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Rachel Sarabia-Estrada, Alejandro Ruiz-Valls, Sagar R. Shah, A. Karim Ahmed, Alvaro A. Ordonez, Fausto J. Rodriguez, Hugo Guerrero-Cazares, Ismael Jimenez-Estrada, Esteban Velarde, Betty Tyler, Yuxin Li, Neil A. Phillips, C. Rory Goodwin, Rory J. Petteys, Sanjay K. Jain, Gary L. Gallia, Ziya L. Gokaslan, Alfredo Quinones-Hinojosa and Daniel M. Sciubba

a lack of influence on nociception and locomotion of the gait). 9 , 19 , 21 , 23 , 40 In this study, we sought to develop and evaluate an orthotopic animal model involving human-derived chordoma growing in the L-5 vertebral body of immunocompromised rats. With progressive growth, these tumors affected the locomotion and nociceptive behavior of rats as well as the bone anatomy, based on imaging evidence. Thus, this model clinically and radiographically represents the human condition of spinal chordoma. Tumor Growth Chordomas are thought to arise from remnants of

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Jenell R. Smith and Beth A. Winkelstein

permeability and enhance nociception are not defined. Thrombin is a bioactive blood-borne enzyme restricted from the CNS under normal healthy conditions. 33 , 38 When introduced into the CNS, certain concentrations of thrombin induce cellular cascades that promote nociception when applied for an extended duration. 19 , 36 , 37 Of those spinal effects, astrocyte activation has been shown to occur in parallel with pain-related behaviors induced by a variety of neuropathic insults in animal models. 21 , 41 , 42 Exogenous thrombin administered to the spinal cord produces

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Ronald F. Young, Terrence D. Oleson and Kent M. Perryman

The first proposal, which has received recent neurophysiological support, 37 stated that the trigeminal nucleus caudalis was the exclusive termination point of primary afferent fibers related to facial nociception. 10, 44 Such afferents were assumed to synapse with second-order neurons, which relayed nociceptive-related information centrally to the thalamus and other higher centers for cognitive processing. Anatomical 46 and physiological 14, 20, 41, 42, 58 evidence of internuclear interaction within the various divisions of the spinal trigeminal brain

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Andrew G. Shetter and William H. Sweet

-related changes in regional glucose utilization outside lemniscal pathways. Specifically, there were no increased densities in the reticular core of the brain stem, the medial thalamus, or the limbic lobe, all of which are thought to form a neural system concerned with the motivational-affective aspects of nociception. 3 Discussion This work was initiated as part of a general effort to determine the usefulness of the 2-DG method in investigating trigeminal pain mechanisms. Dental-pulp stimulation was selected for study because it is widely acknowledged to be noxious in

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John B. Leslie and W. David Watkins

, neurotransmission, and nociception. The reader may explore these areas in greater depth by examining other detailed reviews and articles included in the references. Biochemistry of Prostaglandins Structure The naturally occurring prostaglandins are a group of 20-carbon unsaturated fatty acids containing a cyclopentane ring and two adjacent carbon side chains. For purposes of nomenclature, the structures of most eicosanoids are compared to prostanoic acid ( Fig. 1 ), although it should be emphasized that the predominant precursor for the eicosanoids in humans is

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Shanmukha Srinivas, Arvin R. Wali and Martin H. Pham

, locomotion was evaluated with the rotarod, grid walk, open field, and pellet-reaching tasks; strength was evaluated with the inclined plane test; and sensory function was evaluated with the hind paw withdrawal test. A plethora of behavioral studies demonstrated positive effects of riluzole on motor function including locomotion, 21 , 27 , 34 , 38 , 48 , 58 , 57 strength, 1 , 47 , 48 and stance and stride length. 47 , 49 With regard to sensory function, behavioral studies have suggested that riluzole decreases nociception 24 and spastic reflexes, 30 which is both

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Waleed M. Renno, Ludmil Benov and Khalid M. Khan

pressure thresholds expressed in grams were measured using an analgesy meter (Model 37215, UGO Basile). Three consecutive mechanical nociceptive threshold values were measured for each hind limb, and the mean and standard deviation (SD) of the paw pressure latencies were calculated. 13 , 37 , 48–50 , 53 Thermal nociception: A modified hot-plate test (50°C, Model 39D Hot Plate Analgesia Meter, Columbus Instruments) was performed, with the withdrawal response threshold defined as the time elapsed from the onset of hot-plate contact to the withdrawal of the hind paw (paw

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Frank J. Tomecek, C. Scott Anthony, Chris Boxell and Jennifer Warren

The authors provide an indepth analysis of discography, a provocative diagnostic tool to determine the origin of low-back pain. Injecting the intervertebral disc with radiopaque dye provides physicians with several useful pieces of information. First, the modality provides radiographic evaluation of the integrity of the nucleus pulposus and anular rings to determine tears or other lesions that could be creating low-back pain. Second, and very important, is its measure of disc nociception. A normal disc should not cause pain when injected; however, a disc that is physiologically compromised can mimic the pain previously experienced by a patient. The authors review the indications, technique, and interpretation of discography to allow a better understanding of when to use this diagnostic test and what to do with the results.

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Josef Pleticha, Timothy P. Maus, Jodie A. Christner, Michael P. Marsh, Kendall H. Lee, W. Michael Hooten and Andreas S. Beutler

Dorsal root ganglia (DRG) are critical anatomical structures involved in nociception. Intraganglionic (IG) drug delivery is therefore an important route of administration for novel analgesic therapies. Although IG injection in large animal models is highly desirable for preclinical biodistribution and toxicology studies of new drugs, no method to deliver pharmaceutical agents into the DRG has been reported in any large species. The present study describes a minimally invasive technique of IG agent delivery in domestic swine, one of the most common large animal models. The technique utilizes CT guidance for DRG targeting and a custom-made injection assembly for convectionenhanced delivery (CED) of therapeutic agents directly into DRG parenchyma. The DRG were initially visualized by CT myelography to determine the optimal access route to the DRG. The subsequent IG injection consisted of 3 steps. First, a commercially available guide needle was advanced to a position dorsolateral to the DRG, and the dural root sleeve was punctured, leaving the guide needle contiguous with, but not penetrating, the DRG. Second, the custom-made stepped stylet was inserted through the guide needle into the DRG parenchyma. Third, the stepped stylet was replaced by the custom-made stepped needle, which was used for the IG CED. Initial dye injections performed in pig cadavers confirmed the accuracy of DRG targeting under CT guidance. Intraganglionic administration of adeno-associated virus in vivo resulted in a unilateral transduction of the injected DRG, with 33.5% DRG neurons transduced. Transgene expression was also found in the dorsal root entry zones at the corresponding spinal levels. The results thereby confirm the efficacy of CED by the stepped needle and a selectivity of DRG targeting. Imaging-based modeling of the procedure in humans suggests that IG CED may be translatable to the clinical setting.

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Ronald F. Young and Kent M. Ferryman

-scratch responses to stimulation on the contralateral side. Discussion The trigeminal nucleus caudalis (NV Caud) was assigned a primary role in orofacial nociception following the clinical description of facial analgesia with preservation of tactile sensation after trigeminal tractotomy in man. 12 Subsequently, three physiological hypotheses were advanced to explain this role. The first theory proposed that the NV Caud was the exclusive locus of termination of nociceptive primary afferent 5 fibers from orofacial structures, and that low-threshold mechanoreceptive