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OBJECTIVE Percutaneous balloon compression (PBC) is a popular treatment option for trigeminal neuralgia. However, the efficacy of PBC is widely considered to be associated with the occurrence of sensitive complications, although neither this correlation nor the underlying mechanisms have been established. The objectives of the present study were to identify factors predicting time to pain recurrence after PBC and identify factors predicting a severe sensitive complication. METHODS The authors conducted a retrospective study on patients who underwent PBC for the first time between 1985 and 2019 in two French hospitals. Data were retrieved from patients’ medical records. Potential clinical and radiological predictors for time to pain recurrence and severe sensitive complication were evaluated using a Cox model and a logistic regression, respectively. RESULTS A total of 131 patients were included in the study, with a median follow-up of 3.0 years. Pain recurrence occurred in 77 patients, and the median time to pain recurrence was 2.0 years. In the multivariate analysis, six independent factors predicting pain recurrence were identified: 1) longer duration of presurgical symptoms; 2) localization of the pain along the mandibular branch of the trigeminal nerve (V3); 3) atypical pain; 4) diagnosis of multiple sclerosis; 5) use of a medical device not specifically adapted for trigeminal neuralgia surgery; and 6) duration of balloon compression > 60 seconds. Regarding the secondary objective, 26 patients presented a severe sensitive complication after PBC, which the authors defined as the development of a new sensitivity disorder of the cornea, deafferentation pain known as anesthesia dolorosa, and/or long-lasting hypoesthesia augmentation characterized by the new appearance or increase in size or intensity of an area of hypoesthesia in the face for at least 3 months. The only predictor associated with a severe sensitive complication in the multivariate analysis was compression duration > 60 seconds. CONCLUSIONS These results show that the risk of postoperative complications can be assessed at the patient level, the most important modifiable parameter being the time of compression by the balloon. Although this study shows the relevance of a personalized medicine approach, its clinical application remains to be validated.

During the first wave of the coronavirus disease-2019 (COVID-19) pandemic, it was necessary to prepare for the possibility of triaging patients who could benefit from access to an intensive care unit (ICU). In our neuroscience institution, the challenge was to continue to manage usual neurological emergencies as well as the influx of COVID-19 patients.We report the experience of an ethical consulting unit to support care clinical decisions during the first wave of the pandemic (March 16 to April 30, 2020). Three objective evaluation criteria were defined: 2 of these criteria, patient's factors and general disease severity (Simplified Acute Physiology Score II), were common to all patients, and the third was the specific severity of the disease (neurological for brain injury, respiratory for COVID-19). Given our scarce resources, we used a high probability of a 3-month modified Rankin Scale ≤3 as the criterion for further resuscitation and management.A total of 295 patients were admitted during the first pandemic wave; 111 with COVID-19 and 184 with neurological emergencies. The ethical unit's expertise was sought for 75 clinical situations in 56 patients (35 COVID-19 and 21 neurological). Decisions were as follows: 11% no limitation on care, 5% expectant care with reassessment (maximum therapy to assess possible progress pending decision), 67% partial limitation (no intensification of care or no transfer to ICU), and 17% limitation of curative care. At no time did a lack of availability of ICU beds require the ethical unit to advise against admission to the ICU.Our ethical consulting unit allowed for collegial ethical decision-making in line with international recommendations. This model could be easily transferred to other triage situations, provided it is adapted to the local context.

Preserving cortical frontal bridging veins draining into the superior sagittal sinus is a factor of good neurological outcome in anterior interhemispheric transcallosal approaches, classically performed to reach intraventricular tumors. Challenging the idea that veins are utterly variable, we propose a statistical analysis of 100 selective cerebral angiographies to determine where to place the craniotomy in order to expose the most probable vein-free area. The mean distance to the first pre-coronal vein was 6.66 cm (± 1.73, 1.80 to 13.00) and to the first post-coronal vein 0.94 cm (± 0.92, 0 to 3.00) (p < 0.001). The probability of absence of bridging veins was 92.0% at 4 cm anterior to the coronal suture versus 37.5% at 1 cm and 12.5% at 2 cm posteriorly. The length of the surgical corridor (distance between the first pre-coronal and post-coronal vein) was 7.60 cm (± 1.72, 3.00 to 14.10). Overall, the ideal centering point of the craniotomy was 2.86 cm (± 1.08, − 0.65 to 6.50) ahead of the coronal suture. The mean number of veins within 6 cm behind the coronal suture was 8.47 (± 2.11, from 3 to 15) versus 0.530 (± 0.82, from 0 to 3) ahead of the coronal suture (p < 0.001). These findings support a purely pre-coronal 5 cm craniotomy for interhemispheric approaches.

Secondary to the creation of a surgical corridor and retraction, white matter tracts degenerate, causing long-term scarring with potential neurological consequences. Third and lateral ventricle tumors require surgery that may lead to cognitive impairment. Our objective is to compare the long-term consequences of a transcortical transfrontal approach and an interhemispheric transcallosal approach on corpus callosum and frontal white matter tracts degeneration. Surgical patients with ventricular tumor accessible through both approaches were included and clinico-radiological data were retrospectively analyzed. The primary endpoint was the callosotomy length at 3-month post-operative T1 MRI, corrected by the extension of the tumor and the use of neuronavigation. Secondary outcomes included perioperative criteria such as bleeding, use of retractors and duration, FLAIR hypersignal on 3-month MRI, and re-do surgeries. To assess white matter tract interruption, 3-month FLAIR hypersignal was superposed to a tractography atlas. Seventy patients were included, 57 (81%) in the transfrontal group and 13 (19%) in the interhemispheric group. There was no difference in the mean callosotomy length on 3-month MRI (12.3 mm ± 5.60 transfrontal vs 11.7 mm ± 3.92 interhemispheric, p = 0.79) on univariate and multivariate analyses. The callosotomy length was inferior by - 3.13 mm for tumors located exclusively in the third ventricle (p = 0.016), independent of the approach. Retractors were used more often in transfrontal approaches (60% vs 33%, p 0.001). The extent of frontal FLAIR hypersignal was higher after transfrontal approach (14.1 mm vs 0.525 mm, p 0.001), correlated to the use of retractors (p 0.05). After the interhemispheric approach, no tract other than corpus callosum was interrupted, whereas, after the transfrontal approach, frontal arcuate fibers and projections from the thalamus were interrupted in all patients, the cingulum in 19 (33%), the superior fronto-occipital fasciculus in 15 (26%), and the superior longitudinal fasciculus in 2 (3%). Transfrontal and interhemispheric approaches to the third and lateral ventricles both lead to the same long-term damage to the corpus callosum, but the transfrontal approach interrupts several white matter tracts essential to cognitive tasks such as attention and planning, even in the non-dominant hemisphere. These results encourage all neurosurgeons to be familiar with both approaches and favor the interhemispheric approach when both can give access to the tumor with a comparable risk. Neuropsychological studies are necessary to correlate these anatomical findings to cognitive outcomes.

ObjectivesConvexity spontaneous subacute subdural hematoma (CSSSH) frequently relapse after one or more surgical drainages. This may be due to spontaneous intracranial hypotension (SIH), for which the gold standard treatment is the epidural blood patch. In this study, we report 4 cases of refractory CSSSH treated with rescue epidural saline patch, although history and imaging studies showed no evidence of SIH.MethodsAll 4 patients received a lumbar saline epidural rescue patch for consciousness impairment associated with refractory CSSSH, and one is particularly detailed. No patient had typical radiologic signs of SIH or, on the contrary, uncal herniation that could have indicated intracranial hypertension.ResultsThe Glasgow Coma Scale score improved significantly in the days after application of the epidural patch in 3 patients. All patients showed an improvement of the CT scan. Two patients underwent lumbar pressure measurement to confirm low values before the epidural injection, and for one, the intrathecal pressure profile during epidural patching is presented.DiscussionAn epidural patch may be considered in managing CSSSH with no uncal herniation, even in the absence of signs of SIH on brain and spinal imaging. Whether it should be combined with surgical evacuation or used as first-line therapy remains to be determined.

Preserving cortical frontal bridging veins draining into the superior sagittal sinus is a factor of good neurological outcome in anterior interhemispheric transcallosal approaches, classically performed to reach intraventricular tumors. Challenging the idea that veins are utterly variable, we propose a statistical analysis of 100 selective cerebral angiographies to determine where to place the craniotomy in order to expose the most probable vein-free area. The mean distance to the first pre-coronal vein was 6.66 cm (± 1.73, 1.80 to 13.00) and to the first post-coronal vein 0.94 cm (± 0.92, 0 to 3.00) (p0.001). The probability of absence of bridging veins was 92.0% at 4 cm anterior to the coronal suture versus 37.5% at 1 cm and 12.5% at 2 cm posteriorly. The length of the surgical corridor (distance between the first pre-coronal and post-coronal vein) was 7.60 cm (± 1.72, 3.00 to 14.10). Overall, the ideal centering point of the craniotomy was 2.86 cm (± 1.08, - 0.65 to 6.50) ahead of the coronal suture. The mean number of veins within 6 cm behind the coronal suture was 8.47 (± 2.11, from 3 to 15) versus 0.530 (± 0.82, from 0 to 3) ahead of the coronal suture (p0.001). These findings support a purely pre-coronal 5 cm craniotomy for interhemispheric approaches.

International audience; ObjectiveThe great heterogeneity of meningiomas is challenging and we need to distinguish relevant subgroups. Spheno-orbital osteomeningiomas (SOOM) constitute a clinically specific entity, with slow-growing benign osteo-meningiomatous tumors, which recur after surgery in one fourth of cases. Neurosurgical daily practice, supported by the literature, shows that the vast majority of patients with SOOM are women, and we explored whether their epidemiological and hormonal profiles suggest a progesterone influence.MethodsWe retrospectively documented all radiologically and histologically confirmed cases of SOOM operated in 2005–2019 in our institution. We completed the clinical and hormone history by systematic telephone interviews.ResultsIn the literature, SOOM occur significantly more often in women than other meningiomas (749/847, 86.4% versus 73.8%, p = 0.002). Among 175 cases, we included 124 patients, 93.5% were women, younger than men (51 ± 5 versus 63 ± 8, p = 0.02). Women’ meningiomas showed more progesterone receptors (96.4% versus 50%, p

Background Occipital arteriovenous malformations (AVMs) carry a high risk of postoperative morbidity because of their anatomic relation to the visual cortex and optic radiations. Data regarding endovascular management of these lesions are scant. Objective To report our single-center experience with occipital AVMs, most of which were treated endovascularly, with a special interest for postoperative visual impairment. Methods From a prospective database, we assessed the clinical and radiological data of all patients with an occipital AVM managed between 1997 and 2018. The extension of the nidus to the primary visual cortex was assessed and correlated to the pre- and postintervention visual symptomatology. Modified Rankin Scale and visual fields (VFs) were assessed pre- and post-treatment and at the last follow-up. Results A total of 83 patients (47 males [56.6%]) with an occipital AVM were included in the study. Mean age at presentation was 33.5 ± 15.0 yr (min-max = 7-76). A total of 34 patients (41%) presented with hemorrhage related to the AVM. A total of 57 patients (68.7%) underwent endovascular treatment (EVT) alone, 20 (24.1%) underwent embolization and surgery, 3 (3.6%) underwent embolization and radiosurgery, and 3 (3.6%) were conservatively managed. A complete obliteration of the AVM was achieved in 53 patients (66.3%). A post-treatment worsening of the VF was found in 24 of the treated patients (30%), 3 patients (9%) for ruptured AVMs, and in 21 patients (46%) for unruptured AVMs. Morbidity rate was 3.7% and mortality rate was 2.5%. Conclusion EVT of occipital AVM carries a non-negligible rate of complications, especially regarding visual functions.

Background Predictors of visual outcomes after optic nerve decompression are controversial. Objective To identify the predictors of poor visual outcomes after surgery of meningiomas responsible of a compressive optic neuropathy. Methods We focused on paraoptic meningiomas (POMs), which gathered tuberculum sellae meningiomas (TSMs) and anterior clinoid meningiomas (ACMs) responsible for visual impairment or threatening visual function, that underwent surgery at our institution between January 2009 and December 2015 and analyzed the clinical and radiological findings of our patients. Results Among 112 patients who underwent surgery for a POM, a preoperative visual deficit was present in 108 patients (96.4%). Six months after surgery, 79 patients (70.5%) had a visual improvement, 15 patients (13.4%) had an unchanged vision, and 18 patients (16.1%) had deteriorated vision. A preoperative visual deficit of 6 mo or more was a strong predictor of poor visual outcome after surgery (P = .034). Poor visual outcome after surgery was not significantly related to the size of the tumor (P = .057), the age of the patient (P = .94), or the tumor extension into the optic canal (P = .47). Conclusion The duration of preoperative visual deficit was found to be a strong predictor of poor visual outcomes after surgery in POMs Other predictors of poor visual outcomes are still needed and are currently under evaluation in a prospective study at our institution.

International audience; Transcranial brain therapy has recently emerged as a non-invasive strategy for the treatment of various neurological diseases, such as essential tremor or neurogenic pain. However, treatments require millimetre-scale accuracy. The use of high frequencies (typically ≥1 MHz) decreases the ultrasonic wavelength to the millimetre scale, thereby increasing the clinical accuracy and lowering the probability of cavitation, which improves the safety of the technique compared with the use of low-frequency devices that operate at 220 kHz. Nevertheless, the skull produces greater distortions of high-frequency waves relative to low-frequency waves. High-frequency waves require high-performance adaptive focusing techniques, based on modelling the wave propagation through the skull. This study sought to optimise the acoustical modelling of the skull based on computed tomography (CT) for a 1 MHz clinical brain therapy system. The best model tested in this article corresponded to a maximum speed of sound of 4000 m.s-1 in the skull bone, and it restored 86% of the optimal pressure amplitude on average in a collection of six human skulls. Compared with uncorrected focusing, the optimised non-invasive correction led to an average increase of 99% in the maximum pressure amplitude around the target and an average decrease of 48% in the distance between the peak pressure and the selected target. The attenuation through the skulls was also assessed within the bandwidth of the transducers, and it was found to vary in the range of 10 ± 3 dB at 800 kHz and 16 ± 3 dB at 1.3 MHz.

The prognosis of unruptured giant basilar artery (BA) aneurysms is very poor. No treatment has shown efficacy in survival. This pilot case-control study examines the overall survival (OS) benefit of combined surgical and endovascular management of giant BA aneurysms.Combined treatment including posterior fossa craniectomy followed by endovascular treatment was performed in 3 patients with giant BA aneurysms. OS of the 3 patients was compared with a control group of 6 patients (ratio 1:2) treated with the endovascular procedure only.The mean survival time was 32.6 months in the craniectomy group (SD 9.01, 95% confidence interval [14.9, 50.3]) and 3.5 months in the control group (SD = 2.08, 95% confidence interval [0.001, 7.6]; Mantel-Cox test P0.04). At mean follow-up of 36.5 months (SD 10.2), 2 of 3 patients had a favorable outcome with a Glasgow Outcome Scale score of 5. Univariate analysis determined that women had a statistically higher OS than men (33.7 months vs. 3.058 months for men; log-rank test P = 0.011). A similar outcome was obtained in the presence of a circulating posterior communicating artery (P = 0.03) and in the presence of an endovascular right vertebral artery occlusion (P = 0.022).Our study suggests that preventive posterior fossa craniectomy increases significantly OS of patients with giant BA aneurysms.

When dealing with paraclinoid carotid aneurysms, the distinction between intradural and extradural location is a major component for decision-making as only intradural aneurysms carry a risk of subarachnoid hemorrhage (SAH). The aim of this study was to test the accuracy and reliability of computed tomography (CT) bony landmarks for the distinction between intradural and extradural paraclinoid aneurysms. All patients referred to this institution for a single paraclinoid aneurysm were retrospectively identified. The study included only the patients who presented with diffuse SAH, thus proving the intradural location of the aneurysm. The preoperative images were assessed by two physicians in order to locate the aneurysms using the tuberculum sellae (TS) and the optic strut (OS) landmarks. A total of 15 patients were included in the study. There were 4 cases (27%) of disagreement with the OS bony landmark and no cases of disagreement with the TS landmark. No aneurysm was consensually considered as extradural by both readers with both bony landmarks; however, five aneurysms (33%) were considered to be extradural by at least one of the physicians with at least one of the two bony landmarks. The results of the study showed several disagreements when using the OS landmark. More importantly, several aneurysms were considered as extradural with at least one of these two CT bony landmarks, even though they were all associated with an SAH. More reliable and accurate landmarks are warranted.

One of the procedural risks in arteriovenous malformation (AVM) embolization is possible migration of the embolic agent into the venous drainage with an incomplete nidus occlusion, which may lead to severe hemorrhagic complications. This report presents the case of a 29-year-old man who presented with a deep intraparenchymal hematoma on the left side secondary to the spontaneous rupture of a claustral AVM. Upon resorption of the hematoma, the patient underwent an initial therapeutic session of N-butyl-2 cyanoacrylate endovascular embolization, with the purpose of reducing the AVM volume and flow before performing Gamma Knife radiosurgery. After glue injection into one of the arterial feeders, the control angiography showed a partial migration of the glue cast into the straight sinus, with most of the nidus still visible. Because of the bleeding risk due to possible venous hypertension, it was decided to try to retrieve the glue from the vein by using a stent retriever via jugular access. This maneuver allowed a nearly complete removal of the glue cast, thereby restoring normal venous flow drainage. The patient showed no clinical worsening after the procedure. To the authors’ knowledge, this is the first report of the use of the Solitaire FR device as a rescue glue retriever. This method should be considered by physicians in cases of unintended glue migration into the venous circulation during AVM embolization.

BACKGROUND AND PURPOSE: Surgical resection is usually considered as the first-line curative strategy for low-grade (Spetzler-Martin grade I–II) brain arteriovenous malformations because it has a high cure rate and low complications. The role of endovascular treatment remains to be clarified in this indication, especially after A Randomized Trial of Unruptured Brain Arteriovenous Malformations. Our objective was to assess the safety and efficacy of first-line endovascular treatment in low-grade brain arteriovenous malformation management at our institution. MATERIALS AND METHODS: Patients with low-grade brain arteriovenous malformations treated primarily with embolization in our department between January 2005 and December 2015 were retrieved from our prospectively collected registry. The primary outcome was the brain arteriovenous malformation obliteration rate, and secondary outcomes were disability or death secondary to brain arteriovenous malformation embolization assessed through modification of the modified Rankin Scale. RESULTS: Two hundred twenty-four patients completed endovascular treatment during the study period and represent our study population. Complete exclusion of brain arteriovenous malformations was achieved in 205 patients (92%), including 62.1% of brain arteriovenous malformation exclusions after a single endovascular treatment session. One patient died of a hemorrhagic complication after endovascular treatment, leading to a mortality rate of 0.4%. Twelve patients (5%) kept a permanent neurologic deficit secondary to a complication of the endovascular treatment. An overall good outcome (mRS 0–2) was reported in 179 patients (80%). CONCLUSIONS: Endovascular treatment might be a suitable alternative to surgical resection for complete exclusion of selected low-grade brain arteriovenous malformations.

Background In most cases, glioblastomas are associated with seizures, headaches, neurological deficits, aphasia, or bleeding. But these tumors are rarely associated with cerebral infarction and never so deadly. Case report A 40-year-old man presented with sudden morning isolated aphasia. One hour later, he developed a motor deficit at right upper member, quickly completed with a total right hemiplegia. Imaging studies revealed a left frontotemporal enhancing glioblastoma with a perilesional edema which produced an important mass effect on the posterior arm of the external capsule, on the primary motor cortex posteriorly and the entire sylvian valley anteriorly. Due to major surgical risks associated with left middle cerebral artery (MCA) inclusion and large edema, we decided to postpone the tumor removal and introduce quickly high concentrations of steroids. Twenty-four hours after his admittance, the patient presented a sudden impaired consciousness, coma, and a left mydriasis. A brain magnetic resonance image (MRI) revealed a left malignant MCA infarction, deadly for the patient. Conclusion To our knowledge, glioblastomas complicated by fatal ischemic stroke have not been reported. We discuss the pathology of such an event and try to figure out if it was predictable based on MRI finding, and inevitable with precocious surgery.

Purpose: Objective Shear wave elastography (SWE) enabled living tissue assessment of stiffness. This is routinely used for breast, thyroid and liver diseases, but there is currently no data for the brain. We aim to characterize elasticity of normal brain parenchyma and brain tumors using SWE. Materials and Methods: Patients with scheduled brain tumor removal were included in this study. In addition to standard ultrasonography, intraoperative SWE using an ultrafast ultrasonic device was used to measure the elasticity of each tumor and its surrounding normal brain. Data were collected by an investigator blinded to the diagnosis. Descriptive statistics, box plot analysis as well as intraoperator and interoperator reproducibility analysis were also performed. Results: 63 patients were included and classified into four main types of tumor: meningiomas, low-grade gliomas, high-grade gliomas and metastasis. Young’s Modulus measured by SWE has given new insight to differentiate brain tumors: 33.1 ± 5.9 kPa, 23.7 ± 4.9 kPa, 11.4 ± 3.6 kPa and 16.7 ± 2.5 kPa, respectively, for the four subgroups. Normal brain tissue has been characterized by a reproducible mean stiffness of 7.3 ± 2.1 kPa. Moreover, low-grade glioma stiffness is different from high-grade glioma stiffness (p = 0.01) and normal brain stiffness is very different from low-grade gliomas stiffness (p Conclusion: This study demonstrates that there are significant differences in elasticity among the most common types of brain tumors. With intraoperative SWE, neurosurgeons may have innovative information to predict diagnosis and guide their resection.

International audience

This study was made to assess the possibilities and limits of minimally invasive transoral approach to the nasopharynx using the Da Vinci surgical robot. It was conducted on eleven corpses, without need for palatine split; using surgical robots Da Vinci models S HD and Si HD. We have defined "anatomical key landmarks" on all sides of the nasopharynx, to confirm our hypothesis. All of the nasopharynx could be visualized and transorally reached by the robot with a validation of all the key landmarks. The advantages and shortcomings of this technique were discussed, as well as the ability to use those results on human subjects. This study allowed us to show the possibility to access the nasopharynx by minimally invasive transoral robotic surgery. This new technique opens a new field for surgery of the skull base or the nasopharynx.

Purpose We describe our protocol of three-dimensional (3D) Roadmap intracranial navigation and image fusion for analysis of the angioarchitecture and endovascular treatment of brain arteriovenous malformations (AVMs). Methods We performed superselective catheterization of brain AVMs feeders under 3D-Roadmap navigation. Angiograms of each catheterized artery on two registered orthogonal views were transferred to the imaging workstations, and dedicated postprocessing imaging software allowed automated multiple overlays of the arterial supply of the AVM superselective acquisitions on the global angiogram in angiographic or 3D views and on coregistered MRI datasets. Results 11 untreated brain AVMs (4 with hemorrhagic presentation) were explored. The superselective acquisitions were performed under 3D-Roadmap navigation in 74 arteries, for a total of 79 targeted arteries. Imaging analysis was available at table side or postoperatively for discussion of the therapeutic strategy. No complications occurred during superselective catheterization. The accuracy of the coregistration of angiogram and MRI was submillimetric after automated mutual information coregistration, with manual re-registration by the physicians. Conclusions Superselective angiograms acquired under 3D-Roadmap navigation can be postprocessed with multiple overlays. The fluoroscopic navigation under 3D-Roadmapping and the coregistration of 3D rotational angiography, selective angiography, and 3D MR datasets appears reliable with millimeter accuracy, and could be implemented in the critical brain AVM embolization setting to allow refined analysis of AVM angioarchitecture.

Transoral robotic surgery (TORS) offers new possibilities that have not been experimented in the field of minimally invasive skull base neurosurgery. We propose to evaluate the feasibility of transoral approach to the sella turcica with the da Vinci system on cadavers. We performed four robot-assisted dissections on human fresh cadavers in order to reach the pituitary fossa by the oral cavity. Cavum mucosa dissection was performed by the head and neck surgeon at the console and then the sphenoid was drilled by the neurosurgeon at the bedside, with intraoperative fluoroscopy and a "double surgeon" control. Mucosa closure was attempted with robotic arms. We succeeded in performing a sellar opening in all cadavers with a minimally invasive approach, as the hard palate was never drilled. The video endoscope offered a large view inside the sphenoidal sinus, as observed in transnasal endoscopy, but with 3D visualization. The camera arm could be inserted into the sphenoidal sinus, and instrument arms in the pituitary fossa. Operative time to reach the pituitary fossa was approximately 60 min in all procedures: 20 min of initial setup, 10 min of mucosal dissection, and 30 min of sphenoid surgery. New anatomical landmarks were defined. Advantages and pitfalls of such an unpublished technique were discussed. This is the first cadaveric study reported da Vinci robotic transoral approach to the sella turcica with a minimally invasive procedure. This innovative technique may modify the usual pituitary adenoma removal as the sella is approached infero-superiorly.

Object This work aimed at evaluating the accuracy of MR-guided high-intensity focused ultrasound (MRgHIFU) brain therapy in human cadaver heads. Methods Eighteen heads of fresh human cadavers were removed with a dedicated protocol preventing intracerebral air penetration. The MR images allowed determination of the ultrasonic target: a part of the thalamic nucleus ventralis intermedius implicated in essential tremor. Osseous aberrations were corrected with simulation-based time reversal by using CT data from the heads. The ultrasonic session was performed with a 512-element phased-array transducer system operating at 1 MHz under stereotactic conditions with thermometric real-time MR monitoring performed using a 1.5-T imager. Results Dissection, imaging, targeting, and planning have validated the feasibility of this human cadaver model. The average temperature elevation measured by proton resonance frequency shift was 7.9°C ± 3°C. Based on MRI data, the accuracy of MRgHIFU is 0.4 ± 1 mm along the right/left axis, 0.7 ± 1.2 mm along the dorsal/ventral axis, and 0.5 ± 2.4 mm in the rostral/caudal axis. Conclusions Despite its limits (temperature, vascularization), the human cadaver model is effective for studying the accuracy of MRgHIFU brain therapy. With the 1-MHz system investigated here, there is millimetric accuracy.

A wide spectrum of methods is used to image brain activation in vivo, such as functional MRI (fMRI) or positron emission tomography. Both techniques have excellent depth penetration but do not provide good spatial nor temporal resolution. By contrast, ultrasound imaging achieves good spatiotemporal resolution in depth, but until now its poor sensitivity has limited its use to the imaging of major vessels. Functional ultrasound (fUS) derived from the key concept of ultrafast imaging (up to 20 000 frames/s) [1] overcomes this limitation. fUS enables high spatiotemporal resolution imaging of microvasculature dynamics in response to brain activation and was previously validated in rodents [2]. We aim to demonstrate that fUS could find activation maps accurately during brain surgery in humans without requiring electrocortical stimulation mapping (ESM). A clinical study including 10 patients with brain lesion is undertaken, with both fMRI and ESM as gold standard. Patients underwent fMRI before surgery, data were intraoperatively used for ultrasound probe positioning on a targeted functional area using a neuronavigation system (Brainlab AG, Feldkirchen, Germany) and probe location was also confirmed by ESM. A sterilized linear probe driven by an ultrafast ultrasound scanner (Aixplorer, Supersonic Imagine, France) was placed directly on the brain after skull opening. Patients, awake during this part of their surgery, were asked to perform a specific task (motor, sensory or language). fUS imaging with a 6000 Hz frame rate determines regions of brain activity based on the cerebral blood volume (CBV) increase due to neurovascular coupling. This first pilot study demonstrates the ability of fUS imaging to map with a high signal-to-noise ratio (SNR) the stimulus-based neuronal activation in depth in real time during brain surgery. Such technique could be extremely useful for neurosurgeons to improve their surgery and therefore patient quality of life.

The posterior inferior cerebellar artery (PICA) is a vessel located between the intra- and extracranial circulation. The artery is characterized by a complex embryological development and numerous anatomical variants. The authors present a case of the PICA supplied by both a hypertrophic anterior spinal artery and a hypoplastic bulbar artery. This unusual arrangement somehow completes the list of previously published variants, and the spontaneous rupture of a related aneurysm confirmed the fragility of this network. The authors discuss anatomical and treatment considerations.

Background and objective Laser-induced thermal therapy (LITT), coupled with magnetic resonance thermal imaging (MRTI) guidance, provides a minimally invasive and safe approach to treat brain tumors, especially metastases. We report here our experience using this treatment for recurrent glioblastomas. Materials and Methods Four patients, from 40 to 58 years old, were diagnosed with glioblastoma. After total resection, chemotherapy and radiation therapy, recurrence occurred. As each was ineligible for a second surgery, LITT was proposed as salvage therapy. Under stereotactic guidance, a fiberoptic applicator was inserted within the tumor LITT was performed under continuous MRTI. Real-time feedback control based on MRTI was employed to assess the quality of local tissue destruction and to prevent unwanted damage to nearby structures. Results The procedure was well tolerated with no peroperative neurological deterioration. In the short-term follow-up, one transient supplementary motor area syndrome, one epileptic seizure, and one cerebrospinal fluid leakage occurred. All were successfully managed. Post-procedure MRI showed no complication, satisfying treatment volume, and a decrease in size of the treated tumor. For all patients, recurrence was observed with a mean/median progression free survival of 37/30 days. Mean/median overall survival after LITT was 10.5/10 months. Conclusion Focal tumor control was performed safely using minimally invasive LITT with real-time MRTI control. LITT could be considered as salvage therapy for high-grade recurrent gliomas if a 1-day treatment is considered useful for a few weeks gain in survival. Larger experience will be required to define indications for such infiltrative disease and accurately determine a potentially significant survival gain in good neurological condition associated with this 1-day procedure. Lasers Surg. Med. 44: 361–368, 2012. © 2012 Wiley Periodicals, Inc.

Purpose: This study aims to demonstrate, using human cadavers the feasibility of energy-based adaptive focusing of ultrasonic waves using magnetic resonance acoustic radiation force imaging (MR-ARFI) in the framework of non-invasive transcranial high intensity focused ultrasound (HIFU) therapy. Methods: Energy-based adaptive focusing techniques were recently proposed in order to achieve aberration correction. The authors evaluate this method on a clinical brain HIFU system composed of 512 ultrasonic elements positioned inside a full body 1.5 T clinical magnetic resonance (MR) imaging system. Cadaver heads were mounted onto a clinical Leksell stereotactic frame. The ultrasonic wave intensity at the chosen location was indirectly estimated by the MR system measuring the local tissue displacement induced by the acoustic radiation force of the ultrasound (US) beams. For aberration correction, a set of spatially encoded ultrasonic waves was transmitted from the ultrasonic array and the resulting local displacements were estimated with the MR-ARFI sequence for each emitted beam. A noniterative inversion process was then performed in order to estimate the spatial phase aberrations induced by the cadaver skull. The procedure was first evaluated and optimized in a calf brain using a numerical aberrator mimicking human skull aberrations. The full method was then demonstrated using a fresh human cadaver head. Results: The corrected beam resulting from the direct inversion process was found to focus at the targeted location with an acoustic intensity 2.2 times higher than the conventional non corrected beam. In addition, this corrected beam was found to give an acoustic intensity 1.5 times higher than the focusing pattern obtained with an aberration correction using transcranial acoustic simulation-based on X-ray computed tomography (CT) scans. Conclusions: The proposed technique achieved near optimal focusing in an intact human head for the first time. These findings confirm the strong potential of energy-based adaptive focusing of transcranial ultrasonic beams for clinical applications.

Gas nuclei exist naturally in living bodies. Their activation initiates cavitation activity, and is possible using short ultrasonic excitations of high amplitude. However, little is known about the nuclei population in vivo, and therefore about the rarefaction pressure required to form bubbles in tissue. A novel method dedicated to in vivo investigations was used here that combines passive and active cavitation detection with a multi-element linear ultrasound probe (4–7 MHz). Experiments were performed in vivo on the brain of trepanated sheep. Bubble nucleation was induced using a focused single-element transducer (central frequency 660 kHz, f -number = 1) driven by a high power (up to 5 kW) electric burst of two cycles. Successive passive recording and ultrafast active imaging were shown to allow detection of a single nucleation event in brain tissue in vivo. Experiments carried out on eight sheep allowed statistical studies of the bubble nucleation process. The nucleation probability was evaluated as a function of the peak negative pressure. No nucleation event could be detected with a peak negative pressure weaker than −12.7 MPa, i.e. one order of magnitude higher than the recommendations based on the mechanical index. Below this threshold, bubble nucleation in vivo in brain tissues is a random phenomenon. (Some figures in this article are in colour only in the electronic version)

CSF leakages constitute a major complication of intradural procedures, especially for posterior fossa and skull base surgery. Dural suture watertightness is a decisive issue, and neurosurgeons routinely use different products to reinforce their dural closure. We have designed an experimental system capable of testing CSF leak pressure levels in order to compare two types of sutures in vitro and particularly four different sealants.Twenty-five fresh human cadaveric dural samples were removed and prepared for testing in a pressure chamber system connected to a hydraulic pressure motor. CSF leak levels were objectively registered. First, simple interrupted stitches were compared to running simple closure on 50-mm linear suture. Secondly, four sealants (two sealants/glues, Bioglue®, Duraseal®; two haemostatics, Tachosil®, Tissucol®) were tested. Statistical analysis was performed with paired Student's t-test.No significant difference between interrupted closure and running suture was observed (p = 0.079). All sealants increased the watertightness of the suture significatively. However, comparison of the means of the differences for each product revealed large variations. In the conditions of our experiment, one sealant (Duraseal®) and one haemostatic (Tachosil®) seemed to show better results. We observed two different types of leakage: at the dura-sealant interface and through the sealant itself.We have developed an experimental device capable of testing dural closure watertightness. Interrupted stitch suturing seemed no different from running simple closure. On the contrary, the sealants tested show different watertightness capacities.

To evaluate the in vivo accuracy of the new Pressio(®) device for intraparenchymal monitoring of intracranial pressure (ICP) versus the Codman(®) device and intraventricular measurement external ventricular drainage (EVD).Data were collected retrospectively for 30 consecutive patients admitted into a 25-bed neurosurgical intensive care unit of a university hospital between January and December 2009. Patients received both intraventricular and intraparenchymal ICP monitoring with Pressio(®) (n = 15) or Codman(®) (n = 15).We obtained 3,089 data points from the 30 patients. Mean difference between intraparenchymal and EVD pressure (bias) was -0.6 mmHg, and limits of agreement (1.96 SD of the bias) were -8.1 to 6.9 mmHg with Pressio(®) and 0.3 mmHg with limits of agreement of -6.7 to 7.1 mmHg with Codman(®) (NS). The temporal difference was -0.7 ± 1.6 mmHg/100 h of monitoring with Pressio(®) and 0.1 ± 1.6 mmHg/100 h of monitoring with Codman(®) over the study period (NS).Intraparenchymal pressure measured with both transducers approximates intraventricular cerebrospinal fluid pressure with an accuracy of ±7 mmHg.

Resume Un systeme de therapie base sur l’utilisation de faisceaux ultrasonores de forte intensite focalises a travers la paroi crânienne a ete developpe pour le traitement extracorporel des lesions cerebrales. La compatibilite electromagnetique de ce systeme permet un monitoring en cours de traitement par imagerie de resonance magnetique (IRM). Ce systeme a ete concu et valide experimentalement apres implantation dans un systeme IRM clinique 1,5 T Philips Achieva. La correction des aberrations induites sur le faisceau par la propagation a travers l’os crânien est realisee grâce a l’acquisition pretraitement d’un volume 3D scanner X de la structure osseuse du crâne servant de parametre d’entree a des simulations numeriques 3D de la propagation d’ondes ultrasonores. Les distorsions de phase estimees par simulation sont utilisees pour corriger les aberrations induites par la boite crânienne en utilisant le concept de retournement temporal des ondes. Des experiences in vitro sur des crânes humains montrent que le systeme est capable d’atteindre une qualite de focalisation millimetrique du faisceau au point cible desire dans le cerveau. Le suivi de l’elevation de temperature par IRM pendant le traitement assure un controle et une fiabilite incontestable pour cette nouvelle technologie qui sera dans un avenir tres proche validee cliniquement pour le traitement des tumeurs cerebrales et pathologies neurologiques.

OBJECTIVEThe aim of this study was to confirm the feasibility of an innovative transoral robotic surgery (TORS), using the da Vinci Surgical System, for patients with sellar tumors. This technique was designed to offer a new minimally invasive approach, without soft-palate splitting, that avoids the rhinological side effects of classic endonasal approaches.METHODSThe authors performed a prospective study of TORS in patients with symptomatic sellar tumors. Specific anatomical features were required for inclusion in the study and were determined on the basis of preoperative open-mouth CT scans of the brain. The main outcome measure was sellar accessibility using the robot. Resection quality, mean operative time, postoperative changes in patients' vision, side effects, and complications were additionally reported.RESULTSBetween February and May 2016, 4 patients (all female, mean age 49.5 years) underwent TORS for resection of sellar tumors as participants in this study. All patients presented with symptomatic visual deficits confirmed as bitemporal hemianopsia. All tumors had a suprasellar portion and a cystic part. In all 4 cases, the operation was performed via TORS, without the need for a second surgery. Sella turcica accessibility was satisfactory in all cases. In 3 cases, tumor resection was complete. The mean operative time was 2 hours 43 minutes. Three patients had a significant visual improvement at Day 1. No rhinological side effects or complications in patients occurred. No pathological examination was performed regarding the fluid component of the tumors. There was 1 postoperative delayed CSF leak and 1 case of transient diabetes insipidus. Side effects specific to TORS included minor sore throat, transient hypernasal speech, and 1 case of delayed otitis media. The mean length of hospital stay and mean follow up were 8.25 days and 82 days, respectively.CONCLUSIONSTo our knowledge, this is the first report of the surgical treatment of sellar tumors by means of a minimally invasive TORS. This approach using the da Vinci Surgical System seems feasible and constitutes an innovative neurosurgical technique that may avoid the adverse side effects and technical disadvantages of the classic transsphenoidal route. Moreover, TORS allows an inferosuperior approach to the sella turcica, which is a key point, as the tumor is approached in the direction of its growth.

International audience; The role of transoral robotic surgery (TORS) in the skull base emerges and represents the natural progression toward miniinvasive resections in confined spaces. The accessibility of the sella via TORS has been recently described on fresh human cadavers. An anatomic study is mandatory to know if this approach would be feasible in the majority of patients regardless of their oral morphological features. From 30 skull base CT scans from patients who were asked to open their mouth as wide as they can, we measured specific dimensions of the oral cavity and the skull base, such as length of the palate, mouth opening and distance from the sella to the palate. All data were acquired on a sagittal midline plane and on a 25° rotation plane, which simulated the axis of the robotic instruments. Looking at the projection of the dental palatine line on the sella, we studied possible predictive factors of sellar accessibility and tried to bring objective data for surgical feasibility. We also proposed an angle α to study the working angle at the skull base. We observed that the maximal mouth opening was a good predictive factor of sellar accessibility by TORS (p

Introduction La chirurgie hypophysaire s’est enrichie des techniques endoscopiques transnasales. Neanmoins, certains ecueils peuvent etre soulignes : complications rhinologiques, vision en 2D. Parallelement, la chirurgie assistee par le robot da Vinci, qui offre une vision en 3D et une demultiplication du geste, s’est developpee par voie transorale pour les cancers ORL. Apres validation par des travaux cadaveriques, nous proposons une etude de faisabilite d’une nouvelle voie d’abord transorale des tumeurs hypophysaires, assistee par robotique. Patients et methode Apres recueil du consentement et realisation d’un scanner craniofacial « bouche ouverte », les patients porteurs de lesions sellaires sont inclus dans une recherche biomedicale. La chirurgie se deroule selon les etapes suivantes : (1) installation des bras du robot ; (2) dissection muqueuse de la muqueuse du cavum ; (3) temps osseux d’ouverture du sinus sphenoidal puis de la selle ; (4) temps intrasellaire puis fermeture. Le critere principal d’evaluation est l’accessibilite de la lesion. Les criteres secondaires sont ceux de toutes etudes sur la chirurgie hypophysaire et incluent aussi les effets secondaires de l’abord transoral. Resultats Nous rapportons 4 patients, inclus entre fevrier et mai 2016, porteurs de lesions sellaires kystiques responsables d’une compression chiasmatique avec hemianopsie bitemporale. L’accessibilite de la lesion par notre abord est satisfaisante dans tous les cas, sans necessite de conversion par une voie endonasale. Le temps operatoire moyen est de 2 h40. Trois patients ont une resection totale. Aucun desagrement rhinologique n’est rapporte. Concernant les complications generales, sont mentionnes une fuite de LCS a j7 et un diabete insipide transitoire. Concernant les complications de l’abord transoral, nous rapportons des maux de gorge ( n = 4), une voix nasonnee ( n = 3) et une otite moyenne retardee ; tous ces symptomes sont mineurs et resolutifs sous medication. Conclusion Nous presentons les premiers patients operes de tumeurs sellaires kystiques par une voie transorale robotisee inedite. Cette derniere semble offrir 2 avantages prometteurs : aucun desagrement rhinologique et abord de la selle selon une direction inferosuperieure, qui correspond a l’axe de croissance tumoral. Nous prevoyons de poursuivre notre etude par des tumeurs solides et cherchons a developper une instrumentation dediee.

Ultrasonography is proving to be an invaluable tool in brain surgery. Recently, new ultrasonic modalities called shear wave elastography (SWE) enabled living tissue assessment of stiffness. SWE is routinely used for breast or liver diseases, but brain data are missing. We aim to characterize elasticity of normal brain and brain tumors by using SWE and to study if there is a relationship between SWE and intracranial pressure (ICP). Improving quality of brain tumor resection and predict brain swelling are major concerns for neurosurgeons. A clinical study was undertaken, including normal brain and tumors data collected from intraoperative SWE. The aim is to improve shear wave imaging for brain tissue investigation by correlating in vivo stiffness data and histology. At the same time ICP was studied, first ex vivo and then during in vivo surgery, to observe brain swelling by using SWE. Shear waves were generated by using ultrasonic acoustic radiation force and imaged in real-time by an ultrafast ultrasound scanner up to 20 000 frames/s. This study demonstrates that there are significant differences in elasticity among the most common types of brain tumors. We show that SWE could help for diagnosis during tumor resection by distinguishing benign tumors from malignant tumors (AUROC: 0.77, p

Erdheim-Chester disease (ECD) is a rare non–Langerhans cell histiocytosis characterized by the accumulation of foamy CD68+CD1a− histiocytes. Tissue infiltration preferentially affects long bones and retroperitoneal and peri-aortic spaces, but almost any organ or system can be affected.1 Cardiac and neurologic involvements are associated with significantly higher levels of mortality and morbidity.2

Oculomotor nerve palsy (ONP) is a common clinical manifestation of ruptured or unruptured posterior communicating artery (PcomA) aneurysms. Although microsurgical clip ligation has been proven a safe and durable treatment, endovascular management is emerging as an increasingly popular alternative. The aim of our study is to compare the recovery rate from ONP and assess the safety and long-term durability of both techniques. We have reviewed the retrospective data concerning twenty-two patients treated at our institution between 2004 and 2012 for PcomA aneurysms with ONP. Seven patients were operated on via a standard pterional approach, and fourteen were treated by endovascular occlusion with coils. One patient was managed conservatively. Pre-treatment and post-treatment severity of ONP was recorded, as well as the duration of symptoms before admission and treatment-related complications. All seven patients who underwent surgery improved, with six total recoveries and one partial recovery. Among the fourteen patients treated by embolization, thirteen initially recovered, but long-term follow-up revealed three cases of exacerbation of ONP after refilling of the aneurysms. Two of them were clipped, and one embolized. Also, one partially resolved patient underwent a second embolization. No severe complications occurred in either group. Despite the small number of patients, our study suggests that both surgical clipping and embolization are safe and effective methods in regards to functional recovery (complete ONP recovery in about 85 % of the cases). However, coiling may lead to delayed recurrence of third cranial nerve (CN) palsy at long-term follow-up, requiring additional treatment.

This work aimed at evaluating the accuracy of MR-guided high-intensity focused ultrasound (MRgHIFU) brain therapy in human cadaver heads.Eighteen heads of fresh human cadavers were removed with a dedicated protocol preventing intracerebral air penetration. The MR images allowed determination of the ultrasonic target: a part of the thalamic nucleus ventralis intermedius implicated in essential tremor. Osseous aberrations were corrected with simulation-based time reversal by using CT data from the heads. The ultrasonic session was performed with a 512-element phased-array transducer system operating at 1 MHz under stereotactic conditions with thermometric real-time MR monitoring performed using a 1.5-T imager.Dissection, imaging, targeting, and planning have validated the feasibility of this human cadaver model. The average temperature elevation measured by proton resonance frequency shift was 7.9°C ± 3°C. Based on MRI data, the accuracy of MRgHIFU is 0.4 ± 1 mm along the right/left axis, 0.7 ± 1.2 mm along the dorsal/ventral axis, and 0.5 ± 2.4 mm in the rostral/caudal axis.Despite its limits (temperature, vascularization), the human cadaver model is effective for studying the accuracy of MRgHIFU brain therapy. With the 1-MHz system investigated here, there is millimetric accuracy.

Background Malignant optic glioma of adulthood is a rare, invasive neoplasm of the anterior visual pathway. In this article, the clinical features of a case series of 3 malignant optic nerve glioblastomas (World Health Organization grade IV) are presented, and the modalities of treatment and their associated survivals are discussed through a review of the existing literature to date. Methods A retrospective case series study was led for 3 patients diagnosed with primary optic nerve and chiasm glioblastoma, coming from 2 referral neurosurgical centers. An electronic search was conducted on MEDLINE via PUBMED, COCHRANE, from October 1973 to April 2016. Cohort, case reports, and case series were screened for investigating treatment and overall survival (OS) of malignant optic nerve gliomas. Pooled means and 95% confidence intervals of OS for each treatment were generated. Results From our retrospective case series, all patients had initial visual impairment (2 women and 1 man). The histologic diagnosis was done by biopsy. The patients' mean age was 67.3 years (standard deviation [SD] 18.5). The disease was rapidly lethal for all patients: median OS was 5 months (SD: 15.1). Two patients underwent chemotherapy by single cure of temozolomide, while the third one was treated with a radiochemotherapy protocol. Due to the fact that there is no gold standard treatment as first-choice treatment, a large heterogeneity in first-choice oncologic treatment is observed. However, we did not find any significant differences for OS between World Health Organization grade III and grade IV optic gliomas. Conclusion Malignant optic glioma is a rare and fatal disease in adults. Despite the modalities of treatment, the treatment outcomes remain unsatisfactory. There is no significant difference in the median OS of patients with malignant optic nerve, as compared with those diagnosed with other supratentorial glioblastoma. Chemoradiotherapy with temozolomide currently remains the best treatment in terms of OS. Advances in the understanding of tumor biology have yet failed to translate into effective treatment regimens.

Background The aim of this study in patients with traumatic brain injury (TBI) was to assess the effectiveness of continuous cerebrospinal fluid (CSF) drainage in controlling intracranial pressure (ICP) and minimizing the use of other ICP-lowering interventions potentially associated with serious adverse events. Methods We studied 20 TBI patients. In each patient, we compared four consecutive 12-hour periods covering the 24 hours before CSF drainage (NoDr1 and NoDr2) and the 24 first hours of drainage (Dr1 and Dr2). During each period, we recorded ICP, cerebral perfusion pressure (CPP), sedation, propofol infusion rate, and number of hypertonic saline boluses. Results With continuous CSF drainage, ICP decreased significantly from 18 ± 6 mmHg (NoDr1) and 19 ± 7 mmHg (NoDr2) to 11 ± 5 mmHg (Dr1) and 12 ± 7 mmHg (Dr2). CPP increased significantly with drainage. Drainage led to a significant decrease in the number of hypertonic saline boluses required for ICP elevation, from 35 in 16 patients (80%) (NoDr1/2) to eight in five patients (25%) (Dr3/4). Drainage was not associated with changes in the midazolam or sufentanil infusion rates. The propofol infusion rate was non-significantly lower with drainage. No significant differences in serum sodium, body temperature, or PaCO2 occurred across the four 12-hour periods. Conclusion CSF drainage may not only lower ICP levels, but also decreases treatment intensity during the 24 hours following EVD placement in TBI patients. Because EVD placement may be associated with adverse event, the exact role for each of the available ICP-lowering interventions remains open to discussion.

International audience; Many techniques are described to treat Chiari type I malformation. One of them is a splitting of the dura, removing its outer layer only to reduce the risks of cerebrospinal fluid (CSF) leak. We try to show the effectiveness of this technique from histological and biomechanical observations of dura mater. Study was performed on 25 posterior fossa dura mater specimens from fresh human cadavers. Dural composition and architecture was assessed on 47 transversal and sagittal sections. Uniaxial mechanical tests were performed on 22 dural samples (15 entire, 7 split) to focus on the dural macroscopic mechanical behavior comparing entire and split samples and also to understand deformation mechanisms. We finally created a model of volume expansion after splitting. Dura mater was composed of predominant collagen fibers with a few elastin fibers, cranio-caudally orientated. The classical description of two distinct layers remained inconstant. Biomechanical tests showed a significant difference between entire dura, which presents an elastic fragile behavior, with a small domain where deformation is reversible with stress, and split dura, which presents an elasto-plastic behavior with a large domain of permanent strain and a lower stress level. From these experimental results, the model showed a volume increase of approximately 50% below the split area. We demonstrated the capability of the split dura mater to enlarge for suitable stress conditions and we quantified it by biomechanical tests and experimental model. Thus, dural splitting decompression seems to have a real biomechanical substrate to envision the efficacy of this Chiari type I malformation surgical technique.