The telovelar approach for fourth ventricular tumors in children: is removal of the posterior arch of C1 necessary?

PURPOSE: Various surgical nuances of the telovelar approach have been suggested. The necessity of removing the posterior arch of C1 to accomplish optimal tumor exposure is still debated. Therefore, we report on our experience and technical details of the fourth ventricular tumor resection in a modified prone position without systematic removal of the posterior arch of C1. METHODS: A retrospective analysis of all pediatric patients, who underwent a fourth ventricular tumor resection in the modified prone position between 2012 and 2021, was performed. RESULTS: We identified 40 patients with a median age of 6 years and a M:F ratio of 25:15. A telovelar approach was performed in all cases. In 39/40 patients, the posterior arch of C1 was not removed. In the remaining patient, the reason for removing C1 was tumor extension below the level of C2 with ventral extension. Gross or near total resection could be achieved in 34/39 patients, and subtotal resection in 5/39 patients. In none of the patients, a limited exposure, sight of view, or range of motion caused by the posterior arch of C1 was encountered, necessitating an unplanned removal of the posterior arch of C1. Importantly, in none of the cases, the surgeon had the impression of a limited sight of view to the most rostral parts of the fourth ventricle, which necessitated a vermian incision. CONCLUSION: A telovelar approach without the removal of the posterior arch of C1 allows for an optimal exposure of the fourth ventricle provided that critical nuances in patient positioning are considered.

The value of cryoablation in orbital surgery.

Aim of this article is to give an overview of the technical background and the advantages of modern devices for different applications of cryoablation in cranio-orbital neurosurgery.The treatment of orbital lesions is complicated by the complex and potentially inapparent anatomy due to retro-orbital fat. With the help of cryoprobes different well-defined lesions such as cavernous venous malformations can be safely and effectively removed thanks to the cryoadhesive effect. Their use has been described in several different approaches including traditional lateral or transcranial orbitotomy but also anterior transconjunctival as well as transnasal endoscopic approaches. Recently, single-use devices were introduced that allow the use of cryosurgery also without the need for large investment or service costs.

Risk factors for unfavorable outcome after spontaneous intracerebral hemorrhage in elderly patients.

BACKGROUND: Spontaneous intracerebral hemorrhage (SICH) of the elderly is a devastating form of stroke with a high morbidity and economic burden. There is still a limited understanding of the risk factors for an unfavorable outcome where a surgical therapy may be less meaningful. Thus, the aim of this study is to identify factors associated with unfavorable outcome and time to death in surgically treated elderly patients with SICH. METHODS: We performed a single-center retrospective study of 70 patients (age > 60 years) with SICH operated between 2008 and 2020. Functional outcome was assessed by modified Rankin Scale. Various clinical and neuroradiological variables including type of neurosurgical treatment, anatomical location of hemorrhage, volumetry and distribution of hemorrhage were assessed. Univariate and multivariate logistic regression models were performed. Length of stay (LOS) and hospital costs are presented. RESULTS: The overall mortality (mean follow-up time of 22 months) in this study was 32/70 patients (45.71%), 30-days mortality was 8/70 (11.42%), and 12-months mortality was 22/70 (31.43%). Average LOS was 73.5 days with a median of 58, 766 € estimated in hospital costs per patient. Multivariate analysis for 12-months mortality was significant for intraventricular hemorrhage (IVH) (p = 0.007, HR = 1.021, 95% CI = 1.006 - 1.037). ROC analysis for 12-months mortality for IVH volume >= 7 cm3 presented an are under the curve of 0.658. CONCLUSIONS: We identified IVH volume > 7 cm3 as an independent prognostic risk factor for mortality in elderly patients after SICH. This may help clinicians in decision-making for this critical and growing subgroup of patients.

Use of a 3D exoscope in microvascular decompression of the trigeminal nerve root.

For microvascular decompression surgery, adequate visualization of the trigeminal nerve root is essential. Several visualization techniques with operating microscopes, endoscopes, a combination of both, and exoscopes have been described. In this video, the authors use a 4K 3D exoscope (ORBEYE) as it offers superb optical image quality with a high degree of magnification and illumination in the cerebellopontine angle. Other advantages are surgeon ergonomics, a very good depth of field for the entire operating team, and potentially evolving visualization technologies like narrow-band imaging-essential points for microvascular decompression surgery where the aim is to create the best possible visibility in a narrow corridor. The video can be found here: https://stream.cadmore.media/r10.3171/2023.10.FOCVID23149.

Where to Draw Cerebrospinal Fluid from an External Ventricular Drain? Comparison of Cerebrospinal Fluid Parameters between Two Different Collection Sites.

BACKGROUND: High cerebrospinal fluid (CSF) sampling frequency is considered a risk factor for external ventricular drain (EVD)-associated infections. To reduce manipulation at the proximal port and potentially minimize the risk of an infection, we aimed to analyze whether CSF parameters sampled from the far distal collection bag could provide reliable results compared to the proximal port. METHODS: We included patients who were treated with an EVD at our neurosurgical intensive care unit (ICU) between June 2021 and September 2022. CSF sampling, including microbiological analysis, was performed simultaneously from the proximal port and the collection bag. Spearman's correlation coefficients were calculated to assess the correlation of CSF cell count, protein, lactate and glucose between the two sample sites. RESULTS: We analyzed 290 pairs of CSF samples in 77 patients. Ventriculitis was identified in 4/77 (5%) patients. In 3/4 patients, microbiological analysis showed the same bacterial species at both sample sites at the same time. Spearman's correlation coefficient showed that CSF cell count (r = 0.762), lactate (r = 0.836) and protein (r = 0.724) had a high positive correlation between the two collection sites, while CSF glucose (r = 0.663) showed a moderate positive correlation. CONCLUSION: This study shows that biochemical CSF parameters can be reliably assessed from the EVD collection bag.

Technical Note: Advantages of a 2-Room Intraoperative 3-Tesla Magnetic Resonance Imaging Operating Suite for Performing Laser Interstitial Thermal Therapy in Pediatric Epilepsy and Tumor Surgery.

OBJECTIVE: Magnetic resonance thermography-guided laser interstitial thermal therapy (LITT) provides a minimally invasive treatment option in children with central nervous system tumors or medically intractable epilepsy. However, transporting anesthetized children between an operating room (OR) and a radiologic suite creates logistical challenges. Thus we describe advantages of using a 2-room intraoperative magnetic resonance imaging (MRI) concept for LITT. METHODS: Patients were pinned in a head frame that doubles as the lower part of the MRI head coil. Preoperative MRI was performed for accurate neuronavigation, after which laser fibers were stereotactically implanted. Transport between OR and MRI was achieved by sliding the top of the OR table onto a trolly. RESULTS: We performed 12 procedures in 11 children, mean age 7.1 years (range: 2 to 14 years). Ten children suffered from medically intractable epilepsy, and 1 child had a pilocytic midbrain astrocytoma. Two fibers were placed in 8 and 1 fiber in 4 procedures. Mean entry point and target errors were 2.8 mm and 3.4 mm, respectively. Average transfer time from OR to MRI and vice versa was 9 minutes (±1 minute, 40 seconds). Altogether, 50% of the seizure patients were seizure free (Engel grade I) at 22 months' follow-up time. One hemorrhagic event, which could be managed nonoperatively, occurred. We recorded no surgical site or intracranial infections. CONCLUSIONS: All LITT procedures were successfully carried out with head frame in the sterile environment. The intraoperative MRI suite proved to be advantageous for minimally invasive procedures, especially in young children resulting in short transports while maintaining high accuracy and safety.

The Effect of Oral Nimodipine on Cerebral Metabolism and Hemodynamic Parameters in Patients Suffering Aneurysmal Subarachnoid Hemorrhage.

INTRODUCTION: Nimodipine is routinely administered to aneurysmal subarachnoid hemorrhage patients to improve functional outcomes. Nimodipine can induce marked systemic hypotension, which might impair cerebral perfusion and brain metabolism. METHODS: Twenty-seven aneurysmal subarachnoid hemorrhage patients having multimodality neuromonitoring and oral nimodipine treatment as standard of care were included in this retrospective study. Alterations in mean arterial blood pressure (MAP), cerebral perfusion pressure (CPP), brain tissue oxygen tension (pbtO2), and brain metabolism (cerebral microdialysis), were investigated up to 120 minutes after oral administration of nimodipine (60 mg or 30 mg), using mixed linear models. RESULTS: Three thousand four hundred twenty-five oral nimodipine administrations were investigated (126±59 administrations/patient). After 60 mg of oral nimodipine, there was an immediate statistically significant (but clinically irrelevant) drop in MAP (relative change, 0.97; P<0.001) and CPP (relative change: 0.97; P<0.001) compared with baseline, which lasted for the whole 120 minutes observation period (P<0.001). Subsequently, pbtO2 significantly decreased 50 minutes after administration (P=0.04) for the rest of the observation period; the maximum decrease was -0.6 mmHg after 100 minutes (P<0.001). None of the investigated cerebral metabolites (glucose, lactate, pyruvate, lactate/pyruvate ratio, glutamate, glycerol) changed after 60 mg nimodipine. Compared with 60 mg nimodipine, 30 mg induced a lower reduction in MAP (relative change, 1.01; P=0.02) and CPP (relative change, 1.01; P=0.03) but had similar effects on pbtO2 and cerebral metabolism (P>0.05). CONCLUSIONS: Oral nimodipine reduced MAP, which translated into a reduction in cerebral perfusion and oxygenation. However, these changes are unlikely to be clinically relevant, as the absolute changes were minimal and did not impact cerebral metabolism.

Retrospective comparison of percutaneous balloon compression and radiofrequency-thermocoagulation in the management of trigeminal neuralgia.

PURPOSE: To compare percutaneous balloon compression (PBC) and radiofrequency thermocoagulation (RFTC) for the treatment of trigeminal neuralgia. METHODS: This was a retrospective single-center analysis of data from 230 patients with trigeminal neuralgia who underwent 202 PBC (46%) and 234 RFTC (54%) from 2002 to 2019. Comparison of demographic data and trigeminal neuralgia characteristics between procedures as well as assessment of 1) initial pain relief by an improved Barrow Neurological Institute (BNI) pain intensity scale of I-III; 2) recurrence-free survival of patients with a follow-up of at least 6 months by Kaplan-Meier analysis; 3) risk factors for failed initial pain relief and recurrence-free survival by regression analysis; and 4) complications and adverse events. RESULTS: Initial pain relief was achieved in 353 (84.2%) procedures and showed no significant difference between PBC (83.7%) and RFTC (84.9%). Patients who suffered from multiple sclerosis (odds ratio 5.34) or had a higher preoperative BNI (odds ratio 2.01) showed a higher risk of not becoming pain free. Recurrence-free survival in 283 procedures was longer for PBC (44%) with 481 days compared to RFTC (56%) with 421 days (p=0.036) but without statistical significance. The only factors that showed a significant influence on longer recurrence-free survival rates were a postoperative BNI ≤ II (P=<0.0001) and a BNI facial numbness score ≥ 3 (p = 0.009). The complication rate of 22.2% as well as zero mortality showed no difference between the two procedures (p=0.162). CONCLUSION: Both percutaneous interventions led to a comparable initial pain relief and recurrence-free survival with a low and comparable probability of complications. An individualized approach, considering the advantages and disadvantages of each intervention, should guide the decision-making process. Prospective comparative trials are urgently needed.

Incidence, risk factors, and treatment of incidental durotomy during decompression in degenerative lumbar spine conditions.

BACKGROUND: The purpose of this study was to identify independent risk factors for incidental durotomy (ID) during decompressive lumbar spine surgery, and to describe its treatment. METHODS: This retrospective review includes 650 patients who underwent lumbar decompression at a tertiary institution between January 2015 and October 2019. Data collection was obtained through one independent researcher. The incidence rate and treatment of ID was evaluated by a chart review of operative notes, patient charts, physiotherapy reports, and nursing reports. RESULTS: The incidence rate of ID was 12.6%. The most common reason for admission was disc herniation (63.2%), followed by vertebral stenosis (22.1%). ID resulted in significantly longer operation time (P=0.0001) and length of hospitalization (P=0.0001). A correlation between ID and patient's diagnosis (P=0.0078) as well as the chosen type of surgery (P=0.0404) with an Odds Ratio to cause ID of 1.9 for laminectomy and 1.6 for undercutting compared to microdiscectomy were found. However, age, sex, surgeon experience, lumbar level, revision surgery, as well as multilevel surgery were not significantly correlated with the incidence of ID. Dural tears were closed with dural sealant (47.2%), polyester 4-0 sutures (11.1%) or a combination of both (37.5%) and the majority of patients had bed rest of at least two days. By usage of these treatment methods no patient needed reoperation. CONCLUSIONS: Diagnosis of vertebrostenosis as well as laminectomy were significantly correlated with the incidence of ID. Treatment with intraoperative closure and postoperative bed rest even though not standardized led to complication free outcomes.

The effect of perioperative non-steroidal anti-inflammatory drugs and male sex on the recurrence rates after chronic subdural hematoma evacuation.

BACKGROUND: Drugs that inhibit blood clot formation are a risk factor for the development and recurrence of chronic subdural hematoma (cSDH). The use of non-steroidal anti-inflammatory drug (NSAID) was associated with higher bleeding rates in non-neurosurgical patients, but their influence on cranial hematomas is unclear. We sought to better describe the hazard associated with their use in cSDH patients and find additional risk factors. METHODS: We performed a retrospective analysis of patients undergoing burr hole drainage for cSDH over a period of 15 years. Demographic and surgical details were extracted from individual patient records. Patients were followed for up to 90 days with SDH recurrence requiring repeat surgery as the primary endpoint. Univariate and multivariate Cox regression models were performed to identify risk factors and their effect size. RESULTS: We included 361 patients, who underwent burr hole drainage for cSDH. Recurrences occurred in 73 patients (20.2%) after a median time period of 18 days. Sixty-six patients in our cohort were taking NSAIDs perioperatively. The recurrence rate was not higher in NSAID users compared to other patients with 18.2% and 20.7%, respectively. 23.5% of men, yet only 12.7% of women had recurrences revealing male sex as a risk factor in a uni- and multivariate regression. Not placing a drain was a risk factor for early recurrences, which resulted in a prolonged hospital stay. CONCLUSIONS: We identified male sex as a risk factor for cSDH recurrence after burr hole drainage, while perioperative NSAID use did not increase recurrence rates.

Predicting the need for cerebrospinal fluid shunt implantation after spontaneous intracerebral hemorrhage: a challenging task.

Objectives: The development of persistent hydrocephalus in patients after spontaneous intracerebral hemorrhage (ICH) is still poorly understood, and many variables predicting the need for a cerebrospinal fluid (CSF)-shunt have been described in the literature with varying results. The aim of this study is to find predictive factors for shunt dependency. Methods: We performed a retrospective, single-center study of 99 neurosurgically treated patients with spontaneous ICH. Variables, including age, Glasgow Coma Scale (GCS), intraventricular hemorrhage (IVH), location of hemorrhage, acute hydrocephalus, and volumetric analysis of IVH, ICH, and intraventricular CSF were compared between patients with and without CSF-shunt implantation. Furthermore, receiver operating characteristics (ROC) for ICH, IVH, and intraventricular CSF volume parameters were calculated. Results: CSF-shunt implantation was performed significantly more often in patients after thalamic (p = 0.03) and cerebellar ICH (p = 0.04). Moreover, a lower ratio between the total hemorrhage volume and intraventricular CSF volume (p = 0.007), a higher IVH distribution in the third ventricle, and an acute hydrocephalus (p < 0.001) with an increased intraventricular CSF volume (p < 0.001) were associated with shunt dependency. Our ROC model demonstrated a sensitivity of 82% and a specificity of 65% to predict the necessity for a shunt at a cutoff value of 1.9 with an AUC of 0.835. Conclusion: Volumetric analysis of ICH, IVH, and intraventricular CSF may improve the prediction of CSF shunt implantation in patients with spontaneous ICH.

Pushing the Limits of the Prone Position in the Intraoperative Magnetic Resonance Suite.

BACKGROUND: Patient positioning is an integral part of surgical planning, and numerous variations have been suggested to optimize the prone position. So far, however, little attention has been given to address the restrictions and special needs in an intraoperative MRI suite. OBJECTIVE: To share our experience of transforming the modified prone position from the conventional operating room to the intraoperative MRI suite. METHODS: Two-room 3T intraoperative MRI suite. Detailed description of the technical pearls is provided. RESULTS: Ten procedures in 9 consecutive patients (2 female and 7 male) were performed. The median age was 8 years ranging from 4 to 71 years. We experienced no complication from patient positioning. Neither size (range 104-182 cm) nor weight (range 18-98 kg) of the patients was a limiting factor. In none of them, the surgeon experienced an adverse event from inadequate patient positioning and the surgical goals could be achieved without restrictions. An intraoperative MRI could be acquired in all of them with the same image quality as observed for standard positions. CONCLUSION: A transition of the modified prone position from the conventional operating room to the intraoperative MRI suite is feasible, if some crucial steps are considered. We provide a detailed technical description that could be used as a guide by others.

Technical Assessment of Microvascular Decompression for Trigeminal Neuralgia Using a 3-Dimensional Exoscope: A Case Series.

BACKGROUND: Detailed anatomic visualization of the root entry zone of the trigeminal nerve is crucial to successfully perform microvascular decompression surgery (MVD) in patients with trigeminal neuralgia. OBJECTIVE: To determine advantages and disadvantages using a 3-dimensional (3D) exoscope for MVD surgery. METHODS: A 4K 3D exoscope (ORBEYE) was used by a single surgical team for MVD in a retrospective case series of 8 patients with trigeminal neuralgia in a tertiary center. Clinical and surgical data were collected, and advantages/disadvantages of using the exoscope for MVD were recorded after each surgery. Descriptive statistics were used to summarize the data. RESULTS: Adequate MVD of the trigeminal nerve root was possible in all patients by exclusively using the exoscope. It offered bright visualization of the cerebellopontine angle and the root entry zone of the trigeminal nerve that was comparable with a binocular operating microscope. The greatest advantages of the exoscope included good optical quality, the pronounced depth of field of the image for all observers, and its superior surgeon ergonomics. Disadvantages were revealed with overexposure at deep surgical sites and the lack of endoscope integration. In 6 patients, facial pain improved significantly after surgery (Barrow Neurological Institute pain intensity score I in 5 and III in 1 patient), whereas it did not in 2 patients (Barrow Neurological Institute score IV and V). No complications occurred. CONCLUSION: Utilization of a 3D exoscope for MVD is a safe and feasible procedure. Surgeons benefit from better ergonomics, excellent image quality, and an improved experience for observers.

Awake brain surgery for language mapping in pediatric patients: a single-center experience.

OBJECTIVE: The goal of this study was to evaluate the feasibility, benefit, and safety of awake brain surgery (ABS) and intraoperative language mapping in children and adolescents with structural epilepsies. Whereas ABS is an established method to monitor language function in adults intraoperatively, reports of ABS in children are scarce. METHODS: A retrospective chart review of pediatric patients ≤ 18 years of age who underwent ABS and cortical language mapping for supratentorial tumors and nontumoral epileptogenic lesions between 2008 and 2019 was conducted. The authors evaluated the global intellectual and specific language performance by using detailed neuropsychological testing, the patient's intraoperative compliance, results of intraoperative language mapping assisted by electrocorticography (ECoG), and postsurgical language development and seizure outcomes. Descriptive statistics were used for this study, with a statistical significance of p < 0.05. RESULTS: Eleven children (7 boys) with a median age of 13 years (range 10-18 years) underwent ABS for a lesion in close vicinity to cortical language areas as defined by structural and functional MRI (left hemisphere in 9 children, right hemisphere in 2). Patients were neurologically intact but experiencing seizures; these were refractory to therapy in 9 patients. Compliance during the awake phase was high in 10 patients and low in 1 patient. Cortical mapping identified eloquent language areas in 6/10 (60%) patients and was concordant in 3/8 (37.5%), discordant in 3/8 (37.5%), and unclear in 2/8 (25%) patients compared to preoperative functional MRI. Stimulation-induced seizures occurred in 2 patients and could be interrupted easily. ECoG revealed that afterdischarge potentials (ADP) were involved in 5/9 (56%) patients with speech disturbances during stimulation. None of these patients harbored postoperative language dysfunction. Gross-total resection was achieved in 10/11 (91%) patients, and all were seizure free after a median follow-up of 4.3 years. Neuropsychological testing using the Wechsler Intelligence Scale for Children and the verbal learning and memory test showed an overall nonsignificant trend toward an immediate postoperative deterioration followed by an improvement to above preoperative levels after 1 year. CONCLUSIONS: ABS is a valuable technique in selected pediatric patients with lesions in language areas. An interdisciplinary approach, careful patient selection, extensive preoperative training of patients, and interpretation of intraoperative ADP are pivotal to a successful surgery.

Feasibility of intraoperative motor evoked potential monitoring during tethered cord surgery in infants younger than 12 months.

PURPOSE: Feasibility, reliability, and safety assessment of transcranial motor evoked potentials (MEPs) in infants less than 12 months of age. METHODS: A total of 22 patients with a mean age of 33 (range 13-49) weeks that underwent neurosurgery for tethered cord were investigated. Data from intraoperative MEPs, anesthesia protocols, and clinical records were reviewed. Anesthesia during surgery was maintained by total intravenous anesthesia (TIVA). RESULTS: MEPs were present in all patients for the upper extremities and in 21 out of 22 infants for the lower extremities. Mean baseline stimulation intensity was 101 ± 20 mA. If MEPs were present at the end of surgery, no new motor deficit occurred. In the only case of MEP loss, preoperative paresis was present, and high baseline intensity thresholds were needed. MEP monitoring did not lead to any complications. TIVA was maintained with an average propofol infusion rate of 123.5 ± 38.2 µg/kg/min and 0.46 ± 0.17 µg/kg/min for remifentanil. CONCLUSION: In spinal cord release surgery, the use of intraoperative MEP monitoring is indicated regardless of the patient's age. We could demonstrate the feasibility and safety of MEP monitoring in infants if an adequate anesthetic regimen is applied. More data is needed to verify whether an irreversible loss of robust MEPs leads to motor deficits in this young age group.

Optimizing maximum resection of glioblastoma: Raman spectroscopy versus 5-aminolevulinic acid.

OBJECTIVE: The objective of this study was to assess and compare the potential of 5-aminolevulinic acid (5-ALA) and Raman spectroscopy (RS) in detecting tumor-infiltrated brain in patients with glioblastoma (GBM). METHODS: Between July 2020 and October 2021, the authors conducted a prospective clinical trial with 15 patients who underwent neurosurgical treatment of newly diagnosed and histologically verified GBM. A solid contrast-enhancing tumor core and peritumoral tissue were investigated intraoperatively for cancer cells by using 5-ALA and RS to achieve pathology-tailored maximum resection. In each case, a minimum of 10 biopsies were sampled from navigation-guided areas. Two neuropathologists examined the biopsies for the presence of neoplastic cells. The detection performance of 5-ALA and RS alone and in combination was assessed. Pre- and postoperative MRI, Karnofsky Performance Status (KPS), and National Institutes of Health Stroke Scale (NIHSS) scores were compared, and median progression-free survival (PFS) was evaluated. RESULTS: A total of 185 biopsy samples were harvested from the contrast-enhancing tumor core (n = 19) and peritumoral tissue (n = 166). In the tumor core, 5-ALA and RS each showed a sensitivity of 100%. In the peritumoral tissue, 5-ALA was less sensitive than RS in detecting cancer (46% vs 69%) but showed higher specificity (81% vs 57%). When the two methods were combined, the accuracy of tumor detection was increased by about 10%. Pathology-tailored resection led to a 52% increase in resection volume comparing the volume of preoperative contrast enhancement with the postoperative resection cavity on MRI (p = 0.0123). Eloquent brain involvement prevented gross-total resection in 4 patients. Four weeks after surgery, mean KPS (p = 0.7637) and NIHSS scores (p = 0.3146) were not significantly different from preoperative values. Of the 13 patients who had received postoperative chemoradiotherapy, 4 did not show any progression after a median follow-up of 14 months. The remaining 9 patients had a median PFS of 8 months. CONCLUSIONS: According to the study data, RS is capable of detecting tumor-infiltrated brain with higher sensitivity but lower specificity than the current standard of 5-ALA. With further technological and workflow advancements, RS in combination with protoporphyrin IX fluorescence may contribute to pathology-tailored glioma resection in the future.

Risk Factors Promoting External Ventricular Drain Infections in Adult Neurosurgical Patients at the Intensive Care Unit-A Retrospective Study.

Objectives: Multiple risk factors have been described to be related to external ventricular drain (EVD) associated infections, with results varying between studies. Former studies were limited by a non-uniform definition of EVD associated infection, thus complicating a comparison between studies. In this regard, we assessed risk factors promoting EVD associated infections and propose a modified practice-oriented definition of EVD associated infections. Methods: We performed a retrospective, single-center study on patients who were treated with an EVD, at the neurosurgical intensive care unit (ICU) at a tertiary center between 2008 and 2019. Based on microbiological findings and laboratory results, patients were assigned into an infection and a non-infection group. Patient characteristics and potential risk factors were compared between the two groups (p < 0.05). Receiver operating characteristics (ROC) for significant clinical, serum laboratory and cerebrospinal fluid (CSF) parameters were calculated. Results: In total, 396 patients treated with an EVD were included into the study with a mean age of 54.3 (range: 18-89) years. EVD associated infections were observed in 32 (8.1%) patients. EVD insertion at another hospital (OR 3.86), and an increased CSF sampling frequency of more than every third day (OR 12.91) were detected as major risk factors for an EVD associated infection. The indication for EVD insertion, surgeon's experience, the setting of EVD insertion (ICU vs. operating room) and the operating time did not show any significant differences between the two groups. Furthermore, ROC analysis showed that clinical, serum laboratory and CSF parameters did not provide specific prediction of EVD associated infections (specificity 44.4%). This explains the high overtreatment rate in our cohort with the majority of our patients who received intrathecal vancomycin (63.3%), having either negative microbiological results (n = 12) or were defined as contaminations (n = 7). Conclusions: Since clinical parameters and blood analyzes are not very predictive to detect EVD associated infections in neurosurgical patients, sequential but not too frequent microbiological and laboratory analysis of CSF are still necessary. Furthermore, we propose a uniform classification for EVD associated infections to allow comparability between studies and to sensitize the treating physician in determining the right treatment.

Microvascular decompression in trigeminal neuralgia: predictors of pain relief, complication avoidance, and lessons learned.

OBJECTIVE: To analyze characteristics associated with long-term pain relief after microvascular decompression (MVD) for trigeminal neuralgia (TGN). Description of associated morbidity and complication avoidance. METHODS: One hundred sixty-five patients with TGN underwent 171 MVD surgeries at the authors' institution. Patient characteristics and magnetic resonance imaging (MRI) datasets were obtained through the hospital's archiving system. Patients provided information about pre- and post-operative pain characteristics and neurologic outcome. Favorable outcome was defined as a Barrow Neurological Institute (BNI) pain intensity score of I to III with post-operative improvement of I grade. RESULTS: Type of TGN pain with purely paroxysmal pain (p = 0.0202*) and TGN classification with classical TGN (p = 0.0372*) were the only significant predictors for long-term pain relief. Immediate pain relief occurred in 90.6% of patients with a recurrence rate of 39.4% after 3.5 ± 4.6 years. MRI reporting of a neurovascular conflict had a low negative predictive value of 39.6%. Mortality was 0% with major complications observed in 8.2% of patients. Older age was associated with lower complication rates (p = 0.0009***). Re-MVD surgeries showed improved long-term pain relief in four out of five cases. CONCLUSIONS: MVD is a safe and effective procedure even in the elderly. It has the unique potential to cure TGN if performed on a regular basis, and if key surgical steps are respected. Early MVD should be offered in case of medical treatment failure and paroxysmal pain symptoms. The presence of a neurovascular conflict on MRI is not mandatory. In case of recurrence, re-MVD is a good treatment option that should be discussed with patients. HIGHLIGHTS: • Long-term analysis of pain relief after MVD. • Positive predictors for outcome: classical TGN and purely paroxysmal pain. • Presence of neurovascular conflict in MRI is not mandatory for MVD surgery. • Analysis of complications and surgical nuances for avoidance. • MVD is a safe procedure also in the elderly.

Quantitative analysis of human brain microdialysate for target site pharmacokinetics of major anesthetics ketamine, midazolam and propofol.

Brain microdialysis samples of intensive care patients treated with the essential anesthetics ketamine, midazolam and propofol were investigated. Importantly, despite decades of clinical use, comprehensive human cerebral pharmacokinetic data of these drugs is still missing. To encounter this apparent lack of knowledge, we combined cerebral microdialysis with leading-edge analytical instrumentation to monitor the neurochemistry of living human patients. For the quantitative analysis, high performing analytical approaches were developed that can handle minute sample volumes and possible ultralow target analyte levels. The developed methods provided detection limits below 100 ng L-1 for all target analytes and high precision (below 4% RSD intraday). Methods were linear between LODs and 100 µg L-1 for ketamine, 75 µg L-1 for midazolam and 10 µg L-1 for propofol respectively, with coefficients of determination R2≥ 0.999. Further, being aware of the error-prone and demanding translation of microdialysis levels to interstitial concentrations, in vitro approaches for recovery testing of microdialysis probes as well as internal normalization approaches were conducted. Thus, we herein report the first cerebral pharmacokinetic data of ketamine, midazolam and propofol determined in microdialysis samples of 15 neurointensive care patients. We could prove blood-brain barrier penetration of all of the investigated anesthetics and could correlate applied dosages and actual brain exposition of ketamine. However, we emphasize the need of an expanded prospective study including individual microdialysis recovery testing as well as matched serum and/or cerebrospinal fluid collection for a more comprehensive cerebral pharmacokinetic understanding.