Investigating the functional neuroanatomy of concrete and abstract word processing through direct electric stimulation (DES) during awake surgery.

Neuropsychological, neuroimaging and electrophysiological studies demonstrate that abstract and concrete word processing relies not only on the activity of a common bilateral network but also on dedicated networks. The neuropsychological literature has shown that a selective sparing of abstract relative to concrete words can be documented in lesions of the left anterior temporal regions. We investigated concrete and abstract word processing in 10 patients undergoing direct electrical stimulation (DES) for brain mapping during awake surgery in the left hemisphere. A lexical decision and a concreteness judgment task were added to the neuropsychological assessment during intra-operative monitoring. On the concreteness judgment, DES delivered over the inferior frontal gyrus significantly decreased abstract word accuracy while accuracy for concrete words decreased when the anterior temporal cortex was stimulated. These results are consistent with a lexical-semantic model that distinguishes between concrete and abstract words related to different neural substrates in the left hemisphere.

Application of intraoperative indocyanine green angiography for CNS tumors: results on the first 100 cases.

PURPOSE: To investigate the application of indocyanine green (ICG) videoangiography during microsurgery for central nervous system (CNS) tumors. METHODS: One hundred patients with CNS tumors who underwent microsurgical resection from December 2006 to December 2008 were retrospectively analyzed. The diagnosis was high grade glioma in 54 cases, low grade in 17 cases, meningioma in 14 cases, metastasis in 12 cases and hemangioblastoma in 3 cases. Overall, ICG was injected intraoperatively 194 times. The standard dose of 25mg of dye was injected intravenously and intravascular fluorescence from within the blood vessels was imaged through an ad hoc microscope with dedicated software (Pentero, Carl Zeiss Co., Oberkochen, Germany). Pre-resection and post-resection arterial, capillary and venous ICG videoangiographic phases were intraoperatively observed and recorded. RESULTS: ICG videangiography allowed for a good evaluation of blood flow in the tumoral and peritumoral exposed vessels in all cases. No side effects due to ICG were observed. CONCLUSIONS: ICG video-angiography is a significant method for monitoring blood flow in the exposed vessels during microsurgical removal of CNS tumors. Pre-resection videoangiography provides useful information on the tumoral circulation and the pathology-induced alteration in surrounding brain circulation. Post-resection examination allows for an immediate check of patency of those vessels that are closely related to the tumor mass and that the surgeon does not want to damage.

Vacuum ultraviolet silicon photomultipliers applied to BaF2cross-luminescence detection for high-rate ultrafast timing applications.

Inorganic scintillators are widely used for fast timing applications in high-energy physics (HEP) experiments, time-of-flight positron emission tomography and time tagging of soft and hard x-ray photons at advanced light sources. As the best coincidence time resolution (CTR) achievable is proportional to the square root of the scintillation decay time it is worth studying fast cross-luminescence, for example in BaF2which has an intrinsic yield of about 1400 photons/MeV. However, emission bands in BaF2are located in the deep-UV at 195 nm and 220 nm, which sets severe constraints on photodetector selection. Recent developments in dark matter and neutrinoless double beta decay searches have led to silicon photomultipliers (SiPMs) with photon detection efficiencies of 20%-25% at wavelengths of 200 nm. We tested state-of-the-art devices from Fondazione Bruno Kessler and measured a best CTR of 51 ± 5 ps full width at half maximum when coupling 2 mm × 2 mm × 3 mm BaF2crystals excited by 511 keV electron-positron annihilation gammas. Using these vacuum ultraviolet SiPMs we recorded the scintillation kinetics of samples from Epic Crystal under 511 keV excitation, confirming a fast decay time of 855 ps with 12.2% relative light yield and 805 ns with 84.0% abundance, together with a smaller rise time of 4 ps beyond the resolution of our setup. The total intrinsic light yield was determined to be 8500 photons/MeV. We also revealed a faster component with 136 ps decay time and 3.7% light yield contribution, which is extremely interesting for the fastest timing applications. Timing characteristics and CTR results on BaF2samples from different producers and with different dopants (yttrium, cadmium and lanthanum) are given, and clearly show that the the slow 800 ns emission can be effectively suppressed. Such results ultimately pave the way for high-rate ultrafast timing applications in medical diagnosis, range monitoring in proton or heavy ion therapy and HEP.

Microsurgical endoscopic-assisted retrosigmoid intradural suprameatal approach: anatomical considerations.

AIM: The aim of this study was to evaluate the feasibility of microscopic endoscopic assisted suprameatal tubercle drilling with a retrosigmoid approach and it focuses on the anatomic structures identified with the endoscope. The advantages of the 30 degrees optic view are also described. METHODS: Fifty dry temporal bones were studied in order to estimate the variability of the prominence of the suprameatal tubercle. Eight fresh cadaveric specimens were prepared for a retrosigmoid approach to allow for microscopic endoscopic assisted suprameatal tubercle drilling. The increase in trigeminal exposure and neurovascular structures visualization with the endoscope, using 0 degrees and 30 degrees optics were then evaluated. RESULTS: Three major types of the suprameatal tubercle were found: 1) a large size tubercle (> 6 mm, 9/50 cases); 2) a medium size tubercle (3-6 mm, 37/50 cases); and 3) an almost absent suprameatal tubercle (< 3 mm, 4/50 cases). Microscopic endoscopic assisted suprameatal tubercle drilling with opening of the Meckel's Cave was found to be technically feasible in all cases. The increase in trigeminal nerve exposition was of 9 mm on average. Endoscopic exploration with 0 degrees and 30 degrees optics made possible the identification of all neurovascular structures in the area. CONCLUSION: Microscopic endoscopic assisted suprameatal tubercle drilling is a feasible procedure that allows the identification of all neurovascular structures in the cerebellopontine angle and petrous apex region. The opening of Meckel's Cave may be particularly useful for lesions located in the cerebellopontine angle having a minor component that extends anteriorly and laterally in the middle cranial fossa.

Self-closing Nitinol U-Clips for intracranial arterial microanastomosis: a preliminary experience on seven cases.

PURPOSE: To report experience on the use of self-closing nitinol U-Clips for different types of intracranial arterial microanastomosis. METHODS: We treated 7 patients (3 females and 4 males, age ranging from 25 to 68 yo) admitted from November 2005 to January 2008 to the Neurological Institute C. Besta of Milan. One patient had cerebral hypoperfusion and the others a complex intracranial aneurysm. In each patient a bypass procedure was completed by using self-closing Nitinol U-Clips for intracranial arterial microanastomoses. RESULTS: The total time of temporary occlusion was 15.71 +/- 4.386 min. Bypass patency was confirmed intraoperatively by near-infrared indocyanine green videoangiography and microdoppler in each patient. No spasm of the graft was encountered and immediate post-operative bypass patency was confirmed in 6/7 patients. The graft thrombosed in 1 patient with antiphospholipid syndrome. 1 patient died from a massive Subarachnoid Hemorrhage due to rupture of an aneurysm while waiting for an endovascular procedure. In the 5 patients at the last follow-up, long-term patency of the bypass was confirmed and no neurological deficits occurred related to the procedure. CONCLUSION: This is the first report of the use of U-Clips for intracranial microanastomosis. Our data indicated that it is a safe technique, reduces the time taken to perform an anastomosis and the risk of an ischemic complication. Further studies of the longer-term patency of bypass as performed with U-Clips are required.

Endoscopic radial artery harvesting for U-clip EC-IC bypass in the treatment of a giant petrous internal carotid artery aneurysm: technical case report.

INTRODUCTION: High-flow extracranial-intracranial (EC-IC) bypass and aneurysm trapping constitutes a well-known surgical solution for internal carotid artery (ICA) aneurysms that are not amenable to clip ligation or endovascular therapy. The advantages of the radial artery (RA) as a conduit for myocardial revascularization have become widely accepted, with a better patency rate than that of the saphenous vein. CASE REPORT: A 66-year-old woman was found to harbour a right giant, partially thrombosed aneurysm of the intrapetrous segment of the internal carotid artery. Endoscopic harvesting of the RA was achieved combining a resterilizable retractor and a vessel sealing system. After neck dissection, the main trunk of the middle cerebral artery (MCA), its branches, and part of the aneurysm were isolated through a right fronto-orbito-zygomatic craniotomy. The external carotid artery, distal to the origin of the facial artery, was chosen in the neck for an end-to-end microanastomosis. The temporal branch of the MCA was selected for an end-to-side microanastomosis with the radial graft using ten U-clips. The total temporary occlusion time was 13 min. The post-operative course was uneventful. CONCLUSION: Endoscopic technique provides improved patient satisfaction, especially in terms of length of the surgical incision, when compared to the conventional approach. Combined with the innovative use of U-clips, this case illustrates how new technologies can simplify ECA-ICA bypass surgery while yielding a better cosmetic and functional outcome.

Endoscopic treatment of colloid cysts of the third ventricle: long-term results in a series of 6 consecutive cases.

AIM: Colloid cysts of the third ventricle represent 0.5-2% of all intracranial tumors. Several surgical approaches have been proposed for the treatment of these lesions and endoscopy is the most recent one, but the best treatment still remains controversial. We decided to treat colloid cysts with endoscopic approach since 1999. In this paper we present our results in 6 consecutive cases admitted at our institution from 1999 to 2004. METHODS: There were 4 males and 2 females. The mean age was 51.6 (range 29-77). All the cysts were symptomatic. The presenting symptom was headache in 4 patients, gait disturbance in 2, altered vision in 2, mental status change in 2, urinary incontinence in 2, loss of consciousness in 2 and short-term memory loss in 1 patient. All the endoscopic procedures were performed via a right precoronal burr hole, with a rigid endoscope. RESULTS: The removal was radiologically complete in 4 cases and incomplete in 2. Overall outcome was good in all cases, with an improvement of colloid cyst-related hydrocephalus in all the patients. There was no surgical mortality. The mean follow-up period was 52.5 months. No tumor recurrences were observed. Complications occurred in only one patient: a septic ventriculitis, venous thrombosis of the right leg and pulmonary embolism developed, but completely resolved during the hospitalization time. CONCLUSION: The endoscopic approach for the removal of colloid cysts of the third ventricle represents a safe procedure, and can be considered a very good option for the treatment of these lesions.

Cortical and subcortical motor mapping in rolandic and perirolandic glioma surgery: impact on postoperative morbidity and extent of resection.

AIM: Surgery for gliomas located inside or in proximity of motor cortex or tracts requires cortical and subcortical mapping to locate motor function; direct electrical stimulation of brain cortex or subcortical pathways allows identification and preservation of motor function. In this study we evaluated the effect which subcortical motor mapping had on postoperative morbidity and extent of resection in a series of patients with gliomas involving motor areas or pathways. METHODS: One hundred and forty-six patients were included in the study. Intraoperative findings of primary motor cortex or subcortical tracts were reported, together with incidence of new postoperative deficits at short (1 week) and long term (1 month) examination. The relationship between intraoperative identification of subcortical motor tracts and extent of resection was reported. RESULTS: The motor strip was found in 133 patients (91%) and subcortical motor tracts in 91 patients (62.3%). New immediate postoperative motor deficits were documented in 59.3% of patients in whom a subcortical motor tract was identified intra-operatively and in 10.9% of those in whom subcortical tracts were not observed; permanent deficits were observed in 6.5% and 3.5%, respectively. A total resection was achieved in 94.4% of patients with high-grade gliomas and in 46.1% of those with low-grade gliomas.

Impact of selected composition and ripening conditions on CO2 solubility in semi-hard cheese.

Despite CO2 being one of the most important gases affecting the quality of most semi-hard cheeses, the thermodynamic properties of this molecule in relation to cheese ripening have rarely been investigated. In this study the CO2 solubility coefficient was experimentally assessed in semi-hard cheese as a function of the most relevant compositional and ripening variables. As expected, CO2 solubility was found to linearly decrease with temperature in the range 2-25 °C. Unexpectedly, solubility was not significantly different at 39% and 48% moisture, while it was found lower at 42%. Unavoidable changes in protein content of the three cheese variants is suspected to produce an interaction with water content, leading to complex interpretation of the results. Increasing salt content in cheese from 0 to 2.7%w/w significantly decreased CO2 solubility by about 25%, probably due to the increased bonded water molecules in the cheese water phase.

An appraisal of the impact of compositional and ripening parameters on CO2 diffusivity in semi-hard cheese.

This study focuses on CO2 diffusivity, which is one of the most important factors impacting eye growth in semi-hard cheese, but yet has scarcely been investigated in literature. The effect of compositional and ripening parameters on experimental CO2 diffusivity in semi-hard cheese was studied. CO2 diffusivity in semi-hard cheese showed a complex relationship with temperature in the range 4-25°C, represented by a quadratic curve with the highest diffusivity at 13°C. Salt was found to impact CO2 diffusivity, with a decrease of about 60% for 0-2.7% w/w salt addition, which may be ascribed to viscosity increase of the cheese matrix and "salting in" effect of protein. CO2 diffusivity was found to increase with moisture content from 39% to 42% w/w, then it decreased from 42% to 48% w/w. Inevitable changes in protein content of the three cheese variants may be responsible for the complex behaviour observed.

Feasibility of simultaneous sodium fluorescein and indocyanine green injection in neurosurgical procedures.

OBJECTIVE: The objective of this study is to assess the feasibility of simultaneous Sodium Fluorescein (SF) and Indocyanine Green (ICG) injection during neurosurgical procedures. PATIENTS AND METHODS: Three patients harboring a high-grade glioma (HGG) were retrospectively identified in the surgical database of the Neurosurgical Unit 2 at the Foundation IRCCS Istituto Neurologico C. Besta in Milan, by having received intraoperatively both SF for tumor resection and ICG for vasculature angiographic studies in the same surgical procedure. We identified 2 males and 1 female (age range 25-60). Lesions were located in the left temporo-polar area and hippocampus (1 case), right superior frontal gyrus (1 case), left supplementary motor area (1 case). All the three lesions showed Magnetic Resonance Imaging (MRI) characteristics of HGG and, for this reason, in all patients a fluorescein-guided tumor removal was proposed. In the same surgical procedure ICG videoangiography was considered necessary in order to study arterial and venous vasculature, given by the strict relation of the tumor with an unexpected Posterior Communicating Artery (PComA) aneurysm in one case and with cortical drainage veins complexes in the other two cases. In all cases a microscope equipped with both YELLOW560 and IR800 integrated filters (Pentero 900, Carl Zeiss, Oberkorchen, Germany) was used. Fluorescein was i.v. injected at a dose of 5mg/kg immediately after patient intubation. ICG was i.v. injected in bolus on demand of the operating surgeon at a dose of 12.5mg. RESULTS: No side-effects related to simultaneous injection of SF and ICG were identified. In all three cases, the use of SF allowed to better visualize the tumor areas during surgical removal, thus leading to a radical resection until no macroscopic appearance of residual tumor mass and no fluorescence was visible in the surgical cavity. ICG videoangiography confirmed the patency of branches of internal carotid artery after clipping of an unexpected small PComA aneurysm found intraoperatively during tumor removal in one case, while in patient 2 and 3 it allowed to evaluate patency and study flow pattern in cortical drainage veins that were intimately related to the tumors and the way of the surgical approach. Postoperative MRI showed a Gross Total Resection of the tumors in all cases. CONCLUSIONS: This study showed for the first time the feasibility of intravenous SF injection and ICG videoangiography in the same surgical procedure. The presence of different fluorescence filters on the same surgical microscope allows the surgeon to recognize and safely resect the tumor and simultaneously evaluate local brain vascularization.

Novel methodology for the in situ assessment of CO2 production rate and its application to anaerobic ripened cheese.

CO2 is produced by many microorganisms present in cheese and it can affect cheese quality both during processing and storage. The knowledge of the extent of CO2 production by cheese microorganism (CO2 production rate coefficients) may be used to predict gas exchange in cheese/packaging systems, helping dairy industries in the right choice of the packaging (higher/lower gas permeability) and mastering of cheese ripening. However very few coefficients for CO2 production rate have been published and the ones assessed in vitro (not inside real food) may not well describe the activity of the microorganisms in situ. We have therefore developed a methodology for the in situ assessment of CO2 production rate and applied it to cheese with propionic acid fermentation. The proposed methodology is based on infra-red measurement of CO2 and it allows measuring its accumulation up to 1% with 0.001% resolution, while monitoring the level of oxygen. The method showed a good repeatability, with a low coefficient of variation within samples (6.6%) and between samples (8.4%) compared to 10-30% between samples found in literature. The method was compared with a gas chromatography based method, which is also described.

Spontaneous arteriovenous fistula of the vertebral artery. Three case reports.

Three cases of spontaneous arteriovenous fistulas of the vertebral artery (VAF) are reported. In one case the only symptom was a cervical bruit; in the other two cases, symptoms of multiple cervical radiculopathy were also observed. Definitive diagnostic findings were obtained by Doppler ultrasonography, computed tomography, magnetic resonance imaging, and angiography. Clinical signs of radiculopathy disappeared after endovascular balloon occlusion of the fistula, in about 1 month. In one case the vertebral artery was occluded without clinical consequences.

Microvascular density and vascular endothelial growth factor expression in normal pituitary tissue and pituitary adenomas.

Microvessel density (MVD) represents a measure of angiogenesis and may be used as an indicator of neoplastic aggressiveness. Vascular endothelial growth factor (VEGF) plays a pivotal role as angiogenic promoter by stimulating endothelial cell proliferation and migration and enhancing vascular permeability. The aim of this study was to investigate MVD and VEGF expression in human pituitary adenomas and normal pituitary gland tissues by immunohistochemistry, and to correlate data with clinical characteristics. Fragments from 46 pituitary adenomas (18 non-functioning, 12 ACTH-secreting, 12 GH-secreting, 4 PRL-secreting) and 19 specimens of normal anterior pituitary gland obtained at surgery were evaluated. MVD in normal anterior pituitary was significantly higher than in tumors (69.2 +/- 28.5 vs 29.3 +/- 19.7; p < 0.0001). Within adenomas, no difference was found in MVD when different histotype, size, sex, age, rate of recurrence or medical pre-surgical treatment were considered. The degree of vascularity was somewhat related only to clinical invasiveness, as evaluated by pre-surgical MRI grading (grade 0 p < 0.05 vs grade 1 and vs grade 2). No statistically significant difference in VEGF expression was found between normal tissue and adenomas and among tumors of different histotype (p = 0.3978). Size, sex, age, rate of recurrence and medical pre-surgical treatment did not influence VEGF expression. No correlation was found between MVD and VEGF expression. In conclusion, MVD was reduced in pituitary adenomas with respect to normal gland. VEGF expression is however well preserved in adenomas and this might contribute to adequate tumoral vascular supply with complex mechanisms other than endothelial cells proliferation.