Leukocyte- and Platelet-Rich Fibrin versus Commercially Available Fibrin Sealants in Elective Cranial Surgery: A Cost-Minimization Analysis.

BACKGROUND: Previous findings from a clinical trial demonstrated noninferiority of Leukocyte- and platelet-rich fibrin (L-PRF) compared to commercially available fibrin sealants in preventing postoperative cerebrospinal fluid leakage, necessitating intervention. This cost-effectiveness evaluation aims to assess the value-for-money of both techniques for dural closure in supratentorial and infratentorial surgeries. METHODS: Cost-effectiveness was estimated from a health care payer's perspective alongside a randomized clinical trial comprising 328 patients. The analysis focused on clinical and health-related quality of life outcomes, as well as direct medical costs including inpatient costs, imaging and laboratory costs, and outpatient follow up costs up to twelve weeks after surgery. RESULTS: Clinical and health-related quality of life data showed no significant differences between L-PRF (EuroQol five dimensions questionnaire 0.75 ± 0.25, 36-item Short Form Survey 63.93% ± 20.42) and control (EuroQol five dimensions questionnaire 0.72 ± 0.22, 36-item Short Form Survey 60.93% ± 20.78) groups. Pharmaceutical expenses during initial hospitalization were significantly lower in the L-PRF group (€190.4, interquartile range 149.9) than in the control group (€394.4, interquartile range 364.3), while other cost categories did not show any significant differences, resulting in an average cost advantage of €204 per patient favoring L-PRF. CONCLUSIONS: This study demonstrates L-PRF as a cost-effective alternative for commercially available fibrin sealants in dural closure. Implementing L-PRF can lead to substantial cost savings, particularly considering the frequency of these procedures.

Encephalocraniocutaneous lipomatosis phenotype associated with mosaic biallelic pathogenic variants in the NF1 gene.

Encephalocraniocutaneous lipomatosis (ECCL) is a sporadic congenital condition characterised by ocular, cutaneous and central nervous system involvement. Mosaic activating variants in FGFR1 and KRAS have been reported in several individuals with this syndrome. We report on a patient with neurofibromatosis type 1 (NF1) with a germline pathogenic variant in the NF1 gene and an ECCL phenotype, suggesting ECCL to be part of a spectrum of malformations associated with NF1 pathogenic variants. An anatomical hemispherectomy was performed for intractable epilepsy. Through genetic analysis of blood, cerebral tissue and giant cell lesions in both jaws, we identified the germline NF1 pathogenic variant in all samples and a second-hit pathogenic NF1 variant in cerebral tissue and both giant cell lesions. Both NF1 variants were located on different alleles resulting in somatic mosaicism for a biallelic NF1 inactivation originating in early embryogenesis (second-hit mosaicism or Happle type 2 mosaicism). The biallelic deficit in NF1 in the left hemicranium explains the severe localised, congenital abnormality in this patient. Identical first and second-hit variants in a giant cell lesion of both upper and lower jaws provide confirmatory evidence for an early embryonic second hit involving at least the neural crest. We suggest that the ECCL phenotype may be part of a spectrum of congenital problems associated with mosaic NF1 nullisomy originating during early embryogenesis. The biallelic NF1 inactivation during early embryogenesis mimics the severe activation of the RAS-MAPK pathway seen in ECCL caused by embryonic mosaic activating FGFR1 and KRAS variants in the cranial region. We propose that distinct mechanisms of mosaicism can cause the ECCL phenotype through convergence on the RAS-MAPK pathway.

Retention rate of vagus nerve stimulation for the treatment of drug-resistant epilepsy: A single-centre, retrospective study.

The aim of this single-centre, retrospective, observational study was to evaluate long-term effectiveness of vagus nerve stimulation (VNS) in drug-resistant epilepsy (DRE) by using retention rate as a surrogate measure for seizure reduction. We included all patients with DRE, treated at the adult neurology department of the University Hospitals Leuven and who started VNS therapy from January 1, 1994, until May 1, 2021, with follow-up data cutoff on January 1, 2023. Retention rate of VNS was defined as the percentage of patients who maintain VNS at established time points. We estimated cumulative retention rate and battery replacement rate and correlated these with seizure reduction, using Kaplan-Meier analysis. Statistical analysis of potential predictors of VNS outcome (age, sex and epilepsy duration at implantation) was performed using mono- and multivariate analyses. VNS was started in 110 patients with DRE, with a mean follow-up of 8.7 years (SD 6.5). VNS was discontinued in 55 patients (50%), with ineffectiveness as the main reason for discontinuation (98%). The battery was replaced at least once in 42 patients (38%). Estimated retention rates were 70%, 52%, 45% and 33% after 5, 10, 15 and 20 years, respectively. Estimated first battery replacement rates were 16%, 42% and 47% after 5, 10 and 15 years, respectively. Both estimates showed a statistically significant correlation with seizure reduction. No independent predictors of long-term outcome of VNS were found. This is the first long-term study using retention rate of VNS to assess effectiveness. VNS is a well-tolerated therapy, but retention rates decline with long follow-up.

Leukocyte- and platelet-rich fibrin in cranial surgery: a single-blinded, prospective, randomized controlled noninferiority trial.

OBJECTIVE: CSF leakage is a major complication after cranial surgery, and although fibrin sealants are widely used for reinforcing dural closure, concerns exist regarding their safety, efficacy, and cost. Leukocyte- and platelet-rich fibrin (L-PRF), an autologous platelet concentrate, is readily available and inexpensive, making it a cost-effective alternative for commercially available fibrin sealants. This study aimed to demonstrate the noninferiority of L-PRF compared with commercially available fibrin sealants in preventing postoperative CSF leakage in supra- and infratentorial cranial surgery, with secondary outcomes focused on CSF leakage risk factors and adverse events. METHODS: In a single-blinded, prospective, randomized controlled interventional trial conducted at a neurosurgery department of a tertiary care center (UZ Leuven, Belgium), patients undergoing elective cranial neurosurgery were randomly assigned to receive either L-PRF (active treatment) or commercially available fibrin sealants (control) for dural closure in a 1:1 ratio. RESULTS: Among 350 included patients, 328 were analyzed for the primary endpoint (44.5% male, mean age 52.3 ± 15.1 years). Six patients (5 in the control group, 1 in the L-PRF group) presented with CSF leakage requiring any intervention (relative risk [RR] 0.20, one-sided 95% CI -∞ to 1.02, p = 0.11), confirming noninferiority. Of these 6 patients, 1 (in the control group) presented with CSF leakage requiring revision surgery. No risk factors for reconstruction failure in combination with L-PRF were identified. RRs for adverse events such as infection (0.72, 95% CI -∞ to 1.96) and meningitis (0.36, 95% CI -∞ to 1.25) favored L-PRF treatment, although L-PRF treatment showed slightly more bleeding events (1.44, 95% CI -∞ to 4.66). CONCLUSIONS: Dural reinforcement with L-PRF proved noninferior to commercially available fibrin sealants, with no safety issues. Introducing L-PRF to standard clinical practice could result in important cost savings due to accessibility and lower cost. Clinical trial registration no.: NCT03812120 (ClinicalTrials.gov).

Leukocyte- and platelet-rich fibrin in endoscopic endonasal skull base reconstruction: study protocol for a multicenter prospective, parallel-group, single-blinded randomized controlled non-inferiority trial.

BACKGROUND: Recent advances in endoscopic endonasal transsphenoidal approaches (EETA) for skull base lesions have resulted in a significant increase in extent and complexity of skull base defects, demanding more elaborate and novel reconstruction techniques to prevent cerebrospinal fluid (CSF) leakage and to improve healing. Currently, commercially available fibrin sealants are often used to reinforce the skull base reconstruction. However, problems have been reported regarding hypersensitivity reactions, efficacy, and costs. This trial aims to investigate autologous leukocyte- and platelet-rich fibrin (L-PRF) membranes as an alternative for commercially available fibrin glues in EETA-related skull base reconstruction reinforcement. METHODS/DESIGN: This multicenter, prospective randomized controlled trial aims to demonstrate non-inferiority of L-PRF membranes compared to commercially available fibrin sealants in EETA cases (1) without intra-operative CSF-leak as dural or sellar floor closure reinforcement and (2) in EETA cases with intra-operative CSF-leak (or very large defects) in which a classic multilayer reconstruction has been made, as an additional sealing. The trial includes patients undergoing EETA in three different centers in Belgium. Patients are randomized in a 1:1 fashion comparing L-PRF with commercially available fibrin sealants. The primary endpoint is postoperative CSF leakage. Secondary endpoints are identification of risk factors for reconstruction failure, assessment of rhinological symptoms, and interference with postoperative imaging. Additionally, a cost-effectiveness analysis is performed. DISCUSSION: With this trial, we will evaluate the safety and efficacy of L-PRF compared to commercially available fibrin sealants. TRIAL REGISTRATION: ClinicalTrials.gov NCT03910374. Registered on 10 April 2019.

European training requirements in neurological surgery: A new outcomes-based 3 stage UEMS curriculum.

Introduction: Post-graduate training in medical education has seen a seismic shift from time-based to competency-based training. We describe a competency-based European Training Requirement (ETR) in neurological surgery that is applicable across all European centres. Research question: To develop the ETR in Neurological Surgery using a competency-based approach. Material and methods: The competency-based approach ETR in neurosurgery was developed in accordance with the European Union of Medical Specialists (UEMS) Training Requirements guidelines. The UEMS ETR template, based upon the UEMS Charter on Post-graduate Training was utilized. Consultation took place with Council and Board members of the European Association of Neurosurgical Societies (EANS), the Young Neurosurgeons forum of the EANS and members of the UEMS. Results: We describe a competency-based curriculum comprising 3 stages of training. Five entrustable professional activities, outpatient care, inpatient care, emergency on call, operative competencies and team working are described. The curriculum emphasizes the importance of high levels of professionalism, early consultation with other specialists where relevant and the importance of reflective practice. Outcomes must be reviewed at annual performance reviews. Evidence of competency should be multifaceted and include work-based assessments, logbook data, multisource feedback, patient feedback and examination performance. Required competencies for certification/licensing are provided. Approval for the ETR was provided by the UEMS. Discussion and conclusion: A competency-based ETR was developed and approved by UEMS. This provides a suitable framework for the development of national curricula that train neurosurgeons to an internationally recognized level of capability.

Leukocyte- and platelet-rich fibrin in cranial surgery: study protocol for a prospective, parallel-group, single-blinded randomized controlled non-inferiority trial {1}.

BACKGROUND: CSF leakage is a major complication after cranial surgery, thus, adequate dural closure must be performed. Commercially available fibrin sealants are currently considered the gold standard for dural closure, but problems have been reported regarding safety, efficacy, and costs. This trial aims to investigate autologous leukocyte- and platelet-rich fibrin (L-PRF) as an alternative to commercially available fibrin sealants. METHODS/DESIGN: This single-blinded, prospective randomized controlled interventional trial aims to demonstrate the non-inferiority of L-PRF compared to commercially available fibrin sealants for dural closure. This trial will include patients undergoing cranial neurosurgery (supratentorial and infratentorial) with intentional opening of the dura. Patients are randomized in a 1:1 fashion comparing L-PRF to commercially available fibrin sealants. The primary endpoint is postoperative CSF leakage within 12 weeks after surgery. Secondary endpoints are complications such as bleeding or wound infections. Additionally, a cost-effectiveness analysis is performed. DISCUSSION: With this trial, we will evaluate the safety and efficiency of L-PRF compared to commercially available fibrin sealants. TRIAL REGISTRATION: ClinicalTrials.gov NCT03812120. Registered on 22 January 2019.

Controversies in treatment strategies in patients with foot drop due to peroneal nerve entrapment: Results of a survey among specialists.

Introduction: Peroneal nerve entrapment is a frequent cause of foot drop. Despite being frequent, no guidelines exist to recommend surgical or non-invasive treatment, leading to important variations in daily practice. Research question: To map variation in daily practice. Materials and methods: An online Qualtrics survey was distributed among neurosurgeons, neurologists, orthopaedic surgeons and physical medicine and rehabilitation physicians through various national and international scientific organizations, mapping current treatment strategies. Descriptive statistics and non-parametric tests were used to analyse data with SPSS. Results: Responses from 181 out of 221 participants from 35 countries were analysed. A large majority of participants agreed that good evidence supporting any treatment strategy is lacking (77.9%) and that daily practice is mostly guided by own beliefs and experience (84.0%). Both non-invasive treatment and neurolysis are well established treatment strategies (supported by respectively 92.3% and 93.4% of physicians). Timing of neurolysis and duration of non-invasive treatment varied considerably. Duration of non-invasive treatment was significantly shorter in the group of surgeons compared to non-surgeons (p â€‹= â€‹0.033). Most physicians consider neurolysis a valid treatment option. However, significant more non-surgeons than surgeons were opposed to surgical treatment (p â€‹= â€‹0.001). Discussion and conclusion: Important differences in attitudes were observed not only between, but also within specialisms, regardless of physician experience. This survey highlights important variations in daily practice for foot drop due to peroneal entrapment and emphasizes the need for future controlled studies.

Exploring stem cell biology in pituitary tumors and derived organoids.

Pituitary tumorigenesis is highly prevalent and causes major endocrine disorders. Hardly anything is known on the behavior of the local stem cells in this pathology. Here, we explored the stem cells' biology in mouse and human pituitary tumors using transcriptomic, immunophenotyping and organoid approaches. In the prolactinoma-growing pituitary of dopamine receptor D2 knock-out mice, the stem cell population displays an activated state in terms of proliferative activity and distinct cytokine/chemokine phenotype. Organoids derived from the tumorous glands' stem cells recapitulated these aspects of the stem cells' activation nature. Upregulated cytokines, in particular interleukin-6, stimulated the stem cell-derived organoid development and growth process. In human pituitary tumors, cells typified by expression of stemness markers, in particular SOX2 and SOX9, were found present in a wide variety of clinical tumor types, also showing a pronounced proliferative status. Organoids efficiently developed from human tumor samples, displaying a stemness phenotype as well as tumor-specific expression fingerprints. Transcriptomic analysis revealed fading of cytokine pathways at organoid development and passaging, but their reactivation did not prove capable of rescuing early organoid expansion and passageability arrest. Taken together, our study revealed and underscored an activated phenotype of the pituitary-resident stem cells in tumorigenic glands and tumors. Our findings pave the way to defining the functional position of the local stem cells in pituitary tumor pathogenesis, at present barely known. Deeper insight can lead to more efficient and targeted clinical management, currently still not satisfactorily.

Randomized Trial Comparing Burr Hole Craniostomy, Minicraniotomy, and Twist Drill Craniostomy for Treatment of Chronic Subdural Hematoma.

BACKGROUND: The mainstay of treatment for symptomatic or large chronic subdural hematoma (CSDH) is surgery, but controversy still exists regarding the best surgical technique. Three different techniques are commonly used: burr hole craniostomy (BHC), minicraniotomy (MC), and twist drill craniostomy (TDC). OBJECTIVE: To determine which surgical technique for drainage of CSDH offers best results. METHODS: We set up a multicenter prospective randomized trial (Comparison of Chronic Subdural Hematoma Treatment [COMPACT] trial) comparing BHC, MC, and TDC for the surgical treatment of CSDH. The primary end point was reoperation rate, and secondary end points included complication rates and clinical outcome. Patients were considered to have good outcome when they did not undergo reoperation, suffered no surgical or medical complication, and had no related mortality. Clinical outcome was also evaluated by evolution of the Markwalder score and the modified Rankin score. RESULTS: Two-hundred forty-five patients were included in the final analysis: 79 BHC, 84 MC, and 82 TDC. Mean duration of surgery was shorter for TDC than for BHC and MC ( P < .001). Reoperation rate was 7.6% for BHC, 13.1% for MC, and 19.5% for TDC ( P = .07). This trend toward better results for BHC was not statistically significant in logistic regression analysis. The proportion of patients with good outcome was 78.5% for BHC group, 76.2% for MC, and 69.5% for TDC ( P = .4). Evolution of the Markwalder score and modified Rankin score were not significantly different between treatment groups. CONCLUSION: All 3 techniques are effective at treating patients with CSDH with eventual 6-month outcome being similar. Although not reaching statistical significance in our study, BHC offers the lowest recurrence rate combined with manageable complication rate.

Usefulness of intraoperative monitoring in microvascular decompression for hemifacial spasm: a systematic review and meta-analysis.

OBJECTIVE: To review the diagnostic accuracy and possible added value of Brainstem Auditory Evoked Potentials (BAEP) monitoring and Lateral Spread Response (LSR) monitoring in microvascular decompression surgery for hemifacial spasms. METHODS: For this systematic review we followed the PRISMA guidelines. We searched different databases and bibliographies of articles. We included studies on BAEP and LSR monitoring that reported data on hearing outcome or efficacy. Selected studies were assessed for bias using the MINORS tool. RESULTS: 64 articles were selected for qualitative synthesis, 42 met inclusion criteria for meta-analysis. The overall incidence of hearing loss was 3.4%. For BAEP monitoring AUC and pooled OR with 95% confidence interval were 0.911 (0.753-0.933) and 7.99 (3.85-16.60) respectively. Short-term data on LSR monitoring showed an overall spasm relief rate of 89% with pooled OR, sensitivity and specificity with a 95% confidence interval of 8.80 (4.82-16.08), 0.911 (0.863-0.943) and 0.451 (0.342-0.564) respectively. Long-term data on LSR monitoring showed an overall spasm relief rate of 95% with pooled OR, sensitivity and specificity with a 95% confidence interval of 4.06 (2.15-7.64), 0.871 (0.817-0.911) and 0.39 (0.294-0.495) respectively. CONCLUSION: The alarm criteria, a wave V latency prolongation of 1ms or a wave V amplitude decrement of 50%, proposed by the 'American Clinical Neurophysiology Society' are a sensitive predictor for postoperative hearing loss. Other BAEP wave changes, for example, complete loss of wave V, are more specific but correspond to irreversible damage and are therefore not useful as warning criteria. LSR monitoring has high diagnostic accuracy at short-term follow-up. At long-term follow-up, diagnostic accuracy decreases because most patients get spasm relief regardless of their LSR status. LSR persistence after surgery has a good long-term outcome, as long as an extensive exploration of the facial nerve has been performed.

Development of a Composite Pain Scale in Foals: A Pilot Study.

Prompt pain management is crucial in horses; however, tools to assess pain are limited. This study aimed to develop and pilot a composite scale for pain estimation in foals. The "Foal Composite Pain Scale" (FCPS) was developed based on literature and authors' expertise. The FCPS consisted of 11 facial expressions, 4 behavioural items, and 5 physical items. Thirty-five pain-free foals (Control Group) and 15 foals experiencing pain (Pain Group) were used. Foals were video-recorded at different time points: the Control Group only at inclusion (C), while the Pain Group at inclusion (T1), after an analgesic treatment (T2), and at recovery (T3). Physical items were also recorded at the same time points. Videos were scored twice by five trained observers, blinded to group and time points, to calculate inter- and intra-observer reliability of each scale item. Fleiss' kappa values ranged from moderate to almost perfect for the majority of the items, while the intraclass correlation coefficient was excellent (ICC = 0.923). The consistency of FCPS was also excellent (Cronbach's alpha = 0.842). A cut-off ≥ 7 indicated the presence of pain. The Pain Group scores were significantly higher (p < 0.001) than the Control Group and decreased over time (T1, T2 > T3; p = 0.001). Overall, FCPS seems clinically applicable to quantify pain and improve the judgment of the quality of life in foals, but it needs modifications based on these preliminary findings. Consequently, further studies on a larger sample size are needed to test the feasibility and validity of the refined FCPS.

Comparing Blind and Ultrasound-Guided Retrobulbar Nerve Blocks in Equine Cadavers: The Training Effect.

In standing ophthalmic surgery in horses, a retrobulbar nerve block (RNB) is often placed blindly for anesthesia and akinesia. The ultrasound (US)-guided RNB may have fewer complications, but the two techniques have only been compared once in equine cadavers. This study compares the techniques for success and complication rates and analyzes the effect of training on US guidance. Twenty-two equine cadavers were divided into three groups: blind RNBs were performed bilaterally in eight cadavers, US-guided RNBs were performed bilaterally in seven cadavers, and after US-guided training, blind RNBs were performed bilaterally in seven cadavers. All RNBs were performed by the same two inexperienced operators, and a combination of contrast medium (CM; 1.25 mL) and methylene blue dye (1.25 mL) were injected (2.5 mL total volume). Needle positioning in the periorbita and the distance of the CM to the optic foramen were assessed using computerized tomography (CT). Dye spreading was evaluated by dissection. In group 1, 37.5% of the injections were in the optimal central position in the periorbita; in group 2, 75% and in group 3, 71.4%. There was no significant difference between the groups regarding needle position (groups 1 and 2 p = 0.056; groups 1 and 3 p = 0.069, groups 2 and 3 p = 0.8). The mean CM distribution distance was not significantly different between all groups. Group 1 had 18.75% intraocular injections versus 0% in group 2 and 7.1% in group 3 (not significant). US guidance showed no significant increases in accuracy nor decreases in complications. However, the effects on accuracy showed a trend towards significant improvement, and larger scale follow-up studies might show significant training effects on US guidance.

Treatment of ruptured subclavian steal flow-related vertebrobasilar junction aneurysms: Case report on surgical and endovascular considerations from two cases.

INTRODUCTION: Subclavian steal phenomenon causes retrograde flow through the vertebral artery, ipsilateral to the affected subclavian artery, which rarely leads to flow-related vertebrobasilar junction (VBJ) aneurysms. CASE DESCRIPTIONS: We describe two cases of subarachnoid hemorrhage from such ruptured aneurysms in which the retrograde flow direction in the vertebral artery complicated surgical and endovascular treatment. DISCUSSION: Reversed flow in the vertebral artery, ipsilateral to the stenotic subclavian artery leads to a lack of proximal control in surgical clipping of these VBJ aneurysms and jeopardizes stability of coil and stent placement in endovascular aneurysm treatments in this setting. CONCLUSION: From these 2 experiences over 7 years, treatment considerations emerged for future cases.

Evidence in peroneal nerve entrapment: A scoping review.

BACKGROUND AND PURPOSE: Daily management of patients with foot drop due to peroneal nerve entrapment varies between a purely conservative treatment and early surgery, with no high-quality evidence to guide current practice. Electrodiagnostic (EDX) prognostic features and the value of imaging in establishing and supplementing the diagnosis have not been clearly established. METHODS: We performed a literature search in the online databases MEDLINE, Embase, and the Cochrane Library. Of the 42 unique articles meeting the eligibility criteria, 10 discussed diagnostic performance of imaging, 11 reported EDX limits for abnormal values and/or the value of EDX in prognostication, and 26 focused on treatment outcome. RESULTS: Studies report high sensitivity and specificity of both ultrasound (varying respectively from 47.1% to 91% and from 53% to 100%) and magnetic resonance imaging (MRI; varying respectively from 31% to 100% and from 73% to 100%). One comparative trial favoured ultrasound over MRI. Variable criteria for a conduction block (>20%-≥50) were reported. A motor conduction block and any baseline compound motor action potential response were identified as predictors of good outcome. Based predominantly on case series, the percentage of patients with good outcome ranged 0%-100% after conservative treatment and 40%-100% after neurolysis. No study compared both treatments. CONCLUSIONS: Ultrasound and MRI have good accuracy, and introducing imaging in the standard diagnostic workup should be considered. Further research should focus on the role of EDX in prognostication. No recommendation on the optimal treatment strategy of peroneal nerve entrapment can be made, warranting future randomized controlled trials.

The incidence of postoperative cerebrospinal fluid leakage after elective cranial surgery: a systematic review.

Cerebrospinal fluid (CSF) leakage is a major complication after elective neurosurgical procedures. The aim of this systematic literature review is to summarize the incidence rates of postoperative cerebrospinal fluid leakage for neurosurgical procedures, classified by surgical approach. The Pubmed, Cochrane, Embase, and Web of Science databases were searched for studies reporting the outcome of patients undergoing elective neurosurgical procedures. The number of patients, surgical approach, and indication for surgery were recorded for each study. Outcomes related to CSF leakage such as clinical manifestation and treatment were reported as well. One hundred and thirteen studies were included, reporting 94,695 cases. Overall, CSF leaks were present in 3.8% of cases. Skull base surgery had the highest rate of CSF leakage with 6.2%. CSF leakage occurred in 5.9% of anterior skull base procedures, 6.4% of middle fossa, and 5.2% of transpetrosal surgeries. 5.8% of reported infratentorial procedures were complicated by CSF leakage versus 2.9% of supratentorial surgeries. CSF leakage remains a common serious adverse event after cranial surgery. There exists a need for standardized procedures to reduce the incidence of postoperative CSF leakage, as this serious adverse event may lead to increased health care costs.

A most unusual diagnosis via an unusual route: tunneling through Meckel's cave.

A 73-year-old woman presented with progressive symptoms of cranial nerve (V, VI, VIII) palsies, ataxia and gait disturbance due to a rapidly growing atypical trigeminocavernous mass. Percutaneous stereotactic transoval biopsy via Hartel's route revealed an exceedingly rare solitary trigeminal metastasis of a clear cell renal cell carcinoma, treated 16 years earlier without any other evidence of systemic disease. A minimally invasive, intra-operatively navigated approach is presented with detailed description of the stereotactic technique and technical considerations. The transoval biopsy expands the surgical repertoire for atypical Meckel cave lesions with diagnostic uncertainty. A frameless navigated technique should be state-of-the-art in contemporary neurosurgical practice.

Single-Unit Recordings Reveal the Selectivity of a Human Face Area.

The exquisite capacity of primates to detect and recognize faces is crucial for social interactions. Although disentangling the neural basis of human face recognition remains a key goal in neuroscience, direct evidence at the single-neuron level is limited. We recorded from face-selective neurons in human visual cortex in a region characterized by functional magnetic resonance imaging (fMRI) activations for faces compared with objects. The majority of visually responsive neurons in this fMRI activation showed strong selectivity at short latencies for faces compared with objects. Feature-scrambled faces and face-like objects could also drive these neurons, suggesting that this region is not tightly tuned to the visual attributes that typically define whole human faces. These single-cell recordings within the human face processing system provide vital experimental evidence linking previous imaging studies in humans and invasive studies in animal models.SIGNIFICANCE STATEMENT We present the first recordings of face-selective neurons in or near an fMRI-defined patch in human visual cortex. Our unbiased multielectrode array recordings (i.e., no selection of neurons based on a search strategy) confirmed the validity of the BOLD contrast (faces-objects) in humans, a finding with implications for all human imaging studies. By presenting faces, feature-scrambled faces, and face-pareidolia (perceiving faces in inanimate objects) stimuli, we demonstrate that neurons at this level of the visual hierarchy are broadly tuned to the features of a face, independent of spatial configuration and low-level visual attributes.

Effect of different inspired fractions of oxygen on F-shunt and arterial partial pressure of oxygen in isoflurane-anaesthetized and mechanically ventilated Shetland ponies.

OBJECTIVE: To determine the effect of fraction of inspired oxygen (FiO2) on intrapulmonary shunt fraction as measured by F-shunt in ponies during isoflurane anaesthesia. STUDY DESIGN: Prospective, randomized clinical study. ANIMALS: A group of 23 adult Shetland ponies undergoing a total of 32 anaesthetic procedures. METHODS: Ponies were premedicated intravenously (IV) with detomidine (0.01 mg kg-1) and either morphine (0.1 mg kg-1) or butorphanol (0.02 mg kg-1). Anaesthesia was induced with ketamine (2.2 mg kg-1) and midazolam (0.07 mg kg-1) administered IV. Ponies were randomly allocated to maintenance of anaesthesia with isoflurane in oxygen (group TH; FiO2 = 0.95) or a mixture of oxygen and medical air (group TL; FiO2 = 0.65); all ponies were given a constant rate of infusion of detomidine. Animals were mechanically ventilated to maintain PaCO2 between 40 and 50 mmHg. Arterial blood gas analysis was performed every 30 minutes. The F-shunt equation was calculated for each time point T0, T30, T60 and T90. Data were analysed using linear mixed model analysis and presented as mean ± standard deviation (p < 0.05). RESULTS: PaO2 was greater in group TH than in group TL (TH: 406 ± 90, 438 ± 83, 441 ± 69 and 464 ± 53 mmHg versus TL: 202 ± 90, 186 ± 84, 172 ± 85 and 191 ± 98 mmHg at T0, T30, T60 and T90, respectively; p < 0.0001). In TH, F-shunt was < TL. Significant differences were found at T60 (TH: 13.2% ± 4.3 versus TL: 19.4% ± 8.3; p = 0.016) and T90 (TH: 11.7% ± 3.5 versus TL: 18.6% ± 9.5; p = 0.036). CONCLUSIONS AND CLINICAL RELEVANCE: Our findings do not support a beneficial effect of using a reduced FiO2 to improve oxygenation in anaesthetized and mechanically ventilated Shetland ponies.