Embolization of the middle meningeal artery for the prevention of chronic subdural hematoma recurrence in high-risk patients: a randomized controlled trial-the EMPROTECT study protocol

BACKGROUND

Middle meningeal artery (MMA) embolization has been proposed as a treatment of chronic subdural hematoma (CSDH). The benefit of the procedure has yet to be demonstrated in a randomized controlled trial. We aim to assess the efficacy of MMA embolization in reducing the risk of CSDH recurrence 6 months after burr-hole surgery compared with standard medical treatment in patients at high risk of postoperative recurrence.

METHODS

The EMPROTECT trial is a multicenter open label randomized controlled trial (RCT) involving 12 French centers. Adult patients (≥18 years) operated for CSDH recurrence or for a first episode with a predefined recurrence risk factor are randomized 1:1 to receive either MMA embolization within 7 days of the burr-hole surgery (experimental group) or standard medical care (control group). The number of patients to be included is 342.

RESULTS

The primary outcome is the rate of CSDH recurrence at 6 months. Secondary outcomes include the rate of repeated surgery for a homolateral CSDH recurrence during the 6-month follow-up period, the rate of disability and dependency at 1 and 6 months, defined by a modified Rankin Scale (mRS) score ≥4, mortality at 1 and 6 months, total cumulative duration of hospital stay during the 6-month follow-up period, directly or indirectly related to the CSDH and embolization procedure-related complication rates.

CONCLUSIONS

The EMPROTECT trial is the first RCT evaluating the benefit of MMA embolization as a surgical adjunct for the prevention of CSDH recurrence. If positive, this trial will have a significant impact on patient care.

TRIAL REGISTRATION NUMBER

NCT04372147.

Surgical treatment of hemifacial spasms: how to predict failure and complications through a series of 200 patients

Primary hemifacial spasm (pHFS) is a benign but disabling movement disorder caused by a neurovascular conflict involving the facial nerve. Surgical treatment by microvascular decompression (MVD) is the most effective therapeutic. Predictors of surgical failure and surgical complications are still lacking. The aim of this study is to identify such predictors through the retrospective analysis of a series of 200 consecutive patients. All patients who underwent MVD for pHFS from January 1991 to December 2017 were included. All patients had at least two years follow-up. In addition to the demographic data, the outcome and the complications were collected. The primary outcome analysis showed that 7.5% of patients had a recurrence. Multiple and AICA related neurovascular conflicts were statistically associated to a higher recurrence rate after MVD (respectively p < 0.001 and p = 0.02). Permanent facial palsy occurred in 2.5% of patients, hearing loss in 9.0% (2.0% of complete unilateral impairment) and dizziness in 2.5%. The risk of each of these peripheral neurological impairments was statistically increased by a long duration between the first pHFS symptom and the MVD (p < 0.001). In case of recurrence, a second MDV was offered. Long term follow-up showed that all patients had a complete resolution of the HFS. Post-operative complication rate was not significantly increased after a second MVD. Multiple and AICA related neurovascular conflicts are associated to a higher risk of surgical failure. When a pHFS recurrence occurs, a second surgical procedure is associated with excellent outcome without significant increase of post-operative complications and should therefore be recommended.

Ethical Management of COVID-19 Pandemic at a Neurological Hospital: The Ethicovid Report

BACKGROUND

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.

METHODS

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.

RESULTS

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.

CONCLUSIONS

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.

Rescue Epidural Saline Patch for Comatose Patients With Refractory Convexity Spontaneous Subacute Subdural Hematoma: Case Report

Objectives

Convexity 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.

Methods

All 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.

Results

The 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.

Discussion

An 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.

Multivariate models to predict pain recurrence and sensitive complications after percutaneous balloon compression in trigeminal neuralgia

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.

Interhemispheric transcallosal approach: going further based on the vascular anatomy

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.

Microsurgical Transcranial Approach of 112 Paraoptic Meningiomas: A Single-Center Case Series

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.

Visual Field Defect Before and After Endovascular Treatment of Occipital Arteriovenous Malformations

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.

Advanced multiparametric magnetic resonance imaging of multinodular and vacuolating neuronal tumor

BACKGROUND AND PURPOSE

Multinodular and vacuolating neuronal tumor (MVNT) of the cerebrum is a rare brain lesion with suggestive imaging features. The aim of our study was to report the largest series of MVNTs so far and to evaluate the utility of advanced multiparametric magnetic resonance (MR) techniques.

METHODS

This multicenter retrospective study was approved by our institutional research ethics board. From July 2014 to May 2019, two radiologists read in consensus the MR examinations of patients presenting with a lesion suggestive of an MVNT. They analyzed the lesions' MR characteristics on structural images and advanced multiparametric MR imaging.

RESULTS

A total of 64 patients (29 women and 35 men, mean age 44.2 ± 15.1 years) from 25 centers were included. Lesions were all hyperintense on fluid-attenuated inversion recovery and T2-weighted imaging without post-contrast enhancement. The median relative apparent diffusion coefficient on diffusion-weighted imaging was 1.13 [interquartile range (IQR), 0.2]. Perfusion-weighted imaging showed no increase in perfusion, with a relative cerebral blood volume of 1.02 (IQR, 0.05) and a relative cerebral blood flow of 1.01 (IQR, 0.08). MR spectroscopy showed no abnormal peaks. Median follow-up was 2 (IQR, 1.2) years, without any changes in size.

CONCLUSIONS

A comprehensive characterization protocol including advanced multiparametric magnetic resonance imaging sequences showed no imaging patterns suggestive of malignancy in MVNTs. It might be useful to better characterize MVNTs.

Reliability of Bony Landmarks to Predict Intradural Location of Paraclinoid Aneurysms

PURPOSE

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.

METHODS

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.

RESULTS

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.

CONCLUSION

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.

Endovascular Treatment for Low-Grade (Spetzler-Martin I-II) Brain Arteriovenous Malformations

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.

Transoral robotic surgery for sellar tumors: first clinical study

OBJECTIVE

The 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.

METHODS

The 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.

RESULTS

Between 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.

CONCLUSIONS

To 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.

Intraoperative Functional Ultrasound Imaging of Human Brain Activity

The functional mapping of brain activity is essential to perform optimal glioma surgery and to minimize the risk of postoperative deficits. We introduce a new, portable neuroimaging modality of the human brain based on functional ultrasound (fUS) for deep functional cortical mapping. Using plane-wave transmissions at an ultrafast frame rate (1 kHz), fUS is performed during surgery to measure transient changes in cerebral blood volume with a high spatiotemporal resolution (250 µm, 1 ms). fUS identifies, maps and differentiates regions of brain activation during task-evoked cortical responses within the depth of a sulcus in both awake and anaesthetized patients.

Ex vivo optimisation of a heterogeneous speed of sound model of the human skull for non-invasive transcranial focused ultrasound at 1 MHz

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.

In Vivo Measurement of Brain Tumor Elasticity Using Intraoperative Shear Wave Elastography

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 < 0.01). 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.

Rescue N-butyl-2 cyanoacrylate embolectomy using a Solitaire FR device after venous glue migration during arteriovenous malformation embolization: technical note

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.

Anterior spinal and bulbar artery supply to the posterior inferior cerebellar artery revealed by a ruptured aneurysm: case report

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.

Glioblastoma complicated by fatal malignant acute ischemic stroke: MRI finding to assist in tricky surgical decision

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.

Multimodal angiographic assessment of cerebral arteriovenous malformations: a pilot study

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-assisted skull base surgery to approach the sella turcica: cadaveric study

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.

Targeting accuracy of transcranial magnetic resonance-guided high-intensity focused ultrasound brain therapy: a fresh cadaver model

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.

Conservative management of a large occipital extradural haematoma

A 26-year-old male presented with a mild confusion and hemianopsia after traumatic brain injury. Cerebral CT-scan revealed a 62.5 cm(3) left occipital extradural haematoma (EDH). Although conventional neurosurgical management would have been to evacuate the haematoma, a conservative strategy was preferred, and the patient made a total recovery.

MR-guided adaptive focusing of therapeutic ultrasound beams in the human head

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.

Study of dural suture watertightness: an in vitro comparison of different sealants

BACKGROUND

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.

METHODS

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.

RESULTS

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.

CONCLUSIONS

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.

In vivo bubble nucleation probability in sheep brain tissue

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.

In vivo bubble nucleation probability in sheep brain tissue

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.

In vivo accuracy of two intraparenchymal intracranial pressure monitors

PURPOSE

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).

METHODS

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).

RESULTS

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).

CONCLUSIONS

Intraparenchymal pressure measured with both transducers approximates intraventricular cerebrospinal fluid pressure with an accuracy of ±7 mmHg.

[The mystery of prehistoric trepanations: Is neurosurgery the world eldest profession?]

Trepanation is known to be the first surgical procedure ever performed. Its origins date from the Neolithic Age in Europe and the operation was particularly performed in South America at the Pre-Colombian era, a few thousand years later. Based on many archeological studies on trepanned skulls, we compare the differences and similarities of these two periods through epidemiological, topographical, and technical approaches. Signs of bony regeneration are assessed in an attempt to understand the postoperative survival of trepanned patients. The literature in surgery and archeology does not mention the possible relation between trepanations and growing skull fractures. However, it is reasonable to think that these cranial holes, occurring after a pediatric skull fracture, could mimic real trepanation orifices. The possible connections between these two entities are discussed. The etiological hypotheses on prehistoric trepanation are reviewed.