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We describe recent work on the development of a Compton scatter polarimeter for measuring the polarization of hard X-rays (100-300 keV) from astrophysical sources. Results from measurements with a laboratory prototype are summarized, along with comparisons to Monte Carlo simulations. We also present our latest design concept, which envisions a complete polarimeter module on the front end of a 5-inch position-sensitive PMT Although the emphasis of our development effort is towards measuring hard X-rays from solar flares, our latest design has the advantage that it is sensitive over a rather large field-of-view (> 1 steradian), a feature that makes the design especially attractive for [Gamma]-ray burst studies.

Copyright of Revista Batista Pioneira is the property of Revista Batista Pioneira and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The zona incerta (ZI) is a small gray matter region of the deep brain first identified in the 19th century, yet direct in vivo visualization and characterization has remained elusive. Noninvasive detection of the ZI and surrounding region could be critical to further our understanding of this widely connected but poorly understood deep brain region and could contribute to the development and optimization of neuromodulatory therapies. We demonstrate that high resolution (submillimetric) longitudinal (T1) relaxometry measurements at high magnetic field strength (7 T) can be used to delineate the ZI from surrounding white matter structures, specifically the fasciculus cerebellothalamicus, fields of Forel (fasciculus lenticularis, fasciculus thalamicus, and field H), and medial lemniscus. Using this approach, we successfully derived in vivo estimates of the size, shape, location, and tissue characteristics of substructures in the ZI region, confirming observations only previously possible through histological evaluation that this region is not just a space between structures but contains distinct morphological entities that should be considered separately. Our findings pave the way for increasingly detailed in vivo study and provide a structural foundation for precise functional and neuromodulatory investigation. [ABSTRACT FROM AUTHOR]

Background Ultrasound guidance is now a standard nerve localization technique for peripheral nerve block (PNB). Ultrasonography allows simultaneous visualization of the target nerve, needle, local anesthetic injectate, and surrounding anatomical structures. Accurate deposition of local anesthetic next to the nerve is essential to the success of the nerve block procedure. Due to limitations in the visibility of both needle tip and nerve surface, the precise relationship between needle tip and target nerve is unknown at the moment of injection. Importantly, nerve injury may result both from an inappropriately placed needle tip and inappropriately placed local anesthetic. The relationship between the block needle tip and target nerve is of paramount importance to the safe conduct of peripheral nerve block. Methods This review summarizes the evolution of nerve localization in regional anesthesia, characterizes a problem faced by clinicians in performing ultrasound-guided nerve block, and explores the potential technological solutions to this problem. Results To date, technology newly applied to PNB includes real-time 3D imaging, multi-planar magnetic needle guidance, and inline injection pressure monitoring. This review postulates that optical reflectance spectroscopy and bioimpedance may allow for accurate identification of the relationship between needle tip and target nerve, currently a high priority deficit in PNB techniques. Conclusions Until it is known how best to define the relationship between needle and nerve at the moment of injection, some common sense principles are suggested. [ABSTRACT FROM AUTHOR]

The management of severe, medically intractable pain is a significant challenge for neurosurgeons and pain management physicians. An existing technique that can effectively alleviate contralateral chronic pain is cordotomy, interruption of the lateral spinothalamic tract of the spinal cord. Since 1912, cordotomy has evolved from a relatively morbid open surgical procedure to a percutaneous radiofrequency procedure with low morbidity. However, since cordotomy is utilized primarily in cancer pain patients, long-term patient follow-up is rare, and the potential duration of analgesia following cordotomy is not known. Here we describe a case with a 41-year follow-up of percutaneous cordotomy for noncancer pain that resulted in over 35 years of complete analgesia, the longest recorded in the literature to date. This case demonstrates that percutaneous cordotomy can provide long-lasting, complete analgesia in some patients and merits continuation as a part of the neurosurgical arsenal of pain therapies. Copyright © 2012 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]

In 1942, it was thought that basal ganglia surgery would cause permanent unconsciousness and significant impairment of motor control. By 1947, when human stereotactic surgery was introduced, the first target was the globus pallidus in a patient with chorea. What happened during those 5 years to set the stage for stereotactic surgery? During the last half of the 19th century, it was first noted that motor disorders were often accompanied by atrophy of various parts of the basal ganglia, and when histopathology became part of necropsy, that relationship between movement disorders and the basal ganglia was strengthened. The impairment of fine motor control was noted in experiments that involved lesioning the basal ganglia, which led to the conclusion that disease of the basal ganglia might cause motor impairment. Finally, in 1939, Russel Meyers took the bold move of surgically resecting the head of the caudate nucleus at craniotomy in a patient with Parkinson’s disease, demonstrating that Dandy was wrong in the view that the basal ganglia were the center of consciousness, and that symptoms and motor control might be improved by caudate lesions without motor impairment. He reported his first patient in a meeting in 1940, which was published in 1942, and was encouraged to investigate basal ganglia surgery further. Although results were encouraging, the mortality rate was prohibitive. Since the introduction of pallidoansotomy in 1947, basal ganglia surgery has become both safe and effective and has been expanded and refined. Copyright © 2006 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]

Objective: Study of percutaneous computed tomography (CT)-guided transdiscal low cervical cordotomy undertaken to treat pain in cancer patients. Methods: At the Department of Neurosurgery, Ain Shams University, Cairo, Egypt, 8 cancer pain patients, with either impaired pulmonary function or a previous cordotomy on an opposite side (sleep apnea was a feared complication) that prevented the possibility of undergoing a C1–2 cordotomy, underwent a percutaneous CT-guided transdiscal low cervical cordotomy (C4–5 or C5–6) to treat cancer pain. Results: Seven patients experienced initial improvement. One patient re-experienced pain within 2 weeks and 1 patient experienced no pain relief. In 6 patients in whom the cordotomy procedure was completed, satisfactory or complete pain relief, throughout a 6-month follow-up period was reported. In contrast, in 2 patients in whom the cordotomy was not completed there was no persistent pain relief. Conclusion: Percutaneous CT-guided cordotomy remains a successful procedure to control pain in cancer patients, and is an affordable viable option under circumstances where economic disadvantage is an overriding determinate. Copyright © 2005 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]

Spatial distribution of the clinical effects induced by deep brain stimulation during the intraoperative investigation of the subthalamic nucleus (STN) for Parkinson’s disease (PD) was analysed in 17 patients under local anesthesia. The stimulation parameters were 130 hertz, 100 µs, and voltage ranged from 0.05 to 5 volts. Optimal motor response was assessed as the total and lasting disappearance of wrist rigidity on the side opposite to stimulation.Among the adverse effects induced by stimulation, special attention was given to frequently observed autonomic effects (AE). Full motor response was achieved in 49.2% of the 301 points evaluated,with a mean voltage (MV) of 0.94 volts; paresthesiae occurred in 6.6% (MV: 2 volts), dystonia in 10.6% (MV: 3.4 volts), autonomic effects in 19.6% (MV: 3.1 volts) and oculomotor effects in 31.6% (MV: 3 volts). The motor target was located in the posterodorsal part of the nucleus and the optimal point for motor response was close to the superior limit of the nucleus. Whereas other adverse effects occurred relatively far from the motor target, AE occurred with statistic significance near this point. Their neural substrates, such as limbic system and their relationship with postoperative behavioral disorders, are discussed. [ABSTRACT FROM AUTHOR]

Neuromodulation, as defined as the use of electrical stimulation by implanted stimulators to treat various neurological conditions, has developed gradually from long experience with electrical stimulation of the nervous system. Indications are still evolving, and the field is advancing at an ever increasing rate. Copyright © 2005 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]

In medical practice, each time span has a dogma of that period. Now, in the science and technology age, one particular dogma is very extensively accepted and used in pain practice. There is a general belief in neurosurgical practice that lesioning of the pain conducting system is accepted as ablative and dangerous. This idea is a dogma and it is wrong. In modern times, modern stereotactic pain surgery is performed in three important steps. First, morphology and localization of the pain conducting pathways are demonstrated with special imaging techniques; the surgeon approaches the target percutaneously by a specially designed needle electrode system. Second, the function of the target and surrounding structures can be defined by stimulation just after the target is totally, partially, or selectively destroyed by radiofrequency lesion. Third, lesioning of the system is controlled at every step of the procedure. These procedures are applied with morphological real-time demonstration, physiological evaluation of the target, and, finally, controlled lesioning. In this way, this surgery is performed safely and effectively. In this paper, I describe the techniques of this method based on a 17-year experience with three different stereotactic destructive procedures: CT-guided percutaneous cordotomy, trigeminal tractotomy, and extralemniscal myelotomy. [ABSTRACT FROM AUTHOR]

Neurosurgical techniques for management of cancer pain can be divided into two categories: reconstructive and ablative. For patients with pain from spinal metastatic disease, the newer surgical methods of anterior decompression and stabilization provide reliable pain control while preventing serious neurologic progression. Minimally invasive techniques for vertebral stabilization, such as vertebroplasty, may also effectively relieve pain from spinal metastases associated with low morbidity. Traditionally, stereotactic and functional neurosurgical techniques have been used to produce selective lesions in neuroanatomic pathways that mediate pain. Improvements in pharmacologic therapy, including treatment with intraspinal opioids, have led to a marked reduction in the use of ablative stereotactic methods. Nevertheless, cordotomy and certain other selectively destructive procedures still have a role in the management of patients with unremitting cancer pain. Technological developments in methods of lesion production could lead to the increased use of these methods. [ABSTRACT FROM AUTHOR]

Copyright of Douleur et Analgésie is the property of John Libbey Eurotext Ltd. and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In this article the technique of CT-Guided Selective Cordotomy is described. The advantages of CT guidance in percutaneous cordotomy are the measurement of spinal cord diameters at the lesion site for each individual patient, direct visualization of target electrode relations, demonstration of spinal cord displacement during the procedure and localization of the electrode system in a specific part of the spinothalamic tract. Local destruction of the spinothalamic tract leads to selective cordotomy. Since 1987, CT-Guided Cordotomy has been applied to 54 cases of intractable cancer pain. In 33 of the 54 cases, the cordotomy was selective enough to be successful with a local denervation of the area where the pain was dominant. Except for one temporary hemiparesis and one temporary ataxia, no complications or side effects were observed. [ABSTRACT FROM AUTHOR]

This study investigated the nature of synaptic inputs from the Forel's field H (FFH) in the medial mesodiencephalic junction to inferior oblique (IO) motoneurons in the oculomotor nucleus and superior oblique (SO) motoneurons in the trochlear nucleus in anesthetized cats, using intracellular recording techniques. Stimulation of the FFH induced monosynaptic EPSPs in IO motoneurons on both sides. Paired stimulation of the ipsilateral FFH and contralateral vestibular nerve substantiated that the FFH-induced EPSPs were caused mainly by direct excitatory fibers from the FFH to IO motoneurons and partly by axon collaterals of excitatory neurons in the vestibular nuclei. Among parts of the FFH, the medial part was most effective for producing the EPSPs. Systematic tracking with the stimulating electrode in and around the FFH revealed that effective sites of stimulation inducing negative field potentials in the IO subdivision of the oculomotor nucleus, identified as extracellular counterparts of the EPSPs in IO motoneurons, were also located in the interstitial nucleus of Cajal, nearby reticular formation and posterior commissure, besides within and near the medial part of the FFH. Areas far rostral, dorsal and ventral to the FFH were ineffective. EPSP-IPSPs or EPSPs were mainly induced in SO motoneurons on both sides by FFH stimulation. Latencies of these EPSPs and IPSPs were close to those of the EPSPs in IO motoneurons, indicating their monosynaptic nature. Effective stimulation sites for inducing these synaptic potentials overlapped those for the EPSPs in IO motoneurons. Based on these results, it was suggested that excitatory and inhibitory premotor neurons directly controlling IO and SO motoneurons were located within and near the medial part of the FFH. [ABSTRACT FROM AUTHOR]

The article discusses several scientific projects and science programs for French high school students. It states that giving the high school students opportunities to explore the world scientifically can revive their inquisitive attitudes. It explores various programs for science courses of high school students including sustainable development workshops, field trips, and experiments designed by scientists at Tous Chercheurs laboratory.