|ognizant Communication Corporation|
REVIEWS IN ANALGESIA
An International Journal
VOLUME 9, NUMBER 2
Reviews in Analgesia, Vol. 9, pp. 55-70
1542-961X/07 $90.00 + .00
Copyright © 2007 Cognizant Comm. Corp.
Printed in the USA. All rights reserved.
Descending Control of Pain During Persistent Peripheral Damage
Instituto Venezolano de Investigaciones Cientificas (IVIC), Apartado 21827, Caracas 1020A, Venezuela
Abnormal afferent activity during persistent peripheral damage such as inflammation or nerve lesion causes hyperexcitability in spinal cord nociceptive neurons. The spinal hyperexcitability is additionally facilitated and/or inhibited by influences that originate at the periaqueductal gray matter, the rostral ventromedial medulla, and other structures of the descending pain control system. The hyperalgesia and allodynia induced by persistent damage is thus the result of converging afferent, spinal, and descending mechanisms. This review discusses findings in experimental animals that provide information on the structures, pathways, and mediators responsible for facilitating and inhibiting the neuronal responses and behavioral reactions that characterize persistent pain conditions. Particular attention is given to studies showing that the descending pain control system is itself modified during persistent pain. Knowledge of the mechanisms involved is essential for achieving analgesia by decreasing descending facilitation and increasing descending inhibition of spinal nociception.
Key words: Hyperalgesia; Inflammation; Neuropathic pain; Rostral ventromedial medulla; Periaqueductal gray; Descending pain control system
Address correspondence to Prof. Dr. Horacio Vanegas at his present address: Physiological Institute, Friedrich Schiller University, Teichgraben 8, 07740 Jena, Germany. Tel: (49) (3641) 938864; Fax: (49) (3641) 938812; E-mail: firstname.lastname@example.org
Postherpetic Neuralgia: Basic Research and Clinical Implications
Gunnar Wasner,1,2 Susan M. Fleetwood-Walker,3 Emer M. Garry,3 Catherine Abbadie,4 Robert W. Johnson,5 and Ralf Baron2
1Prince of Wales Medical Research Institute, University of
New South Wales, Sydney, NSW, Australia
2Division of Neurological Pain Research and Therapy, Department of Neurology, Christian-Albrechts-Universität Kiel, Kiel, Germany
3Centre for Neuroscience Research, Division of Veterinary Biomedical Sciences, University of Edinburgh, Summerhall, Edinburgh, EH9 1QH, UK
4Department of Pharmacology, RY80Y-140, Merck Research Laboratories, Rahway, NJ 07065, USA
5Pain Management Clinic, Bristol Royal Infirmary, Bristol, UK
Postherpetic neuralgia (PHN) is a neuropathic pain syndrome as a common complication of herpes zoster. Because of its severity and chronicity, PHN has a major impact on the quality of life and daily functioning, in particular in the elderly, and more effective treatment strategies are needed. A better understanding of the underlying disease processes and pain mechanisms is of utmost importance for such an optimized therapy. This review gives an overview on the clinical characteristics, pathophysiology, and therapeutic options in PHN. It will especially focus on recent findings in epidemiology, animal studies, and human research on PHN. In view of these different disease aspects, a drug-based treatment algorithm is provided with suggestions for prevention of PHN and its pain management.
Key words: Postherpetic neuralgia; Herpes zoster; Epidemiology; Mechanisms; Treatment; Vaccination; Analgesics
Address correspondence to Priv.-Doz. Dr. med. Gunnar Wasner, Prince of Wales Medical Research Institute, University of New South Wales, Barker St, Gate 1, Randwick, Sydney, NSW 2031, Australia. Tel: +61 2 93991039; E-mail: email@example.com
Cytokine-Induced Pain: Basic Science and Clinical Implications
Nurcan Üçeyler and Claudia Sommer
Department of Neurology, University of Würzburg, 97080 Würzburg, Germany
The knowledge about the role of cytokines in pain, mainly gained by animal experiments, is increasingly corroborated by clinical data. In several painful disorders, a correlation between cytokine and pain levels has been found. In this article we focus on the latest data from cytokine research at bench and bedside and summarize current knowledge about the therapeutic implications that have risen from two decades of cytokine and pain research. For some cytokines, the mechanisms leading to pain have recently been clarified at the molecular level. There is a growing consensus on a proalgesic role of proinflammatory cytokines not only in inflammatory but also in neuropathic pain and other conditions. Gene therapy has been used to exploit the analgesic role of anti-inflammatory cytokines experimentally, and drugs modulating the cytokine system have started to find their way into clinical trials.
Key words: Cytokines; Neuropathic pain; Tumor necrosis factor-a;; Interleukins
Address correspondence to Prof. Dr. Claudia Sommer, Department of Neurology, University of Würzburg, Josef-Schneider Str. 11, 97080 Würzburg, Germany. Tel: +49 931-201-23763; Fax: +49 931-201-23697; E-mail: firstname.lastname@example.org
Whiplash Injury Pain: Basic Science and Current/Future Therapeutics
Division of Physiotherapy, School of Health and Rehabilitation Sciences, The University of Queensland, Brisbane, Australia
Whiplash is a common and often disabling condition that incurs both significant personal and economic costs. While many people recover, up to 40% develop persistent symptoms. There is now considerable evidence that demonstrates whiplash to be a complex condition, particularly in those with poor recovery. This group is characterized by widespread sensory and motor hypersensitivity indicative of central hyperexcitability, motor dysfunction, psychological distress, and report higher initial levels of pain. There is some relationship between the sensory hypersensitivity and certain psychological substrates but these relationships are not consistent. Furthermore, both physical and psychological factors are predictors of poor functional recovery, indicating a complex interplay between these factors exists. Most intervention studies have considered whiplash as a homogenous condition and this may account for only modest effects offered by most interventions. Future research should account for the heterogeneity of the whiplash condition. The challenge will be to improve treatment strategies for the management of both physical and psychological aspects of whiplash, particularly in the important early acute stage postinjury.
Key words: Whiplash; Sensory hypersensitivity; Psychological distress; Chronic pain development
Address correspondence to Dr. Michele Sterling, The Whiplash Research Unit, Division of Physiotherapy, The University of Queensland, Brisbane, Australia, 4072. Tel: +61 7 3365 4569; Fax: +61 7 3365 2775; E-mail: email@example.com