Through the orbit and beyond: Current state and future perspectives in endoscopic orbital surgery on behalf of the EANS frontiers committee in orbital tumors and the EANS skull base section

Introduction

Orbital surgery has always been disputed among specialists, mainly neurosurgeons, otorhinolaryngologists, maxillofacial surgeons and ophthalmologists. The orbit is a borderland between intra- and extracranial compartments; Krönlein's lateral orbitotomy and the orbitozygomatic infratemporal approach are the historical milestones of modern orbital-cranial surgery.

Research question

Since its first implementation, endoscopy has significantly impacted neurosurgery, changing perspectives and approaches to the skull base. Since its first application in 2009, transorbital endoscopic surgery opened the way for new surgical scenario, previously feasible only with extensive tissue dissection.

Material and methods

A PRISMA based literature search was performed to select the most relevant papers on the topic.

Results

Here, we provide a narrative review on the current state and future trends in endoscopic orbital surgery.

Discussion and conclusion

This manuscript is a joint effort of the EANS frontiers committee in orbital tumors and the EANS skull base section.

P14.12 Gyriform infiltration as imaging biomarker for adult diffuse astrocytic glioma, IDH wildtype, with molecular features of glioblastoma

BACKGROUND

Diffuse astrocytic gliomas, IDH wildtype, with molecular features of glioblastoma (molecular glioblastomas) are associated with a poor prognosis. We previously found that these tumors frequently display gyriform infiltration, defined as areas of elective cortical hypersignal on MRI FLAIR sequence. The objective of the present study was to assess the diagnostic value of gyriform infiltration as an imaging marker for these tumors.

MATERIAL AND METHODS

MRI scans from 430 patients with newly diagnosed glioma (molecular glioblastoma n = 31, IDH wildtype glioblastoma n = 298, IDH-mutant astrocytoma n = 50, IDH-mutant and 1p19q codeleted oligodendroglioma n= 51) were evaluated for the presence of a gyriform infiltration by 2 independent reviewers. Sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) were calculated to assess the performance of the presence of a gyriform infiltration for identifying molecular glioblastoma.

RESULTS

A gyriform infiltration was observed in 16/31 (52%) patients with a molecular glioblastoma, 40/298 (13%) patients with an IDH-wildtype glioblastoma but in none of the patients with an IDH-mutant astrocytomas or an IDH-mutant and 1p19q codeleted oligodendroglioma. Among the 56 patients with a gyriform infiltration, 54 patients had an IDH wildtype pTERT mutant glioma and 2 an IDH wildtype pTERT wildtype glioma. Interrater agreement was good (κ= 0.68, P < 0.001). Specificity, sensitivity, PPV and NPV of the presence of a gyriform infiltration for the diagnosis of molecular glioblastoma were 90%, 29%, 52% and 96% and for the diagnosis of an IDHwt pTERT mutant glioma were 97%, 15%, 96% and 20%. The presence of a gyriform infiltration was associated with a worse prognosis in the entire cohort (13.6 months vs 29.3 months, P = .001).

CONCLUSION

Gyriform infiltration is a specific imaging marker of molecular glioblastomas and IDH wildtype pTERT mutant diffuse gliomas.

Petroclival meningiomas: update of current treatment and consensus by the EANS skull base section

BACKGROUND

The optimal management of petroclival meningiomas (PCMs) continues to be debated along with several controversies that persist.

METHODS

A task force was created by the EANS skull base section along with its members and other renowned experts in the field to generate recommendations for the management of these tumors. To achieve this, the task force reviewed in detail the literature in this field and had formal discussions within the group.

RESULTS

The constituted task force dealt with the existing definitions and classifications, pre-operative radiological investigations, management of small and asymptomatic PCMs, radiosurgery, optimal surgical strategies, multimodal treatment, decision-making, and patient's counselling.

CONCLUSION

This article represents the consensually derived opinion of the task force with respect to the management of PCMs.

Cerebral empyema and abscesses due to Cutibacterium acnes

INTRODUCTION

Cutibacterium acnes is a commensal bacterium of the skin, frequently reported in prosthetic shoulder or spinal implant infections, but rarely in cranial and intracranial infections.

METHODS

We retrospectively reviewed patients with intracranial samples positive to Cutibacterium acnes managed in the neurosurgical units of our hospital of Lyon, France, between 2008-2016.

RESULTS

We included 29 patients, of whom 23 had empyema (with or without abscess), 17 had cranial osteomyelitis, and six only had abscess. Prior neurosurgery was reported in 28 patients, and the remaining patient had four spontaneous abscesses. Twelve patients had polymicrobial infections, including methicillin-susceptible Staphylococcus in 11 cases. The clinical diagnosis was difficult because of indolent and delayed symptoms: a CT scan or MRI was required. Thirteen patients (52%) had material at the infection site. All patients with bone flap implant or bones from biological banks had a bone flap-associated infection. Drainage was surgically performed in 25 cases or by CT scan-guided aspiration in four cases. All patients received an adapted antibiotic therapy (from three weeks to six months). The outcome was favorable in 28 patients. Three patients relapsed during the antibiotic therapy, requiring further surgery.

CONCLUSION

Cutibacterium acnes can be responsible for postoperative empyema and cerebral abscesses, with particular indolent forms, which make their diagnosis difficult. They are often polymicrobial and associated with bone flap osteomyelitis. Their outcome is favorable after drainage and adapted antibiotic therapy.

P14.88 Comparison of SNaPshot PCR and digital droplet PCR for the identification of TERT promoter in non-diagnostic biopsies from glioma patients

BACKGROUND

We previously showed that TERT promotor (pTERT) mutations can be detected in a high proportion of non-diagnostic biopsies from glioma patients using SNaPshot PCR. The aim of the present study was to assess the diagnostic value of digital droplet PCR (ddPCR) in this setting.

MATERIAL AND METHODS

pTERT mutations were retrospectively assessed using SNaPshot PCR and ddPCR in the non-diagnostic biopsies of 14 adult patients who underwent an initial non-diagnostic needle biopsy that led to perform another biopsy that finally demonstrated a pTERT-mutant glioma.

RESULTS

Median age at diagnosis was 69 years and the median interval between the initial and final biopsy was 22 days. The initial biopsy consisted of unspecific infiltrating glial cells (n=10), hemorrhage, necrosis and/or fibrosis (n=4). Using SNaPshot PCR, the final biopsy found an IDH-WT pTERT-mutant glioma in 12 cases (glioblastoma n=12), an IDH-mutant pTERT-mutant oligodendroglioma in one case and an IDH-WT pTERT-WT glioblastoma in one case. Retrospectively, a pTERT mutation was identified by both ddPCR and SNaPshot in the non-diagnostic biopsies in 85% (11 /13) of pTERT mutant-gliomas. No mutation was detected in the non-diagnostic biopsies of IDH-WT pTERT-WT gliomas using either technique. Overall, a pTERT mutation were detected in 79% (11/14) of non-diagnostic biopsies.

CONCLUSION

Digital Droplet PCR, as SNaPshot PCR, enables the identification of pTERT mutations in a high rate of non-diagnostic biopsies from glioma patients. The sensitivity of both techniques seems similar in this setting.

P14.13 Incidence of pseudoprogression in high-grade IDH-mutant gliomas

BACKGROUND

Pseudoprogression (PsP) is a well-known concern in IDH-wildtype glioblastomas. The aim of the present study was to describe its incidence in high-grade IDH-mutant gliomas.

MATERIAL AND METHODS

We retrospectively analyzed the characteristics of a consecutive series of high-grade IDH-mutant gliomas treated with radiotherapy (RT) with or without chemotherapy between March 2009 and September 2017. PsP was defined as a new enhanced lesion that occurred after RT and subsequently disappeared or remained stable during follow-up for a least 6 months.

RESULTS

The study population consisted of 38 anaplastic IDH-mutant and 1p/19q codeleted oligodendrogliomas, 34 IDH-mutant anaplastic astrocytomas and 18 IDH-mutant glioblastomas. Treatment consisted of radiotherapy alone (n=8, 9%), radiotherapy and PCV chemotherapy (n=63, 70%) and temozolomide radiochemotherapy (n=19, 21%). After a median follow-up of 3.5 years (range 1–8 years), 24 patients (28%) presented a PsP that occurred after a median delay of 10 months after radiotherapy (2 to 32 months). PsP was more frequent in patients treated with RT+PCV than in those treated with RT+TMZ (34% vs 10%, p=0.05). During the first two years after RT completion, 19 patients (21%) presented a PsP and 15 patients (17%) a true progression. At last follow-up, 1 patient (4%) in the PsP group had died compared to 10 patients (16%) in the group of patients without PsP.

CONCLUSION

PsP is a frequent issue in IDH-mutant high-grade gliomas. Its timing of onset is delayed compared to the timing of PsP onset reported in IDH-wildtype glioblastomas. The association between the use of PCV chemotherapy and PsP requires validation in an independent series.

P13.02 Conventional MRI radiomics in the diagnosis of early- and pseudo-progression

BACKGROUND

After radiochemotherapy, 20% to 30% of patients with early worsening MRI experience pseudoprogression (Psp) which is not distinguishable from early progression (EP). We aimed to assess the diagnostic performance and survival predictive ability of radiomics in patients with suspected EP or Psp.

MATERIAL AND METHODS

Radiomics features (RF) of 76 patients (53 EP and 23 Psp) retrospectively identified were extracted from conventional MRI based on four volumes-of-interest. Subjects were randomly assigned into training and validation groups. Classification model (EP versus Psp) consisted of a random forest algorithm after univariate filtering. Overall (OS) and progression-free survivals (PFS) were predicted using a semi-supervised principal component analysis and, forecasts were evaluated using C index and integrated Brier scores (IBS).

RESULTS

Using 11 RFs, radiomics classified patients with 75.0% and 76.0% accuracy, 81.6% and 94.1% sensitivity, 50.0% and 37.5% specificity, respectively in training and validation phases. Addition of MGMT promoter status improved accuracy to 83% and 79.2% and, specificity to 63.6% and 75%.

OS model included 14 RFs and stratified low- and high-risk patients both in the training (hazard ratio (HR), 3.63, p=0.002) and the validation (HR, 3.76, p=0.001) phases. Similarly, PFS model stratified patients during training (HR, 2.58, p=0.005) and validation (HR, 3.58, p=0.004) phases using 5 RF. OS and PFS forecasts had C index of 0.65 and 0.69 and IBS of 0.122 and 0.147, respectively.

CONCLUSION

Conventional MRI radiomics has promising diagnostic value, especially when combined with MGMT promoter status, but specificity remains moderate. In addition, our results suggest a potential for predicting OS and PFS.

ALK7 expression in prolactinoma is associated with reduced prolactin and increased proliferation

Prolactinoma represents the most frequent hormone-secreting pituitary tumours. These tumours appear in a benign form, but some of them can reach an invasive and aggressive stage through an unknown mechanism. Discovering markers to identify prolactinoma proliferative and invading character is therefore crucial to develop new diagnostic/prognostic strategies. Interestingly, members of the TGFβ-Activin/BMP signalling pathways have emerged as important actors of pituitary development and adult function, but their role in prolactinomas remains to be precisely determined. Here, using a heterotopic allograft model derived from a rat prolactinoma, we report that the Activins orphan type I receptor ALK7 is ectopically expressed in prolactinomas-cells. Through immunohistological approaches, we further confirm that normal prolactin-producing cells lack ALK7-expression. Using a series of human tumour samples, we show that ALK7 expression in prolactinomas cells is evolutionary conserved between rat and human. More interestingly, our results highlight that tumours showing a robust expression of ALK7 present an increased proliferation as address by Ki67 expression and retrospective analysis of clinical data from 38 patients, presenting ALK7 as an appealing marker of prolactinoma aggressiveness. Beside this observation, our work pinpoints that the expression of prolactin is highly heterogeneous in prolactinoma cells. We further confirm the contribution of ALK7 in these observations and the existence of highly immunoreactive prolactin cells lacking ALK7 expression. Taken together, our observations suggest that Activin signalling mediated through ALK7 could therefore contribute to the hormonal heterogeneity and increased proliferation of prolactinomas.

Headholders' - complications in neurosurgery: A review of the literature and recommendations for its use

Several types of headholders are routinely used in neurosurgical practice to secure the head in a precise position, providing better security during surgical dissection as well as an absence of eye compression during prone positions. Nevertheless, potentially lethal complications might occur. We performed a review of the literature via PubMed and Google Scholar using the terms "Mayfield skull clamp", "Sugita headholders", "headholder complications" and "skull clamp complications". Twenty-six complications directly related to the use of headholders were identified through 19 papers published from 1981 to 2014: mainly skull fractures with or without a dural laceration (50%), epidural hematomas (23.8%), skull fractures with or without a dural laceration (50%), and air embolism (9.5%). The authors propose recommendations for the safe use of headholders.

[Management of craniofacial type 1 neurofibromatosis]

Type I neurofibromatosis (NF) is the most common autosomal dominant disease. It concerns one in 3000 births, the penetrance is close to 100% and 50% of new cases are de novo mutations (17q11.2 chromosome 17 location). Cranio-maxillofacial region is concerned in 10% of the cases, in different forms: molluscum neurofibroma, plexiform neurofibroma, cranio-orbital neurofibroma, parotido-jugal neurofibroma, cervical neurofibroma. These lesions have different prognosis depending on the craniofacial localization: ocular functional risk, upper airway compressive risk, nerve compression risk, aesthetic and social impact. The maxillofacial surgeon in charge of patients with type I NF should follow the patient from the diagnosis and organize the different surgical times in order to take care about the different issues: vital, functional and aesthetic. We describe the treatment of facial localizations of type 1 NF as it is done at the University Hospital of Lyon and at the Rhône-Alpes-Auvergne neurofibromatosis reference center.

The minimally invasive endoscopic management of septated chronic subdural hematomas: surgical technique

BACKGROUND

Fibrin membranes and compartmentalization within the subdural space are a frequent cause of failure in the treatment of chronic subdural hematomas (CSH). This specific subtype of CSH classically requires craniotomy, which carries significant morbidity and mortality rates, particularly in elderly patients. In this work, we describe a minimally invasive endoscopic alternative.

METHODS

Under local scalp anesthesia, a rigid endoscope is inserted through a parietal burr hole in the subdural space to collapse fibrin septa and cut the internal membrane. It also allows cauterization of active bleedings and the placement of a drain under direct visualization.

CONCLUSIONS

The endoscopic treatment of septated CSH represents a minimally invasive alternative to craniotomy especially for the internal membranectomy.

[Shifting paradigm in skull base surgery: Roots, current state of the art and future trends of endonasal endoscopic approaches]

During the last two decades, endoscopic endonasal approach has completed the minimally invasive skull base surgery armamentarium. Endoscopic endonasal skull base surgery (EESBS) was initially developed in the field of pituitary adenomas, and gained an increasing place for the treatment of a wide variety of skull base pathologies, extending on the midline from crista galli process to the occipitocervical junction and laterally to the parasellar areas and petroclival apex. Until now, most studies are retrospective and lack sufficient methodological quality to confirm whether the endoscopic endonasal pituitary surgery has better results than the microsurgical trans-sphenoidal classical approach. The impressions of the expert teams show a trend toward better results for some pituitary adenomas with the endoscopic endonasal route, in terms of gross total resection rate and probably more comfortable postoperative course for the patient. Excepting intra- and suprasellar pituitary adenomas, EESBS seems useful for selected lesions extending onto the cavernous sinus and Meckel's cave but also for clival pathologies. Nevertheless, this infatuation toward endoscopic endonasal approaches has to be balanced with the critical issue of cerebrospinal fluid leaks, which constitutes actually the main limit of this approach. Through their experience and a review of the literature, the authors aim to present the state of the art of this approach as well as its limits.

Syndrome de Nelson: évolution d'un adénome hypophysaire corticotrope agressif

Nelson's syndrome was defined in 1958 as the association of an expanding pituitary tumor with high ACTH secretion after bilateral adrenalectomy for Cushing's disease. Pituitary MRI and ACTH measurements led to the definition of Nelson's syndrome as the proliferation of a corticotrophic microadenoma or an aggressive and highly proliferative tumor residue induced by the decreased glucocorticoid inhibition after bilateral adrenalectomy. Now, the problem is not the definition of Nelson's syndrome but rather the identification of markers predictive of tumor growth. Based on a typical case and a review of the literature, we point out some predictive markers of tumor growth after bilateral adrenalectomy: young age at diagnosis, presence of tumor residue on pituitary MRI before adrenalectomy, markers of tumor aggressiveness (Ki-67>3%, mitoses, nuclear PTTG) and increase of ACTH levels during the first months following adrenalectomy.

Cellules dendritiques et gliomes : un espoir en immunothérapie ?

Immunotherapy has been explored for several decades to try to improve the prognosis of gliomas, but until recently no therapeutic benefit has been achieved. The discovery of dendritic cells, the most potent professional antigen presenting cells to initiate specific immune response, and the possibility of producing them ex vivo gave rise to new protocols of active immunotherapy. In oncology, promising experimental and clinical therapeutic results were obtained using these dendritic cells loaded with tumor antigen. Patients bearing gliomas have deficit antigen presentation making this approach rational. In several experimental glioma models, independent research teams have showed specific antitumor responses using these dendritic cells. Phase I/II clinical trials have demonstrated the feasibility and the tolerance of this immunotherapeutic approach. In neuro-oncology, the efficiency of such an approach remains to be established, similarly in oncology where positive phase III studies are missing. Nevertheless, dendritic cells comprise a complex network which is only partially understood and capable of generating either immunotolerance or immune response. Numerous parameters remain to be explored before any definitive conclusion about their utility as an anticancer weapon can be drawn. It seems however logical that immunotherapy with dendritic cells could prevent or delay tumor recurrence in patients with minor active disease. A review on glioma and dendritic cells is presented.

IRM de diffusion-perfusion dans l’évaluation des lymphomes cérébraux

Because of the increasing incidence of cerebral lymphoma, it is critical for patient management to recognize the MR features of this disease. We present the characteristic morphological and functional MRI features of this tumor. The findings on MRI studies, including morphological, diffusion and perfusion imaging, performed in 9 biopsy-proven cases of cerebral lymphoma with 13 lesions are presented and analyzed, and are discussed in comparison with published literature data. All patients underwent diffusion-weighted imaging with a single shot echo-planar pulse sequence. Dynamic susceptibility-contrast MRI was performed using a T2*-weighted gradient-echo echo-planar sequence after intravenous injection of chelates of gadolinium at the rate of 6 ml/s and a temporal resolution of 1 second. All cases of cerebral lymphoma appeared hypointense or isointense on T1-weighted images and in 75% of cases iso- or hypointense on T2-weighted images. All lesions enhanced except one in a patient receiving steroid therapy. On diffusion-weighted images, tumours were hyperintense with normal or decreased ADC values (0.717+/-0.152.10-3 mm2/sec, range: 0.550-1.014) and an ADC ratio tumour/normal white matter of 0.974+/-0.190 (range: 0.768-1.410). On perfusion, the signal intensity-time curve of each tumour showed a characteristic type of curve with a significant increase of the signal intensity above the baseline and a low maximum relative cerebral blood volume ratio (rCVBmax) of 1.43+/-0.64 (0.55-2.62). Due to their higher cellularity, the lack of neoangiogenesis, and the increased permeability of the blood-brain barrier related to the infiltration of blood vessels wall by lymphomatous cells, cerebral lymphoma presents characteristic diffusion and perfusion MRI features that should be useful for diagnosis and patient follow-up.