|ognizant Communication Corporation|
REVIEWS IN ANALGESIA
An International Journal
VOLUME 9, NUMBER 1
Reviews in Analgesia, Vol. 9, pp. 1-12
1542-961X/06 $90.00 + .00
Copyright © 2006 Cognizant Comm. Corp.
Printed in the USA. All rights reserved.
Craniofacial Sensorimotor Reflexes in Pain: Basic Science and Clinical Implications
Experimental Neurosurgery, Department of Neurosurgery, RWTH Aachen University, Pauwelsstrasse 30, D-52074 Aachen, Germany
Somatosensory stimulation of cutaneous afferents in the craniofacial region elicits the trigemino-facial blink reflex. This sensorimotor reflex of the orbicularis oculi muscle consists of three components R1, R2, and R3. The bilateral R2 can be evoked by weak electrical stimulation of tactile Ab fibers as well as by selective excitation of Ad nociceptors via laser radiant heat. Experiments utilizing the diffuse noxious inhibitory control system and the phenomenon of spatial summation suggest the convergent nature of the R2 reflex. Similar to the withdrawal reflexes in the spinal system, the blink reflex is an appropriate model to investigate nociception and pain processing in the craniofacial area. Studies in healthy volunteers and patients suffering from orofacial pain or headache stress the importance of this advanced reflex model in physiology and pathology of the trigeminal system.
Key words: Blink reflex; Brain stem; Headache; Laser; Nociception; Orofacial
Address correspondence to Jens Ellrich, M.D., Ph.D., Professor of Experimental Neurosurgery, Experimental Neurosurgery Section, Department of Neurosurgery, Pauwelsstrasse 30, D-52074 Aachen, Germany. Tel: +49-241-80-89521; Fax: +49-241-80-82491; E-mail: firstname.lastname@example.org
The Involvement of Monocyte Chemoattractant Protein-1 in Peripheral Nerve Injury-Induced Neuropathic Pain
Unité de Neurobiologie cellulaire, Centre de Recherche Université Laval Robert-Giffard, 2601, Chemin de la Canardière, Québec, Québec, G1J 2G3 Canada
Peripheral nerve injury induced-neuropathic pain is a common clinical symptom, with a pathogenesis. It involves not only the nervous system, but also many other systems. In this review, we summarize recent findings regarding the contribution of monocyte chemoattractant protein-1 (MCP-1), a CC family chemokine, in the etiology of this pathology. Constitutively present in the immune system, MCP-1 could be induced in damaged sensory neurons; its receptor, CCR2, is also present within the central nervous system. Under the powerful chemoattractant effect of MCP-1, monocytes/macrophages are recruited around the injured nerve and proinflammatory substances released by these immune cells increase the peripheral sensitization. In addition to its classical function in cell trafficking, MCP-1 could contribute to central sensitization by directly increasing neuronal excitability or by modulation of spinal inhibitory GABAergic transmission. It is also suggested that MCP-1 could be an important molecule mediating neuron-glia interaction and triggering spinal glial activation. Binding of MCP-1 to CCR2 activates different signaling pathways upon the cellular environment and may define their physiopathological effect. These emerging observations provide new insights into the full spectrum of neuropathic pain and present continuing challenges for drug discovery.
Key words: Chemokine; Monocyte/macrophage recruitment; Neuron-glia interaction; Neuropathic pain
Address correspondence to Dr. Ji Zhang, Unité de Neurobiologie cellulaire, Centre de Recherche Université Laval Robert-Giffard, 2601, Chemin de la Canardière, Québec, Québec, G1J 2G3 Canada. Tel: 1-418-663-5747; Fax: 1-418-663-8756; E-mail: Ji.Zhang@crulrg.ulaval.ca
Using the Internet to Improve the Study and Management of Pain: Could the Health System Meet Our Expectations?
Alejandro R. Jadad1,2 and Jacqueline L. Bender1,3
1Centre for Global eHealth Innovation, University Health
Network and University of Toronto, Toronto, Canada
2Departments of Health Policy, Management and Evaluation; Public Health Sciences; and Anesthesia, University of Toronto, Toronto, Canada
3Department of Public Health Sciences, Faculty of Medicine, University of Toronto, Toronto, Canada
Following the successful management of pain that preceded the deaths of one (each) of their parents, the authors developed heightened expectations about the ability of the health system to meet the needs of patients. In this article, they present a vision for a health system that is trustworthy, understandable, accountable, responsive, and efficient; that does not only focus on treating a disease, but promotes the highest possible levels of health for each person throughout life, regardless of location or circumstance. They provide examples that strive to achieve this vision, within the context of pain management, building on the power of information and communication technologies. The projects include "knowledge distilleries" that support evidence-based decision making, virtual communities that handle information overload, and tools to access knowledge at the point of need, to enhance health professional-public communication and to speed up the dissemination of success stories on the management of pain, worldwide.
Key words: Pain; Internet; Communication; Evidence
Address correspondence to Alejandro R. Jadad, M.D., D.Phil. FRCPC, Centre for Global eHealth Innovation, R. Fraser Elliott Building, 4th Floor, 190 Elizabeth Street, Toronto, Ontario, M5G 2C4 Canada. Tel: 416-340-4800, ext. 6903; Fax: 416-340-3595; E-mail: email@example.com
Cold Receptors in the DRG: Basic Science and Clinical Implications
Koichi Obata, Kimiko Kobayashi, Tetsuo Fukuoka, and Koichi Noguchi
Department of Anatomy and Neuroscience, Hyogo College of Medicine, Nishinomiya, Hyogo 663-8501, Japan
Cold hypersensitivity is a well-documented symptom of chronic pain; however, the underlying mechanisms of this enhanced sensitivity to cold are poorly understood. The transient receptor potential (TRP) superfamily of cation channels contains four temperature-sensitive channels, named TRPV1-4, that are activated by heat stimuli from warm to that in the noxious range. Recently, two other members, TRPA1 and TRPM8, have been cloned and characterized as possible candidates as cold transducers. Using in situ hybridization histochemistry, we characterized the precise distribution of TRPA1 and TRPM8 mRNAs in the rat dorsal root ganglion (DRG). Our data suggest the heterogeneity of TRPA1 and TRPM8 expression by subpopulations of DRG neurons, and this may result in the difference of cold-sensitive sensory neurons in the sensitivity to chemicals. Although the role of TRPA1 in cold transduction is still controversial, blocking TRPA1 in sensory neurons could provide a fruitful strategy for the development of novel analgesics.
Key words: TRPA1; TRPM8; NGF; Primary afferent neurons; Noxious cold; Hyperalgesia
Address correspondence to Koichi Noguchi, M.D., Ph.D., Department of Anatomy and Neuroscience, Hyogo College of Medicine, 1-1 Mukogawa-cho, Nishinomiya, Hyogo 663-8501, Japan. Tel: 0798-45-6415; Fax: 0798-45-6417; E-mail: firstname.lastname@example.org
Safety Aspects of Postoperative Pain Management
Tee Yong Tan1 and Stephan A. Schug2
1Department of Anaesthesia and Pain Medicine, Royal Perth
Hospital GPO Box X 2213, Perth, WA 6847, Australia
2UWA Anaesthesia, School of Medicine and Pharmacology, University of Western Australia, Perth, WA 6847, Australia
Acute pain after surgery remains poorly managed despite many advances in its treatment. Limitations of its efficacy include safety concerns about the side effects associated with the use of the different analgesics and techniques. The use of multimodal analgesia has become a cornerstone in the management of acute postoperative pain and thereby renewed interest in the widespread use of nonopioids to provide postoperative analgesia. This review focuses on the safety aspects of nonopioids and patient-controlled and epidural analgesia. With appropriate use, acetaminophen is by far the safest and most cost-effective nonopioid analgesic that is available in clinical practice. Major safety concerns focus on hepatotoxicity in relative overdoses. Nonselective NSAIDs and selective coxibs are also effective postoperative analgesics and important components of multimodal analgesia. The current debate on the cardiovascular safety of these compounds in long-term use has clouded the discussion of other areas of concern; overall, coxibs offer a number of safety advantages over NSAIDs in the postoperative setting. Patient-controlled administration of systemic opioids is in general safe, but requires attention to "patient/disease"- and "technique/equipment"related factors to improve safety of the technique. Epidural analgesia carries inherent risks and the increasing perioperative use of modern anticoagulants will require careful consideration in the future. From an organizational point of view, Acute Pain Services with well-trained personnel and established standard operating procedures are the best way to minimize the potential hazards of modern postoperative analgesia.
Key words: Nonsteroidal anti-inflammatory drugs (NSAIDs); COX-2 inhibitors (Coxibs); Acetaminophen (paracetamol); Patient-controlled analgesia (PCA); Epidural analgesia; Safety; Postoperative pain
Address correspondence to Professor Stephan A. Schug, M.D., FANZCA,
FFPMANZCA, UWA Anaesthesia, Level 2, MRF Building G Block, Royal Perth
Hospital, GPO Box X2213, Perth, WA 6847, Australia. Tel: +61-8-9224 0201;
Fax: +61-8-9224 0279; E-mail: email@example.com