Every Patent Foramen Ovale Should Be Closed

At present, the patent foramen ovale (PFO) does not receive the deserved medical attention. The PFO poses a serious threat to health and even the life of mankind. The first respective case report in the medical literature dates back to the 19th century. It led to death. The fact that a PFO is present in roughly 25% of people underscores its overall potential to cause harm. Yet at the same time, the sheer number discourages the medical community from screening for it and from treating it. About 5% of the population have particularly dangerous forms of PFOs. Such PFOs portray a high enough risk for clinical events, the likes of death, stroke, myocardial infarction, or ocular, visceral, and peripheral embolism, to justify screening for them. Highly significant health incidents being at stake, it appears obvious that PFO closure should be used for primary prevention. This is supported by the fact that closing a PFO is the simplest intervention in cardiology, with presumably the highest clinical yield. Being mainly a preventive measure, PFO closure represents a mechanical vaccination. When closing PFOs for one of the rarer therapeutic indications (migraine, platypnea orthodeoxia, etc.), patients automatically profit from the collateral benefit of getting, at the same time, mechanically vaccinated for life against paradoxical embolism. Vice versa, closing a PFO for the prevention of paradoxical embolism betters or cures migraine or exercise dyspnea not infrequently, thereby improving quality of life as a collateral benefit.

Enabling Navigation and Augmented Reality in the Sitting Position in Posterior Fossa Surgery Using Intraoperative Ultrasound

Despite its broad use in cranial and spinal surgery, navigation support and microscope-based augmented reality (AR) have not yet found their way into posterior fossa surgery in the sitting position. While this position offers surgical benefits, navigation accuracy and thereof the use of navigation itself seems limited. Intraoperative ultrasound (iUS) can be applied at any time during surgery, delivering real-time images that can be used for accuracy verification and navigation updates. Within this study, its applicability in the sitting position was assessed. Data from 15 patients with lesions within the posterior fossa who underwent magnetic resonance imaging (MRI)-based navigation-supported surgery in the sitting position were retrospectively analyzed using the standard reference array and new rigid image-based MRI-iUS co-registration. The navigation accuracy was evaluated based on the spatial overlap of the outlined lesions and the distance between the corresponding landmarks in both data sets, respectively. Image-based co-registration significantly improved (p < 0.001) the spatial overlap of the outlined lesion (0.42 ± 0.30 vs. 0.65 ± 0.23) and significantly reduced (p < 0.001) the distance between the corresponding landmarks (8.69 ± 6.23 mm vs. 3.19 ± 2.73 mm), allowing for the sufficient use of navigation and AR support. Navigated iUS can therefore serve as an easy-to-use tool to enable navigation support for posterior fossa surgery in the sitting position.

Unresponsiveness to Chiari Malformation Type I Surgery Can Be Related to the Accompanying Chiari Network

Surgical treatment is indicated for Chiari malformation type 1 (CMI) with tonsillar descent (TD) of >5 mm and other clinical manifestations. However, some patients remain unresponsive to surgery; this is an active topic of discussion. A patient presented to the emergency department with dizziness and an impaired gait. He had a history of hypertension. Magnetic resonance investigations revealed a 9-mm TD and cervical syringomyelia. There was no evidence of interatrial septum pathology on transthoracic echocardiography performed preoperatively. Although his complaints were attributed to CMI and surgery was performed, his symptoms remained persistent. Two years later, when the patient's dizziness increased, a posterior fossa transient ischemic attack (TIA) was suspected. A large patent foramen ovale (PFO) and Chiari network (CN) were also detected on transesophageal echocardiography. His complaints were resolved following PFO closure. Our case suggests that neurosurgeons should be informed about the results of the companionship of a PFO and CN. Before deciding on CMI surgery for patients with only dizziness complaints, a detailed investigation of accompanying cardiac pathologies is paramount to ensure accurate diagnosis and treatment.

Patent Foramen Ovale Percutaneous Closure: Evolution and Ongoing Challenges

Patent foramen ovale (PFO) concerns nearly a quarter of the general population and incidence may reach up to 50% in patients with cryptogenic stroke. Recent randomized clinical trials confirmed that percutaneous closure of PFO-related stroke reduces the risk of embolic event recurrence. PFO also comes into play in other pathogenic conditions, such as migraine, decompression sickness or platypnea-orthodeoxia syndrome, where the heterogeneity of patients is high and evidence for closure is less well-documented. In this review, we describe the current indications for PFO percutaneous closure and the remaining challenges, and try to provide future directions regarding the technique and its indications.

Before the Knife: A Detailed Step-by-Step Description of an Optimized Semi-Sitting Position in Posterior Fossa Surgery

BACKGROUND

In an ample armamentarium in neurosurgery, the semi-sitting position has produced debate regarding its benefits and risks. Although the position is apparently intuitive, many have abandoned its use since its initial inception, because of reported complexity and potential complications, leading to impracticality. However, through standardization, it has been shown not only to be safe but to carry with it many advantages, including less risk of secondary neurovascular injuries and better visualization of the surgical field. As with any surgical technical nuance, the semi-sitting position has advantages and disadvantages that must be weighed before the decision is made to adopt it or not, not only in a case-by-case scenario but also from a departmental standpoint. As we attempt to show, the advantages from a standardized approach for the semi-sitting position in experienced institutions may be more than sufficient to significantly outweigh the disadvantages, making it the preferable option for most, although not all, posterior fossa surgical interventions.

METHODS

In the present study, we aim to elaborate a straightforward narrative of the steps before incision, in an attempt to simplify the complexity of the position, alleviating its disadvantages and exponentially concentrating on its benefits. In nearly 100 steps, we carefully describe the points that culminate with the skin incision, initiating the intraoperative part of the procedure. Each step, therefore, is detailed in full, not in an effort to create a strict manual of the semi-sitting position but rather to facilitate understanding and put the technique into effect in a real-life scenario, thus simplifying what some depict as complex and time consuming.

CONCLUSIONS

Although several of the steps described are also relevant and integral parts of other surgical positioning, we intend to create a protocol, in a stepwise fashion, to allow facilitated following, to be easily implemented in departments with different levels of experience. The steps comprise nursing care through to electrophysiologic and anesthesiologic approaches, along with neurosurgical cooperation, making it a team approach, not only to avoid position-related complications but also to optimize preoperative standardization, constructing a safe, efficient, and patient-centered scenario, to set the best possible stage for the next step: the intraoperative part of the intervention.

Resection of posterior fossa tumors in the semi-sitting position in children younger than 4 years of age

PURPOSE

The semi-sitting position for resection of posterior fossa tumors is a matter of ongoing debate. Here we report about our experience with this approach in children younger than 4 years of age.

METHODS

We retrospectively analyzed data of children younger than 4 years of age operated on in our institution in the semi-sitting position over a 15-year period. Patients were intraoperatively monitored for venous air embolism (VAE) by transthoracic Doppler (TTD) or transesophageal echocardiography (TEE). The severity of VAE was classified according to the Tübingen grading scale. Intraoperative incidents of VAE were recorded and the patients' course was followed postoperatively with a special focus on possible complications.

RESULTS

Twenty-four children (18 boys, 6 girls) were operated on in the semi-sitting position (26 operations). Mean age was 2.2 years (± 1.0), range between 0.4 and 3.9 years. External ventricular drains were inserted in 18 children with hydrocephalus preoperatively. VAE was detected in 6 instances during surgery (6/26 (23.1%)). In 3 patients with grade 1 VAE, no additional treatment was necessary. In one patient with grade 2 VAE, intracardiac air suction via the central venous catheter was performed, and in two patients with grade 4 VAE, additional cathecholamine-infusion was administered. No major intraoperative complications occurred. Postoperative CT images showed pneumocephalus in all children. In two children, small asymptomatic impression skull fractures at the site of the Mayfield pin occurred. Revision surgery was necessary in one child with a suboccipital CSF fistula.

CONCLUSION

The semi-sitting position for resection of tumors in the posterior fossa in children younger than 4 years of age can be safely performed in experienced centers taking special caution to detect and treat potential complications in an interdisciplinary setting.

Patent foramen ovale and perioperative stroke in noncardiac surgery: a systematic review and meta-analysis

BACKGROUND

Patent foramen ovale (PFO) is associated with perioperative stroke in noncardiac surgery. The magnitude of this association was assessed in a systematic review and meta-analysis.

METHODS

Electronic databases were searched up to June 2022 for studies assessing the association between patent foramen ovale and perioperative stroke in adult patients undergoing noncardiac surgery. The primary analysis was limited to studies reporting effect estimates adjusted for significant clinical confounders. We calculated the adjusted odds ratio (aOR) and 95% confidence interval (CI).

RESULTS

We included nine retrospective and two prospective observational studies, including 21 257 082 patients. The presence of a patent foramen ovale was independently associated with stroke at 30 days after surgery (aOR=6.68 [95% CI: 3.51-12.73]; P<0.001) and at longest follow-up available (aOR=7.36 [95% CI: 3.56-15.21]; P<0.001). The odds of stroke at 30 days varied according to surgical specialty: neurosurgery (aOR=4.52 [95% CI: 3.17-6.43]), vascular surgery (aOR=7.15 [95% CI: 2.52-20.22]), thoracic surgery (aOR=10.64 [95% CI: 5.97-18.98]), orthopaedic surgery (aOR=11.85 [95% CI: 5.38-26.08]), general surgery (aOR=14.40 [95% CI: 10.88-19.06]), and genitourinary surgery (aOR=17.28 [95% CI: 10.36-28.84]).

CONCLUSIONS

The presence of a patent foramen ovale is associated with a large and consistent increase in odds of stroke across all explored surgical settings. Prospective trials should further explore this association by systematically assessing patent foramen ovale and stroke prevalence and identifying a specific population at risk. This is crucial for the elaboration of prevention plans and may improve perioperative outcomes.

Pineal cyst management: A single-institution experience spanning two decades

Background:

Pineal cysts (PCs) are benign lesions commonly found on intracranial imaging. Despite their high prevalence, there is no clear consensus on the most appropriate management of patients with PCs, especially those with symptomatic nonhydrocephalic cysts.

Methods:

A retrospective analysis was performed on 142 patients with PCs (103 surgical cases and 39 conservatively managed cases). Data were examined, including clinical presentation, imaging findings, ophthalmological status, natural course, postoperative outcomes, and complications.

Results:

Surgical group: the most common symptom was headache (92%), followed by signs of intracranial hypertension due to hydrocephalus (22%). New radiological feature of PCs was found in 11 patients. From 71 patients with long-term follow-up, headache completely resolved in 44 (62%) patients; marked improvement was observed in 20 (29%); in 7 (9%) – headache remained unchanged. The most common postoperative complication was neuro-ophthalmological disorders (23%), with a tendency for resolution in the long-term follow-up period. Neuro-ophthalmological symptoms at last follow-up included upward gaze palsy (6%) and skew deviation (5%), followed by convergence disorders (3%) and eyelid-retraction (2%). Natural course group: PC size remained stable in 34 (87%) patients during the follow-up period. The patient’s gender or age was not a significant predictor of cyst growth (P = 0.4, P = 0.56).

Conclusion:

The majority of patients with a newly diagnosed PC remain clinically and radiologically stable. Patients with nonhydrocephalic PCs and intractable headaches experience significant relief in headache symptoms, but are at risk of mild to moderate neuro-ophthalmological disorders. The natural course of PCs and factors promoting their growth still remains poorly defined.

Analysis of risk factors for venous air embolism in the semisitting position and its impact on outcome in a consecutive series of 740 patients

OBJECTIVE

Routine use of the semisitting position, which offers several advantages, remains a matter of debate. Venous air embolism (VAE) is a potentially serious complication associated with the semisitting position. In this study, the authors aimed to investigate the safety of the semisitting position by analyzing data over a 20-year period.

METHODS

The incidence of VAE and its perioperative management were analyzed retrospectively in a consecutive series of 740 patients who underwent surgery between 1996 and 2016. The occurrence of VAE was defined by detection of bubbles on transthoracic Doppler echocardiography (TTDE) or transesophageal echocardiography (TEE) studies, a decrease of end-tidal CO2 (ETCO2) by 4 mm Hg or more, and/or an unexplained drop in systolic arterial blood pressure (≥ 10 mm Hg). From 1996 until 2013 TTDE was used, and from 2013 on TEE was used. The possible risk factors for VAE and its impact on surgical performance were analyzed.

RESULTS

There were 404 women and 336 men with a mean age at surgery of 49 years (range 1-87 years). Surgery was performed for infratentorial lesions in 709 patients (95.8%), supratentorial lesions in 17 (2.3%), and cervical lesions in 14 (1.9%). The most frequent pathology was vestibular schwannoma. TEE had a higher sensitivity than TTDE. While TEE detected VAE in 40.5% of patients, TTDE had a detection rate of 11.8%. Overall, VAE was detected in 119 patients (16.1%) intraoperatively. In all of these patients, VAE was apparent on TTDE or TEE. Of those, 23 patients also had a decrease of ETCO2, 18 had a drop in blood pressure, and 23 had combined decreases in ETCO2 and blood pressure. VAE was detected in 24% of patients during craniotomy before opening the dura mater, in 67% during tumor resection, and in 9% during wound closure. No risk factors were identified for the occurrence of VAE. Two patients had serious complications due to VAE. Surgical performance in vestibular schwannoma surgery was not affected by the presence of VAE.

CONCLUSIONS

This study shows that the semisitting position is overall safe and that VAE can be managed effectively. Persistent morbidity is very rare. The authors suggest that the semisitting position should continue to have a place in the standard armamentarium of neurological surgery.

Preanesthetic Evaluation and Preparation for Neurosurgical Procedures: An Indian Perspective

Background A questionnaire-based survey was conducted to determine the preanesthetic evaluation (PAE) practices among the members of the Indian Society of Neuroanesthesiology and Critical Care (ISNACC). The survey aimed to assess the current clinical practice of PAE and optimization of neurosurgical patients in India.

Methods An online questionnaire was designed by the working group of ISNACC and circulated among its active members. Response to individual questions was considered significant if 50% or more respondents concurred. The survey questions to which less than 50% of respondents concurred were identified as inconclusive results.

Results Out of 438 active ISNACC members, 218 responded. Responses were obtained from various parts of the country. The majority of participants were practicing neuroanesthesiology. Questions asked were regarding clinical assessment, preoperative optimization, prognostication, and airway management in neurosurgery. More than 50% of practitioners acceded to most of the questions; however, the percentage of responses varied across different questions (50–100%). The questions related to preoperative duplex scanning in chronically immobilized patients, preoperative cognitive testing, and risk stratification during neurosurgical procedures received an inconclusive response (< 50%).

Conclusion The survey highlights the variable PAE practices perused by ISNACC members across the country. A guideline for uniform PAE practices may help to enhance research and improve perioperative care.

Use of the 3D exoscope for the supracerebellar infratentorial approach in the concorde position: an effective and ergonomic alternative. Illustrative cases

BACKGROUND

The supracerebellar infratentorial approach provides wide flexibility as a far-reaching corridor to the pineal region, posterior third ventricle, posterior medial temporal lobe, posterolateral mesencephalon, quadrigeminal cistern, and thalamus. Traditionally, the patient is placed in the sitting position, allowing gravity retraction on the cerebellum to widen the supracerebellar operative corridor beneath the tentorium. What this approach gains in anatomical orientation it lacks in surgeon ergonomics, as the sitting position presents technical challenges, forces the surgeon to adopt to an uncomfortable posture while performing the microsurgical dissection/tumor resection under the microscope, and is also associated with an increased risk of venous air embolism.

OBSERVATIONS

In this article, the authors present the use of the three-dimensional (3D) exoscope with a standard prone Concorde position as an alternative for the treatment of lesions requiring a supracerebellar infratentorial approach for lesions in the pineal region, posterior third ventricle, and the superior surface of the cerebellar vermis. The authors present four illustrative cases (one pineal cyst, one ependymoma, and two cerebellar metastases) in which this approach provided excellent intraoperative visualization and resulted in good postoperative results. A step-by-step description of our surgical technique is reviewed in detail.

LESSONS

The use of the 3D exoscope with the patient in the prone Concorde position is an effective and ergonomically favorable alternative to the traditional sitting position for the treatment of lesions requiring a supracerebellar infratentorial approach. This technique allows improved visualization of deep structures, with a possible decreased risk of potential complications.

A Retrospective Evaluation of the Retrosigmoidal Approach for Petroclival Meningioma Surgery and Prognostic Factors Affecting Clinical Outcome

Introduction

Petroclival meningioma (PCM) remains a major neurosurgical challenge. There are still controversial strategic treatment concepts about surgical approach, the extent of resection, and postoperative radiotherapy. We aimed to evaluate prognostic factors influencing the progression-free survival (PFS) rates of PCM, with a particular focus on the retrosigmoidal approach, the role of the extent of resection, and postoperative radiotherapy.

Methods

Eighty-nine patients with complete follow-up data were included. All patients were operated on via a retrosigmoidal approach, of whom 19 underwent gross total resection (GTR) and 70 underwent subtotal resection (STR). In the subgroups of tumors with infiltration of the cavernous sinus, 41 patients received near total resection (NTR) and 24 STR. Thirty-one patients received postoperative radiotherapy of the residual tumor and 58 were treated with surgery alone. Kaplan–Meier analyses and Cox regression were used to identify significant factors associated with treatment.

Results

GTR (p=0.0107) and postoperative radiotherapy (p=0.014) were associated with significantly improved PFS. Even the subgroup analysis of extended PCM with infiltration of the cavernous sinus (CS) showed an advantage for PFS after near total resection (NTR) (p=0.0017). The additional radiotherapy of the residual tumor in the CS in this subgroup also showed a beneficial effect on PFS (p=0.012).

Conclusion

The extension of surgical resection remains the most important prognostic factor in relation to oncological outcomes. However, the GTR of extended PCM with infiltration of the CS is associated with significant neurological morbidity and requires additional adjuvant therapy concepts. Postoperative radiotherapy is an important element in the treatment of the residual tumor after surgery.

[Sitting position in neurosurgery: realizing the risks]

The author discusses potential intraoperative complications following neurosurgical interventions in sitting position: venous air embolism and paradoxical air embolism, postural hypotension, pneumocephalus, cervical flexion neuropathy, positional damage to peripheral nerves and others. Naturally, prevention of these complications is also considered, and the most effective approach is surgery in lying position.

[Intraoperative transesophageal echocardiography as monitoring procedure in noncardiac surgery patients]

Transesophageal echocardiography (TEE) is firmly established in cardiac surgery for diagnostics, hemodynamic monitoring and as a guiding tool. Dynamic and (patho)physiological processes of the heart can be immediately depicted. Ideally, therapeutic changes can be derived. For this reason, TEE is increasingly used in high-risk non-cardiac surgery interventions and in the interventional setting. In the first part of this advanced training series, general aspects regarding TEE examinations as well as indications and contraindications are presented. Clinical fields of application, where TEE can play a role in hemodynamic monitoring are outlined. The second part focusses on an emergency examination pathway and differential diagnoses, which can be made in the event of intraoperative hemodynamic instability or unexplained hypoxemia using TEE. The article concludes with an outlook on the use of computer-aided evaluation of TEE images.

A practical guide to patient position and complication management in neurosurgery: a systematic qualitative review

PURPOSE

Adequate patient positioning is of paramount importance in neurosurgery. Complications related to the position are common and make up for more than 16% of the claims towards anaesthesiologists and neurosurgeons. This paper aims to provide the anaesthesiologist with a practical guide to avoid common pitfalls related to the patient positioning process.

METHOD

We performed a systematic review of the medical literature for the identification, screening, and inclusion of articles. The bibliographic search was conducted on June 1st, 2021 by two of the authors. In this review, we included articles indexed by MEDLINE, Cochrane Library, or Google Scholar.

RESULTS

We retrieved a total of 5706 unique papers from our initial search. However, after the initial screening, 5363 papers were removed is not related to our research leaving a total of 343 papers. We examined the full text of all the 343 articles including 68 of them in the final qualitative analysis.

DISCUSSION

In this review we examine the most common neurosurgical positions: supine, sitting, lateral, park-bench, prone, jack-knife, and knee-chest. For each of them, the proper positioning and related complications are described. Particular attention is given to the prevention and management of these complications, providing a practical guide for clinicians.

Air-embolism in the semi-sitting position for craniotomy: A narrative review with emphasis on a single centers experience

Albeit the semi-sitting position in neurosurgery has been in use for several decades, its application remains controversial in the neurosurgical and neuro-anaesthesia communities. The imminent and most feared risk of the sitting position is air entry into the vascular system due to the negative intravascular pressure leading to potentially life-threatening air embolism with its consequences. Recent advents in neurosurgical (improvement of the operating microscope, employment of intra-operative neurophysiological monitoring) and neuro-anaesthesia care (new anaesthetics, advanced monitoring modalities) have significantly impacted the approach to these surgeries. Vigilant intra-operative observation by an experienced team and peri-operative patient management guided by institutional protocols improves the safety profile of these surgeries. This review outlines the workflow and protocols used in our institution for all cases of semi-sitting position for skull base neurosurgery.

European position paper on the management of patients with patent foramen ovale. Part II - Decompression sickness, migraine, arterial deoxygenation syndromes and select high-risk clinical conditions

Patent foramen ovale (PFO) is implicated in the pathogenesis of a number of medical conditions but to date only one official position paper related to left circulation thromboembolism has been published. This interdisciplinary paper, prepared with the involvement of eight European scientific societies, reviews the available evidence and proposes a rationale for decision making for other PFO-related clinical conditions. In order to guarantee a strict evidence-based process, we used a modified grading of recommendations, assessment, development, and evaluation (GRADE) methodology. A critical qualitative and quantitative evaluation of diagnostic and therapeutic procedures was performed, including assessment of the risk/benefit ratio. The level of evidence and the strength of the position statements were weighed and graded according to predefined scales. Despite being based on limited and observational or low-certainty randomised data, a number of position statements were made to frame PFO management in different clinical settings, along with suggestions for new research avenues. This interdisciplinary position paper, recognising the low or very low certainty of existing evidence, provides the first approach to several PFO-related clinical scenarios beyond left circulation thromboembolism and strongly stresses the need for fresh high-quality evidence on these topics.

Patent foramen ovale and long-term risk of ischaemic stroke after surgery

AIMS

Pre-operatively diagnosed patent foramen ovale (PFO) is associated with an increased risk of ischaemic stroke within 30 days after surgery. This study aimed to assess the PFO-attributable ischaemic stroke risk beyond the perioperative period.

METHODS AND RESULTS

This observational study of adult patients without history of stroke undergoing non-cardiac surgery with general anaesthesia examined the association of PFO with ischaemic stroke 1 and 2 years after surgery using multivariable logistic regression. Of the 144 563 patients included, a total of 1642 (1.1%) and 2376 (1.6%) ischaemic strokes occurred within 1 and 2 years after surgery, 54 (4.7%) and 76 (6.6%) among patients with PFO, and 1588 (1.1%) and 2300 (1.6%) among patients without PFO, respectively. The odds of ischaemic stroke within 1 and 2 years after surgery were increased in patients with PFO: adjusted odds ratio (aOR) 2.01, 95% confidence interval (CI) 1.51-2.69; P < 0.001 and aOR 2.10, 95% CI 1.64-2.68; P < 0.001, respectively. Among patients who underwent contrast transoesophageal echocardiography, the frequency of PFO was 27%, and the increased stroke risk in patients with PFO was robust (aOR 3.80, 95% CI 1.76-8.23; P = 0.001 for year 1). The PFO-attributable risk was mitigated by post-operative prescription of combination antithrombotic therapy (odds ratio 0.41, 95% CI 0.22-0.75; P for interaction = 0.004).

CONCLUSION

Patients with PFO are vulnerable to ischaemic stroke for an extended period of time after surgery. Physicians should consider implementing PFO screening protocols in patients scheduled for major non-cardiac surgery.

Estimation of the head elevation angle that causes clinically important venous air embolism in a semi-sitting position for neurosurgery: a retrospective observational study

Introduction:

The benefits of a sitting position for neurosurgery involving the posterior fossa remain controversial. The main concern is the risk of venous air embolism (VAE). A recent study showed that the rate of VAE was higher when the head was elevated to 45° than when it was elevated to 30°. However, the degree of head elevation that causes clinically important VAE is unclear. The purpose of this study was to estimate the head elevation angle at which the probability of VAE is 50% by using EtCO₂ monitoring to detect of VAE.

Methods:

The anesthesia records of 23 patients who underwent neurosurgery in a sitting position were reviewed retrospectively. Intraoperative ventilation was set to maintain EtCO₂ at approximately 38-42 mmHg. The head elevation angle in each case was determined from a photograph taken by the anesthesiologist or brain surgeon. Nineteen of the 23 cases had photographs available that contained a horizontal reference in the background. Seven cases were treated as VAE during the operation. Six of these cases met the criteria for VAE in this study. Data analysis was performed on a total of 18 patients. The angle between the line connecting the hip joint and the shoulder joint and the horizontal reference was obtained by ImageJ software. Logistic regression was performed using the Python programming language to determine the head elevation angle at which the probability of air embolism was 50%.

Results:

The decision boundary in the logistic regression was 35.7°. This head elevation angle was the boundary where the probability of VAE was 50%.

Conclusion:

The angle of head elevation that caused clinically important VAE was estimated to be 35.7°.

[Convulsive syndrome as a manifestation of acute cerebral damage due to paradoxical air embolism in neurosurgical patients. Series of clinical cases and literature review]

Introduction

Paradoxical air embolism (PAE) is a rare potentially fatal complication followed by entering of air emboli from the right cardiac chambers and pulmonary artery to large circulation circle.

Objective

To analyze five patients who underwent neurosurgical intervention complicated by PAE and early postoperative convulsive syndrome.

Material and methods

There were five patients who developed early postoperative convulsive syndrome after previous neurosurgery in sitting position complicated by PAE. Convulsive syndrome required intensive care at the ICU. MRI confirmed ischemic foci de novo outside the zone of surgical intervention in all cases. All patients underwent video-EEG monitoring in order to select anticonvulsant therapy and evaluate its effectiveness. The authors were able to match the epileptogenic focus in the cerebral cortex with MRI data. Available literature data devoted to the problem of convulsive syndrome after neurosurgery complicated by PAE were analyzed.

Results

The focus of epileptiform activity coincided with one of the foci of hyperintense MR signal in all cases.

Conclusion

Video-EEG monitoring is advisable in patients with impaired consciousness who underwent neurosurgery complicated by PAE.

The Effects of Patient Positioning on the Outcome During Posterior Cranial Fossa and Pineal Region Surgery

Background: Surgery on posterior cranial fossa (PCF) and pineal region (PR) carries the risks of intraoperative trauma to the brainstem structures, blood loss, venous air embolism (VAE), cardiovascular instability, and other complications. Success in surgery, among other factors, depends on selecting the optimal patient position. Our objective was to find associations between patient positioning, incidence of intraoperative complications, neurological recovery, and the extent of surgery.

Methods: This observational study was conducted in two medical centers: The Ohio State University Wexner Medical Center (USA) and The Burdenko Neurosurgical Institute (Russian Federation). Patients were distributed in two groups based on the surgical position: sitting position (SP) or horizontal position (HP). The inclusion criteria were adult patients with space-occupying or vascular lesions requiring an open PCF or PR surgery. Perioperative variables were recorded and summarized using descriptive statistics. The post-treatment survival, functional outcome, and patient satisfaction were assessed at 3 months.

Results: A total of 109 patients were included in the study: 53 in SP and 56 in HP. A higher proportion of patients in the HP patients had >300 mL intraoperative blood loss compared to the SP group (32 vs. 13%; p = 0.0250). Intraoperative VAE was diagnosed in 40% of SP patients vs. 0% in the HP group (p < 0.0001). However, trans-esophageal echocardiographic (TEE) monitoring was more common in the SP group. Intraoperative hypotension was documented in 28% of SP patients compared to 9% in HP group (p = 0.0126). A higher proportion of SP patients experienced a new neurological symptom compared to the HP group (49 vs. 29%; p = 0.0281). The extent of tumor resection, postoperative 3-months survival, functional outcome, and patient satisfaction were not different in the groups.

Conclusions: The SP was associated with, less intraoperative bleeding, increased intraoperative hypotension, VAE, and postoperative neurological deficit. More HP patients experienced macroglossia and increased blood loss. At 3 months, there was no difference of parameters between the two groups.

Clinical Trial Registration:ClinicalTrials.gov: registration number NCT03364283.

Quality of life following surgical treatment of lesions within the pineal region

OBJECTIVEPineal region tumors are a rare and heterogeneous group of lesions. The optimal therapeutic approach is currently a topic of controversy, particularly in light of the potential operative risks and complications. The potential beneficial effects of surgery have already been described, but information about neurological outcome and, in particular, health-related quality of life (HRQOL) is still lacking in the literature. The aim of this study was to assess the therapeutic effect of resection of pineal region lesions, emphasizing grade of tumor resection, neurological outcome, quality of life, and the necessity of additional shunt procedures.METHODSThe authors performed a prospective study of HRQOL in 32 patients who had undergone surgical treatment of lesions in the pineal region (20 tumors and 12 cysts) between 2008 and 2014. All patients had at least 6 months of follow-up, with reexamination including standardized neurological assessment, an evaluation of dependency using the modified Rankin Scale, and an evaluation of HRQOL. The authors retrospectively examined patient charts and collected information regarding imaging studies, neurological status prior to surgery, surgical strategies used, any complications, and histological diagnoses.RESULTSIn this study, there was no surgery-associated mortality or major morbidity. Permanent minor morbidity was reported for 4 patients (13%). Comparing pre- and postoperative neurological symptoms, 75% of tumor patients had either complete resolution or improvement of preoperative symptoms; symptoms were unchanged in 10% of tumor patients and deteriorated in 15%. In patients with pineal cysts, long-term follow-up showed that 42% of patients were free of any symptoms and 58% experienced improvement of their preoperative symptoms. These outcomes were also reflected in the modified Rankin Scale scores, which demonstrated significant improvement following resection of pineal region lesions. Furthermore, significant improvements in HRQOL scores occurred in global health status, in all functional scales, and in pain, nausea and vomiting, fatigue, and insomnia (p < 0.0001). Moreover, a significant reduction in the necessity for permanent shunt procedures was observed after gross-total tumor resection compared with subtotal resection (p = 0.035) of pineal cysts.CONCLUSIONSDespite potential risks, (radical) surgery is a highly effective and safe treatment option for pineal region lesions and should be considered for the majority of patients.

Effects of Crystalloid Preloading (20 ml/kg) on Hemodynamics in Relation to Postural Changes in Patients Undergoing Neurosurgical Procedures in Sitting Position

Background:

Hemodynamic disturbances are common during positioning the patients from supine to sitting for neurosurgical procedures. The reported incidence of hypotension varies from 5% to 32%. The aim of the study was to study the effect of crystalloid preloading on hemodynamic parameters during positioning the patient from supine to sitting position.

Materials and Methods:

In this prospective observational trial, 20 patients were enrolled. Two patients had a patent foramen ovale on transesophageal echocardiography and were excluded from the study. All the patients received 20 ml/kg of crystalloid (Ringer's lactate) before initiation of positioning. Physiological hemodynamic parameters such as heart rate, mean arterial pressure, central venous pressure, cardiac output (CO), stroke volume variation (SVV), cardiac index (CI), stroke volume (SV), and maximum and minimum inferior vena caval diameter (IVCD) were recorded after induction, during positioning at 30°, 60° inclination of the operating table and after the final sitting position.

Results:

Hemodynamic parameters were well maintained during positioning of the patients from supine to sitting position. Crystalloid preloading prevented the hypotension during positioning. There were no significant changes in hemodynamic parameters such as CO, SVR, SVV, CI, and SV. We did not find any correlation with changes in IVCD with changes in CO.

Conclusion:

A volume of 20 ml/kg of crystalloid preloading before positioning the patient from supine to sitting position maintains the hemodynamic stability and avoids the vasopressor requirement.

A critical comparison between the semisitting and the supine positioning in vestibular schwannoma surgery: subgroup analysis of a randomized, multicenter trial

OBJECTIVE

Patient positioning in vestibular schwannoma (VS) surgery is a matter of ongoing discussion. Factors to consider include preservation of cranial nerve functions, extent of tumor resection, and complications. The objective of this study was to determine the optimal patient positioning in VS surgery.

METHODS

A subgroup analysis of a randomized, multicenter trial that investigated the efficacy of prophylactic nimodipine in VS surgery was performed to investigate the impact of positioning (semisitting or supine) on extent of resection, functional outcomes, and complications. The data of 97 patients were collected prospectively. All procedures were performed via a retrosigmoid approach. The semisitting position was chosen in 56 patients, whereas 41 patients were treated while supine.

RESULTS

Complete resection was obtained at a higher percentage in the semisitting as compared to the supine position (93% vs 73%, p = 0.002). Logistic regression analysis revealed significantly better facial nerve function in the early postoperative course in the semisitting group (p = 0.004), particularly concerning severe facial nerve paresis (House-Brackmann grade IV or worse; p = 0.002). One year after surgery, facial nerve function recovered. However, there was still a tendency for better facial nerve function in the semisitting group (p = 0.091). There were no significant differences between groups regarding hearing preservation rates. Venous air embolism with the necessity to terminate surgery occurred in 2 patients in the semisitting position (3.6%). Supplementary analysis with a 2-tailed permutation randomization with 10,000 permutations of treatment choice and a propensity score matching showed either a tendency or significant results for better facial nerve outcomes in the early postoperative course and extent of resection in the semisitting group.

CONCLUSIONS

Although the results of the various statistical analyses are not uniform, the data indicate better results concerning both a higher rate of complete removal (according to the intraoperative impression of the surgeon) and facial nerve function after a semisitting as compared to the supine position. These advantages may justify the potential higher risk for severe complications of the semisitting position in VS surgery. The choice of positioning has to consider all individual patient parameters and risks carefully.

Venous air embolisms and sitting position in Helsinki pineal region surgery

Background

Nowadays, the sitting position has lost favor among neurosurgeons partly due to assumptions of increased complications, such as venous air embolisms (VAEs) and hemodynamic disturbances. The aim of our study is to describe the importance of some anesthetic considerations and the utility of antigravity trousers as well, together with a skillful neurosurgery and an imperative proper teamwork, in order to prevent the risk of severe VAE during pineal region surgery. We routinely use them for the variant of the sitting position we developed, the "praying position."

Methods

A retrospective review of 51 pineal lesions operated on in the "praying position" using antigravity trousers was carried out. In the "praying position" the legs of the patient are kept parallel to the floor. Hence, antigravity trousers are used to generate an adequate cardiac preload.

Results

VAE associated to persistent hemodinamic changes was nonexistent in our series. The rate of VAE was 35.3%. VAEs were diagnosed mainly by monitoring of the end-tidal CO₂ (83.33%). A venous system lesion was the cause in most of the cases. When VAE was suspected, an inmediate reaction based on a good teamwork was imperative. No cervical spine cord injury nor peripheral nerve damage were reported. The average microsurgical time was 48 ± 33 min.

Conclusions

The risks of severe VAE during pineal region surgery in the "praying-sitting position" may be effectively prevented by some essential anesthetic considerations and the use of antigravity trousers together with a skillful neurosurgery, and an imperative proper teamwork.

Predictors of ventricular tension pneumocephalus after posterior fossa surgery in the sitting position

BACKGROUND

Ventricular pneumocephalus is a rare but potentially life-threatening complication of cranial surgery in the sitting position.

OBJECTIVE

The objective of the study is to assess the incidence and risk factors of postoperative ventricular pneumocephalus.

METHODS

We performed a retrospective chart review of 307 consecutive patients (147 men, 160 women) treated at our institution by intracranial surgery in the sitting position from January 2010 to October 2014. Ventricular air entrapment with lack of arousal or neurologic deterioration requiring external ventriculostomy (EVD) was defined as ventricular tension pneumocephalus (VTP). Demographic variables were recorded along with radiological and clinical data. The occurrence of pneumocephalus was correlated with patient-related and surgical variables.

RESULTS

VTP was observed in 12 cases (3.9%). These patients had higher intraventricular air volumes (48.5 cm³ (CI 95% [29.06-67.86])) compared to asymptomatic patients (7.4 cm³ (CI 95% [5.43-9.48])). Opening of the fourth ventricle was the most potent predictor of VTP (OR = 34.7, CI 95% [4.4-273.5], p = 0.001). In patients undergoing no additional treatment for pneumocephalus, ventricular air volume declined to an average of 41.7% of the initial postoperative volume on postoperative day 3.

CONCLUSIONS

Entrapment of intracranial and particularly ventricular air requiring emergent EVD occurred in 3.9% cases of intracranial surgery in the sitting position. Especially the opening of the fourth ventricle was associated with the development of VTP, which should warrant particularly diligent postoperative observation of these patients. In cases without neurological symptoms, the rate of spontaneous air resorption is sufficiently high to warrant expectant management.

Praying Sitting Position for Pineal Region Surgery: An Efficient Variant of a Classic Position in Neurosurgery

BACKGROUND

The sitting position has lost favor among neurosurgeons partly owing to assumptions of increased complications, such as venous air embolisms and hemodynamic disturbances. Moreover, the surgeon must assume a tiring posture. We describe our protocol for the "praying position" for pineal region surgery; this variant may reduce some of the risks of the sitting position, while providing a more ergonomic surgical position.

METHODS

A retrospective review of 56 pineal lesions operated on using the praying position between January 2008 and October 2015 was performed. The praying position is a steeper sitting position with the upper torso and the head bent forward and downward. The patient's head is tilted about 30° making the tentorium almost horizontal, thus providing a good viewing angle. G-suit trousers or elastic bandages around the lower extremities are always used.

RESULTS

Complete lesion removal was achieved in 52 cases; subtotal removal was achieved in 4. Venous air embolism associated with persistent hemodynamic changes was nonexistent in this series. When venous air embolism was suspected, an immediate reaction based on good teamwork was imperative. No cervical spine cord injury or peripheral nerve damage was reported. The microsurgical time was <45 minutes in most of the cases. Postoperative pneumocephalus was detected in all patients, but no case required surgical treatment.

CONCLUSIONS

A protocolized praying position that includes proper teamwork management may provide a simple, fast, and safe approach for proper placement of the patient for pineal region surgery.

[Paradoxical embolism: Myth or reality?]

Paradoxical embolism should be suspected in front of a clinical phenomenon of thromboembolism associated with an anatomical right-to-left shunt. Others potential cardiac sources of thromboembolism must be ruled out. Strokes constitute the most frequent clinical manifestations of paradoxical embolism. Right-to-left left shunts are in connection with intracardiac defects (atrial septal defect and patent foramen ovale) or pulmonary arteriovenous malformations. The probability that a discovered PFO is stroke-related can be evaluated by a score. Therapeutic approaches for secondary prevention of recurrent stroke include antithrombotic and/or percutaneous treatments. The choice strategy begins to be clearer with the recent results of randomized controlled studies.

The semisitting position: analysis of the risks and surgical outcomes in a contemporary series of 425 adult patients undergoing cranial surgery

OBJECTIVE

The objective of this study was to analyze the incidence of the primary complications related to positioning or surgery and their impact on neurological outcome in a consecutive series of patients undergoing elective surgery in the semisitting position.

METHODS

The authors prospectively collected and retrospectively analyzed data from adult patients undergoing elective surgery in the semisitting position for a cranial disease. Patients were managed perioperatively according to a standard institutional protocol, a standardized stepwise positioning, and surgical maneuvers to decrease the risk of venous air embolism (VAE) and other complications. Intraoperative and postoperative complications were recorded. Neurointensive care unit (NICU) length of stay (LOS) and hospital LOS were the intermediate endpoints. Neurological outcome was the primary endpoint as determined by the modified Rankin scale (mRS) score at 6 months after surgery.

RESULTS

Four hundred twenty-five patients were included in the analysis. VAE occurred in 90 cases (21%) and it made no significant statistical difference in NICU LOS, hospital LOS, and neurological outcome. No complication was directly related to the semisitting position, although 46 patients (11%) experienced at least 1 surgery-related complication and NICU LOS and hospital LOS were significantly prolonged in this group. Neurological outcome was significantly worse for patients with complications (p < 0.0001).

CONCLUSIONS

Even in the presence of intraoperative VAE, the semisitting position was not related to an increased risk of postoperative deficits and can represent a safe additional option for the benefit of specific surgical and patient needs.

Circumferential Reconstruction of Subaxial Cervical and Cervicothoracic Spine by Simultaneously Combined Anterior-posterior Approaches in the Sitting Position

OBJECTIVE

To introduce and analyze the feasibility of a new surgical strategy for circumferential reconstruction of subaxial cervical and cervicothoracic spine by simultaneously combined anterior-posterior approach in the sitting position.

METHODS

A retrospective review was performed for seven patients who underwent the above surgical procedure between July 2011 and January 2015. Among the seven patients, there were six men and one woman, with an average age of 52 years (range, 36-79 years). Six patients were confirmed to have a lower subaxial cervical fracture and dislocation with a locked facet joint, and the other patient had an invasive tumor involving both anterior and posterior parts of vertebrae and lamina, detected by radiological examination. The levels involved for all patients were from C₄ to T₂ . According to American Spinal Injury Association (ASIA) classification, one case was class A, four were class B, and two were class D. The patients were restricted in the sitting position with traction and a halo in extension to immobilize the head during the operation. The simultaneously combined anterior-posterior operation for reduction, decompression or tumor resection and circumferential reconstruction was carried out.

RESULTS

Both anterior and posterior procedures were successfully completed simultaneously in the sitting position in all cases. There were no perioperative complications. The average operative time was 175 ± 32 min (range, 120-240 min), and the mean blood loss was 430 ± 85 mL (range, 200-1100 mL). The patients were followed up for 35.8 months (range, 18-60 months). The symptom of neck pain improved distinctly and no evidence of implant failure was noted in any patients. Neurological status improvement was confirmed in six patients, who had suffered incomplete paralysis. The ASIA grade improved in five patients, and two cases had no change in grade.

CONCLUSIONS

The "sitting position" simultaneously combined anterior-posterior approach is safe and is superior to the traditional prone position and supine position, and the surgical results are satisfactory.

Venous air embolism in the sitting position in cranial neurosurgery: incidence and severity according to the used monitoring

BACKGROUND

There is an ongoing debate about the sitting position (SP) in neurosurgical patients. The SP provides a number of advantages as well as severe complications such as commonly concerning venous air embolism (VAE). The best monitoring system for the detection of VAE is still controversial.

METHODS

In this retrospective analysis we compared 208 patients. Transesophageal echocardiography (TEE) or transthoracic Doppler (TTD) were used as monitoring devices to detect VAE; 101 cases were monitored with TEE and 107 with TTD.

RESULTS

The overall incidence of VAE was 23% (TTD: 10%; TEE: 37%), but the incidence of clinically relevant VAE (drop in end-tidal carbon dioxide above 3 mmHg) was higher in the TTD group (9 out of 17 VAE, 53%) compared to the TEE group (19 out of 62 VAE, 31%). None of the patients with recorded VAE had clinically significant sequelae.

CONCLUSIONS

In this small sample we found more VAE events in the TEE group, but the incidence of clinically relevant VAE was rare and comparable to other data. There is no consensus in the definition of clinically relevant VAE.

A systematic review about the position-related complications of acoustic neuroma surgery via suboccipital retrosigmoid approach: Sitting versus lateral

This systematic review wasdesigned to compare the complications of acoustic neuroma surgery via the suboccipital retrosigmoid approach in the sitting versus lateral positions. Searches for randomized trials and observational studies about the complications of acoustic neuroma surgery were performed in five medical databases (though October 2015) including PubMed, MEDLINE (In-Process and Other Non-Indexed Citations), EMBASE, Cochrane Central Register of Controlled Trials (CENTRAL) and PsycINFO. Primary outcomes in this study were venous air emboli, neuropsychological defects, CSF leak, facial and abducens nerves palsy, postoperative deafness, hydrocephalus and mortality. Secondary outcomes were total tumor removal, facial and cochlear nerves preservation and ataxia. 843 abstracts and titles were reviewed and 10 studies (two non-randomized comparative studies and 8 non-comparative case series) were included for data extraction. Because of the heterogeneity of the studies, small number of participants and methodological shortcomings, findings were evaluated qualitatively. No impressive advantage was found in surgical or neurological outcomes for use of the sitting or lateral positions in patients with acoustic neuroma surgery. According to the available evidence, it seems that both sitting and lateral positions can be used with an equivalent safety for acoustic neuroma surgery via the retrosigmoid suboccipital approach. There seems a clear need for comparative studies to compare harms and other outcomes for these two positions.

Contemporary analysis of the intraoperative and perioperative complications of neurosurgical procedures performed in the sitting position

OBJECTIVE Historically, performing neurosurgery with the patient in the sitting position offered advantages such as improved visualization and gravity-assisted retraction. However, this position fell out of favor at many centers due to the perceived risk of venous air embolism (VAE) and other position-related complications. Some neurosurgical centers continue to perform sitting-position cases in select patients, often using modern monitoring techniques that may improve procedural safety. Therefore, this paper reports the risks associated with neurosurgical procedures performed in the sitting position in a modern series. METHODS The authors reviewed the anesthesia records for instances of clinically significant VAE and other complications for all neurosurgical procedures performed in the sitting position between January 1, 2000, and October 8, 2013. In addition, a prospectively maintained morbidity and mortality log of these procedures was reviewed for instances of subdural or intracerebral hemorrhage, tension pneumocephalus, and quadriplegia. Both overall and specific complication rates were calculated in relation to the specific type of procedure. RESULTS In a series of 1792 procedures, the overall complication rate related to the sitting position was 1.45%, which included clinically significant VAE, tension pneumocephalus, and subdural hemorrhage. The rate of any detected VAE was 4.7%, but the rate of VAE requiring clinical intervention was 1.06%. The risk of clinically significant VAE was highest in patients undergoing suboccipital craniotomy/craniectomy with a rate of 2.7% and an odds ratio (OR) of 2.8 relative to deep brain stimulator cases (95% confidence interval [CI] 1.2-70, p = 0.04). Sitting cervical spine cases had a comparatively lower complication rate of 0.7% and an OR of 0.28 as compared with all cranial procedures (95% CI 0.12-0.67, p < 0.01). Sitting cervical cases were further subdivided into extradural and intradural procedures. The rate of complications in intradural cases was significantly higher (OR 7.3, 95% CI 1.4-39, p = 0.02) than for extradural cases. The risk of VAE in intradural spine procedures did not differ significantly from sitting suboccipital craniotomy/craniectomy cases (OR 0.69, 95% CI 0.09-5.4, p = 0.7). Two cases (0.1%) had to be aborted intraoperatively due to complications. There were no instances of intraoperative deaths, although there was a single death within 30 days of surgery. CONCLUSIONS In this large, modern series of cases performed in the sitting position, the complication rate was low. Suboccipital craniotomy/craniectomy was associated with the highest risk of complications. When appropriately used with modern anesthesia techniques, the sitting position provides a safe means of surgical access.

[Perioperative transesophageal echocardiography in non-cardiac surgery. Update]

AIM

The aim of this article is to impart knowledge concerning focused transesophageal echocardiographic examination (TEE) for non-cardiac surgery which is an essential part of perioperative monitoring. It allows a rapid echocardiographic examination without interference with the surgical field or under limited transthoracic examination conditions. New recommendations for a comprehensive perioperative TEE examination with expanded standard views and the recently published consensus statement for a shortened baseline examination were crucial for this study.

MATERIAL AND METHODS

The background is the peer-reviewed literature from PubMed.

RESULTS

Apart from cardiac surgery TEE has two main applications: firstly, the evaluation of patients developing acute life-threatening hemodynamic instability in the operating room, in the emergency room or in the intensive care unit (ICU). Secondly, TEE is used as planned intraoperative monitoring when severe hemodynamic, pulmonary or neurological complications are expected because of the type of surgery or due to the cardiopulmonary medical history of the patient. In 2013 a total of 11 relevant standard views were defined for the basic perioperative TEE examination in non-cardiac surgery. These 11 views should be performed for each patient. Appropriate extension to a comprehensive examination may be necessary if complex pathology is obvious.

DISCUSSION

Even in non-cardiac surgery TEE is an important tool allowing clarification of a life-threatening perioperative hemodynamic instability within a few minutes. Furthermore, the hemodynamic management of high-risk patients can be facilitated. Appropriate qualification and continuous training are necessary in order to assure the competence of the examiner.

The relationship of patent foramen ovale location with severity of stroke: A new risk factor for paradoxical embolism

OBJECTIVE

Patent foramen ovale (PFO) is a common developmental anomaly and is well associated with paradoxical embolism and cryptogenic stroke. The aim of this study was to investigate the relationship of PFO location with severity of cryptogenic stroke.

MATERIALS AND METHODS

Fifty patients with cryptogenic stroke and echocardiographically proven PFO were classified according to the severity of stroke. In order to define the location of PFOs, an imaginary line dividing the length of interatrial septum vertically into two equal parts was drawn manually at axial plane on cardiac multidetector computed tomography. PFOs located at superior part of this imaginary line was defined as superiorly located PFO, while PFOs located at inferior part of this imaginary line was defined as inferiorly located PFO.

RESULTS

Fourteen patients (28%) revealed mild, 20 patients (40%) revealed moderate and 16 patients (32%) had severe stroke. Based on PFO location, there were 34 patients (68%) with superiorly (group 1), and 16 patients (32%) with inferiorly (group 2) located PFO. It was found that patients of group 1 had significantly higher frequency of moderate or severe stroke compared to those of group 2 (p < 0.005) CONCLUSION: In conclusion, the patients with superiorly located PFO had higher frequency of severe stroke compared to the patients with inferiorly located PFO. Since this is a preliminary study, clinical application and importance of this finding necessitates further large-scale interventional studies.

[Paradoxical air embolism resulted in acute myocardial infarction and massive ischemic brain injury in a patient operated on in a sitting position]

Paradoxical air embolism (PAE) is a rare life-threatening complication when air emboli enter arteries of the systemic circulation and cause their occlusion. Here, we describe a clinical case of PAE developed during neurosurgery in a patient in the sitting position. PAE led to injuries to the cerebral blood vessels, coronary arteries, and lungs, which caused death of the patient. An effective measure for preventing PAE is abandoning surgery in the sitting position in favor of surgery in the prone position.

Improved Postoperative Facial Nerve and Hearing Function in Retrosigmoid Vestibular Schwannoma Surgery Significantly Associated with Semisitting Position

OBJECTIVE

The pros and cons of semisitting positioning (SSP) versus lateral, horizontal positioning (LP) during retrosigmoid vestibular schwannoma (VS) surgery, especially concerning postoperative cranial nerve and brain stem preservation, are under continuous discussion.

METHODS

In a single-center retrospective cohort study, 30 VSs operated on in SSP compared with 30 operated on in LP with comparable demography were analyzed. During SSP surgery, transesophageal echocardiographic monitoring for venous air embolism was used continuously. Electrophysiologic cranial nerve monitoring was used in both groups.

RESULTS

Length of surgery was significantly different between both groups: 183 minutes mean in SSP surgery versus 365 minutes mean in LP surgery (P = 0.0001). Postoperative rates of facial palsy and hearing loss were also significantly different. Six months postoperatively, 63% had normal facial nerve function after SSP surgery, whereas in LP surgery, 40% had no facial palsy (P = 0.02). Hearing preservation rate was also significantly different: 44% in SSP surgery compared with 14% in LP surgery who had preserved hearing (P = 0.006). Because of cerebrospinal fluid leaks, there were 3 operative revisions in the LP group (10%) and 1 (3.3%) in the SSP group. A clinically insignificant venous air embolism rate was found in 3.3% of patients (1/30) during SSP surgery. The neurologic outcome after 6 months was 1.2 on the Rankin Scale in the LP group and 1.0 in the SSP group, with zero mortality.

CONCLUSIONS

SSP compared with LP surgery was associated with significantly shorter operation time and better facial and cochlear nerve function in VS surgery postoperatively, without differences in complication rates.

Carbon dioxide field flooding reduces the hemodynamic effects of venous air embolism occurring in the sitting position

PURPOSE

Although the utility of the sitting position is undisputed for biomechanical and ergonomic reasons, it has been debated in recent years for its risks, particularly venous air embolism (VAE). In order to reduce the hemodynamic effect of VAE, we changed the composition of the surgical field air partially replacing nitrogen with carbon dioxide (CO2) that better dissolves in human tissues.

METHODS

First, we tested our method on a test dummy in the sitting position. Infrared CO2 sensors were placed close to the wound opening and on the facial mask of the surgeon. An oxygen sensor was connected to a computer for data recording (ALTAIR(®), MSA Safety). This model showed that 10 L/min CO2 flow provides efficient air displacement, maintaining safety for the surgeon. We reproduced the above-described surgical field environment in ten consecutive cases of posterior fossa surgery performed in the sitting position. A homogeneous group of ten patients operated in the sitting position with standard setting environment was used for control. We intraoperatively monitored VAE with trans-esophageal echocardiography (TEE), end-tidal CO2 (ETCO2), CO2 arterial pressure (PaCO2), and hemodynamic changes.

RESULTS

Although the percentage of VAE was 70% in both groups, hemodynamic effects occurred in 10% of cases in the study group and in 40% of cases in the control group.

CONCLUSIONS

Our preliminary study shows that a CO2-enriched sitting position surgical microenvironment significantly reduces the hemodynamic effects of VAE, more likely because arterial CO2 emboli are more soluble and consequently much better tolerated than air emboli.

Intrajugular balloon catheter reduces air embolism in vitro and in vivo

Background

Neurosurgical procedures requiring a sitting position may put the patient at risk of a potentially life-threatening air embolism. Transient manual jugular venous compression limits further air entry in this situation. This study presents an alternative technique aimed at reducing the risk of air embolism.

Methods

In an in vitro model, an intrajugular balloon catheter was inserted to demonstrate that this device prevents air embolism. In an in vivo study, this device was bilaterally placed into jugular vessels in pigs. Using an ultrasound technique, blood flow was monitored and jugular venous pressure was recorded before and during cuff inflation. Air was applied proximally to the inflated cuffs to test the hypothesis that this novel device blocks air passage.

Results

In vitro, the intrajugular balloon catheter reliably prevented further air entry (n=10). Additionally, accumulated air could be aspirated from an orifice of the catheter (n=10). In vivo, inflation of the catheter balloon completely obstructed venous blood flow (n=8). Bilateral inflation of the cuff significantly increased the proximal jugular venous pressure from 9.8 (2.4) mm Hg to 14.5 (2.5) mm Hg (n=8, P<0.05). Under conditions mimicking an air embolism, air passage across the inflated cuffs was prevented and 78 (20%) (n=6) of the air dose could be aspirated by the proximal orifice of the catheter.

Conclusions

These findings may serve as a starting point for the development of intrajugular balloon catheters designed to reduce the risk of air embolism in patients undergoing neurosurgery in a sitting position.

Comparison of outcomes following complex posterior fossa surgery performed in the sitting versus lateral position

The sitting position during surgery is thought to provide important advantages, yet it remains controversial. We compared surgical and neurological outcomes for patients operated on in the sitting versus lateral position. Technically difficult procedures performed from the years 2001-2008 for complex lesions in the posterior fossa (vestibular schwannomas, other cerebellopontine angle tumors, foramen magnum meningiomas, brainstem cavernomas, pineal region tumors) were included. Outcomes in the two surgical positions were compared for all 243 patients (93 sitting, 38.3%; 150 lateral, 61.7%) and for 130/243 patients with vestibular schwannomas (50 sitting, 38.5%; 80 lateral, 61.5%). Sitting and lateral patient subgroups were clinically comparable. There were no surgical mortalities. The extent of removal and surgical and neurological outcomes were comparable. We found no advantage in surgical or neurological outcomes for use of the sitting or lateral surgical positions in technically difficult posterior fossa procedures. In vestibular schwannoma surgeries facial nerve preservation (House-Brackmann score 1-2) was related to extent of resection but not to surgical position. The choice of operative position should be based on lesion characteristics and the patient's preoperative medical status as well as the experience and preferences of the surgeons performing the procedure.