Radiofrequency thermocoagulation under neuromonitoring guidance and general anesthesia for treatment of refractory trigeminal neuralgia.

OBJECTIVE: Radiofrequency thermocoagulation (RFT) for refractory trigeminal neuralgia is usually performed in awake patients to localize the involved trigeminal branches. It is often a painful experience. Here, we present RFT under neuromonitoring guidance and general anesthesia. METHOD: Stimulation of trigeminal branches at the foramen ovale with the tip of the RFT cannula is performed under short general anesthesia. Antidromic sensory-evoked potentials (aSEP) are recorded from the 3 trigeminal branches. The cannula is repositioned until the desired branch can be stimulated and lesioned. CONCLUSION: aSEP enable accurate localization of involved trigeminal branches during RFT and allow performing the procedure under general anesthesia.

Targeted Epidural Blood Patch Injection Through a Mini-Open Approach for Treatment of Spontaneous Intracranial Hypotension.

BACKGROUND AND OBJECTIVES: Spontaneous intracranial hypotension is recognized as a cause for refractory headache. Treatment can range from blind blood patch injection to microsurgical repair of the cerebrospinal fluid (CSF) leak. The objective of the study was to investigate the safety and efficacy of the targeted blood patch injection (TBPI) technique through a mini-open approach in treatment of refractory intracranial hypotension. METHODS: We retrospectively reviewed cases of 20 patients who were treated for spontaneous intracranial hypotension at our institute between 2011 and 2022. Head and spine MRI and whole-spine myelography were performed in an attempt to localize the CSF leak. All patients underwent implantation of two epidural drains above and beneath the index level through a minimally invasive interlaminar microsurgical approach under general anesthesia. Then, blood patch was injected under clinical surveillance. Treatment success and surgical complications were evaluated postoperatively and at follow-up. RESULTS: Patients presented with orthostatic headache, vertigo, sensory deficits, and hypacusis (95%, 15%, 15%, and 10%, respectively). Subdural effusions were present in 65% of the cases. A CSF leak was identified in all patients. The exact site of the CSF leak could be identified in 80% of cases. TBPI was performed with an average blood amount of 37.5 mL. A significant improvement of symptoms was reported in 90% of the cases. A total of 15% of the patients showed recurrent symptoms and underwent a second TBPI, resulting in symptom relief. No therapy-related complications were reported. CONCLUSION: TBPI is a safe and efficient treatment for spontaneous intracranial hypotension. It is performed in a minimally invasive procedure and can be repeated, if necessary, with a very low-risk profile.

Oral Drug Absorption and Drug Disposition in Critically Ill Cardiac Patients.

(1) Background: In critically ill cardiac patients, parenteral and enteral food and drug administration routes may be used. However, it is not well known how drug absorption and metabolism are altered in this group of adult patients. Here, we analyze drug absorption and metabolism in patients after cardiogenic shock using the pharmacokinetics of therapeutically indicated esomeprazole. (2) Methods: The pharmacokinetics of esomeprazole were analyzed in a consecutive series of patients with cardiogenic shock and controls before and after elective cardiac surgery. Esomeprazole was administered orally or with a nasogastric tube and once as an intravenous infusion. (3) Results: The maximum plasma concentration and AUC of esomeprazole were, on average, only half in critically ill patients compared with controls (p < 0.005) and remained lower even seven days later. Interestingly, esomeprazole absorption was also markedly compromised on day 1 after elective surgery. The metabolites of esomeprazole showed a high variability between patients. The esomeprazole sulfone/esomeprazole ratio reflecting CYP3A4 activity was significantly lower in critically ill patients even up to day 7, and this ratio was negatively correlated with CRP values (p = 0.002). The 5'-OH-esomeprazole and 5-O-desmethyl-esomeprazol ratios reflecting CYP2C19 activity did not differ significantly between critically ill and control patients. (4) Conclusions: Gastrointestinal drug absorption can be significantly reduced in critically ill cardiac patients compared with elective patients with stable cardiovascular disease. The decrease in bioavailability indicates that, under these conditions, any vital medication should be administered intravenously to maintain high levels of medications. After shock, hepatic metabolism via the CYP3A4 enzyme may be reduced.

Endoscope-enhanced fluorescence-guided microsurgery increases survival in patients with glioblastoma.

PURPOSE: Extent of resection (EOR) predicts progression-free survival (PFS) and may impact overall survival (OS) in patients with glioblastoma. We recently demonstrated that 5-aminolevulinic acid-(5-ALA)-fluorescence-enhanced endoscopic surgery increase the rate of gross total resection. However, it is hitherto unknown whether fluorescence-enhanced endoscopic resection affects survival. METHODS: We conducted a retrospective single-center analysis of a consecutive series of patients who underwent surgery for non-eloquently located glioblastoma between 2011 and 2018. All patients underwent fluorescence-guided microscopic or fluorescence-guided combined microscopic and endoscopic resection. PFS, OS, EOR as well as clinical and demographic parameters, adjuvant treatment modalities, and molecular characteristics were compared between microscopy-only vs. endoscopy-assisted microsurgical resection. RESULTS: Out of 114 patients, 73 (65%) were male, and 57 (50%) were older than 65 years. Twenty patients (18%) were operated on using additional endoscopic assistance. Both cohorts were equally distributed in terms of age, performance status, lesion location, adjuvant treatment modalities, and molecular status. Gross total resection was achieved in all endoscopy-assisted patients compared to about three-quarters of microscope-only patients (100% vs. 75.9%, p=0.003). The PFS in the endoscope-assisted cohort was 19.3 months (CI95% 10.8-27.7) vs. 10.8 months (CI95% 8.2-13.4; p=0.012) in the microscope-only cohort. OS in the endoscope-assisted group was 28.9 months (CI95% 20.4-34.1) compared to 16.8 months (CI95% 14.0-20.9), in the microscope-only group (p=0.001). CONCLUSION: Endoscope-assisted fluorescence-guided resection of glioblastoma appears to substantially enhance gross total resection and OS. The strong effect size observed herein is contrasted by the limitations in study design. Therefore, prospective validation is required before we can generalize our findings.

Positioning of epidural electrode for motor cortex stimulation in general anesthesia based on intraoperative electrophysiological monitoring to treat refractory trigeminal neuropathic pain.

BACKGROUND: Motor cortex stimulation (MCS) represents a treatment option for refractory trigeminal neuralgia (TGN). Usually, patients need to be awake during surgery to confirm a correct position of the epidural electrode above the motor cortex, reducing patient's comfort. METHOD: Epidural cortical mapping (ECM) and motor evoked potentials (MEPs) were intraoperatively performed for correct localization of motor cortex under general anesthesia that provided comparable results to test stimulation after letting the patient to be awake during the operation. CONCLUSION: Intraoperative ECM and MEPs facilitate a confirmation of correct MCS-electrode position above the motor cortex allowing the MCS-procedure to be performed under general anesthesia.

Mini review: Current status and perspective of S100B protein as a biomarker in daily clinical practice for diagnosis and prognosticating of clinical outcome in patients with neurological diseases with focus on acute brain injury.

Prognosticating the clinical outcome of neurological diseases is essential to guide treatment and facilitate decision-making. It usually depends on clinical and radiological findings. Biomarkers have been suggested to support this process, as they are deemed objective measures and can express the extent of tissue damage or reflect the degree of inflammation. Some of them are specific, and some are not. Few of them, however, reached the stage of daily application in clinical practice. This mini review covers available applications of the S100B protein in prognosticating clinical outcome in patients with various neurological disorders, particularly in those with traumatic brain injury, spontaneous subarachnoid hemorrhage and ischemic stroke. The aim is to provide an understandable picture of the clinical use of the S100B protein and give a brief overview of the current limitations that require future solutions.

Impact of the SARS-CoV-2 pandemic on the survival of patients with high-grade glioma and best practice recommendations.

The severe acute respiratory syndrome coronavirus type 2 (SARS-CoV-2) has changed the clinical day-to-day practice. The aim of this study was to evaluate the impact of the pandemic on patients with high-grade glioma (HGG) as well as to derive best practice recommendations. We compared a multi-institutional cohort with HGG (n = 251) from 03/2020 to 05/2020 (n = 119) to a historical cohort from 03/2019 to 05/2019 (n = 132). The endpoints were outcome (progression-free survival (PFS) and overall survival (OS)) as well as patterns of care and time intervals between treatment steps. The median OS for WHO grade 4 gliomas was 12 months in 2019 (95% Confidence Interval 9.7-14.3 months), and not reached in 2020 (p = .026). There were no other significant differences in the Kaplan-Meier estimates for OS and PFS between cohorts of 2019 and 2020, neither did stratification by WHO grade reveal any significant differences for OS, PFS or for patterns of care. The time interval between cranial magnetic resonance imaging (cMRI) and biopsy was significantly longer in 2020 cohort (11 versus 21 days, p = .031). Median follow-up was 10 months (range 0-30 months). Despite necessary disease containment policies, it is crucial to ensure that patients with HGG are treated in line with the recent guidelines and standard of care (SOC) algorithms. Therefore, we strongly suggest pursuing no changes to SOC treatment, a timely diagnosis and treatment with short time intervals between first symptoms, initial diagnosis, and treatment, as well as a guideline-based cMRI follow-up.

Postoperative Quality of Life in Patients with Pyogenic Spondylodiscitis.

BACKGROUND: Pyogenic spondylodiskitis affects a fragile patient population frequently fraught with severe comorbidities. Data on long-term outcomes, especially for patients undergoing surgery, are scarce. The aim of this study was to assess the long-term quality of life after surgical instrumentation. METHODS: Data of 218 patients who were treated for spondylodiskitis at our institution between January 2008 and July 2017 were reviewed. In-hospital death and mortality rates at 1 year and follow-up were assessed. A survey was conducted using the following questionnaires: Oswestry Disability Index (ODI), Short Form Work Ability Index (SF-WAI), 36-Item Short Form Health Survey (SF-36), and Short Form McGill Pain Questionnaire (SF-MPQ). We investigated the correlation between the assessed variables and clinical data including patient age, comorbidity score at admission, number of operated levels, corpectomy, and length of hospital stay. RESULTS: In-hospital mortality rate was 1.8% and 1-year mortality rate was 5.5%. At the final follow-up (mean 7 ± 6 years), the mortality rate was 45.4%. Seventy-four patients were lost to follow-up or refused to participate in the study. Forty-four patients responded to the survey and had a mean age of 73 years and mean follow-up of 7 ± 2 years. In the ODI questionnaire, disability grades were classified as minimal (23%), moderate (21%), severe (19%), complete (33%), and bed bound (4%). We found a significant correlation between inability to return to work and severe disability on ODI (p < 0.001), as well as a low score on any component of the SF-36 (p < 0.05). CONCLUSION: Despite low in-hospital and 1-year mortality rates, patients with surgically treated pyogenic spondylodiskitis are prone to long-term limitation in all domains of quality of life, especially in physical health and work ability.

Meningeosis Neoplastica in Patients with Glioblastoma: Analysis of 36 Cases.

BACKGROUND: Meningeosis neoplastica is a rare manifestation of high-grade gliomas and is usually associated with a devastating outcome. The aim of this bicenter series was to investigate the clinical course and outcome of patients with meningiosis neoplastica. METHODS: This case series included patients in whom surgery was performed for World Health Organization grade IV primary and secondary glioblastoma (GBM) at the University Medical Center Göttingen, Göttingen, Germany between 2009 and 2021 and Burdenko Institute of Neurosurgery, Moscow, Russia between 2012 and 2018. Inclusion criteria were manifestation of clinical and neuroradiologic signs of leptomeningeal, ependymal, or spinal dissemination of GBM at various time points during the course of the disease. RESULTS: Meningeosis neoplastica was found in 36 patients. Nine patients developed spinal metastases and 12 ependymal dissemination and 15 patients had a leptomeningeal manifestation of high-grade glioma. The median age of patients at first diagnosis of primary tumor was 56 years. Typical symptoms were headache, nausea, vomiting, and acute paraplegia. The median overall survival was 11 months and progression-free survival was 8 months. Meningeosis neoplastica developed a median 2 months after the initial tumor diagnosis. Salvage therapies included ventriculoperitoneal shunting, decompression of spinal metastases, and spinal radiation therapy. The median time between meningeosis manifestation and death was 3 months. CONCLUSIONS: Meningeosis neoplastica is a rare manifestation of GBM. It has a poor prognosis. The overall survival after the manifestation of meningeosis was barely longer than 3 months. Salvage therapies did not improve the outcome in our patient cohort.

The Role of Diskectomy in Reducing Infectious Complications after Surgery for Lumbar Spondylodiscitis.

BACKGROUND: Surgery for pyogenic Spondylodiscitis as an adjunct to antibiotic therapy is an established treatment. However, the technique and extent of surgical debridement remains a matter of debate. Some propagate diskectomy in all cases. Others maintain that stand-alone instrumentation is sufficient. METHODS: We reviewed charts of patients who underwent instrumentation for pyogenic Spondylodiscitis with a minimum follow-up of 1 year. Patients were stratified according to whether they underwent diskectomy plus instrumentation or posterior instrumentation alone. Outcome measures included the need for surgical revision due to recurrent epidural intraspinal infection, wound revision, and construct failure. RESULTS: In all, 257 patients who underwent surgery for pyogenic Spondylodiscitis were identified. Diskectomy and interbody procedure (group A) was performed in 102 patients, while 155 patients underwent instrumentation surgery for Spondylodiscitis without intradiskal debridement (group B). The mean age was 67 ± 12 years, and 102 patients (39.7%) were females. No significant differences were found in the need for epidural abscess recurrence therapy (group A [2.0%] and 5 cases in group B [3%; p = 0.83]) and construct failure (p = 0.575). The need for wound revisions showed a tendency toward higher rates in the posterior instrumentation-only group, which failed to reach significance (p = 0.078). CONCLUSIONS: Overall, intraspinal relapse of surgically treated pyogenic diskitis was low in our retrospective series. The choice of surgical technique was not associated with a significant difference. However, a somewhat higher rate of wound infections requiring revision in the group where no diskectomy was performed has to be weighed against a longer duration of surgery in an already ill patient population.

Complications, Length of Hospital Stay, and Cost of Care after Surgery for Pyogenic Spondylodiscitis.

BACKGROUND: Infectious Spondylodiscitis is a heterogeneous disease usually affecting a fragile patient population with multiple comorbidities. Therefore, surgical and medical complications are important considerations before initiating treatment. METHODS: This retrospective analysis included data of 218 patients who underwent surgical treatment for pyogenic Spondylodiscitis between 2008 and 2016. Groups were divided into length of hospital stay (LOS) (group I ≤21 days and group II>21 days). Analysis included patient age, gender, Charlson comorbidity index, smoking, obesity, osteoporosis, colonization with multidrug-resistant bacteria, preoperative neurologic deficit, pre- and postoperative inflammation markers (CRP and WBC), duration of surgery, number of operated segments, vertebrectomy, and postoperative medical and surgical complications. The case value for each patient expressed in Euro was retrieved from hospital records and included in the analysis. RESULTS: Duration of stay after surgical treatment of Spondylodiscitis was ≤21 days (range: 4-21 days; mean: 16 days) in 41% of patients and >21 days (range: 22-162 days; mean: 41 days) in 59% of the patients. Multivariate analysis showed that both medical complications (odds ratio [OR]: 2.62; 95% confidence interval [CI]: 1.24-5.56; p=0.012) and surgical site infection (OR: 6.04; 95% CI: 2.35-15.51; p<0.001) were independently associated with a long hospital stay. Case values averaged at €21,667±1,579 (minimum: €2,888; maximum: €203,802) and correlated significantly with the length of hospital stay (Pearson's correlation coefficient: 0.681; p<0.05). The occurrence of a postoperative complication increased the cost of care significantly from €17,790 to 24,527 on average (p=0.025). CONCLUSIONS: This study provides benchmark data for patients treated surgically for Spondylodiscitis. Surgical site infection and medical complications are the main drivers of prolonged hospital stays and cost of care.

Prognostic differences and implications on treatment strategies between butterfly glioblastoma and glioblastoma with unilateral corpus callosum infiltration.

Approximately 25% of glioblastomas show at diagnosis a corpus callosum infiltration, which is associated with poor prognosis. The extent of corpus callosum involvement, however, ranges from partial unilateral to complete bilateral infiltration. The role of surgery in glioblastoma with corpus callosum involvement is controversial. In this study, we aimed to examine prognostic differences between glioblastoma with unilateral and glioblastoma with bilateral corpus callosum infiltration, and to evaluate possible treatment strategy implications. Patients with newly diagnosed glioblastoma from 2010 to 2019 were included. Corpus callosum infiltration was assessed in contrast-enhanced T1-weighted preoperative magnetic resonance imaging. Extent of resection, adjuvant treatments and overall survival were evaluated. Corpus callosum involvement was found in 96 (26.4%) out of 363 patients with newly diagnosed glioblastoma. Bilateral corpus callosum infiltration was found in 27 out of 96 patients (28%), and 69 patients had unilateral corpus callosum infiltration. Glioblastoma with corpus callosum affection had significantly lower median overall survival compared to glioblastoma without corpus callosum involvement (9 vs. 11 months, p = 0.02). A subgroup analysis of glioblastoma with unilateral corpus callosum infiltration revealed a significant difference in median overall survival dependent on extent of resection (6.5 without gross total resection vs. 11 months with gross total resection, Log-rank test p = 0.02). Our data confirms a shorter overall survival in glioblastoma subpopulation with corpus callosum involvement, especially for glioblastoma with bilateral corpus callosum infiltration. However, patients with partial corpus callosum infiltration undergoing gross total resection exhibited a significant survival benefit compared to their counterparts without gross total resection. Whenever reasonably achievable gross total resection should be considered as an integral part of the treatment strategy in glioblastoma with partial corpus callosum infiltration.

Tissue Healing in Hemicraniectomy.

Introduction Decompressive hemicraniectomy (DHC) is a last-resort treatment for refractory intracranial hypertension. Perioperative morbidity is associated with high risks of wound healing disturbances (WHD). Recently, a retromastoidal frontoparietooccipital (RMF) incision type was performed to avoid healing disturbance due to enhanced tissue flap perfusion compared to the classical reverse "question mark" ("Dandy flap") incision. The goal of this study was to analyze the details of tissue healing problems in DHC.  Materials and methods A total of 60 patients who underwent DHC were retrospectively analyzed. In 30 patients the "Dandy flap" incision (group A) and in 30 patients the RMF incision (group B) was made. Since no evidence-based data for the incision type that favors better wound healing exists, the form of incision was left at the surgeon´s discretion. Documentation of the patients was screened for the incidence of WHD: wound necrosis, dehiscence, and cerebrospinal fluid (CSF) leakage. Patient age, the time interval from surgery until the appearance of WHD, the length of surgeries in minutes, and the indications of the DHC were analyzed. A Chi-square test of independence was performed to examine the relationship between the incision type and the appearance of WHD with the statistical significance level set at p<0.05. The mean age of the patients, the mean time interval from surgery until the occurrence of WHD, and the mean length of the surgery between the two groups were compared using an independent sample t-test with the statistical significance level set at p<0.05. Results The most common indication for DHC in both groups was malignant MCA infarction (n=20, 66.6% for group A and n=16, 53.3% for group B). CSF leakage was 20% of the most frequent WHD in each group. Wound necrosis was observed only in group A. Although group B showed 13.3% fewer WHD than group A, this difference was not statistically significant. There was no statistically significant difference in the time range between surgery and the occurrence of WHD between the two groups. The length of surgery in group B was significantly shorter than in group A (120.2 mins vs. 103.7 mins). Conclusion A noticeable trend for reduced WHD was observed in the patient group using the RMF incision type although the difference was not statistically significant. We praise that the RMF incision allows an optimized skin-flap vascularization and, thereby, facilitates better wound healing. We were able to show a statistically shorter length of surgery with the RMF incision in contrast to the classic "Dandy flap" incision. Larger multicenter studies should be implemented to analyze and address the major advantages and pitfalls of the routinely applied incision techniques.

Infratentorial ganglioglioma mimicking a cerebellar metastasis.

We report a case of an infratentorial ganglioglioma in a 56-year-old male, who underwent magnetic resonance imaging (MRI) during the diagnostic workup for a suspected lung cancer. The MRI scan revealed a space-occupying lesion of the left lobulus semilunaris superior cerebelli, which was assumed being a metastasis. The asymptomatic lesion was resected to establish the diagnosis. Histologic and immunohistochemical studies showed a ganglioglioma with World Health Organization grade I characteristics. Although ganglioglioma typically exhibits a supratentorial predilection, it should be included in the differential diagnosis of lesions occurring in the cerebellum.

False-positive results in transcranial motor evoked potentials for outcome prognostication during surgery for supratentorial lesions.

During monitoring of motor evoked potentials (MEP) elicited by transcranial electrical stimulation (TES) for prognostication of postoperative motor deficit, significant MEP changes without postoperative deterioration of motor function represent false-positive results. We aimed to investigate this phenomenon in a large series of patients who underwent resection of supratentorial lesions. TES was applied in 264 patients during resection of motor-eloquent supratentorial lesions. MEP were recorded bilaterally from arm, leg, and/ or facial muscles. The threshold criterion was applied assessing percentage increase in threshold level, which was considered significant if being > 20% higher on affected side than on the unaffected side. Subcortical stimulation was additionally applied to estimate the distance to corticospinal tract. Motor function was evaluated at 24 h after surgery and at 3-month follow-up. Patients with false-positive results were analyzed regarding tumor location, tumor volume, and characteristics of the monitoring. MEP were recorded from 399 muscles (264 arm muscles, 75 leg muscles, and 60 facial muscles). Motor function was unchanged postoperatively in 359 muscles in 228 patients. Among these cases, the threshold level did not change significantly in 354 muscles in 224 patients, while it increased significantly in the remaining 5 muscles in 4 patients (abductor pollicis brevis in all four patients and orbicularis oris in one patient), leading to a false-positive rate of 1.1%. Tumor volume, opening the ventricle, and negative subcortical stimulation did not significantly correlate with false-positive results, while the tumor location in the parietal lobe dorsal to the postcentral gyrus correlated significantly (p = 0.012, odds ratio 11.2, 95% CI 1.8 to 69.8). False-negative results took place in 1.1% of cases in a large series of TES-MEP monitoring using the threshold criterion. Tumor location in the parietal lobe dorsal to the postcentral gyrus was the only predictor of false-positive results.

Endoscope-assisted visualization of 5-aminolevulinic acid fluorescence in surgery for brain metastases.

OBJECTIVE: Fluorescence-guided resection of cerebral metastases has been proposed as an approach to visualize residual tumor tissue and maximize the extent of resection. Critics have argued that tumor cells at the resection margins might be overlooked under microscopic visualization because of technical limitations. Therefore, an endoscope, which is capable of inducing fluorescence, has been applied with the aim of improving exposure of fluorescent tumor tissue. In this retrospective analysis, authors assessed the utility of endoscope assistance in 5-aminolevulinic acid (5-ALA) fluorescence-guided resection of brain metastases. METHODS: Between June 2013 and December 2016, a standard 20-mg/kg dose of 5-ALA was administered 4 hours prior to surgery in 26 patients with suspected single brain metastases. After standard neuronavigated microsurgical tumor resection, a microscope capable of inducing fluorescence was used to examine tumor margins. The authors classified the remaining fluorescence into 3 grades (0 = none, 1 = weak, and 2 = strong). Endoscopic assistance was employed if no or only weak fluorescence was visualized at the resection margins under the microscope. Endoscopically identified fluorescent tissue at the margins was resected and evaluated separately via histological examination to prove or disprove tumor infiltration. RESULTS: Under the microscope, weakly fluorescent tissue was seen at the margins of the resection cavity in 15/26 (57.7%) patients. In contrast, endoscopic inspection revealed strongly fluorescent tissue in 22/26 (84.6%) metastases. In 11/26 (42.3%) metastases no fluorescence at the tumor margins was detected by the microscope; however, strong fluorescence was visualized under the endoscope in 7 (63.6%) of these 11 metastases. In the 15 metastases with microscopically weak fluorescence, strong fluorescence was seen when using the endoscope. Neither microscopic nor endoscopic fluorescence was found in 4/26 (15.4%) cases. In the 26 patients, 96 histological specimens were obtained from the margins of the resection cavity. Findings from these specimens were in conjunction with the histopathological findings, allowing identification of metastatic infiltration with a sensitivity of 95.5% and a specificity of 75% using endoscope assistance. CONCLUSIONS: Fluorescence-guided endoscope assistance may overcome the technical limitations of the conventional microscopic exposure of 5-ALA-fluorescent metastases and thereby increase visualization of fluorescent tumor tissue at the margins of the resection cavity with high sensitivity and acceptable specificity.

Determining the applicability of the RSNA radiology lexicon (RadLex) in high-grade glioma MRI reporting-a preliminary study on 20 consecutive cases with newly diagnosed glioblastoma.

BACKGROUND: The implementation of a collective terminology in radiological reporting such as the RSNA radiological lexicon (RadLex) yields many benefits including unambiguous communication of findings, improved education, and fostering data mining for research purposes. While some fields in general radiology have already been evaluated so far, this is the first exploratory approach to assess the applicability of the RadLex terminology to glioblastoma (GBM) MRI reporting. METHODS: Preoperative brain MRI reports of 20 consecutive patients with newly diagnosed GBM (mean age 68.4 ± 10.8 years; 12 males) between January and October 2010 were retrospectively identified. All terms related to the tumor as well as their frequencies of mention were extracted from the MRI reports by two independent neuroradiologists. Every item was subsequently analyzed with respect to an equivalent RadLex representation and classified into one of four groups as follows: 1. verbatim RadLex entity, 2. synonymous/multiple equivalent(s), 3. combination of RadLex concepts, or 4. no RadLex equivalent. Additionally, verbatim entities were categorized using the hierarchical RadLex Tree Browser. RESULTS: A total of 160 radiological terms were gathered. 123/160 (76.9%) items showed literal RadLex equivalents, 9/160 (5.6%) items had synonymous (non-verbatim) or multiple counterparts, 21/160 (13.1%) items were represented by means of a combination of concepts, and 7/160 (4.4%) entities could not eventually be transferred adequately into the RadLex ontology. CONCLUSIONS: Our results suggest a sufficient term coverage of the RadLex terminology for GBM MRI reporting. If applied extensively, it may improve communication of radiological findings and facilitate data mining for large-scale research purposes.

Transcranial versus Direct Cortical Stimulation for Motor-Evoked Potentials during Resection of Supratentorial Tumors under General Anesthesia (The TRANSEKT-Trial): Study Protocol for a Randomized Controlled Trial.

BACKGROUND: Monitoring of motor function during surgery for supratentorial tumors under general anesthesia applies either transcranial electrical stimulation (TES) or direct cortical stimulation (DCS) to elicit motor-evoked potentials. To date, there is no guideline that favor one method over the other. Therefore, we designed this randomized study to compare between both methods regarding the prediction of postoperative motor deficits and extent of tumor resection. METHODS: This is a multicenter (six centers in Germany and one in Switzerland), double blind, parallel group, exploratory, randomized controlled clinical trial. Patients without or with mild paresis, who are scheduled for surgical resection of motor-eloquent brain tumors under general anesthesia will be randomized to surgical resection under TES or surgical resection under DCS. The primary endpoint is sensitivity and specificity in prognosis of motor function 7 days after surgery. The main secondary endpoint is the extent of tumor resection. The study is planned to include 120 patients within 2 years. DISCUSSION: The present exploratory study should compare TES and DCS regarding sensitivity and specificity in predicting postoperative motor deficit and extent of tumor resection to calculate the required number of patients in a confirmatory trial to test the superiority of one method over the other.

An insight into electrical resistivity of white matter and brain tumors.

BACKGROUND: There is a lack of information regarding electrical properties of white matter and brain tumors. OBJECTIVE: To investigate the feasibility of in-vivo measurement of electrical resistivity during brain surgery and establish a better understanding of the resistivity patterns of brain tumors in correlation to the white matter. METHODS: A bipolar probe was used to measure electrical resistivity during surgery in a prospective cohort of patients with brain tumors. For impedance measurement, the probe applied a constant current of 0.7 µA with a frequency of 140 Hz. The measurement was performed in the white matter within and outside peritumoral edema as well as in non-enhancing, enhancing and necrotic tumor areas. Resistivity values expressed in ohmmeter (Ω∗m) were compared between different intracranial tissues and brain tumors. RESULTS: Ninety-two patients (gliomas WHO II:16, WHO III:10, WHO IV:33, metastasis:33) were included. White matter outside peritumoral edema had higher resistivity values (13.3 ± 1.7 Ω∗m) than within peritumoral edema (8.5 ± 1.6 Ω∗m), and both had higher values than brain tumors including non-enhancing (WHO II:6.4 ± 1.3 Ω∗m, WHO III:6.3 ± 0.9 Ω∗m), enhancing (WHO IV:5 ± 1 Ω∗m, metastasis:5.4 ± 1.3 Ω∗m) and necrotic tumor areas (WHO IV:3.9 ± 1.1 Ω∗m, metastasis:4.3 ± 1.3 Ω∗m), p=<0.001. No difference was found between low-grade and anaplastic gliomas, p = 0.808, while resistivity values in both were higher than the highest values found in glioblastomas, p = 0.003 and p = 0.004, respectively. CONCLUSIONS: The technique we applied enabled us to measure electrical resistivity of white matter and brain tumors in-vivo presumably with a significant effect with regard to dielectric polarization. Our results suggest that there are significant differences within different areas and subtypes of brain tumors and that white matter exhibits higher electrical resistivity than brain tumors.