Navigated, percutaneous, three-step technique for lumbar and sacral screw placement: a novel, minimally invasive, and maximally safe strategy.

BACKGROUND: Minimally invasive spine surgery is a field of active and intense research. Image-guided percutaneous pedicle screw (PPS) placement is a valid alternative to the standard free-hand technique, thanks to technological advancements that provide potential improvement in accuracy and safety. Herein, we describe the clinical results of a surgical technique exploiting integration of neuronavigation and intraoperative neurophysiological monitoring (IONM) for minimally invasive PPS. MATERIALS AND METHODS: An intraoperative-computed tomography (CT)-based neuronavigation system was combined with IONM in a three-step technique for PPS. Clinical and radiological data were collected to evaluate the safety and efficacy of the procedure. The accuracy of PPS placement was classified according to the Gertzbein-Robbins scale. RESULTS: A total of 230 screws were placed in 49 patients. Only two screws were misplaced (0.8%); nevertheless, no clinical sign of radiculopathy was experienced by these patients. The majority of the screws (221, 96.1%) were classified as grade A according to Gertzbein-Robbins scale, seven screws were classified as grade B, one screw was classified as grade D, and one last screw was classified as grade E. CONCLUSIONS: The proposed three-step, navigated, percutaneous procedure offers a safe and accurate alternative to traditional techniques for lumbar and sacral pedicle screw placement. Level of Evidence Level 3. Trial registration Not applicable.

Investigating Glioblastoma Multiforme Sub-Proteomes: A Computational Study of CUSA Fluid Proteomic Data.

Based on our previous proteomic study on Cavitating Ultrasound Aspirator (CUSA) fluid pools of Newly Diagnosed (ND) and Recurrent (R) glioblastomas (GBMs) of tumor core and periphery, as defined by 5-aminolevulinc acid (5-ALA) metabolite fluorescence, this work aims to apply a bioinformatic approach to investigate specifically into three sub-proteomes, i.e., Not Detected in Brain (NB), Cancer Related (CR) and Extracellular Vesicles (EVs) proteins following selected database classification. The study of these yet unexplored specific datasets aims to understand the high infiltration capability and relapse rate that characterizes this aggressive brain cancer. Out of the 587 proteins highly confidently identified in GBM CUSA pools, 53 proteins were classified as NB. Their gene ontology (GO) analysis showed the over-representation of blood coagulation and plasminogen activating cascade pathways, possibly compatible with Blood Brain Barrier damage in tumor disease and surgery bleeding. However, the NB group also included non-blood proteins and, specifically, histones correlated with oncogenesis. Concerning CR proteins, 159 proteins were found in the characterized GBM proteome. Their GO analysis highlighted the over-representation of many pathways, primarily glycolysis. Interestingly, while CR proteins were identified in ND-GBM exclusively in the tumor zones (fluorescence positive core and periphery zones) as predictable, conversely, in R-GBM they were unexpectedly characterized prevalently in the healthy zone (fluorescence negative tumor periphery). Relative to EVs protein classification, 60 proteins were found. EVs are over-released in tumor disease and are important in the transport of biological macromolecules. Furthermore, the presence of EVs in numerous body fluids makes them a possible low-invasive source of brain tumor biomarkers to be investigated. These results give new hints on the molecular features of GBM in trying to understand its aggressive behavior and open to more in-depth investigations to disclose potential disease biomarkers.

Intraoperative CT-guided navigation versus fluoroscopy for percutaneous pedicle screw placement in 192 patients: a comparative analysis.

BACKGROUND: Percutaneous pedicle screw (PPS) placement is a key step in several minimally invasive spinal surgery (MISS) procedures. Traditional technique for PPS makes use of C-arm fluoroscopy assistance (FA). More recently, newer intraoperative imaging techniques have been developed for PPS, including CT-guided navigation (CTNav). The aim of this study was to compare FA and CTNav techniques for PPS with regard to accuracy, complications, and radiation dosage. MATERIALS AND METHODS: A total of 192 patients with degenerative lumbar spondylolisthesis and canal stenosis who underwent MISS posterior fusion ± interbody fusion through transforaminal approach (TLIF) were retrospectively reviewed. Pedicle screws were placed percutaneously using either standard C-arm fluoroscopy guidance (FA group) or CT navigation (CTNav group). Intraoperative effective dose (ED, mSv) was measured. Screw placement accuracy was assessed postoperatively on a CT scan using Gertzbein and Robbins classification (grades A-E). Oswestry disability index (ODI) and visual analog scale (VAS) scores were compared in both groups before and after surgery. RESULTS: A total of 101 and 91 procedures were performed with FA (FA group) and CTNav approach (CTNav group), respectively. Median age was 61 years in both groups, and the most commonly treated level was L4-L5. Median ED received from patients was 1.504 mSv (0.494-4.406) in FA technique and 21.130 mSv (10.840-30.390) in CTNav approach (p < 0.001). Percentage of grade A and B screws was significantly higher for the CTNav group (96.4% versus 92%, p < 0.001), whereas there were 16 grade E screws in the FA group and 0 grade E screws in the CTNav group (p < 0.001). A total of seven and five complications were reported in the FA and CTNav group, respectively (p = 0.771). CONCLUSIONS: CTNav technique increases accuracy of pedicle screw placement compared with FA technique without affecting operative time. Nevertheless, no significant difference was noted in terms of reoperation rate due to screw malpositioning between CTNav and FA techniques. Radiation exposure of patients was significantly higher with CTNav technique. LEVEL OF EVIDENCE: Level 3.

Predicting meningioma consistency and brain-meningioma interface with intraoperative strain ultrasound elastography: a novel application to guide surgical strategy.

OBJECTIVE: Providing new tools to improve surgical planning is considered a main goal in meningioma treatment. In this context, two factors are crucial in determining operating strategy: meningioma-brain interface and meningioma consistency. The use of intraoperative ultrasound (ioUS) elastosonography, a real-time imaging technique, has been introduced in general surgery to evaluate similar features in other pathological settings such as thyroid and prostate cancer. The aim of the present study was to evaluate ioUS elastosonography in the intraoperative prediction of key intracranial meningioma features and to evaluate its application in guiding surgical strategy. METHODS: An institutional series of 36 meningiomas studied with ioUS elastosonography is reported. Elastographic data, intraoperative surgical findings, and corresponding preoperative MRI features were classified, applying a score from 0 to 2 to both meningioma consistency and meningioma-brain interface. Statistical analysis was performed to determine the degree of agreement between meningioma elastosonographic features and surgical findings, and whether intraoperative elastosonography was a better predictor than preoperative MRI in assessing meningioma consistency and slip-brain interface, using intraoperative findings as the gold standard. RESULTS: A significantly high degree of reliability and agreement between ioUS elastographic scores and surgical finding scores was reported (intraclass correlation coefficient = 0.848, F = 12.147, p < 0.001). When analyzing both consistency and brain-tumor interface, ioUS elastography proved to have a rather elevated sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and positive (LR+) and negative likelihood ratio (LR-). This consideration was true especially for meningiomas with a hard consistency (sensitivity = 0.92, specificity = 0.96, PPV = 0.92, NPV = 0.96, LR+ = 22.00, LR- = 0.09) and for those presenting with an adherent slip-brain interface (sensitivity = 0.76, specificity = 0.95, PPV = 0.93, NPV = 0.82, LR+ = 14.3, LR- = 0.25). Furthermore, predictions derived from ioUS elastography were found to be more accurate than MRI-derived predictions, as demonstrated by McNemar's test results in both consistency (p < 0.001) and interface (p < 0.001). CONCLUSIONS: While external validation of the data is needed to transform ioUS elastography into a fully deployable clinical tool, this experience confirmed that it may be integrated into meningioma surgical planning, especially because of its rapidity and cost-effectiveness.

Is age an additional factor in the treatment of elderly patients with glioblastoma? A new stratification model: an Italian Multicenter Study.

OBJECTIVE: Approximately half of glioblastoma (GBM) cases develop in geriatric patients, and this trend is destined to increase with the aging of the population. The optimal strategy for management of GBM in elderly patients remains controversial. The aim of this study was to assess the role of surgery in the elderly (≥ 65 years old) based on clinical, molecular, and imaging data routinely available in neurosurgical departments and to assess a prognostic survival score that could be helpful in stratifying the prognosis for elderly GBM patients. METHODS: Clinical, radiological, surgical, and molecular data were retrospectively analyzed in 322 patients with GBM from 9 neurosurgical centers. Univariate and multivariate analyses were performed to identify predictors of survival. A random forest approach (classification and regression tree [CART] analysis) was utilized to create the prognostic survival score. RESULTS: Survival analysis showed that overall survival (OS) was influenced by age as a continuous variable (p = 0.018), MGMT (p = 0.012), extent of resection (EOR; p = 0.002), and preoperative tumor growth pattern (evaluated with the preoperative T1/T2 MRI index; p = 0.002). CART analysis was used to create the prognostic survival score, forming six different survival groups on the basis of tumor volumetric, surgical, and molecular features. Terminal nodes with similar hazard ratios were grouped together to form a final diagram composed of five classes with different OSs (p < 0.0001). EOR was the most robust influencing factor in the algorithm hierarchy, while age appeared at the third node of the CART algorithm. The ability of the prognostic survival score to predict death was determined by a Harrell's c-index of 0.75 (95% CI 0.76-0.81). CONCLUSIONS: The CART algorithm provided a promising, thorough, and new clinical prognostic survival score for elderly surgical patients with GBM. The prognostic survival score can be useful to stratify survival risk in elderly GBM patients with different surgical, radiological, and molecular profiles, thus assisting physicians in daily clinical management. The preliminary model, however, requires validation with future prospective investigations. Practical recommendations for clinicians/surgeons would strengthen the quality of the study; e.g., surgery can be considered as a first therapeutic option in the workflow of elderly patients with GBM, especially when the preoperative estimated EOR is greater than 80%.

COVID-19 and neurosurgical training and education: an Italian perspective.

BACKGROUND: The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic has an impact also on neurosurgical training and education, especially in most affected countries. We surveyed Italian neurosurgical residents, asking them to provide a brief description and analyze the situation they are experiencing and how the educational system reacted to the pandemic in one of the most affected countries all over the world. METHODS: An 18-question, web-based survey was administered to Italian neurosurgical residents from May 3 to May 11, 2020, by web-link or e-mail invitation. Closed-ended, multiple choice questions were focused on the experience of neurosurgical residents in the last 2 months (from March to May 2020) concerning both clinical and educational aspects. RESULTS: Among 331 Italian neurosurgical residents invited to participate, 192 responded to the survey (58%). According to the participants' responses, in the whole country, only 29.7% of residents were directly involved in the clinical management of COVID-19 patients. Time spent in the clinic and surgical activity was significantly reduced in most of the cases. Educational activities as well as scientific activity and time spent for studying, on the other hand, were reported to be significantly increased by the majority of respondents. CONCLUSIONS: Most Italian neurosurgical residents reported significant changes on both training and education, highlighting a prompt reaction of the educational system in the whole country, regardless the local and regional diffusion of the pandemic.

Cortical Laminar Necrosis as a Result of Status Epilepticus After Resection of Parafalcal Meningioma.

Status epilepticus during the post-operative period is a rare complication for neurosurgery patients. Acute encephalopathic syndromes can present a diagnostic challenge due to the wide range of possible etiologies, and can also have vastly different outcomes. Posterior reversible encephalopathy syndrome is a rare neurological disorder, usually associated with specific medical conditions, that causes a disturbance of CNS homeostasis, while cortical laminar necrosis (CLN) is an unusual type of infarction characterized by selective necrosis of the cerebral cortex with sparing of the white matter. We present a 45-year-old woman who was operated on for left frontal lesion with radiological features compatible with anterior falx meningioma. Postoperative clinical and electroencephalographic data were compatible with non-convulsive status epilepticus originating from the occipito-mesial area. MRI showed bilateral diffuse temporo-occipital abnormally bright cortex as a consequence of neuronal apoptosis compatible with laminar cortical necrosis, and clinical examination revealed persistent cortical blindness. The pathogenesis of encephalopathic syndromes is still unclear. Non-convulsive status epilepticus should be considered as a possible cause of late recovery of consciousness in neurosurgery patients. Delayed treatment may cause irreversible lesions, including in brain areas far from the surgical field.

5-ALA False-Positive in Anaplastic Oligodendroglioma, IDH-mutant and 1p/19q-codeleted.

Pr5-ALA has been well-established for use in intraoperative fluorescence-guided resection of malignant glioma. It is not as strongly supported for use with low-grade gliomas (LGG) because only a few of these, less than 20%, have visible porphyrin accumulation, which is useful for 5-ALA-guided surgery. We report here our experience with 5-ALA uptake in a case of suspected relapse of anaplastic oligodendroglioma, IDH-mutant and 1p/19q-codeleted.

Secondary coiling after incomplete surgical clipping of cerebral aneurysms: a rescue strategy or a treatment option for complex cases? Institutional series and systematic review.

Residual and recurrent intracranial aneurysms after surgical clipping present a persistent risk of bleeding. Secondary coiling after incomplete clipping represents a strategy to occlude the residual sac: feasibility, bleeding risk and outcome were evaluated through a systematic review of literature along with the series of two tertiary referral neurovascular centres. Demographics, ruptured status, aneurysm morphology, topography, exclusion at surgery, timing of secondary coiling, complications, occlusion rate and outcome were analysed. Percentage of incidence and 95% CI were calculated for all variables. T test was used for continue variables, whereas Fisher's test (two-sided) is for categorical ones. Overall, 102 patients (92 cases from literature and 10 cases from institutional series) were included. Mean age at diagnosis was 52.94 ± 12.17 years, and male/female ratio 0.5; 3/4 of aneurysms involved the anterior circulation, whereas » the posterior circulation. An aneurysmal neck remnant was described in 58.43% of cases, an aneurysmal sac remnant in 29.21% and a regrowth in 12.36%. Residual aneurysm rupture was reported in 22% of cases. Complete/near-complete occlusion after secondary coiling was observed in 70% of cases, a partial in 25.56% and a failure in 4.44%. Only one case of perforation was reported. Complications were comparable to standard endovascular procedures. Aneurysms remnants after clipping are often observed in cases difficult anatomical locations. Their bleeding risk is not negligible. Secondary coiling is a rescue strategy to effectively and safely secure the aneurysm remnant. Only in a minority of cases, it is a staged treatment after 'remodelling' of the aneurysm neck.

Improving the Accuracy of Neuronavigation in Cerebral Cavernous Malformation: A Technical Note on 68 Cases.

Cavernous malformations (CM) are benign, low-flow vascular lesions that account for 5% - 13% of all cerebrovascular malformations. Surgery remains the most important treatment strategy, and many different approaches have been developed. We present here our institutional experience with 68 cases using a transcortical neuronavigation approach with some technical nuances to improve navigation accuracy during resection. The technique and clinical outcomes are discussed, with a specific focus on seizure sequels. Demographic data were collected, along with information on clinical and seizure characteristics at presentation, localization and size of CM, presence of multiple localizations, evidence of recent CM-related bleeding on MRI, intervention features, postoperative complications, prescription of anti-epileptic drugs at discharge and seizure outcome. We assume that surgery through a narrow well-defined working corridor would limit brain exposure and manipulation, and hence could significantly affect not only general complications, but also seizure control. The technique is feasible and associated with relatively low rates of minor and major procedure-related complications. It is also a valid method for surgeons in training since the trajectory is planned preoperatively with a senior consultant and the working corridor always follows the catheter, which directly leads to the cavernoma.

Supratotal Resection of Glioblastoma: Is Less More?

BACKGROUND: A relationship between the extent of resection (EOR) and survival has been demonstrated in patients with glioblastomas (GBMs). However, despite gross total resection (GTR) of the enhancing nodule (EN), GBMs usually relapse, generally near the surgical cavity. OBJECTIVE: The aim of this study was to determine the prognostic role of FLAIR resection of GBMs by analyzing pre- and post-operative MRIs to estimate the EOR of EN, FLAIR-hyperintense regions and total tumor volume (TTV). METHODS: Radiologic and clinical outcomes were analyzed retrospectively. Pre- and post-operative EN volume, pre- and postoperative FLAIR volume (POFV), and pre- and postoperative TTV were analyzed. EOR was then calculated for each component. Time-dependent ROC curves and cut-off values for pre- and post-operative volumes and EOR were calculated. A Kaplan-Meier analysis with the log-rank test and Cox regression analysis were then used to analyze progression-free survival (PFS) and overall survival (OS). RESULTS: We did not find any correlation between EOR of FLAIR-altered regions and patient survival. On the other hand, there were statistically significant relationships between the prognosis and both a preoperative EN volume less than 31.35 cm3 (p=0.032) and a postoperative EN volume less than 0.57 cm3 (p=0.015). Moreover, an EOR of EN greater than 96% was significantly associated with the prognosis (p=0.0051 for OS and p=0.022 for PFS). CONCLUSION: Our retrospective, multi-center study suggests that survival in patients with GBM is not affected by the extent of resection of FLAIR-hyperintense areas.

Understanding and overcoming fundamental limits of asymmetric light-light switches.

The interplay between interference and absorption leads to interesting phenomena like coherent perfect absorption and coherent perfect transparency (CPA and CPT), which can be exploited for fully optical modulation. While it is known that it is possible to harness CPA and CPT for switching a strong signal beam with a weak control beam, it is not immediate that this process suffers from a fundamental compromise between the device efficiency (quantified by device loss and modulation depth) and the asymmetry between signal and control intensity desired for operation. This article quantifies this compromise and outlines a possible way to overcome it by means of a combination of optical gain and loss in the same photonic component. A general formulation and a specific device realization are both discussed.

Real-time intraoperative contrast-enhanced ultrasound (CEUS) in vascularized spinal tumors: a technical note.

BACKGROUNDS: Intra-operative ultrasound (ioUS), and the recently introduced contrast-enhanced ultrasound (CEUS) demonstrated to be an extremely valuable tool in oncological cerebral neurosurgery. METHODS: The authors applied ioUS/CEUS techniques to spinal oncological surgery as showed in the illustrative case of a dorsal hemangiopericytoma. RESULTS AND CONCLUSIONS: ioUS and CEUS provide real-time information that proved useful in identifying both vascular and parenchymatous tumoral patterns, anatomical relations with nervous structure, plan surgical strategy, and identify residuals. It allows to visualize unexposed anatomical and pathological structures within the parenchyma and is a valuable guide during resection.

Successful Treatment of Pneumocephalus Using a Free-Style Chimeric Free Flap From a Scarred Thigh.

Pneumocephalus is an air collection in cranial cavity caused by accidental exposition of intracranial compartment after trauma or surgery. Skull base reconstruction with free flap is a useful surgical tool to avoid cerebral herniation or intracranial infection. The authors describe a patient of pneumocephalus following anterior skull base meningioma resection, unsuccessfully treated with 2 attempts of fascia lata grafts harvested from both thighs. A free-style chimeric anterolateral thigh free flap was performed using middle third of rectus femoris muscle to fill the planum spheno-ethmoidalis defect and adipocutaneous paddle for postoperative monitoring and for favoring a tension free skin closure. Free-style dissection with limited undermining in the previously scarred thigh was performed to avoid donor-site complication. Postoperative course was uneventful with complete resolution of the pneumocephalus.

Intra-Operative Ultrasound: Tips and Tricks for Making the Most in Neurosurgery.

PURPOSE: Advances in intraoperative imaging and neuronavigation techniques have positively affected glioma surgery. The desire to reduce brain-shift-related problems while achieving the real-time identification of lesions and residual and anatomical relationships has strongly supported the introduction of intraoperative ultrasound (ioUS) in neuro-oncological surgery. This paper presents tips based on our experience with ioUS in neurosurgery. METHODS: We retrospectively analyzed 264 patients who underwent high-grade glioma (HGG) resection at the University of Turin and 60 patients who were treated at the University of Rome. RESULTS: The main issues are the correct choice of the probe and how to evaluate the anatomy to understand how the information from the three common US planes (axial, sagittal and coronal plane) can be used in each case. It is also important to correctly identify anatomical structures in ioUS imaging. In a normal brain, the sulci, sickle, tentorium, choroid plexus, ependyma and the walls of the vessels are all hyperechoic. In addition, some structures are hypoechoic with a homogeneous acoustic gradient: ventricles, cysts and everything that contains liquor. Tumors are usually hyperechoic in ioUS because of their higher cellularity. Conversely, acute edema that contains fluid is hypoechoic, while chronic edema is hyperechoic. CONCLUSIONS: IoUS is a real-time, accurate and inexpensive imaging method. The difficulties of interpretation can be overcome by experience in US imaging and a better understanding of the interaction between navigation and imaging fusion techniques. Training on a large number of cases is important for the correct assessment of ioUS information to obtain valuable, real-time information during HGG surgery.

Recovery from Chronic Diseases of Consciousness: State of the Art in Neuromodulation for Persistent Vegetative State and Minimally Conscious State.

Chronic diseases of consciousness (CDC) can still be considered a challenging frontier for modern medicine, probably because of their not completely understood physiopathological mechanisms. Following encouraging evidence on cerebral hemodynamics, some authors have hypothesized a role for neuromodulation in the treatment of CDC patients. In the past 40 years, spinal cord stimulation (SCS) and deep brain stimulation (DBS) have been used experimentally for the treatment of patients in a severe altered state of consciousness, with some interesting but not conclusive results. The present review summarizes the data currently available in the literature on this particular and debated topic. On these grounds, further clinical studies are needed to better understand the altered dynamics of neuronal network circuits in CDC patients as a step towards novel therapeutic strategies.

Minipterional Craniotomy for Treatment of Unruptured Middle Cerebral Artery Aneurysms. A Single-Center Comparative Analysis with Standard Pterional Approach as Regard to Safety and Efficacy of Aneurysm Clipping and the Advantages of Reconstruction.

Pterional craniotomy (PT) has long been the standard approach for the treatment of middle cerebral artery (MCA) aneurysms, even though it may cause temporalis muscle atrophy, facial nerve injury, and masticatory difficulties. Minipterional craniotomy (MPT) is an alternative approach that may provide the same surgical corridor, limiting the risk of postoperative esthetic and functional complications. From January 2011 to December 2014 we consecutively performed 68 craniotomies for surgical treatment of unruptured MCA aneuryms: 37 were standard PT and 31 were MPT. There were no significant differences in mean age, sex, and aneurysm topography between the two groups. The mean skin incision length was 14 cm in the PT group and 6 cm in the MPT group. According to the Glasgow Outcome Scale (GOS) and modified Rankin Scale (mRS), there were no significant differences in clinical outcome at discharge or follow-up between the two groups. Also, the rates of complete aneurysm exclusion were comparable. However, the number of patients complaining of masticatory disorders was higher among those treated with PT. Finally, the number of complications observed in the PT group was higher than that in the MPT group, but only the differences in mean hospitalization length and necessity for a dural patch for reconstruction were statistically significant. In conclusion, the MPT approach is a safe and effective alternative to the standard PT for the treatment of unruptured MCA aneurysms.

Craniovertebral Junction Transanasal and Transoral Approaches: Reconstruct the Surgical Pathways with Soft or Hard Tissue Endocopic Lines? This Is the Question.

A variety of pathological conditions may affect the clivus and the craniovertebral junction (CVJ). These include congenital disorders, chronic inflammation, neoplasms, infections, and posttraumatic conditions that could all result in CVJ compression and myelopathy Endoscopic-assisted procedures have been further developed for CVJ decompression and they have now become conventional approaches. The aims of the present study were:(1) to compare "radiological" and "surgical" nasoaxial lines (NAxLs); (2) to introduce an analogous radiological line as a predictor of the superior extension of the transoral approach (palatine inferior dental arch line (PIA); (3) to compare the "radiological" nasopalatine line (NPL) with the "surgical" NPL (SNPL) and surgical PIA (SPIA); (4) to compare "our" SNPL with the NAxL; and (5) to find possible radiological reference points to predict, preoperatively, the maximal extent of superior dissection for the transoral approach (SPIA).

Giant Basilar Artery Aneurysm Involving the Origin of Bilateral Posterior Cerebral and Superior Cerebellar Arteries: Neck Reconstruction with pCONus-Assisted Coiling.

Giant aneurysms of the basilar artery are rare and are frequently associated with obstructive hydrocephalus and brainstem compression. Treatment still remains a challenge both for neurosurgeons and for interventional neuroradiologists. Cases reported in the literature are anecdotal and, overall, their outcomes are poor. We present the case of a patient with a giant aneurysm of the basilar artery tip, involving the origin of both the posterior cerebral and superior cerebellar arteries, who underwent coiling and ventriculoperitoneal shunting for associated obstructive hydrocephalus. A pCONus ® stent (Phenox; Bochum, Germany) was detached with its petals opened over the ostia of the parent vessels, with the aim being to reconstruct the neck of the aneurysm and to preserve the flow in the parent vessel. Moreover, the presence of the stent was useful to maintain the coils within the dome of the aneurysm. The pCONus is a new neurovascular device that is also useful for treating cases of complex basilar artery aneurysms when the ostia of the parent vessel origin is at the level of the aneurysm neck.

Anatomical study of occipital triangles: the 'inferior' suboccipital triangle, a useful vertebral artery landmark for safe postero-lateral skull base surgery.

BACKGROUND: Vertebral artery (VA) identification within the suboccipital triangle is a key step in craniocervical junction surgery. Often VA exposition at this level is arduous (space-occupying lesions, previous surgery); to identify VA more proximally may prove useful in complex cases. An alternative triangle is present just below the suboccipital one, where VA can be easily controlled; we named it the inferior suboccipital triangle (IST). The aim of the study is to identify IST anatomical relations and VA space orientation and evaluate its practical utility in surgery. METHODS: An anatomical study was performed on ten sides of five injected cadaverdic specimens. Relevant anatomical data were databased. RESULTS: The IST is limited superiorly by the inferior oblique muscle, inferolaterally by the posterior intertransversarii muscle and inferomedially by the C2 lamina; VA at this level has a vertical course with a slight medial to lateral direction (mean 10.8°) and minor posterior to anterior inclination (mean 3.4°). VA within the IST has a constant course without significant loops or kinkings; periarterial venous plexus is less represented at this level. The IST measures an average of 1.89 cm2, and VA at this level has an average length of 98 mm. CONCLUSIONS: IST is a significantly large anatomical space where the VA course is rather regular, and its length is sufficient for vascular proximal control purposes. Periarterial venous plexus is less evident at this level, easing the surgical exposure. VA exposition within the IST can be used as an alternative option when space-occupying lesions, scars and stabilisation devices make arterial dissection hazardous in more cranial V3 segments.