) and maintaining a high focal control rate. Only a strict follow-up with clinical and MRI every 3 months will permit to deliver iterative stereotactic radiotherapies without jeopardizing survival. Simultaneous delivering of stereotactic radiotherapy with targeted medicines should be carefully discussed.

[Surgery of brain metastases]. / Place de la chirurgie dans la prise en charge des métastases cérébrales.

Surgical excision of brain metastases has been well evaluated in unique metastases. Two randomized phase III trial have shown that combined with adjuvant whole brain radiotherapy, it significantly improves overall survival. However, even in the presence of multiple brain metastases, surgery may be useful. Also, even in lesions amenable to radiosurgery, surgical resection is preferred when tumors displayed cystic or necrotic aspect with important edema or when located in highly eloquent areas or cortico-subcortically. Furthermore, surgery may have a diagnostic role, in the absence of histological documentation of the primary disease, to rule out a differential diagnosis (brain abscess, lymphoma, primary tumor of the central nervous system or radionecrosis). Finally, the biological documentation of brain metastatic disease might be useful in situations where a specific targeted therapy can be proposed. Selection of patients who will really benefit from surgery should take into account three factors, clinical and functional status of the patient, systemic disease status and characteristics of intracranial metastases. Given the improved overall survival of cancer patients partially due to the advent of effective targeted therapies on systemic disease, a renewed interest has been given to the local treatment of brain metastases. Surgical resection currently represents a valuable tool in the armamentarium of brain metastases but has also become a diagnostic and decision tool that can affect therapeutic strategies in these patients.

[ANOCEF guidelines for the management of brain metastases]. / Recommandations de l'Anocef pour la prise en charge des métastases cérébrales.

The incidence of brain metastases is increasing because of the use of new therapeutic agents, which allow an improvement of overall survival, but with only a poor penetration into the central nervous system brain barriers. The management of brain metastases has changed due to a better knowledge of immunohistochemical data and molecular biological data, the development of new surgical, radiotherapeutic approaches and improvement of systemic treatments. Most of the time, the prognosis is still limited to several months, nevertheless, prolonged survival may be now observed in some sub-groups of patients. The main prognostic factors include the type and subtype of the primitive, age, general status of the patient, number and location of brain metastases, extracerebral disease. The multidisciplinary discussion should take into account all of these parameters. We should notice also that treatments including surgery or radiotherapy may be proposed in a symptomatic goal in advanced phases of the disease underlying the multidisciplinary approach until late in the evolution of the disease. This article reports on the ANOCEF (French neuro-oncology association) guidelines. The management of brain metastases of breast cancers and lung cancers are discussed in the same chapter, while the management of melanoma brain metastases is reported in a separate chapter due to different responses to the brain radiotherapy.

Endoscopic versus stereotactic procedure for pineal tumour biopsies: Comparative review of the literature and learning from a 25-year experience.

BACKGROUND AND PURPOSE: Pineal tumours account for 1% to 4% of brain tumours in adults and for around 10% in children. Except in a few cases where germ cell markers are elevated, accurate histological samples are mandatory to initiate the treatment. Open surgery still has a high morbidity and is often needless. Biopsies can either be obtained by endoscopic or stereotactic procedures. METHODS: Following an extensive review of the literature (PubMed 1970-2013; keywords pineal tumour, biopsy; English and French), 33 studies were analysed and relevant data compared regarding the type of procedure, diagnosis rate, cerebrospinal fluid diversion type and rate, perioperative mortality, morbidity. RESULTS: Endoscopic and stereotactic biopsies showed a diagnosis rate of 81.1% (20%-100%) and 93.7% (82%-100%), respectively. Endoscopic biopsies involved 21.0% of minor and 2.0% of major complications whereas stereotactic biopsies involved 6.4% of minor and 1.6% of major complications. The most frequently reported complication was haemorrhage for both endoscopic and stereotactic procedures, accounting for 4.8% and 4.3%, respectively. Mortality rate was low for both endoscopic and stereotactic procedures, equal to 0.4% and 1.3%, respectively. Local experience of stereotactic biopsies was also reported and corroborated the previous data. CONCLUSIONS: The difference between both procedures is not statistically significant (p>0.05) across large series (≥20patients). Nevertheless, tissue diagnosis appears less accurate with endoscopic procedures than with stereotactic procedures (81.1% versus 93.7%, weighted mean across all series). In our opinion, the neuroendoscopic approach is the best tool for managing hydrocephalus, whereas stereotactic biopsies remain the best way to obtain a tissue diagnosis with accuracy and low morbidity.

Role of radiosurgery in the management of pineal region tumours: indications, method, outcome.

Numerous tumour types can occur in the pineal region. Because these tumours are uncommon and heterogeneous, it is often difficult to establish optimal treatment strategies based on comparative clinical trials. To date, the role of radiosurgery for the treatment of pineal region tumours remains controversial. This report of a 10-year single-department experience and review of the literature focuses on the spectrum of pathologic features found in these pineal parenchymal tumours and on the interest of radiosurgery in their management. Considering pineocytomas, although these tumours have been considered to be radioresistant to fractionated radiotherapy, our results are in agreement with similar results reported in the literature in suggesting that radiosurgery may be an alternative to surgical resection or an adjuvant therapy when the resection is not optimal. When dissemination occurs after radiosurgery, however, craniospinal radiation and chemotherapy are necessary. Radiosurgery has also proven its interest in the treatment of germinomas as an alternative to encephalic radiotherapy with limited long-term damage. Regarding the other pathologies, radiosurgery can be considered as part of a multimodal treatment including surgery, chemo-radiotherapy and its role still has to be clearly defined.

Three-dimensional skeletonization and symbolic description in vascular imaging: preliminary results.

OBJECTIVE: A general method was developed to analyze and describe tree-like structures needed for evaluation of complex morphology, such as the cerebral vascular tree. Clinical application of the method in neurosurgery includes planning of the surgeon's intraoperative gestures. METHOD: We have developed a 3D skeletonization method adapted to tubular forms with symbolic description. This approach implements an iterative Dijkstra minimum cost spanning tree, allowing a branch-by-branch skeleton extraction. The proposed method was implemented using the laboratory software platform (ArtiMed). The 3D skeleton approach was tested on simulated data and preliminary trials on clinical datasets mainly based on magnetic resonance image acquisitions. RESULTS: A specific experimental evaluation plan was designed to test the skeletonization and symbolic description methods. Accuracy was tested by calculating the positioning error, and robustness was verified by comparing the results on a series of 18 rotations of the initial volume. Accuracy evaluation showed a Haussdorff's distance always smaller than 17 voxels and Dice's similarity coefficient greater than 70 %. CONCLUSION: Our method of symbolic description enables the analysis and interpretation of a vascular network obtained from angiographic images. The method provides a simplified representation of the network in the form of a skeleton, as well as a description of the corresponding information in a tree-like view.

[Ependymomas of the lateral ventricle. A series of 27 cases with review of the literature]. / Les épendymomes du ventricule latéral. Analyse de 27 cas et revue de la littérature.

Twenty-seven cases of ependymoma were collected in the French multicentric study dedicated to lateral ventricle tumors. The mean age of patients was 31,5 years. All patients underwent surgery, with complete resection of the tumor in 76% of cases. Histologic examination disclosed 23 grade 2 ependymomas and four grade 3 ependymomas. Postoperative mortality was 7%. Four patients underwent radiotherapy, and five chemotherapy. Local recurrence of the tumor occurred in seven cases, with a mean delay of 48 months. Disseminated disease within the central nervous system was found in only one patient. Median survival in all the 27 patients was 181 months, and median progression-free survival was 106 months. The relevant series of the literature are reviewed in order to precise the prognostic factors of ependymomas and therapeutic strategies.

[Place of stereotactic techniques in the modern management of lateral ventricle tumors. Stereotactic biopsies and radiosurgery]. / Place de la stéréotaxie dans la prise en charge des tumeurs du ventricule latéral. Biopsies stéréotaxiques et radiochirurgie.

The authors make an overview about the use of stereotactic techniques in the management of lateral ventricle tumors. If stereotactic techniques are not in the foreground for the management of lateral ventricle tumors, stereotactic biopsies can be very useful in case of atypical, clinical or radiological presentation of the tumors and radiosurgery can help in case of evolution or re-evolution of tumors after resection. In these cases, stereotactic procedures are very safe. Modern technical evolutions allow the optimization of the stereotactic procedure but also to mix robotic with endoscopic techniques in order to offer new surgical perspectives.