Advanced multiparametric magnetic resonance imaging of multinodular and vacuolating neuronal tumor.

BACKGROUND AND PURPOSE: Multinodular and vacuolating neuronal tumor (MVNT) of the cerebrum is a rare brain lesion with suggestive imaging features. The aim of our study was to report the largest series of MVNTs so far and to evaluate the utility of advanced multiparametric magnetic resonance (MR) techniques. METHODS: This multicenter retrospective study was approved by our institutional research ethics board. From July 2014 to May 2019, two radiologists read in consensus the MR examinations of patients presenting with a lesion suggestive of an MVNT. They analyzed the lesions' MR characteristics on structural images and advanced multiparametric MR imaging. RESULTS: A total of 64 patients (29 women and 35 men, mean age 44.2 ± 15.1 years) from 25 centers were included. Lesions were all hyperintense on fluid-attenuated inversion recovery and T2-weighted imaging without post-contrast enhancement. The median relative apparent diffusion coefficient on diffusion-weighted imaging was 1.13 [interquartile range (IQR), 0.2]. Perfusion-weighted imaging showed no increase in perfusion, with a relative cerebral blood volume of 1.02 (IQR, 0.05) and a relative cerebral blood flow of 1.01 (IQR, 0.08). MR spectroscopy showed no abnormal peaks. Median follow-up was 2 (IQR, 1.2) years, without any changes in size. CONCLUSIONS: A comprehensive characterization protocol including advanced multiparametric magnetic resonance imaging sequences showed no imaging patterns suggestive of malignancy in MVNTs. It might be useful to better characterize MVNTs.

Endovascular Treatment for Low-Grade (Spetzler-Martin I-II) Brain Arteriovenous Malformations.

BACKGROUND AND PURPOSE: Surgical resection is usually considered as the first-line curative strategy for low-grade (Spetzler-Martin grade I-II) brain arteriovenous malformations because it has a high cure rate and low complications. The role of endovascular treatment remains to be clarified in this indication, especially after A Randomized Trial of Unruptured Brain Arteriovenous Malformations. Our objective was to assess the safety and efficacy of first-line endovascular treatment in low-grade brain arteriovenous malformation management at our institution. MATERIALS AND METHODS: Patients with low-grade brain arteriovenous malformations treated primarily with embolization in our department between January 2005 and December 2015 were retrieved from our prospectively collected registry. The primary outcome was the brain arteriovenous malformation obliteration rate, and secondary outcomes were disability or death secondary to brain arteriovenous malformation embolization assessed through modification of the modified Rankin Scale. RESULTS: Two hundred twenty-four patients completed endovascular treatment during the study period and represent our study population. Complete exclusion of brain arteriovenous malformations was achieved in 205 patients (92%), including 62.1% of brain arteriovenous malformation exclusions after a single endovascular treatment session. One patient died of a hemorrhagic complication after endovascular treatment, leading to a mortality rate of 0.4%. Twelve patients (5%) kept a permanent neurologic deficit secondary to a complication of the endovascular treatment. An overall good outcome (mRS 0-2) was reported in 179 patients (80%). CONCLUSIONS: Endovascular treatment might be a suitable alternative to surgical resection for complete exclusion of selected low-grade brain arteriovenous malformations.

Ex vivo optimisation of a heterogeneous speed of sound model of the human skull for non-invasive transcranial focused ultrasound at 1 MHz.

Transcranial brain therapy has recently emerged as a non-invasive strategy for the treatment of various neurological diseases, such as essential tremor or neurogenic pain. However, treatments require millimetre-scale accuracy. The use of high frequencies (typically ≥1 MHz) decreases the ultrasonic wavelength to the millimetre scale, thereby increasing the clinical accuracy and lowering the probability of cavitation, which improves the safety of the technique compared with the use of low-frequency devices that operate at 220 kHz. Nevertheless, the skull produces greater distortions of high-frequency waves relative to low-frequency waves. High-frequency waves require high-performance adaptive focusing techniques, based on modelling the wave propagation through the skull. This study sought to optimise the acoustical modelling of the skull based on computed tomography (CT) for a 1 MHz clinical brain therapy system. The best model tested in this article corresponded to a maximum speed of sound of 4000 m.s-1 in the skull bone, and it restored 86% of the optimal pressure amplitude on average in a collection of six human skulls. Compared with uncorrected focusing, the optimised non-invasive correction led to an average increase of 99% in the maximum pressure amplitude around the target and an average decrease of 48% in the distance between the peak pressure and the selected target. The attenuation through the skulls was also assessed within the bandwidth of the transducers, and it was found to vary in the range of 10 ± 3 dB at 800 kHz and 16 ± 3 dB at 1.3 MHz.

In Vivo Measurement of Brain Tumor Elasticity Using Intraoperative Shear Wave Elastography.

Purpose: Objective Shear wave elastography (SWE) enabled living tissue assessment of stiffness. This is routinely used for breast, thyroid and liver diseases, but there is currently no data for the brain. We aim to characterize elasticity of normal brain parenchyma and brain tumors using SWE. Materials and Methods: Patients with scheduled brain tumor removal were included in this study. In addition to standard ultrasonography, intraoperative SWE using an ultrafast ultrasonic device was used to measure the elasticity of each tumor and its surrounding normal brain. Data were collected by an investigator blinded to the diagnosis. Descriptive statistics, box plot analysis as well as intraoperator and interoperator reproducibility analysis were also performed. Results: 63 patients were included and classified into four main types of tumor: meningiomas, low-grade gliomas, high-grade gliomas and metastasis. Young's Modulus measured by SWE has given new insight to differentiate brain tumors: 33.1 ±â€Š5.9 kPa, 23.7 ±â€Š4.9 kPa, 11.4 ±â€Š3.6 kPa and 16.7 ±â€Š2.5 kPa, respectively, for the four subgroups. Normal brain tissue has been characterized by a reproducible mean stiffness of 7.3 ±â€Š2.1 kPa. Moreover, low-grade glioma stiffness is different from high-grade glioma stiffness (p = 0.01) and normal brain stiffness is very different from low-grade gliomas stiffness (p < 0.01). Conclusion: This study demonstrates that there are significant differences in elasticity among the most common types of brain tumors. With intraoperative SWE, neurosurgeons may have innovative information to predict diagnosis and guide their resection.

Conservative management of a large occipital extradural haematoma.

A 26-year-old male presented with a mild confusion and hemianopsia after traumatic brain injury. Cerebral CT-scan revealed a 62.5 cm(3) left occipital extradural haematoma (EDH). Although conventional neurosurgical management would have been to evacuate the haematoma, a conservative strategy was preferred, and the patient made a total recovery.

Effect of continuous cerebrospinal fluid drainage on therapeutic intensity in severe traumatic brain injury.

BACKGROUND: The aim of this study in patients with traumatic brain injury (TBI) was to assess the effectiveness of continuous cerebrospinal fluid (CSF) drainage in controlling intracranial pressure (ICP) and minimizing the use of other ICP-lowering interventions potentially associated with serious adverse events. METHODS: We studied 20 TBI patients. In each patient, we compared four consecutive 12-hour periods covering the 24 hours before CSF drainage (NoDr1 and NoDr2) and the 24 first hours of drainage (Dr1 and Dr2). During each period, we recorded ICP, cerebral perfusion pressure (CPP), sedation, propofol infusion rate, and number of hypertonic saline boluses. RESULTS: With continuous CSF drainage, ICP decreased significantly from 18 ± 6 mmHg (NoDr1) and 19 ± 7 mmHg (NoDr2) to 11 ± 5 mmHg (Dr1) and 12 ± 7 mmHg (Dr2). CPP increased significantly with drainage. Drainage led to a significant decrease in the number of hypertonic saline boluses required for ICP elevation, from 35 in 16 patients (80%) (NoDr1/2) to eight in five patients (25%) (Dr3/4). Drainage was not associated with changes in the midazolam or sufentanil infusion rates. The propofol infusion rate was non-significantly lower with drainage. No significant differences in serum sodium, body temperature, or PaCO(2) occurred across the four 12-hour periods. CONCLUSION: CSF drainage may not only lower ICP levels, but also decreases treatment intensity during the 24 hours following EVD placement in TBI patients. Because EVD placement may be associated with adverse event, the exact role for each of the available ICP-lowering interventions remains open to discussion.

MR-guided adaptive focusing of therapeutic ultrasound beams in the human head.

PURPOSE: This study aims to demonstrate, using human cadavers the feasibility of energy-based adaptive focusing of ultrasonic waves using magnetic resonance acoustic radiation force imaging (MR-ARFI) in the framework of non-invasive transcranial high intensity focused ultrasound (HIFU) therapy. METHODS: Energy-based adaptive focusing techniques were recently proposed in order to achieve aberration correction. The authors evaluate this method on a clinical brain HIFU system composed of 512 ultrasonic elements positioned inside a full body 1.5 T clinical magnetic resonance (MR) imaging system. Cadaver heads were mounted onto a clinical Leksell stereotactic frame. The ultrasonic wave intensity at the chosen location was indirectly estimated by the MR system measuring the local tissue displacement induced by the acoustic radiation force of the ultrasound (US) beams. For aberration correction, a set of spatially encoded ultrasonic waves was transmitted from the ultrasonic array and the resulting local displacements were estimated with the MR-ARFI sequence for each emitted beam. A noniterative inversion process was then performed in order to estimate the spatial phase aberrations induced by the cadaver skull. The procedure was first evaluated and optimized in a calf brain using a numerical aberrator mimicking human skull aberrations. The full method was then demonstrated using a fresh human cadaver head. RESULTS: The corrected beam resulting from the direct inversion process was found to focus at the targeted location with an acoustic intensity 2.2 times higher than the conventional non corrected beam. In addition, this corrected beam was found to give an acoustic intensity 1.5 times higher than the focusing pattern obtained with an aberration correction using transcranial acoustic simulation-based on X-ray computed tomography (CT) scans. CONCLUSIONS: The proposed technique achieved near optimal focusing in an intact human head for the first time. These findings confirm the strong potential of energy-based adaptive focusing of transcranial ultrasonic beams for clinical applications.

In vivo bubble nucleation probability in sheep brain tissue.

Gas nuclei exist naturally in living bodies. Their activation initiates cavitation activity, and is possible using short ultrasonic excitations of high amplitude. However, little is known about the nuclei population in vivo, and therefore about the rarefaction pressure required to form bubbles in tissue. A novel method dedicated to in vivo investigations was used here that combines passive and active cavitation detection with a multi-element linear ultrasound probe (4-7 MHz). Experiments were performed in vivo on the brain of trepanated sheep. Bubble nucleation was induced using a focused single-element transducer (central frequency 660 kHz, f-number = 1) driven by a high power (up to 5 kW) electric burst of two cycles. Successive passive recording and ultrafast active imaging were shown to allow detection of a single nucleation event in brain tissue in vivo. Experiments carried out on eight sheep allowed statistical studies of the bubble nucleation process. The nucleation probability was evaluated as a function of the peak negative pressure. No nucleation event could be detected with a peak negative pressure weaker than -12.7 MPa, i.e. one order of magnitude higher than the recommendations based on the mechanical index. Below this threshold, bubble nucleation in vivo in brain tissues is a random phenomenon.

[The mystery of prehistoric trepanations: Is neurosurgery the world eldest profession?]. / Le mystère des trépanations préhistoriques : la neurochirurgie serait-elle le plus vieux métier du monde ?

Trepanation is known to be the first surgical procedure ever performed. Its origins date from the Neolithic Age in Europe and the operation was particularly performed in South America at the Pre-Colombian era, a few thousand years later. Based on many archeological studies on trepanned skulls, we compare the differences and similarities of these two periods through epidemiological, topographical, and technical approaches. Signs of bony regeneration are assessed in an attempt to understand the postoperative survival of trepanned patients. The literature in surgery and archeology does not mention the possible relation between trepanations and growing skull fractures. However, it is reasonable to think that these cranial holes, occurring after a pediatric skull fracture, could mimic real trepanation orifices. The possible connections between these two entities are discussed. The etiological hypotheses on prehistoric trepanation are reviewed.

[Early epidural hematoma after CSF shunt for obstructive hydrocephalus]. / Hématome extradural précoce après dérivation interne du liquide céphalorachidien pour hydrocéphalie non communicante.

We present the first case of early epidural hematoma after CSF shunt probably caused by defective material. A 26-year-old man was treated for obstructive hydrocephalus associated with a tonsillar herniation, revealed by headaches and papillary edema. Ventriculoperitoneal shunt was preferred to endoscopic ventriculostomy. Three hours after the operation, the patient fell into a coma, developing a voluminous bifrontal epidural hematoma that was evacuated immediately. The patient completely recovered neurologically. One month later, to treat persistent hydrocephalus, endoscopic ventriculostomy was performed without incident. Then the shunt was removed and an opening threshold close to zero was discovered. Distant MRI showed a reduction in ventricular size, normalization of the tonsils' position and a tumor of the tectal plate. To our knowledge, this is the only case of early epidural hematoma after ventriculoperitoneal shunt. We discuss the choice of treatments for obstructive hydrocephalus and its risks and complications.

Skull bone flap fixation--comparative experimental study to assess the reliability of a new grip-like titanium device (Skull Grip) versus traditional sutures: technical note.

INTRODUCTION: After completing a craniotomy, whenever possible, it is crucial to replace and fix the removed bone flap to the cranium; this in order to keep the brain's protection as well as for cosmetic purposes. Visible skull defects might cause patients psychosocial problems and, most importantly, expose the brain to accidental damage. A fixation device should not only provide optimal attachment of the flap to the skull but also allow fast bony healing to avoid possible pseudoarthrosis and/or osteolytic changes. METHODS: After performing 12 different craniotomies on 4 human cadaver heads the skull flaps were replaced using traditional sutures and a new skull fixation device; for each fixation technique a load-bearing test was performed and the results compared. RESULTS: Bone flaps fixed with the "Skull Grip" showed a strong fixation with optimal plastic deformation when compared to flaps held by sutures that showed less resistance to pressure and could be easily dislocated. CONCLUSION: The "Skull Grip" has shown to be a reliable, effective, and stronger bone flap fixation superior to suturing technique.

Hepatic glucose production during intraperitoneal and intravenous closed-loop insulin regulation of blood glucose in type 1 (insulin-dependent) diabetic patients.

Intraperitoneal infusion of insulin should be more physiological than intravenous insulin since part of the insulin is directed toward the portal vein, which allows the liver to retain its major role in glucose homeostasis. The regulation of hepatic glucose production during the intraperitoneal and intravenous infusions of insulin were compared in eight Type 1 (insulin-dependent), C-peptide-deficient diabetic patients. Primed, continuous infusions of [6,6-2H]glucose were given in the postabsorptive state and during continuous infusion of unlabelled glucose at 1.5 and 4 mg/kg.min, while normoglycaemia was maintained by closed-loop intraperitoneal and intravenous insulin delivery. During all three periods, plasma glucose concentrations remained near normal (variations 3.8-6.1%). The insulin infusion rates required for normal plasma glucose concentrations were essentially the same for the intravenous and intraperitoneal routes in all cases, although the variations were greater with intraperitoneal insulin. Plasma free-insulin levels were only slightly, non-significantly lower with intraperitoneal infusion than with intravenous infusion. Hepatic glucose production was significantly lower with intraperitoneal insulin during all three conditions: basal: 1.71 +/- 0.14, i.p. vs 2.37 +/- 0.26 mg/kg.min, i.v.; 1.5 mg/kg.min glucose infusion: 0.49 +/- 0.23, i.p. vs 0.88 +/- 0.18 mg/kg.min, i.v.; 4 mg/kg.min glucose infusion: 0.31 +/- 0.10, i.p. vs 0.56 +/- 0.12 mg/kg.min, i.v.. These results, obtained with steady-state conditions for plasma glucose, isotopic plasma glucose enrichments and unlabelled glucose infusion rates, suggest that better control of hepatic glucose production leading to normoglycaemia was achieved with the intraperitoneal infusion.

Whole body glucose kinetics in type I diabetes studied with [6,6-2H] and [U-13C]-glucose and the artificial B-cell.

Dynamic aspects of whole body glucose metabolism were assessed in ten young adult insulin-dependent (type I) diabetic men. Using a primed, continuous intravenous infusion of [6,6-2H]glucose and [U-13C]glucose, endogenous production, tissue uptake, carbon recycling, and oxidation of glucose were measured in the postabsorptive state. These studies were undertaken after blood glucose had been maintained overnight at 5.9 +/- 0.4 mmol/L (n = 10), and on another night at 10.5 +/- 0.4 mmol/L (n = 4) or 15.2 +/- 0.6 mmol/L (n = 6). In the normoglycemic state, endogenous glucose production averaged 2.15 +/- 0.13 mg x kg-1 x min-1. This value, as well as the rate of glucose carbon recycling (0.16 +/- 0.04 mg x kg-1 x min-1) and glucose oxidation (1.52 +/- 0.16 mg x kg-1 x min-1) are comparable to those found in nondiabetic controls. In the hyperglycemic states at 10 or 15 mmol/L, endogenous glucose production was increased by 11% (P less than .01) and 60% (P less than .01) compared to the normoglycemic states, respectively. Glucose carbon recycling contributed only a small percentage to this variation in glucose production (15% at the 15 mmol/L glucose level). This suggests that if gluconeogenesis participates in the increased glucose output, it is not dependent on a greater systemic supply of three-carbon precursors. The increased rate of glucose production in the hyperglycemic state was quantitatively offset by a rise in urinary glucose excretion. Glucose tissue uptake, as well as glucose oxidation, did not vary between normoglycemic and hyperglycemic states.(ABSTRACT TRUNCATED AT 250 WORDS)

Differential effects of glucose and fructose on liver L-type pyruvate kinase gene expression in vivo.

Dietary carbohydrates are known to stimulate L-type pyruvate kinase gene expression at the transcriptional level in the liver. However, the short-term effects, the time course, and the mechanism of the gene activation by elemental hexoses in normal fasted rats remain unknown. In the present study, both glucose and fructose were found to stimulate the gene expression at the transcriptional level in liver. However, the kinetics and the extent of the mRNA induction differed according to the carbohydrate given. Fructose stimulated early (2-4 h) and transiently the gene transcription, the RNA precursor, and the mRNA accumulation in 48-h-fasted rats while maximum stimulation of the RNA synthesis by glucose was delayed until the 12th h of refeeding, despite an early rise of plasma insulin. In contrast, insulin release was not required for fructose to trigger the gene transcription, nor did the high cyclic AMP levels in fasted rat liver prevent RNA synthesis by fructose. The agent(s) operating early in fructose-fed animals might be powerful enough to not require insulin for gene activation and to balance the inhibitory action of glucagon in the liver.

Use of 13C-labeled glucose for estimating glucose oxidation: some design considerations.

Use of 13C-labeled glucose for estimating in vivo rates of glucose oxidation faces several difficulties, particularly the accurate determination of the output of 13C in expired air. In an investigation of wholebody glucose metabolism in healthy adult humans, using a continuous intravenous infusion of D-[U-13C]glucose, we found that a precise estimate of the rate of glucose oxidation was difficult to achieve when the study included infusions with unlabeled glucose. Problems arose 1) as a result of the slow rate at which the 13CO2 released by glucose oxidation reaches an equilibrium in expired air CO2 and 2) due to the contribution to 13CO2 output by the natural 13C in the unlabeled glucose that was infused. In a subsequent series of experiments in healthy young adults, we found that the entry of 13CO2 released by the tissues into the bicarbonate pool and into the expired air is relatively slow and a tracer infusion protocol of approximately 6 h is required for determination of glucose oxidation. This applies when metabolic states are changed acutely during the experiment or when unlabeled glucose is infused. However, for resting subjects in the basal postabsorptive state we confirmed that the time required to achieve a steady state in the 13C enrichment of expired air can be shortened significantly by the use of a NaH13CO3 priming dose, even when this dose varies from the ideal.

Glycemic control with closed-loop intraperitoneal insulin in type I diabetes.

Blood glucose levels were compared in eight type I diabetic subjects who were given closed-loop infusions of insulin by intraperitoneal (i.p.) and intravenous (i.v.) routes, in a cross-over randomized study. After a test meal, plasma glucose peaks were significantly higher with i.p. than with i.v. infusion (174 +/- 22 versus 129 +/- 29 mg/dl) and marked hypoglycemia occurred after 180 min in five of eight subjects. These observations appear to be the consequence of a 60-min lag in insulin rise with i.p. administration. Because of this difference in plasma glucose rise, twice as much insulin was administered i.p. than with i.v. Plasma insulin rose to similar values in both cases. Therefore, with present closed-loop systems, i.p. insulin infusion does not lead to better control of glucose levels than i.v. infusion and does not prevent hyperinsulinism. Adjustments of the artificial B-cell algorithms and the injection of a bolus dose must be tested so that the potential advantages of the i.p. route may be achieved.