Aspirin interruption before neurosurgical interventions: A controversial problem.

Aspirin is widely used for primary or secondary prevention of ischemic events. At the same time, chronic aspirin consumption can affect blood clot formation during surgical intervention and increase intraoperative blood loss. This is especially important for high-risk surgery, including neurosurgery. Current European Society of Cardiology guidelines recommend aspirin interruption for at least 7 d before neurosurgical intervention, but this suggestion is not supported by clinical evidence. This narrative review presents evidence that challenges the necessity for aspirin interruption in neurosurgical patients, describes options for aspirin effect monitoring and the clinical implication of these methods, and summarizes current clinical data on bleeding risk associated with chronic aspirin therapy in neurosurgical patients, including brain tumor surgery, cerebrovascular procedures, and spinal surgery.

One-step orbit reconstruction using PMMA implants following hyperostotic sphenoid wing meningioma removal: Evolution of the technique in short clinical series.

Purpose: To report our experience with patient specific implants for one-step orbit reconstruction following hyperostotic SWM removal and to describe the evolution of the technique through three surgical cases. Methods: Three cases of one-step SWM removal and orbit reconstruction are described. All cases are given consecutively to describe the evolution of the technique. Hyperostotic bone resection was facilitated by electromagnetic navigation and cutting guides (templates). Based on a 3D model, silicone molds were made using CAD/CAM. Then PMMA implant was fabricated from these molds. The implant was adjusted and fixed to the cranium with titanium screws after tumor removal. Results: Following steps of the procedure changed over these series: hyperostotic bone resection, implant thickness control, implant overlay features, anatomic adjustments, implant fixation. The proptosis resolved in all cases. In one patient the progressive visual acuity deterioration was recognized during the follow-up. No oculomotor disturbances and no tumor regrowth were found at the follow-up. Conclusion: CAD/CAM technologies enable creation of implants of any size and configuration, and thereby, to increase the extent of bony resection and lower the risk of tumor progression. The procedure is performed in one step which decreases the risk of postoperative morbidity.

Real-time laser speckle contrast imaging for intraoperative neurovascular blood flow assessment: animal experimental study.

The use of various blood flow control methods in neurovascular interventions is crucial for reducing postoperative complications. Neurosurgeons worldwide use different methods, such as contact Dopplerography, intraoperative indocyanine videoangiography (ICG) video angiography, fluorescein angiography, flowmetry, intraoperative angiography, and direct angiography. However, there is no noninvasive method that can assess the presence of blood flow in the vessels of the brain without the introduction of fluorescent substances throughout the intervention. The real-time laser-speckle contrast imaging (LSCI) method was studied for its effectiveness in controlling blood flow in standard cerebrovascular surgery cases in rat common carotid arteries, such as proximal occlusion, trapping, reperfusion, anastomosis, and intraoperative vessel thrombosis. The real-time LSCI method is a promising method for use in neurosurgical practice. This approach allows timely diagnosis of intraoperative disturbance of blood flow in vessels in cases of clip occlusion or thrombosis. Additionally, LSCI allows us to reliably confirm the functioning of the anastomosis and reperfusion after removal of the clips and thrombolysis in real time. An unresolved limitation of the method is noise from movements, but this does not reduce the value of the method. Additional research is required to improve the quality of the data obtained.

Optochiasmatic cavernoma: Surgical treatment and outcomes.

OBJECTIVE: Optochiasmatic cavernoma is an extremely rare cerebral lesion. They account for approximately 1% of all cavernomas of the central nervous system. Reports on this pathology are limited. Abrupt visual deterioration is a common symptom of the disease. Treatment strategy and visual outcomes after different treatment approaches remain a subject for discussion. METHODS: Patients operated in a period 2005-2021 were analyzed in this study. All patients preoperatively underwent computed tomography (CT) scan, CT-angiography, and magnetic resonance imaging (MRI). Visual function of the patients was assessed pre-op, post-op and at the follow-up. Duration of visual dysfunction was noted as well. Surgical details were also extracted from medical notes. All patients were followed up, and control MRI was performed one month after operation. We assessed surgical series of optochiasmatic cavernomas published for last 10 years. Further comparative analysis with our data was performed. RESULTS: Five patients were included into this study. There were four men and one woman. Mean age comprised 33.8 years (range 20-48 years). Most patients were admitted to our hospital due to visual disturbances (80%). Visual function improved in four patients. Visual function was unchanged in one patient, lacking visual disturbancies pre-op. Complication developed in one patient. CONCLUSIONS: Optochiasmatic cavernomas are encountered extremely rare. Despite the use of contemporary diagnostic options, differential diagnosis remains challenging. Full diagnostic work-up is mandatory. After the diagnosis is made, surgical treatment should be considered first. Total microsurgical or endoscopic transsphenoidal removal of the optochiasmatic cavernoma is a relatively safe and effective treatment method facilitating improvement of visual function.

Spinal dural cerebrospinal fluid fistula as a cause of spontaneous intracranial hypotension syndrome: Diagnosis and surgical treatment.

Spontaneous intracranial hypotension (SIH) syndrome most often occurs following a cerebrospinal fluid (CSF) fistula that develops in the spinal space. Neurologists and neurosurgeons lack an understanding of the pathophysiology and diagnosis of this disease, which can make timely surgical care difficult. With the correct diagnostic algorithm, it is possible to identify the exact location of the liquor fistula in 90% of cases; subsequent microsurgical treatment can save the patient from the symptoms of intracranial hypotension and restore the ability to work. Female patient, 57 years old, was admitted with SIH syndrome. Magnetic resonance imaging (MRI) of the brain with contrast confirmed signs of intracranial hypotension. Computed tomography (CT) myelography was performed to pinpoint the location of the CSF fistula. The diagnostic algorithm and successful microsurgical treatment of a patient with spinal dural CSF fistula at the Th3-4 level using a posterolateral transdural approach. The patient was discharged on day 3 after the surgery when these complaints regressed completely. At the control examination of the patient 4 months postoperatively, there were no complaints. Identification of the cause and location of spinal the CSF fistula is a complex process that requires several stages of diagnosis. Examination of the entire back with MRI, CT myelography, or subtraction dynamic myelography is recommended. Microsurgical repair of a spinal fistula is an effective method for the treatment of SIH. The posterolateral transdural approach is effective in the repair of a spinal CSF fistula located ventrally in the thoracic spine.

Stability and Thrombogenicity Analysis of Collagen/Carbon Nanotube Nanocomposite Coatings Using a Reversible Microfluidic Device.

Currently, the development of stable and antithrombogenic coatings for cardiovascular implants is socially important. This is especially important for coatings exposed to high shear stress from flowing blood, such as those on ventricular assist devices. A method of layer-by-layer formation of nanocomposite coatings based on multi-walled carbon nanotubes (MWCNT) in a collagen matrix is proposed. A reversible microfluidic device with a wide range of flow shear stresses has been developed for hemodynamic experiments. The dependence of the resistance on the presence of a cross-linking agent for collagen chains in the composition of the coating was demonstrated. Optical profilometry determined that collagen/c-MWCNT and collagen/c-MWCNT/glutaraldehyde coatings obtained sufficiently high resistance to high shear stress flow. However, the collagen/c-MWCNT/glutaraldehyde coating was almost twice as resistant to a phosphate-buffered solution flow. A reversible microfluidic device made it possible to assess the level of thrombogenicity of the coatings by the level of blood albumin protein adhesion to the coatings. Raman spectroscopy demonstrated that the adhesion of albumin to collagen/c-MWCNT and collagen/c-MWCNT/glutaraldehyde coatings is 1.7 and 1.4 times lower than the adhesion of protein to a titanium surface, widely used for ventricular assist devices. Scanning electron microscopy and energy dispersive spectroscopy determined that blood protein was least detected on the collagen/c-MWCNT coating, which contained no cross-linking agent, including in comparison with the titanium surface. Thus, a reversible microfluidic device is suitable for preliminary testing of the resistance and thrombogenicity of various coatings and membranes, and nanocomposite coatings based on collagen and c-MWCNT are suitable candidates for the development of cardiovascular devices.

Mathematical Analysis of the Effectiveness of Screening for Intracranial Aneurysms in First-Degree Relatives of Persons with Subarachnoid Hemorrhage.

OBJECTIVE: Population screening for aneurysms in patients with risk factors and preventive surgical treatment are beneficial according to numerous studies. One of the most significant risk factors is heredity, namely, the presence of first-degree relatives (FDR) with aneurysmal subarachnoid hemorrhage (aSAH). Nevertheless, there are still no generally accepted approaches or evidence bases regarding the benefits of the aneurysm screening strategy. METHODS: Mathematical modeling of the dynamics of aneurysm development in the population was carried out using an algorithm implementing a discrete Markov's chain. To implement the model, all probabilities of events and distributions are taken from available literature sources. Three-dimensional time of flight noncontrast magnetic resonance angiography was chosen as a screening method. Patients underwent preventive surgical treatment if an aneurysm was detected. RESULTS: Screening and preventive treatment in the general population reduces the prevalence of aneurysms by 1.74% (3.44% in the FDR group) and the prevalence of aSAH by 14.36% (37.48% in the FDR group). Mortality due to aSAH was reduced by 14.44%. The number of disabilities also decreases. The occurrence of deep disability was reduced by 20.2% in the FDR group. Economic analysis of the part of the population consisting of FDRs showed annual savings of ies also decr CONCLUSIONS: The mathematical model demonstrated that screening and preventive treatment of cerebral aneurysms can reduce aSAH-associated morbidity and mortality. In the FDR group, there was decrease in the prevalence of aSAH and decrease in associated mortality. Screening for cerebral aneurysms is cost-effective.

"Unshaved Intradermal Running Suture for Elective Cranial Neurovascular Surgeries".

OBJECTIVE: In this paper, we analyze the experience and propose a method of incision and stitching of the postoperative scalp wound without shaving hair in elective neurosurgical interventions. METHODS: Between January 2021 and May 2022, 44 patients with various neurovascular pathologies were included in the study. The age of the patients varied from 28 to 58 years. All patients underwent elective surgical interventions with intradermal cosmetic sutures without shaving hair. The results of published observational series of neurosurgical patients with unshaved hair were also analyzed. RESULTS: Treatment of the surgical field, scalp, and incision were performed without shaving hair in 44 cases. The technique of intradermal suture without shaving hair was used in 31 cases of the classical pterional approach, in 11 cases of minipteronal, in 1 case of parasagittal, and in 1 case of retrosigmoid suboccipittal approaches. The mean age of the patients was 47.5 years (±8.82). The average length of stay in the clinic was 8.02 days (±2.04). The sutures were removed on the fifth-eighth day. All cases were operated on for elective neurovascular interventions: aneurysms without rupture (95.4%), arteriovenous malformations (2.3%), and cavernous angiomas (2.3%). All but one patient (2.3%) had no wound complications-the suture ruptured at the stage of its removal from the skin. CONCLUSIONS: Our results also show that the use of a nonresorbable intradermal suture combined with hair preservation does not affect the risk of infection.

Laser Speckle Contrast Imaging in Neurosurgery: A Systematic Review.

BACKGROUND: Intraoperative study of blood flow in the brain vessels is among the most critical topics of modern neurosurgery. One of the promising methods for intraoperative monitoring of blood flow is laser speckle contrast imaging (LSCI). This systematic review aims to analyze the experience of using intraoperative LSCI in neurosurgical interventions. METHODS: The literature search was carried out in the PubMed and Web of Science databases using the keywords "Laser-Speckle," "Laser Speckle," "Laser speckle contrast imaging," and "LSCI." We allowed the search to include the following criteria: 1) publication in the English language, 2) full access to the article, 3) information about the method of treatment, and 4) the results presented for at least one patient. RESULTS: The initial search resulted in the detection of 508 publications, of which 476 were eliminated during the initial assessment of titles and abstracts. Two more articles were excluded due to the lack of data in the English language. Twenty articles were found to be focused on nonhuman studies and therefore were excluded. In three more studies treatment of non-neurosurgical patients was reported. The final analysis included 8 articles with 102 patients overall. CONCLUSIONS: LSCI is a promising intraoperative method for intraoperative cerebral blood flow assessing. This method offers several advantages over other modalities. The experience of use is limited to a small number of case series. Further investigation of the method and its implementation in clinical practice is needed.

Surgical Treatment of Large and Giant Anterior Cerebral Artery Aneurysms in the Endovascular Era: Analysis of Large Clinical Series.

OBJECTIVE: Analysis of results of surgical treatment of 112 patients with large and giant anterior cerebral artery (ACA) aneurysms. METHODS: This is the largest clinical series of large and giant ACA aneurysms ever reported. Retrospective analysis of medical charts, radiographic studies, and intraoperative videos was performed. Univariate and multivariate analysis of relations among 3 types of outcomes (complete aneurysm occlusion, ischemic complications, and clinical outcomes) and predicting factors was performed. RESULTS: Most aneurysms were communicant (84.8%). Aneurysms of the A1 segment and distal segments (A2-A5) were encountered rarely. Complete aneurysm occlusion (class I) was shown in 95 cases (90.5%). In 4 patients, only exploration and wrapping were performed because of severe atherosclerosis and chronic intraluminal thrombi. Partial occlusion (class III) was shown in 2 patients, and neck residual (class II) in 4 patients. Cerebral ischemia developed in 29 patients postoperatively. Occlusion or injury of the A1 segment and anterior communicating artery perforators and recurrent branch of Heubner were the most common reason for ischemic complications. At follow-up, 97 patients (86.6%) had favorable outcomes. Ten patients (8.9%) had unfavorable outcomes because of postoperative complications. CONCLUSIONS: Microsurgery provides effective and relatively safe occlusion of complex ACA aneurysms. Direct clipping can be applied in most cases independent of their precise location. In certain cases, alternative methods can be safely used. According to multivariate analysis, giant aneurysm size, aneurysm-related mass effect, involvement of large arterial branches in the aneurysm wall, and intraoperative complications were significant predicting factors for ischemic complications.

Surgical Treatment Efficacy of CSF-Venous Fistulas: Systematic Review.

BACKGROUND: Cerebrospinal fluid (CSF)-venous fistula presents a pathologic connection between spinal subarachnoid space and adjacent epidural vein or veins. It is one of the 3 main causes of spontaneous intracranial hypotension along with dural defects and meningeal diverticulum. We performed a systematic review of the literature and analyzed individual participants' data focusing on clinical outcomes after different treatment modalities of CSF-venous fistula. METHODS: Systematic review was conducted according to PRISMA recommendations. Literature search was performed in PubMed and Web of Science databases with following key phrases: "CSF-venous fistula", "Spontaneous intracranial hypotension". Overall, 97 articles were found during the initial search; 15 were included for the final analysis, with a total number of 137 patients. RESULTS: Epidural blood patch (EBP) was performed as a first-line treatment in 37.1% of patients in individual data group, often not combined with fibrin glue (61.5%). Either partial (69.2%) or no resolution (30.8%) of symptoms was achieved after EBP injection. Nerve root ligation was the most common method of exclusion of CSF-venous fistula. Complete resolution of symptoms was achieved in 69.0% of patients, in 21.4% it was partial and in 9.5% no regress was found. Endovascular treatment was described only in 1 study. CONCLUSIONS: Surgical ligation of fistula is a treatment of choice. In approximately 70% of patients complete long-term resolution of symptoms is achieved after surgery. Endovascular treatment and fibrin glue injections are prospective and evolving options, which require further investigation.

Analysis of a Novel Entry Point for Freehand Ventriculostomy Using Computerized Tomography Scans.

Background External ventricular drain (EVD) placement is one of the most common procedures in neurosurgery. Neurosurgeons generally prefer to access the ventricles via Kocher's point since it is the most common point of entry to this area; however, this point is used to describe different anatomic landmarks and is not well-defined. Objective The present study aims to describe and provide an anatomical assessment of a novel ventriculostomy access point developed by the authors using computerized tomography (CT) scans performed on 100 patients. Materials and methods Data were collected from 100 randomly selected patients with normal ventricular anatomy found on their 1.0 mm-slice CT scans performed at the Burdenko Neurosurgical Center from March 2019 to June 2021. The CT inclusion criteria were: CT slices < or = to 1 mm and absence of brain herniation. Patients with brain mass lesions, severe brain edema, and pneumocephalus were excluded. Age, gender, and ventricular size were not exclusion criteria. Results The mean patient age was 43.58 years (range 4-73), with 50 men and 50 women. The mean Evan's index was 25.7 % (SD=4.38 %, range 10.2-41.0 %). No differences were found between the angles of EVD placement on either side (89.50±1.22 degrees on the right and 89.60±1.14 degrees on the left). Hence, nearly all EVD cases had been placed perpendicularly to the skull surface at a pinpoint location. Conclusion The proposed point of successful ventriculostomy placement in this study was 3 cm from the bregma along the coronal suture. The angle of EVD placement was approximately 90 degrees in almost all patients and was independent of the patient's age and the side of the head that was entered. Little correlation was found between the value of the entry angle and Evan's index. The point is simply identifiable, and its entry is easily accessible in practice.

Surgical treatment of ruptured right middle cerebral artery mycotic aneurysm and central nervous system aspergillosis: Clinical case and literature review.

BACKGROUND: Central nervous system (CNS) aspergillosis is more often met in patients with expressed immune suppression. Still, in 50% of cases of meningitis caused by Aspergillus spp., it is observed in patients without expressed immune suppression. The prognosis of CNS aspergillosis is unfavorable with the general rate of lethality around 70%. CASE DESCRIPTION: Clinical case of a 58-year-old man who developed an Aspergillus abscess in the chiasmosellar region and an associated mycotic aneurysm of the right middle cerebral artery (MCA) and intracerebral hemorrhage. Microsurgical clipping of the fusiform-ectatic aneurysm of the right MCA in the conditions of rupture was performed. An extra-intracranial micro anastomosis was formed on the right. An open biopsy of the neoplasm in the chiasmosellar region was made. The neoplasm was yellow and destroyed the bone plate of the skull base. Biopsy results: Mycotic lesion (aspergillosis). The analysis of surgical treatment for mycotic aneurysms in the acute period of hemorrhage in patients with aspergillosis revealed a high rate of lethality. The issue of the feasibility and effectiveness of complicated revascularization interventions in the patients with hemorrhage and aspergillosis remains unsolved. CONCLUSION: The lack of generally accepted tactics of the treatment of this pathology requires further studies and systemic analysis. A high risk of the lethal outcome in patients with invasive mycotic infection and rupture of mycotic aneurysm highlight the importance of timely diagnostics and the beginning of antimycotic therapy. WThe issue of the evaluation of the revascularization methods effectiveness in patients after surgical treatment of a mycotic aneurysm associated with cerebral aspergillosis remains poor.

External Ventricular Drainage Complication Risks and Accuracy Analysis.

OBJECTIVE: The setting of external ventricular drainage (EVD) is one of the most frequent procedures in the neurosurgical practice. However, complication risks of this procedure may grow from 5% to 39%. The number of publications concerning the advancement of ventricular drainage setting technique and complication risks identification is increasing year after year. We posed a question on the dependence of complication risks and catheter setting accuracy on the different factors of routine practice of the N. N. Burdenko National Medical Research Center for neurosurgery within the scope of this work. METHODS: The data on patients whose EVD was set in the premotor area in 2019 were collected retrospectively. The surgeons were divided into 3 groups according to their experience valued in years. RESULTS: The result of drainage setting was considered satisfactory if its end was in the frontal horn or body of the ipsilateral ventricle. Generally, 122 patients passed EVD placement during 2019. According to computed tomography scans of the brain, the drainage position was satisfactory in 85 patients (75.9%) and unsatisfactory in 27 patients (24.1%). CONCLUSIONS: The procedures were performed by surgeons with <2 years of experience in 16.1% of cases, 2-5 years of experience in 25% of cases, and >5 years of experience in 58.9% of cases. The complication risk and accuracy of drainage setting do not depend on surgeon experience, type of bone access, and position in the premotor area.

Neuronavigation device for stereotaxic external ventricular drainage insertion.

BACKGROUND: The insertion of an external ventricular drainage (EVD) is one of the most frequently used neurosurgical procedures. It is performed to adjust intracranial hypertension in cases of severe craniocerebral injury, acute posthemorrhagic hydrocephalus, meningitis, and oncological diseases related to impaired circulation of cerebrospinal fluid circulation (CSF). METHODS: In 2020, three patients with subarachnoid aneurysmal hemorrhage underwent insertion of an EVD navigation percutaneous stereotaxic device. Three cases introduced. RESULTS: In all cases, satisfactory EVD functioning was noted during the surgery and during the early postoperative period. The EVD insertion procedure took an average of 10 min. The EVD insertion route calculations using the software took about 5-15 min. No cases showed any infection, hemorrhagic complications, or EVD dysfunction. According to the control brain computed tomography data, the catheter position was satisfactory and corresponded to the target coordinates in all cases. CONCLUSION: The use of the device, with its high accuracy and efficiency, can reduce the incidence of unsatisfactory EVD implantation cases in patients with neurosurgical pathology.

External Ventricular Drainage in Patients With Acute Aneurysmal Subarachnoid Hemorrhage After Microsurgical Clipping: Our 2006-2018 Experience and a Literature Review.

Introduction The placement of an external ventricular drain (EVD) is widely practiced in neurosurgery for various diseases and conditions accompanied by impaired cerebrospinal fluid (CSF) circulation, intracranial hypertension (ICHyp), intraventricular hemorrhage (IVH), and hydrocephalus. Specialists have been using this method in patients with acute aneurysmal subarachnoid hemorrhage (aSAH) for more than 50 years. Extensive experience gained at the Burdenko Neurosurgical Center (BNC) in Moscow, the Russian Federation, in the surgical treatment of patients with acute aSAH enabled us to describe the results of using an EVD in patients after microsurgery. The objective of the research was to assess the effectiveness and safety of the EVD and clarify the indications for the microsurgical treatment of aneurysms in patients with acute SAH. Materials and methods From 2006 until the end of 2018, 645 patients registered in the BNC database underwent microsurgery for acute (0-21 days) aSAH. During the case study, we assessed the severity of hemorrhage according to the Fisher scale, the condition of patients on the Hunt-Hess (H-H) scale during surgery, the time of placement of EVD (before, during, and after surgery), and the duration of EVD. The number of patients with parenchymal intracranial pressure (ICP) transducers was assessed by the degree of correlation of ICP data through the EVD and parenchymal ICP transducer. One of the aims of the research was to compare the frequency of using EVD and decompressive craniectomy (DCH). The incidence of EVD-associated meningitis was analyzed. The need for a ventriculoperitoneal shunt (VPS) in patients after using EVD was also assessed. Overall outcomes were assessed using a modified Rankin scale (mRS) at the time of patient discharge. Exclusion criteria were as follows: patients aged less than 18 years and the lack of assessed data. Patients undergoing endovascular and conservative treatments also were excluded. Results Among the patients enrolled in the study, 22% (n=142) had EVD. Among these, 99 cases (69.7%) had EVD installed in the operating room just before the start of the surgical intervention. In some cases, ventriculostomy was performed on a delayed basis (16.3%). A satisfactory outcome (mRS scores of 1 and 2) was observed in 24.7% (n=35). Moderate and profound disability at the time of discharge was noted in 55.7% (n=79). Vegetative outcome at discharge was noted in 8.4% (n=12), and mortality occurred in 12.3% (n=15). Conclusion EVD ensures effective monitoring and reduction of ICP. EVD is associated with a relatively low risk of infectious, liquorodynamic, and hemorrhagic complications and does not worsen outcomes when used in patients with aSAH. We propose that all patients in the acute stage of SAH with H-H severity of III-V should receive EVD immediately before surgery.

Treatment of postoperative vasospasm with intraarterial verapamil after removal of intracranial tumor: patient series.

BACKGROUND: The authors report on four clinical cases with intraarterial verapamil administration to resolve vasospasm in patients who underwent surgery for intracranial tumors. Iatrogenic subarachnoid hemorrhage after tumor resection and subsequent vasospasm (an increase in the systolic linear velocity of blood flow through the M1 segment of the middle cerebral artery of more than 250 cm/sec; Lindegaard index: 4.1) were observed in four patients during the early postoperative period after the removal of intracerebral tumors. Each vasospasm case was confirmed by angiography data, was clinically significant, and manifested as the development of a neurological deficit. OBSERVATIONS: Resolution of vasospasm with the intraarterial administration of verapamil was achieved in all four cases as confirmed by angiographic data in all four cases and complete regression of neurological symptoms in two cases. In all four presented cases, vasospasm was resolved; unfortunately, the resolution did not always lead to significant clinical improvement. However, lethal outcomes were avoided in two cases, and almost full recoveries were achieved in the other two. LESSONS: The authors believe that the removal of intracranial tumors can cause expected and potential complications, such as cerebral vasospasm, which must be diagnosed and treated in a timely manner.

On the many-body nature of intramolecular forces in FFLUX and its implications.

FFLUX is a biomolecular force field under construction, based on Quantum Chemical Topology (QCT) and machine learning (kriging), with a minimalistic and physically motivated design. A detailed analysis of the forces within the kriging models as treated in FFLUX is presented, taking as a test example a liquid water model. The energies of topological atoms are modeled as 3Natoms -6 dimensional potential energy surfaces, using atomic local frames to represent the internal degrees of freedom. As a result, the forces within the kriging models in FFLUX are inherently N-body in nature where N refers to Natoms . This provides a fuller picture that is closer to a true quantum mechanical representation of interactions between atoms. The presented computational example quantitatively showcases the non-negligible (as much as 9%) three-body nature of bonded forces and angular forces in a water molecule. We discuss the practical impact on the pressure calculation with N-body forces and periodic boundary conditions (PBC) in molecular dynamics, as opposed to classical force fields with two-body forces. The equivalence between the PBC-related correction terms in the general virial equation is shown mathematically.

Chondrosarcoma of the Skull Base: A Case Study and Literature Review.

Chondrosarcomas (CSs) are rare malignant tumors composed of cells derived from the transformed chondrocytes. Only 2% of the total cases of CS are found at the skull base, thus representing a 0.1-0.2% prevalence. We present the case of a patient with CS at the middle cranial fossa who was admitted for surgery to the Burdenko National Medical Research Center of Neurosurgery. In addition, we engage in a review of the literature to discuss the current approaches to the diagnostics and surgery of CS and delve deep into its embryo- and oncogenesis.

Formation During Lifetime of Arteriovenous Shunt in Developmental Venous Anomaly That Caused Intracerebral Hemorrhage.

BACKGROUND: Developmental venous anomaly (DVA) or venous angioma is a common anomaly of cerebral veins that is found incidentally in the majority of cases. There are few cases of arteriovenous shunting in DVA associated with a more malignant course of the disease. Whether these DVAs with shunts are of congenital pathology or lifetime formations is unclear. CASE DESCRIPTION: We report a case of lifetime arteriovenous shunt formation in DVA that caused intracerebral hemorrhage in a child. The patient underwent 2 sequential direct surgeries: an emergency evacuation of the intracerebral hematoma and a scheduled excision of the DVA with arteriovenous shunting. CONCLUSIONS: Arteriovenous shunting in DVA may develop during a lifetime and cause intracerebral hemorrhages. This case showed that localization of DVA with arteriovenous shunting in a noneloquent area enables its complete microsurgical excision with favorable functional outcomes.