Postoperative Neurosurgical Infection Rates After Shared-Resource Intraoperative Magnetic Resonance Imaging: A Single-Center Experience with 195 Cases

Profiles of central nervous system surgical site infections in endoscopic transnasal surgery exposing the intradural space

OBJECTIVE

Despite its efficacy and minimal invasiveness, the clean-contaminated nature of endoscopic transnasal surgery (ETS) may be susceptible to central nervous system surgical site infections (CNS-SSIs), especially when involving intradural exposure. However, the profiles of ETS-associated CNS-SSIs are not fully elucidated.

METHODS

The institutional ETS cases performed between May 2017 and March 2023 were retrospectively analysed. The incidences of CNS-SSIs were calculated, and their risk factors examined.

RESULTS

The incidence of CNS-SSIs was 2.3% (7/305) in the entire cohort and 5.0% (7/140) in ETSs with intradural exposure. All the CNS-SSIs were meningitis and developed following ETS with intradural exposure. The incidences were 0%, 5.6% and 5.8% in ETSs with Esposito grade 1, 2 and 3 intraoperative cerebrospinal fluid leakage, respectively. Among the pre- and intra-operative factors, body mass index (unit odds ratio (OR), 0.62; 95% confidence interval (CI), 0.44-0.89; P<0.01), serum albumin (unit OR, 0.03; 95% CI, 0.0007-0.92; P=0.02), and American Society of Anesthesiologists physical status score (unit OR, 20.7; 95% CI, 1.65-259; P<0.01) were significantly associated with CNS-SSIs. Moreover, postoperative cerebrospinal fluid leakage was also significantly associated with CNS-SSIs (OR, 18.4; 95% CI, 3.55-95.0; P<0.01).

CONCLUSIONS

The incidence of ETS-associated CNS-SSIs is acceptably low. Intradural exposure was a prerequisite for CNS-SSIs. Malnutrition and poor comorbidity status should be recognized as important risks for CNS-SSIs in ETS.

Two years of neurosurgical intraoperative MRI in Sweden - evaluation of use and costs

BACKGROUND

The current shortage of radiology staff in healthcare provides a challenge for departments all over the world. This leads to more evaluation of how the radiology resources are used and a demand to use them in the most efficient way. Intraoperative MRI is one of many recent advancements in radiological practice. If radiology staff is performing intraoperative MRI at the operation ward, they may be impeded from performing other examinations at the radiology department, creating costs in terms of exams not being performed. Since this is a kind of cost whose importance is likely to increase, we have studied the practice of intraoperative MRI in Sweden.

METHODS

The study includes data from the first four hospitals in Sweden that installed MRI scanners adjacent to the operating theaters. In addition, we included data from Karolinska University Hospital in Solna where intraoperative MRI is carried out at the radiology department.

RESULTS

Scanners that were moved into the operation theater and doing no or few other scans were used 11-12% of the days. Stationary scanners adjacent to the operation room were used 35-41% of the days. For scanners situated at the radiology department doing intraoperative scans interspersed among all other scans, the proportion was 92%.

CONCLUSION

Our study suggests that performing exams at the radiology department rather than at several locations throughout the hospital may be an efficient approach to tackle the simultaneous trends of increasing demands for imaging and increasing staff shortages at radiology departments.

The impact of intraoperative MRI on cranial surgical site infections-a single-center analysis

PURPOSE

The use of intraoperative MRI (ioMRI) contributes to an improved extent of resection. Hybrid operating room MRI suites have been established, with the patient being transferred to the MRI scanner. In the present descriptive analysis, we compared the rate of surgical site infections (SSI) after intracranial tumor surgery with and without the use of ioMRI.

METHODS

In this retrospective study, we included 446 patients with open craniotomy performed for brain tumor surgery. One hundred fourteen patients were operated on with the use of ioMRI between June 1, 2018, and June 30, 2019 (group 1). During the same period, 126 patients were operated on without ioMRI (group 2). As an additional control group, we analyzed 206 patients operated on from February 1, 2017, to February 28, 2018 when ioMRI had not yet been implemented (group 3).

RESULTS

The rate of SSI in group 1 (11.4%), group 2 (9.5%), and group 3 (6.8%) did not differ significantly (p = 0.352). Additional resection after ioMRI did not result in a significantly elevated number of SSI. No significant influence of re-resection, prior radio-/chemotherapy, blood loss or duration of surgery was found on the incidence of SSI.

CONCLUSION

Despite the transfer to a non-sterile MRI scanner, leading to a prolonged operation time, SSI rates with and without the use of ioMRI did not differ significantly. Hence, advantages of ioMRI outweigh potential disadvantages as confirmed by this real-life single-center study.

Relationship between characteristics of glioma treatment and surgical site infections

PURPOSE

Surgical site infections (SSIs) after neurosurgery are common in daily practice. Although numerous reports have described SSIs in neurosurgery, reports specific to gliomas are limited. This study aimed to investigate the relationship between SSIs and glioma treatment characteristics, such as reoperations, radiation therapy, and chemotherapy.

METHODS

We examined 1012 consecutive patients who underwent craniotomy for glioma between November 2013 and March 2022. SSIs were defined as infections requiring reoperation during the observation period, regardless of their location. We retrospectively analyzed SSIs and patient factors.

RESULTS

During the observation period, SSIs occurred in 3.1% (31/1012). In the univariate analysis, three or more surgeries (P = 0.007) and radiation therapy (P = 0.03) were associated with SSIs, whereas intraoperative magnetic resonance imaging (MRI) was not significantly associated (P = 0.35). Three or more surgeries and radiation therapy were significantly correlated with each other (P < .0001); therefore, they were analyzed separately in the multivariate analysis. Three or more surgeries were an independent factor triggering SSIs (P = 0.02); in contrast, radiation therapy was not an independent factor for SSIs (P = 0.07). Several SSIs localized in the skin occurred more than 1 year after surgery.

CONCLUSIONS

Undergoing three or more surgeries for glioma is an independent risk factor for SSIs. Glioma SSIs can occur long after surgery. These results are considered characteristic of gliomas. We recommend careful long-term observation of patients at a high risk of SSIs.

Intraoperative MR Imaging during Glioma Resection

One of the major issues in the surgical treatment of gliomas is the concern about maximizing the extent of resection while minimizing neurological impairment. Thus, surgical planning by carefully observing the relationship between the glioma infiltration area and eloquent area of the connecting fibers is crucial. Neurosurgeons usually detect an eloquent area by functional MRI and identify a connecting fiber by diffusion tensor imaging. However, during surgery, the accuracy of neuronavigation can be decreased due to brain shift, but the positional information may be updated by intraoperative MRI and the next steps can be planned accordingly. In addition, various intraoperative modalities may be used to guide surgery, including neurophysiological monitoring that provides real-time information (e.g., awake surgery, motor-evoked potentials, and sensory evoked potential); photodynamic diagnosis, which can identify high-grade glioma cells; and other imaging techniques that provide anatomical information during the surgery. In this review, we present the historical and current context of the intraoperative MRI and some related approaches for an audience active in the technical, clinical, and research areas of radiology, as well as mention important aspects regarding safety and types of devices.

Neurosurgery outcomes and complications in a monocentric 7-year patient registry

Introduction

Capturing adverse events reliably is paramount for clinical practice and research alike. In the era of "big data", prospective registries form the basis of clinical research and quality improvement.

Research question

To present results of long-term implementation of a prospective patient registry, and evaluate the validity of the Clavien-Dindo grade (CDG) to classify complications in neurosurgery.

Materials and methods

A prospective registry for cranial and spinal neurosurgical procedures was implemented in 2013. The CDG - a complication grading focused on need for unplanned therapeutic intervention - was used to grade complications. We assess construct validity of the CDG.

Results

Data acquisition integrated into our hospital workflow permitted to include all eligible patients into the registry. We have registered 8226 patients that were treated in 11994 surgeries and 32494 consultations up until December 2020. Similarly, we have captured 1245 complications on 6308 patient discharge forms (20%) since full operational status of the registry. The majority of complications (819/6308 ​= ​13%) were treated without invasive treatment (CDG 1 or CDG 2). At discharge, there was a clear correlation of CDG and the Karnofsky Performance Status (KPS, rho ​= ​-0.29, slope -7 KPS percentage points per increment of CDG) and the length of stay (rho ​= ​0.43, slope 3.2 days per increment of CDG).

Discussion and conclusion

Patient registries with high completeness and objective capturing of complications are central to the process of quality improvement. The CDG demonstrates construct validity as a measure of complication classification in a neurosurgical patient population.

Intraoperative high-field resonance: How to optimize its use in our healthcare system

BACKGROUND AND AIMS

Intraoperative MRI (ioMRI) consists of performing a MRI during brain or spinal surgery. Although it is a safe and useful technique, it is available in a few hospitals. This means some aspects are not perfectly defined or standardized, forcing each center to develop its own solutions. Our goal is to describe the technique, evaluate the changes made to optimize its use and thus be able to facilitate the intraoperative resonance implementation in other neurosurgery departments.

METHODS

A prospective analysis of patients consecutively operated using high-field ioMRI guidance was carried out, describing the type of tumor, clinical data, time and sequences of ioMR, use of intraoperative neurophysiology, preoperative tumor volume, after ioMR, and postoperative, as well as complications.

RESULTS

ioMR was performed in 38 patients selected from among 425 brain tumors (9%) operated on in this interval. The tumor types were: 11 glioblastomas, 8 anaplastic astrocytomas, 5 diffuse astrocytomas, 4 meningiomas, 3 oligodendrogliomas, 2 metastases, 2 epidermoid cysts, 1 astroblastoma, 1 arachnoid cyst and 1 pituitary adenoma. The mean age was 45 years. The mean preoperative tumor volume was 45.22cc, after the ioMR 5.08cc and postoperative 1.28cc. Resection was extended after ioMR in 76%. Gross total resection was achieved in 15 patients and residual tumor of less than 1cc was observed in 8. An intentional tumor tissue was left in an eloquent brain region (mean volume 7cc) in 13 patients. Bleeding and ischemia complications were detected early on ioMR in 5%. MRI length was 47 min on average.

CONCLUSIONS

Intraoperative MRI was a useful and safe technique, and no associated complications were registered.

The value of intraoperative MRI in recurrent intracranial tumor surgery

OBJECTIVE

Identifying tumor remnants in previously operated tumor lesions remains a challenge. Intraoperative MRI (ioMRI) helps the neurosurgeon to reorient and update image guidance during surgery. The purpose of this study was to analyze whether ioMRI is more efficient in detecting tumor remnants in the surgery of recurrent lesions compared with primary surgery.

METHODS

All consecutive patients undergoing elective intracranial tumor surgery between 2013 and 2018 at the authors’ institution were included in this retrospective cohort study. The cohort was divided into two groups: re-craniotomy and primary craniotomy. In contrast-enhancing tumors, tumor suspicion in ioMRI was defined as contrast enhancement in T1-weighted imaging. In non–contrast-enhancing tumors, tumor suspicion was defined as hypointensity in T1-weighted imaging and hyperintensity in T2-weighted imaging and FLAIR. In cases in which the ioMRI tumor suspicion was a false positive and not confirmed during in situ inspection by the neurosurgeon, the signal was defined as a tumor-imitating ioMRI signal (TIM). Descriptive statistics were performed.

RESULTS

A total of 214 tumor surgeries met the inclusion criteria. The re-craniotomy group included 89 surgeries, and the primary craniotomy group included 123 surgeries. Initial complete resection after ioMRI was less frequent in the re-craniotomy group than in the primary craniotomy group, but this was not a statistically significant difference. Radiological suspicion of tumor remnants in ioMRI was present in 78% of re-craniotomy surgeries and 69% of primary craniotomy surgeries. The incidence of false-positive TIMs was significantly higher in the re-craniotomy group (n = 11, 12%) compared with the primary craniotomy group (n = 5, 4%; p = 0.015), and in contrast-enhancing tumors was related to hemorrhages in situ (n = 9).

CONCLUSIONS

A history of previous surgery in contrast-enhancing tumors made correct identification of tumor remnants in ioMRI more difficult, with a higher rate of false-positive ioMRI signals in the re-craniotomy group. The majority of TIMs were associated with the inability to distinguish contrast enhancement from hyperacute hemorrhage. The addition of a specific sequence in ioMRI to further differentiate both should be investigated in future studies.

Intraoperative MRI-based elastic fusion for anatomically accurate tractography of the corticospinal tract: correlation with intraoperative neuromonitoring and clinical status

OBJECTIVE

Tractography is a useful technique that is standardly applied to visualize subcortical pathways. However, brain shift hampers tractography use during the course of surgery. While intraoperative MRI (ioMRI) has been shown to be beneficial for use in oncology, intraoperative tractography can rarely be performed due to scanner, protocol, or head clamp limitations. Elastic fusion (EF), however, enables adjustment for brain shift of preoperative imaging and even tractography based on intraoperative images. The authors tested the hypothesis that adjustment of tractography by ioMRI-based EF (IBEF) correlates with the results of intraoperative neuromonitoring (IONM) and clinical outcome and is therefore a reliable method.

METHODS

In 304 consecutive patients treated between June 2018 and March 2020, 8 patients, who made up the basic study cohort, showed an intraoperative loss of motor evoked potentials (MEPs) during motor-eloquent glioma resection for a subcortical lesion within the corticospinal tract (CST) as shown by ioMRI. The authors preoperatively visualized the CST using tractography. Also, IBEFs of pre- and intraoperative images were obtained and the location of the CST was compared in relation to a subcortical lesion. In 11 patients (8 patients with intraoperative loss of MEPs, one of whom also showed loss of MEPs on IBEF evaluation, plus 3 additional patients with loss of MEPs on IBEF evaluation), the authors examined the location of the CST by direct subcortical stimulation (DSCS). The authors defined the IONM results and the functional outcome data as ground truth for analysis.

RESULTS

The maximum mean ± SD correction was 8.8 ± 2.9 (range 3.8-12.0) mm for the whole brain and 5.3 ± 2.4 (range 1.2-8.7) mm for the CST. The CST was located within the lesion before IBEF in 3 cases and after IBEF in all cases (p = 0.0256). All patients with intraoperative loss of MEPs suffered from surgery-related permanent motor deficits. By approximation, the location of the CST after IBEF could be verified by DSCS in 4 cases.

CONCLUSIONS

The present study shows that tractography after IBEF accurately correlates with IONM and patient outcomes and thus demonstrates reliability in this initial study.

Intraoperative MRI guidance for right deep fronto-temporal glioma resection: how I do it

BACKGROUND

For glial tumor management, the extent of resection (EOR) is the key to enhance tumor control and improve patient outcomes. Intraoperative MRI (IoMRI) neuronavigated microsurgery emerged as a useful neuroimaging tool for performing optimal and safe tumor resection.

METHOD

Here, we present the different steps of the microsurgical resection of a challenging deeply located right fronto-temporal glioma, using intraoperative MRI in an integrated IoMRI imaging platform.

CONCLUSION

Intraoperative MRI neuronavigated microsurgery helps to enhance the tumor resection, while reducing unintended area damages. The use of IoMRI fosters a "staged volume resection," to keep safe, taking into account the progressive intraoperative brain shift.

Impact of additional resection on new ischemic lesions and their clinical relevance after intraoperative 3 Tesla MRI in neuro-oncological surgery

Intraoperative MRI (ioMRI) has become a frequently used tool to improve maximum safe resection in brain tumor surgery. The usability of intraoperatively acquired diffusion-weighted imaging sequences to predict the extent and clinical relevance of new infarcts has not yet been studied. Furthermore, the question of whether more aggressive surgery after ioMRI leads to more or larger infarcts is of crucial interest for the surgeons' operative strategy. Retrospective single-center analysis of a prospective registry of procedures from 2013 to 2019 with ioMRI was used. Infarct volumes in ioMRI/poMRI, lesion localization, mRS, and NIHSS were analyzed for each case. A total of 177 individual operations (60% male, mean age 45.5 years old) met the inclusion criteria. In 61% of the procedures, additional resection was performed after ioMRI, which resulted in a significantly higher number of new ischemic lesions postoperatively (p < .001). The development of new or enlarged ischemic areas upon additional resection could also be shown volumetrically (mean volume in ioMRI 0.39 cm³ vs. poMRI 2.97 cm³; p < .001). Despite the surgically induced new infarcts, mRS and NIHSS did not worsen significantly in cases with additional resection. Additionally, new perilesional ischemia in eloquently located tumors was not associated with an impaired neurological outcome. Additional resection after ioMRI leads to new or enlarged ischemic areas. However, these new infarcts do not necessarily result in an impaired neurological outcome, even when in eloquent brain areas.

Machine Learning Algorithm Identifies Patients at High Risk for Early Complications After Intracranial Tumor Surgery: Registry-Based Cohort Study

INTRODUCTION

Reliable preoperative identification of patients at high risk for early postoperative complications occurring within 24 h (EPC) of intracranial tumor surgery can improve patient safety and postoperative management. Statistical analysis using machine learning algorithms may generate models that predict EPC better than conventional statistical methods.

OBJECTIVE

To train such a model and to assess its predictive ability.

METHODS

This cohort study included patients from an ongoing prospective patient registry at a single tertiary care center with an intracranial tumor that underwent elective neurosurgery between June 2015 and May 2017. EPC were categorized based on the Clavien-Dindo classification score. Conventional statistical methods and different machine learning algorithms were used to predict EPC using preoperatively available patient, clinical, and surgery-related variables. The performance of each model was derived from examining classification performance metrics on an out-of-sample test dataset.

RESULTS

EPC occurred in 174 (26%) of 668 patients included in the analysis. Gradient boosting machine learning algorithms provided the model best predicting the probability of an EPC. The model scored an accuracy of 0.70 (confidence interval [CI] 0.59-0.79) with an area under the curve (AUC) of 0.73 and a sensitivity and specificity of 0.80 (CI 0.58-0.91) and 0.67 (CI 0.53-0.77) on the test set. The conventional statistical model showed inferior predictive power (test set: accuracy: 0.59 (CI 0.47-0.71); AUC: 0.64; sensitivity: 0.76 (CI 0.64-0.85); specificity: 0.53 (CI 0.41-0.64)).

CONCLUSION

Using gradient boosting machine learning algorithms, it was possible to create a prediction model superior to conventional statistical methods. While conventional statistical methods favor patients' characteristics, we found the pathology and surgery-related (histology, anatomical localization, surgical access) variables to be better predictors of EPC.

The Zurich Checklist for Safety in the Intraoperative Magnetic Resonance Imaging Suite: Technical Note

BACKGROUND

Recently, the use of intraoperative magnetic resonance imaging (ioMRI) has evolved in neurosurgery. Challenges related to ioMRI-augmented procedures are significant, since the magnetic field creates a potentially hazardous environment. Strict safety guidelines in the operating room (OR) are necessary. Checklists can minimize errors while increasing efficiency and improving workflow.

OBJECTIVE

To describe the Zurich checklists for safety in the ioMRI environment.

METHODS

We summarize the checklist protocol and the experience gained from over 300 surgical procedures performed over a 4-yr period using this new system for transcranial or transsphenoidal surgery in a 2-room high-field 3 Tesla ioMRI suite.

RESULTS

Particularities of the 2-room setting used at our institution can be summarized as (1) patient transfer from a sterile to a nonsterile environment and (2) patient transfer from a zone without to a zone with a high-strength magnetic field. Steps on the checklist have been introduced for reasons of efficient workflow, safety pertaining to the strength of the magnetic field, or sterility concerns. Each step in the checklist corresponds to a specific phase and particular actions taken during the workflow in the ioMRI suite. Most steps are relevant to any 2-room ioMRI-OR suite.

CONCLUSION

The use of an ioMRI-checklist promotes a zero-tolerance attitude for errors, can lower complications, and can help create an environment that is both efficient and safe for the patient and the OR personnel. We highly recommend the use of a surgical checklist when applying ioMRI.

Safety of resident training in the microsurgical resection of intracranial tumors: Data from a prospective registry of complications and outcome

The aim of the present study was to assess the safety of microsurgical resection of intracranial tumors performed by supervised neurosurgical residents. We analyzed prospectively collected data from our institutional patient registry and dichotomized between procedures performed by supervised neurosurgery residents (defined as teaching procedures) or board-certified faculty neurosurgeons (defined as non-teaching procedures). The primary endpoint was morbidity at discharge, defined as a postoperative decrease of ≥10 points on the Karnofsky Performance Scale (KPS). Secondary endpoints included 3-month (M3) morbidity, mortality, the in-hospital complication rate, and complication type and severity. Of 1,446 consecutive procedures, 221 (15.3%) were teaching procedures. Patients in the teaching group were as likely as patients in the non-teaching group to experience discharge morbidity in both uni- (OR 0.85, 95%CI 0.60-1.22, p = 0.391) and multivariate analysis (adjusted OR 1.08, 95%CI 0.74-1.58, p = 0.680). The results were consistent at time of the M3 follow-up and in subgroup analyses. In-hospital mortality was equally low (0.24 vs. 0%, p = 0.461) and the likelihood (p = 0.499), type (p = 0.581) and severity of complications (p = 0.373) were similar. These results suggest that microsurgical resection of carefully selected intracranial tumors can be performed safely by supervised neurosurgical residents without increasing the risk of morbidity, mortality or perioperative complications. Appropriate allocation of operations according to case complexity and the resident's experience level, however, appears essential.

Incidence, depth, and severity of surgical site infections after neurosurgical interventions

BACKGROUND

Today, there are only few reports on the incidence of surgical site infections (SSIs) in neurosurgery. The objective of this work was to determine the rate of SSI at a tertiary neurosurgical department for benchmarking purpose.

METHODS

Data of consecutive patients undergoing neurosurgical treatment between January 2013 and December 2016 were prospectively entered into a registry. SSIs were diagnosed according to the 2017 Centers for Disease Control and Prevention criteria, with severity graded according to the Clavien-Dindo grade (CDG). We analyzed type and length of surgery (LOS), time to SSI, responsible microorganisms, and its association with the functional status (Karnofsky Performance Status = KPS).

RESULTS

Of n = 5463 procedures, a SSI occurred in n = 106 (1.94%). The highest rates of SSI occurred after vascular (3.4%) and cerebrospinal fluid (CSF) diversion procedures (3%), as well as after procedures performed to treat a previous complication (2.9%). There was no difference in LOS across procedures with and without SSI. The median time between the index procedure and SSI was 15.5 days. SSIs were most frequently diagnosed after hospital discharge (55%). The most common microorganisms were coagulase-negative staphylococci, Staphylococcus aureus, and Escherichia coli. In 62.3% of cases, SSI required invasive treatment (surgical revision). Patients with SSI in the in- and out-patient setting (SSI occurring after hospital discharge) presented both with a median KPS of 80.

CONCLUSIONS

The current report provides an overview on SSI in a contemporary, unselected, large series of patients undergoing modern neurosurgical care for benchmarking purposes. The overall rate of SSI was about 2%, but subpopulations with higher risks were identified where additional measures could be taken to prevent SSI and monitor patients at risk more closely for SSI.

The Relationship Between Colloid Transfusion During Surgical Decompression Hemicraniectomy Period and Postoperative Pneumonia or Long-Term Outcome After Space-Occupying Cerebral Infarction: A Retrospective Study

BACKGROUND

Colloid transfusion during surgical decompressive hemicraniectomy (DHC) to treat space-occupying cerebral infarction induced by middle cerebral artery (MCA) is controversial. A multicenter retrospective study was conducted to determine whether an increased colloid transfusion during surgery is associated with a lower incidence of postoperative pneumonia and better long-term outcomes after space-occupying cerebral infarction.

METHODS

Data from surgical DHC within 48 hours to treat space-occupying cerebral infarction that took place between November 30, 2013, and March 30, 2016, were collected in a multicenter chart. Univariate analysis, Spearman correlation, χ² test, and bivariate and multivariate logistic regression were performed to account for the associations between colloid transfusion and postoperative pneumonia or long-term outcomes (indicated by modified Rankin Scale [mRS] scores).

RESULTS

Univariate analysis showed that surgical duration and mRS were significantly different between the subjects older and younger than 60 years who underwent surgical DHC (P < 0.05). In the entire population studied, increased National Institutes of Health Stroke Scale was associated with a greater incidence of postoperative pneumonia (odds ratio [OR] 1.255, P = 0.003) and increased mRS (OR 1.229, P = 0.014). In the population older than 60 years, it was revealed that increased colloid transfusion was associated with a lower incidence of postoperative pneumonia (OR 0.761, P = 0.030) or better outcomes, as indicated with lower mRS (OR 0.837, P = 0.045).

CONCLUSIONS

Our retrospective study demonstrated that there is a robust association between increased perioperative colloid transfusion and lower incidence of postoperative pneumonia and better outcomes among the patients older than 60 years after space-occupying cerebral infarction.