ognizant Communication Corporation


VOLUME 5, NUMBER 1, 2000

Analgesia, Vol. 5, pp. 1-8, 2000
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Topical Capsaicin for the Treatment of Neuropathic Pain

Perry N. Fuchs,1 Srinivasa N. Raja,2 and Richard A. Meyer3

1Department of Psychology, University of Texas at Arlington, Arlington, TX
2Department of Anesthesiology and Critical Care Medicine, Johns Hopkins School of Medicine, Baltimore, MD
3Departments of Neurosurgery and the Applied Physics Laboratory, Johns Hopkins University, Baltimore, MD

Background: The unique ability of capsaicin to cause morphological and neurochemical alterations of primary afferent fibers associated with the transduction and transmission of noxious peripheral stimuli has provided the rationale for utilizing topical capsaicin for therapeutic treatment.
Purpose: The purpose of this review is to critically evaluate the clinical data on the efficacy of capsaicin for the treatment of neuropathic pain with an emphasis on studies in patients with postherpetic neuralgia and diabetic neuropathy.
Conclusions: Topical capsaicin treatment appears to have only modest beneficial effects for the treatment of neuropathic pain and is unlikely to be useful as the sole therapeutic agent. However, a subset of patients with a predominant peripheral pain mechanism may benefit from this drug. Future research should focus on determining the characteristics of the subset of neuropathic patients that are most likely to benefit from topical capsaicin treatment.

Key words: Capsaicin; Neuropathic pain; Therapeutic treatment

Address correspondence and reprint requests to Perry N. Fuchs, Ph.D., Department of Psychology, University of Texas at Arlington, Box 19528, Arlington, TX 76019. Tel: (817) 272-3427; Fax: (817) 272-2364; E-mail: fuchs@uta.edu

Analgesia, Vol. 5, pp. 9-12, 2000
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Chronic Postoperative Pain as a Main Obstacle to Work Reintegration in 1000 Patients

Emile Berger

Division of Neurosurgery, McGill University & Centre Hospitalier de l'Université de Montréal (CHUM), Montréal, Québec, Canada

Background: A retrospective analysis of 1000 workers' compensation patients who underwent lumbar spine surgery reveals that the main obstacle in returning to remunerative employment was chronic pain in the lower back and legs. Among various reasons propounded in an attempt to explain the etiology of the pain it appears that perineural fibrosis is the main culprit. Various studies are now in progress to devise methods and techniques to prevent perineural fibrosis and it is to be hoped that a solution will be found.
Purpose: The purpose of this study was to establish the late postoperative outcome through a thorough clinical neuro/orthopedic examination and complete review of ancillary tests such as neuro-imaging and EMG. No mailed-in questionnaires or telephone interviews were used in this study.
Methods: One thousand patients, of whom 600 had undergone a single operation and 400 had multiple operations, were evaluated 4 years and 3 months and 3 years and 2 months, respectively, following the last intervention.
Results: Of the 600 patients with single operations, 450 had not returned to work at the time of the examination (75%). Close to 95% in the 400 patients having had multiple operations were still unable to work due to chronic pain. Perineural fibrosis was seen at the time of the second operation in 47% of these patients.
Conclusion: Chronic pain following lumbar spine surgery appears to be the main reason for failure to return to work.

Key words: Chronic postoperative pain; Work reintegration; Lumbar spine surgery; Perineural fibrosis

Address correspondence and reprint requests to Emile Berger, M.D., P.O. Box 75, Côte St-Luc Station, Montréal, Quebec, Canada H4V 1H8. Tel: (514) 484-6643; Fax: (514) 484-5937.

Analgesia, Vol. 5, pp. 13-17, 2000
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Cranio-Cervico-Mandibular Pain Associated With Trigger Points Following Whiplash Injury

Ida Marini, Federico Vecchiet, and Ugo Capurso

Department of Oral Surgery, School of Dentistry, University of Bologna, Bologna, Italy

Background: The relationship between whiplash injuries, neck pain, headache, and temporomandibular disorders (TMD) is controversial. Although many patients reported jaw pain, jaw clicking, locking, crepitius, and limited opening after whiplash injury, symptoms of TMD may be of different origin: psychological, fibromyalgic, chronic fatigue syndrome related, and myofascial trigger points (MTrPs).
Purpose: The aim of this study is to show the correlation between chronic cranio-cervico-mandibular pain and trigger points following whiplash injury.
Methods: Fifty-seven patients (22 males and 35 females) ranging from 16 to 65 years were examined and reported. They had developed cranio-cervico-mandibular discomfort 8 months to 3 years after injury. Patients that only had symptoms of TMJ clicking without pain, previous disc disease, facet joint denervation, or that were involved in litigation were excluded from the study. Examination of the patients included the following: palpation/inspection of all masticatory muscles (temporalis, masseter, buccinator, pterigoideo lateralis, pterigoideo int.) and three neck muscles, auscultation of jaw sounds, functional movements of the mandible, and frequency of headaches. In addition, each patient's MTrPs were mapped out.
Results: 35% of patients registered had TMJ clicking with pain and 61% of them had difficulty with dynamic movement alterations when opening the mouth. MTrPs in the cranio-cervical area were found in 95% of the subjects.
Conclusions: The incidence of clicking with TMJ pain in whiplash patients was found to be quite low. All the subjects had at least one MTrP in the muscles of the neck and the face. The MTrPs can explain the pain in the cranio-cervico-mandibular area. Moreover, the MTrPs in masticatory muscles change in the dynamic opening movement of the mandible.

Key words: Temporomandibular disorders; Whiplash injury; Myofacial trigger points; Temporomandibular joint dysfunction

Address correspondence and reprint requests to Dott.ssa Ida Marini, Via Sant'Angela Merici 60, 25123 Brescia, Italy. Tel: 39-365/34787; Fax: 39-365/375057; E-mail: idmarini@tin.it

Analgesia, Vol. 5, pp. 19-29, 2000
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Peripheral Antihyperalgesic Effects by Adenosine A1 Receptor Agonists and Inhibitors of Adenosine Metabolism in a Rat Neuropathic Pain Model*

Xue Jun Liu and Jana Sawynok

Department of Pharmacology, Dalhousie University, Halifax, Nova Scotia, Canada, B3H 4H7

Background: Spinal or systemic adenosine can alleviate neuropathic pain both in humans and in animal models. Peripheral analgesic effects of adenosine have been demonstrated in rodent inflammatory pain models.
Purpose: To examine the effects of local peripheral administration of adenosine agonists and inhibitors of adenosine metabolism in a rat neuropathic pain model.
Methods: Thermal hyperalgesia and mechanical allodynia were produced by tight ligation of the L5 and L6 spinal nerves in rats, and evaluated by radiant heat or von Frey hairs, respectively. Drugs were administered SC into the dorsal aspect of the rat hind paw.
Results: The adenosine A1 receptor-selective agonists, N6-cyclopentyladenosine (CPA) and R-N6-(2-phenylisopropyl)-adenosine (L-PIA), the adenosine kinase inhibitor, 5´-amino-5´-deoxyadenosine (NH2dAD), and the adenosine deaminase inhibitor, 2´-deoxycoformycin (DCF) reversed thermal hyperalgesia produced by nerve injury. This effect was peripherally mediated, as injection of active doses of these drugs into the nonligated paw produced no effect. The effect was due to an action on cell surface adenosine receptors, as the nonselective adenosine receptor antagonist caffeine completely blocked antihyperalgesic actions. CPA, L-PIA, NH2dAD, and DCF did not produce a peripheral antiallodynic effect, indicating the mechanisms involved in the peripheral maintenance of thermal hyperalgesia and mechanical allodynia are different.
Conclusion: Activating peripheral adenosine receptors, both directly and indirectly, can reverse the thermal hyperalgesia produced by spinal nerve ligation in the rat.

Key words: Neuropathic pain; Adenosine A1 receptor; Adenosine kinase; Adenosine deaminase; Antihyperalgesia

Address correspondence and reprint requests to Xue Jun Liu, Department of Pharmacology, Dalhousie University, Halifax, Nova Scotia, Canada, B3H 4H7. Tel: (902) 494-2596; Fax: (902) 494-1388; E-mail: xliu2@is2.dal.ca

*Parts of this work have been reported previously in abstract form (40,41).

Analgesia, Vol. 5, pp. 31-34, 2000
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Celiac Plexus Neurolysis Complicated by Aortic Intramural Contrast Medium Injection

Marek Suchorzewski,1 Ewa Smigielska,2 Wojciech Bozyk,1 and Andrzej Basinski1

1Outpatient Center for Analgesia, Gdansk, Poland
2Department of Radiology, Nicolas Copernicus County Hospital, Gdansk, Poland

We describe a case of unintended contrast medium injection intramurally to the abdominal aorta during neurolytic celiac plexus block. Neurolytic celiac plexus block was done in spite of the described complication. The patient recovered and we have not encountered any consequences of the above complication either just after the procedure or 5 months later. Lack of resistance during contrast medium injection does not prove the correct position of the needle's tip, but sudden acute pain at the same time can herald aortic intramural position.

Key words: Complications; Celiac plexus block; Regional anesthesia

Address correspondence and reprint requests to Marek Suchorzewski, M.D., ul. Nowe Ogrody 1-6, 80-803 Gdansk, Poland. Tel: +48 58 303 34 34; Fax: +48 58 302 33 67.

Analgesia, Vol. 5, pp. 35-37, 2000
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Glossopharyngeal Neuralgia: A Multimodality Treatment Approach

T. S. Jayalakshmi, G. P. Dureja, and A. P. Bhalla

Department of Anesthesia & Intensive Care, All India Institute of Medical Sciences, New Delhi, India

Eighteen consecutive patients of unilateral glossopharyngeal neuralgia (GN) were studied for 1 year to investigate the efficacy of a multimodality treatment regime. Two combinations of treatment modalities were used. Group A received oral carbamazepine 100-300 mg in divided doses, amitryptiline 10-25 mg, repeated glossopharyngeal nerve blocks with 0.25% 2 ml bupivacaine extraorally, and transcutaneous electrical nerve stimulation (TENS) therapy. Group B received the same drugs as group A and an intraoral approach for glossopharyngeal nerve block and acupuncture instead of TENS therapy. All were reviewed every 4 weeks and followed up for 3 months. Seventy-five percent relief of symptoms was found in all patients of both groups. Multimodality regime was found to be effective and it avoided high dosage of anticonvulsants and adjuvants.

Key words: Glossopharyngeal neuralgia; Multimodality treatment regime; Transcutaneous electrical nerve stimulation

Address correspondence and reprint requests to T. S. Jayalakshmi, Department of Anaesthesia & Intensive Care, All India Institute of Medical Sciences, New Delhi, India. Tel: 91-11-6169399; Fax: 91-11-6862663; E-mail: dr.gpd@yahoo.com