Cranial nerve deficits in giant cavernous carotid aneurysms and their relation to aneurysm morphology and location.

BACKGROUND: Giant cavernous carotid aneurysms (GCCAs) usually exert substantial mass effect on adjacent intracavernous cranial nerves. Since predictors of cranial nerve deficits (CNDs) in patients with GCCA are unknown, we designed a study to identify associations between CND and GCCA morphology and the location of mass effect. METHODS: This study was based on data from the prospective clinical and imaging databases of the Giant Intracranial Aneurysm Registry. We used magnetic resonance imaging and digital subtraction angiography to examine GCCA volume, presence of partial thrombosis (PT), GCCA origins, and the location of mass effect. We also documented whether CND was present. RESULTS: We included 36 GCCA in 34 patients, which had been entered into the registry by eight participating centers between January 2009 and March 2016. The prevalence of CND was 69.4%, with one CND in 41.7% and more than one in 27.5%. The prevalence of PT was 33.3%. The aneurysm origin was most frequently located at the anterior genu (52.8%). The prevalence of CND did not differ between aneurysm origins (p = 0.29). Intracavernous mass effect was lateral in 58.3%, mixed medial/lateral in 27.8%, and purely medial in 13.9%. CND occurred significantly more often in GCCA with lateral (81.0%) or mixed medial/lateral (70.0%) mass effect than in GCCA with medial mass effect (20.0%; p = 0.03). After adjusting our data for the effects of the location of mass effect, we found no association between the prevalence of CND and aneurysm volume (odds ratio (OR) 1.30 (0.98-1.71); p = 0.07), the occurrence of PT (OR 0.64 (0.07-5.73); p = 0.69), or patient age (OR 1.02 (95% CI 0.95-1.09); p = 0.59). CONCLUSIONS: Distinguishing between medial versus lateral location of mass effect may be more helpful than measuring aneurysm volumes or examining aneurysm thrombosis in understanding why some patients with GCCA present with CND while others do not. CLINICAL TRIAL REGISTRATION NO: NCT02066493 ( clinicaltrials.gov ).

Removal of recurrent intraorbital tumour using a system of augmented reality.

The most crucial step in the management of pleomorphic adenoma of the lacrimal gland is choosing the optimal approach for excision. We report the successful removal of a recurrent pleomorphic adenoma of the lacrimal gland in a 42-year-old woman using a specific microscope-based system of augmented reality.

Wall shear stress at the initiation site of cerebral aneurysms.

Hemodynamics are believed to play an important role in the initiation of cerebral aneurysms. In particular, studies have focused on wall shear stress (WSS), which is a key regulator of vascular biology and pathology. In line with the observation that aneurysms predominantly occur at regions of high WSS, such as bifurcation apices or outer walls of vascular bends, correlations have been found between the aneurysm initiation site and high WSS. The aim of our study was to analyze the WSS field at an aneurysm initiation site that was neither a bifurcation apex nor the outer wall of a vascular bend. Ten cases with aneurysms on the A1 segment of the anterior cerebral artery were analyzed and compared with ten controls. Aneurysms were virtually removed from the vascular models of the cases to mimic the pre-aneurysm geometry. Computational fluid dynamics (CFD) simulations were created to assess the magnitude, gradient, multidirectionality, and pulsatility of the WSS. To aid the inter-subject comparison of hemodynamic variables, we mapped the branch surfaces onto a two-dimensional parametric space. This approach made it possible to view the whole branch at once for qualitative evaluation. It also allowed us to empirically define a patch for quantitative analysis, which was consistent among subjects and encapsulated the aneurysm initiation sites in our dataset. To test the sensitivity of our results, CFD simulations were repeated with a second independent observer virtually removing the aneurysms and with a 20 % higher flow rate at the inlet. We found that branches harboring aneurysms were characterized by high WSS and high WSS gradients. Among all assessed variables, the aneurysm initiation site most consistently coincided with peaks of temporal variation in the WSS magnitude.

External Ventricular Catheter Placement: How to Improve.

This cadaveric study outlines the efficiency, safety and precision of cerebral ventricular catheter placement comparing classical freehand technique using anatomical landmarks, neuronavigation and XperCT-guided assistance.

Augmented reality-assisted skull base surgery.

Neuronavigation is widely considered as a valuable tool during skull base surgery. Advances in neuronavigation technology, with the integration of augmented reality, present advantages over traditional point-based neuronavigation. However, this development has not yet made its way into routine surgical practice, possibly due to a lack of acquaintance with these systems. In this report, we illustrate the usefulness and easy application of augmented reality-based neuronavigation through a case example of a patient with a clivus chordoma. We also demonstrate how augmented reality can help throughout all phases of a skull base procedure, from the verification of neuronavigation accuracy to intraoperative image-guidance.

Intra-aneurysmal flow patterns: illustrative comparison among digital subtraction angiography, optical flow, and computational fluid dynamics.

BACKGROUND AND PURPOSE: Digital subtraction angiography is the gold standard vascular imaging and it is used for all endovascular treatment of intracranial anerysms. Optical flow imaging has been described as a potential method to evaluate cerebral hemodynamics through DSA. In this study, we aimed to compare the flow patterns measured during angiography, by using an optical flow method, with those measured by using computational fluid dynamics in intracranial aneurysms. MATERIALS AND METHODS: A consecutive series of 21 patients harboring unruptured saccular intracranial aneurysms who underwent diagnostic angiography before treatment was considered. High-frame-rate digital subtraction angiography was performed to obtain an intra-aneurysmal velocity field by following the cardiac-modulated contrast wave through the vascular structures by using optical flow principles. Additionally, computational fluid dynamics modeling was performed for every case by using patient-specific inlet-boundary conditions measured with the optical flow method from both DSA and 3D rotational angiography datasets. Three independent observers compared qualitatively both the inflow direction and the apparent recirculation in regular DSA, optical flow images, and computational fluid dynamics flow patterns for each patient; κ statistics were estimated. RESULTS: We included 21 patients. In 14 of these 21, the flow patterns were conclusive and matching between the optical flow images and computational fluid dynamics within the same projection view (κ = .91). However, in only 8 of these 14 patients the optical flow images were conclusive and matching regular DSA images (observer κ = 0.87). In 7 of the 21 patients, the flow patterns in the optical flow images were inconclusive, possibly due to improper projection angles. CONCLUSIONS: The DSA-based optical flow technique was considered qualitatively consistent with computational fluid dynamics outcomes in evaluating intra-aneurysmal inflow direction and apparent recirculation. Moreover, the optical flow technique may provide the premises for new solutions for improving the visibility of flow patterns when contrast motion in DSA is not apparent. This technique is a diagnostic method to evaluate intra-aneurysmal flow patterns and could be used in the future for validation and patient evaluation.

Non-assisted versus neuro-navigated and XperCT-guided external ventricular catheter placement: a comparative cadaver study.

BACKGROUND AND PURPOSE: Accurate placement of an external ventricular drain (EVD) for the treatment of hydrocephalus is of paramount importance for its functionality and in order to minimize morbidity and complications. The aim of this study was to compare two different drain insertion assistance tools with the traditional free-hand anatomical landmark method, and to measure efficacy, safety and precision. METHODS: Ten cadaver heads were prepared by opening large bone windows centered on Kocher's points on both sides. Nineteen physicians, divided in two groups (trainees and board certified neurosurgeons) performed EVD insertions. The target for the ventricular drain tip was the ipsilateral foramen of Monro. Each participant inserted the external ventricular catheter in three different ways: 1) free-hand by anatomical landmarks, 2) neuronavigation-assisted (NN), and 3) XperCT-guided (XCT). The number of ventricular hits and dangerous trajectories; time to proceed; radiation exposure of patients and physicians; distance of the catheter tip to target and size of deviations projected in the orthogonal plans were measured and compared. RESULTS: Insertion using XCT increased the probability of ventricular puncture from 69.2 to 90.2 % (p = 0.02). Non-assisted placements were significantly less precise (catheter tip to target distance 14.3 ± 7.4 mm versus 9.6 ± 7.2 mm, p = 0.0003). The insertion time to proceed increased from 3.04 ± 2.06 min. to 7.3 ± 3.6 min. (p < 0.001). The X-ray exposure for XCT was 32.23 mSv, but could be reduced to 13.9 mSv if patients were initially imaged in the hybrid-operating suite. No supplementary radiation exposure is needed for NN if patients are imaged according to a navigation protocol initially. CONCLUSION: This ex vivo study demonstrates a significantly improved accuracy and safety using either NN or XCT-assisted methods. Therefore, efforts should be undertaken to implement these new technologies into daily clinical practice. However, the accuracy versus urgency of an EVD placement has to be balanced, as the image-guided insertion technique will implicate a longer preparation time due to a specific image acquisition and trajectory planning.

Quantification of internal carotid artery flow with digital subtraction angiography: validation of an optical flow approach with Doppler ultrasound.

BACKGROUND AND PURPOSE: Digital subtraction angiography is the reference standard technique to evaluate intracranial vascular anatomy and used on the endovascular treatment of vascular diseases. A dedicated optical flow-based algorithm was applied to DSA to measure arterial flow. The first quantification results of internal carotid artery flow validated with Doppler sonography are reported. MATERIALS AND METHODS: We included 22 consecutive patients who underwent endovascular procedures. To assess the sensitivity of the algorithm to contrast agent-blood mixing dynamics, we acquired high-frame DSA series (60 images/s) with different injection rates: 1.5 mL/s (n = 19), 2.0 mL/s (n = 18), and 3.0 mL/s (n = 13). 3D rotational angiography was used to extract the centerline of the vessel and the arterial section necessary for volume flow calculation. Optical flow was used to measure flow velocities in straight parts of the ICAs; these data were further compared with Doppler sonography data. DSA mean flow rates were linearly regressed on Doppler sonography measurements, and regression slope coefficient bias from value 1 was analyzed within the 95% confidence interval. RESULTS: DSA mean flow rates measured with the optical flow approach significantly matched Doppler sonography measurements (slope regression coefficient, b = 0.83 ± 0.19, P = .05) for injection rate = 2.0 mL/s and circulating volumetric blood flow <6 mL/s. For injection rate = 1.5 mL/s, volumetric blood flow <3 mL/s correlated well with Doppler sonography (b = 0.67 ± 0.33, P = .05). Injection rate = 3.0 mL/s failed to provide DSA-optical flow measurements correlating with Doppler sonography because of the lack of measurable pulsatility. CONCLUSIONS: A new model-free optical flow technique was tested reliably on the ICA. DSA-based blood flow velocity measurements were essentially validated with Doppler sonography whenever the conditions of measurable pulsatility were achieved (injection rates = 1.5 and 2.0 mL/s).

[Continuous EEG monitoring for aneurysmal subarachnoid hemorrhage]. / Intérêt du monitoring EEG continu dans la prise en charge de l'hémorragie sous-arachnoidienne.

Subarachnoid hemorrhage (SAH) still carries a high morbidity and mortality, despite improvement in surgical and medical management. Seizures and delayed cerebral ischemia (DCI) secondary to vasospasm or cortical spreading depression are frequent after SAH. Continuous EEG allows early detection of non-convulsive seizures or delayed cerebral ischemia and may become a promissing tool in the monitoring of SAH patients. However, its use in clinical practice is still limited because many resources are required for recording and analyzing continuous EEG. Moreover, we require more data to confirm the relationship between aggressive treatment of non-convulsive seizure or delayed cerebral ischemia triggered by continuous EEG and outcome.

[Hybrid operation theatre from the perspective of neurosurgery]. / Hybridoperationssaal aus Sicht der Neurochirurgie.

BACKGROUND: The integration of hybrid operation theatre into neurosurgical and neuroradiological routines is revolutionizing in particular the management of neurovascular emergencies, such as subarachnoid aneurysmal hemorrhage (SAH) or ruptured arteriovenous malformations. RESULTS: The direct interaction between neurosurgeons and neuroradiologists in a joint environment changes and accelerates all diagnostic and therapeutic steps because all relevant procedures, including treatment control can be performed in a single room. Interventions of the skull base or the spine are also a domain of such hybrid theatre. CONCLUSION: As this new concept requires organisational changes throughout the entire patient management, a change of mindset is also needed at the institutional level in order to attain maximum benefits from such a setting.

Evaluation of the influence of inlet boundary conditions on computational fluid dynamics for intracranial aneurysms: a virtual experiment.

Inlet boundary conditions (BCs) are important inputs of computational fluid dynamics (CFD) in intracranial aneurysms (IAs). We performed sensibility analysis of CFD to different inlet BCs applied to illustrative patient-specific aneurysm-vessel geometry. BCs corresponding to generic and patient-specific pulsatile flow curves were applied to three vascular geometry models of carotid ophthalmic aneurysm-vessel geometry, in which the inlet lengths were different. CFD outcomes were compared to high frame rate Digital Subtraction Angiography (DSA) sequences. The streamlines were found to match contrast agent (CA) motion pattern in the case where the non-truncated inlet vessel model was coupled to generic Womersley BC solution. Even though dynamic pressure loss (55%) was equal for all models and different BCs, the minimum distance to wall of the fastest velocity fields for the non-truncated model was significantly larger (p=0.002) and mean vorticity sign was different. Significant difference in spatial distributions of wall shear stress (WSS) and oscillating shear stress index (OSI) was found in aneurysm between Womersley and Plugflow BC conditions, only. Reliable CFD for carotid ophthalmic aneurysm would require avoiding truncation of the inlet vessel to be independent of the solution applied to generate CFD.

Transvenous embolization of a ruptured deep cerebral arteriovenous malformation. A technical note.

Ruptured cerebral arteriovenous malformations (AVMs) usually require treatment to avoid re-bleeding. Depending on the angioarchitecture and center strategy, the treatment can be surgical, endovascular, radiosurgical or combined methods. The classic endovascular approach is transarterial, but sometimes it is not always applicable. The transvenous approach has been described as an alternative for the endovascular treatment of small AVMs when arterial access or another therapeutic method is not possible. This approach can be considered when the nidus is small and if there is a single draining vein. We present a technical note on a transvenous approach for the treatment of a ruptured AVM in a young patient.

A DSA-based method using contrast-motion estimation for the assessment of the intra-aneurysmal flow changes induced by flow-diverter stents.

BACKGROUND AND PURPOSE: Flow-diverter stents modify intra-aneurysmal blood flow and induce the progressive thrombosis of intracranial aneurysms followed by stable vascular reconstruction. The aim of this study was to report a new method for the appraisal of intracranial blood flow from DSA performed during endovascular treatment procedures. MATERIALS AND METHODS: A cohort of 24 patients with unruptured IAs who underwent FDS implantation was prospectively recruited. Pre- and post-DSA sequences in combination with 3D rotational angiography were acquired. The quantification of arterial and intra-aneurysmal flow was accomplished by using an optical flow approach. Flow reduction was assessed by using a new metric termed the mean aneurysm flow amplitude ratio. The correlation between the MAFA ratio and the incidence of aneurysm thrombosis was assessed by using receiver operating characteristic analysis and the Fisher exact test when the optimum Youden index was found. RESULTS: The quantification of flow was successfully achieved in 21 of 24 patients (87.5%). On the imaging follow-up, 18 aneurysms developed complete thrombosis (87.5%) and 3 displayed residual circulation (12.5%). The threshold analysis of the MAFA ratio significantly predicted thrombosis at 12 months below a threshold of 1.03 (P=.035). There was no significant correlation between the time for complete occlusion of the aneurysm and contrast stagnation inside the aneurysm after treatment (P>.05). CONCLUSIONS: The MAFA ratio based on DSA flow quantification appears to be a reliable predictor for the assessment of stent treatment outcomes in this small study. These results open the door for perioperative flow quantification and provide indices that may help clinicians make appropriate intraprocedural decisions.

@neurIST - chronic disease management through integration of heterogeneous data and computer-interpretable guideline services.

This paper presents an overview of computerised decision support for clinical practice. The concept of computer-interpretable guidelines is introduced in the context of the @neurIST project, which aims at supporting the research and treatment of asymptomatic unruptured cerebral aneurysms by bringing together heterogeneous data, computing and complex processing services. The architecture is generic enough to adapt it to the treatment of other diseases beyond cerebral aneurysms. The paper reviews the generic requirements of the @neurIST system and presents the innovative work in distributing executable clinical guidelines.

Early surgery for brainstem cavernomas.

BACKGROUND: The purpose was to review our experience with the surgical management of brainstem cavernomas (BSCs) and especially the impact of the surgical timing on the clinical outcome. METHOD: We retrospectively reviewed 22 patients harboring a BSC, who underwent 23 procedures. FINDINGS: Surgery was carried out during the early stage after the last haemorrhage, with a mean delay of 21.6 days (range 4-90 days). Sixteen procedures were performed after a first bleeding event while seven after multiple bleedings. Complete resection was achieved in 19 patients (86.4%). Early after surgery, 12 patients (52.2%) improved neurologically, 5 (21.7%) were stable and 6 (26.1%) worsened. New postoperative deficits were noted after 9 procedures (39.1%). Statistically significant factors for postoperative aggravation were: late surgery (P = 0.046) and multiple bleedings (P = 0.043). No patient operated on within the first 19 days after bleeding did worsen (n = 11), as opposed to 6 out of 12 who did when operated on later. After a mean follow-up of 44.9 months, 20 patients (90.9%) were improved, 1 patient (4.6%) was worse and 1 patient was lost to follow-up (4.6%), after reoperation for rebleeding of a previously completely resected cavernoma. Late morbidity was reduced to 8.6%. The mean Glasgow Outcome Scale (GOS) at the end of the follow-up period was 4.24, compared to a mean preoperative GOS of 3.22 (P<0.001). Complete neurological recovery of motor deficits, sensory disturbances, cranial nerves (CNs), internuclear ophtalmoplegia and cerebellar dysfunction were respectively 41.7%, 38.5%, 52.6%, 60.0% and 58.3%. Among the most affected CNs: CN 3, CN 5 and CN 7 were more prone to completely recover, respectively in 60.0%, 70.0% and 69.2%. CONCLUSIONS: Surgical removal of BSCs is feasible in experienced hands with acceptable morbidity and good outcome. Early surgery and single bleeding were associated with better surgical results.

Inhibition of T-type calcium channels protects neurons from delayed ischemia-induced damage.

Intracellular calcium increase is an early key event triggering ischemic neuronal cell damage. The role of T-type voltage-gated calcium channels in the neuronal response to ischemia, however, has never been studied. Using an in vitro model of ischemia-induced delayed cell death in rat organotypic hippocampal slice cultures, we show that T-type calcium channels inhibitors drastically reduce ischemic cell damage. Immunostaining studies reveal the existence of Ca(V)3.1 and Ca(V)3.2 types of low-voltage-activated calcium channels in rat organotypic hippocampal cultures. Low extracellular calcium (100 nM) or increase of intracellular calcium buffering ability by BAPTA-acetoxymethyl ester significantly reduced ischemia-induced neuronal damage. Pharmacological inhibition of the T-type calcium current by mibefradil, kurtoxin, nickel, zinc, and pimozide during the oxygen-glucose deprivation episode provided a significant protection against delayed neuronal death. Mibefradil and nickel exerted neuroprotective effects, not only if administrated during the oxygen-glucose deprivation episode but also in conditions of postischemic treatment. These data point to a role of T-type calcium currents in ischemia-induced, calcium-mediated neuronal cell damage and suggest a possible new pharmacological approach to stroke treatment.

Nasopharynx paraganglioma with extension in the clivus.

Paraganglioma is a rare benign tumor arising from the sympathetic nervous system. Here we describe an exceptional case of a paraganglioma located in the nasopharynx with an extension through the clivus up to the dura. Atypically, no contact with any major vessels was found. A radical resection of the mass was performed by an anterior transmaxillary approach through a Le Fort I osteotomy. One year follow up reveals no signs of local or distant recurrence. No cosmetic changes can be observed after the surgery and nasal and masticatory functions are unmodified. We review the clinical presentation, workup of paraganglioma, as well as the surgical approaches to the clivus.

Double-lumen balloon microcatheter-assisted occlusion of cerebral vessels with coils: a technical note.

The purpose of this study was to describe a balloon-assisted double-lumen microcatheter technique to perform a controlled and tight coil packing of a vascular segment for vessel occlusion. This technique can be performed immediately after a test occlusion with the balloon kept in place and was, as illustrated in six cases, in our experience safe, straight forward to use and fast.