Letters to the Editor

Use of Capsaicin Cream for Abdominal Wall Scar Pain

TO THE EDITOR: Drs. Suleiman and Johnston make a valuable contribution to the literature with their article "The Abdominal Wall: An Overlooked Source of Pain."¹ Neuromas forming in postsurgical scars are a common source of abdominal wall pain. The patient does not always correlate this pain with the scar, because the pain may not localize to the scar and because of a lack of temporal correlation with surgery (neuromas in scars may not express themselves for days or weeks after surgery). Scar sensitivity can be tested by applying a digital shearing force to the scar or by irritating it with an open paper clip.

Capsaicin cream (0.075 percent), available over the counter, offers an alternative for treating patients who fear syringes and trigger point injections. Capsaicin cream is readily absorbed and selectively binds to the vanilloid receptor subtype 1 (VR1). Capsaicin-sensitive nerves are nociceptors that give rise to small diameter, unmyelinated C fibers (rarely, Ad fibers). The signal propagates to dorsal horn ganglia, evoking release of substance P, somatostatin, and calcitonin-gene related peptide (CGRP).² With repeated exposure to painful stimuli, VR1 receptors become desensitized. This phenomenon underlies the seemingly paradoxical use of capsaicin as an analgesic. Capsaicin cream has been used to treat osteoarthritis, rheumatoid arthritis, diabetic neuropathy, interstitial cystitis, and many other forms of hyperalgesia and allodynia.³

The off-label use of capsaicin cream for treating painful scars is heretofore unreported. Based on our experience (nearly 20 cases since 1994), treating scars with capsaicin may provide permanent pain relief. These results contradict the effects of capsaicin in arthritis, where pain relief requires regular use of capsaicin. Capsaicin cream also alleviates other syndromes described by Drs. Suleiman and Johnston,¹ such as rectus nerve entrapment and postherpetic neuralgia.

Patients must be carefully instructed on the topical application of capsaicin. Apply a very small amount to the scar ("the size of a rice grain"), and massage cream into tissues until little or no cream remains on the surface. Gloves should be worn during application, or hands should be washed carefully and immediately after application. Introducing medication into the eyes or broken skin must be avoided. Advise patients that a burning sensation may occur for up to an hour after application. The transient sensation usually disappears after a few days of regular application. This burning sensation is made worse by heat, humidity, sweating, and bathing in warm water. As the pain diminishes after a few days, the patient can apply more cream ("the size of a pea"), and massage can be applied more vigorously, similar to an osteopathic "myofascial release" procedure.⁴

Compliance can be an issue with capsaicin, because the cream needs to be applied three times a day, at least initially. Pain relief usually begins within two weeks; thereafter the dosage interval can be reduced to twice a day. After two or three months, the patient should try discontinuing the medication. In most cases, the capsaicin has broken the pain-muscle spasm-pain cycle, and the abdominal wall pain does not resume.

JOHN M. MCPARTLAND, D.O., M.S.

Faculty of Health & Environmental Sciences, UNITEC
Private Bag 92025 Mt. Albert
Auckland, New Zealand

REFERENCES

1. Suleiman S, Johnston DE. The abdominal wall: an overlooked source of pain. Am Fam Physician 2001;64:431-8.
2. Szallasi A, DiMarzo V. New perspectives on enigmatic vanilloid receptors. Trends Neurosci 2000;23:491-7.
3. Szallasi A, Blumberg PM. Vanilloid (Capsaicin) receptors and mechanisms. Pharmacol Rev 1999;51: 159-212.
4. Kuchera ML, McPartland JM. Myofascial trigger points: an introduction. In: Ward RC, Jerome JA. Foundations for osteopathic medicine, Baltimore: Williams & Wilkins, 1997:915-8.

IN REPLY: We thank Dr. McPartland for sharing his experiences with using capsaicin cream for the treatment of pain in abdominal wall scars. This use of capsaicin has not been reported previously in the medical literature. However, it makes perfect sense to expect capsaicin to be helpful for this indication. Capsaicin may also be useful in other types of abdominal wall pain in which local irritation of nerve endings may be responsible for the pain. Use of capsaicin is a simple and inexpensive intervention, and there seems little to lose in trying it if other measures fail.

DAVID E. JOHNSTON, M.D.
The Everett Clinic
Everett, WA 98201

When To Begin Treatment in Patients with Elevated TSH Levels?

TO THE EDITOR: I read with interest your article, "Treatment of Hypothyroidism."¹ I found the article informative, but I do have one disagreement. Dr. Hueston's discussion of "subclinical hypothyroidism" suggests that patients with thyroid-stimulating hormone (TSH) levels between 6 and 10 may not progress to overt hypothyroidism and do not necessarily need to be treated. The author recommends an "individualized" approach and gives several parameters to aid in decision-making. One important factor is missing from this discussion: the lipid panel. Patients with "mild thyroid failure" (the new term for subclinical hypothyroidism, since many of these patients have a real clinical problem) usually have dyslipidemia, which may be improved with thyroid hormone replacement. Indeed, mild hypothyroidism is a risk factor for atherosclerosis.

I had the benefit of serving on two expert panels on this illness (funded by the makers of Synthroid). However, lead investigators have convinced me that all patients with an elevated TSH level should be treated unless a contraindication is present. Improvement in several health parameters are often observed in patients who receive treatment, including improved well-being (patients who did not realize they were tired until they felt better), improved lipid panel, and modest weight loss. These patients are often overweight and lose weight much easier when their TSH is normal.

In summary, I consider patients with an elevated TSH level as having hypothyroidism, and patients with normal free thyroxine (T₄) level as having mild thyroid failure, which is a real condition. Why should physicians wait to treat these patients until they, if ever, progress to worse disease? Early treatment is beneficial, especially considering the lipid profile that results from an elevated TSH level.

JOSEPH E. SCHERGER, M.D., M.P.H.
Florida State University
Tallahassee, FL 32306-4300

REFERENCE

1. Hueston WJ. Treatment of hypothyroidism. Am Fam Physician 2001;64:1717-24.

IN REPLY: I appreciate Dr. Scherger's comments regarding my article¹ on hypothyroidism in AFP. The issue of small elevations of thyroid-stimulating hormone (TSH) with normal thyroxine (T₄) levels is still controversial. While it is recognized that hypothyroidism is clearly associated with elevations in cholesterol (and hypercholesterolemia),² there are no population-based data showing that persons with subclinical hypothyroidism are more likely to have higher cholesterol levels. Treatment studies of thyroid in this population have had only a small number of participants,^3-5 included patients with elevated TSH levels after thyroid ablation therapy,⁴ and have not compared the effects of thyroid replacement therapy with other treatment modalities for hyperlipidemia, such as statins. So, I do not believe it is clear that the best course of treatment for these patients is thyroid replacement.

However, given these limitations, a patient at high risk for cardiac disease (e.g., a woman who has had a previous cardiovascular event, has diabetes, is a smoker, or has a strong family history of atherosclerosis) treatment for subclinical hypothyroidism with low doses of thyroxine probably carries more benefits than risks. For elderly, white women (which is the typical demographics of this population) with low risk of cardiac disease, the risk of osteopenia from excessive thyroid use may outweigh any benefits of thyroid replacement. Therefore, I think we must individualize care for our patients with this condition rather than advocating blanket therapy with thyroxine.

WILLIAM J. HUESTON, M.D.
Medical University of South Carolina
Charleston, South Carolina

REFERENCES

1. Hueston WJ. Treatment of hypothyroidism. Am Fam Physician 2001;64:1717-24.
2. Morris MS, Bostom AG, Jacques PF, Selhub J, Rosenberg IH. Hyperhomocysteinemia and hypercholesterolemia associated with hypothyroidism in the third US National Health and Nutrition Examination Study. Atherosclerosis 2001;155:195-200.
3. Nystrom E, Caidahl K, Fager G, Wikkelso C, Lundberg PA, Lindstedt G. A double-blind cross-over 12-month study of L-thyroxine treatment of women with 'subclinical' hypothyroidism. Clin Endocrinol (Oxf) 1988;29:63-75.
4. Cooper DS, Halpern R, Wood LC, Levin AA, Ridgway EC. L-thyroxine therapy in subclinical hypothyroidism: a double-blind, placebo-controlled trial. Ann Intern Med 1984:101:18-24.
5. Jaeschke R, Guyatt G, Gerstein H, Patterson C, Molloyt W, Cook D, et al. Does treatment with L-thyroxine influence health status in middle-aged and older adults with subclinical hypothyroidism? J Gen Intern Med 1996;11:744-9.

Correction

The article "Spironolactone in Left-Sided Heart Failure: How Does It Fit In?" (October 15, 2001, page 1393) contained an error in Table 4 on page 1397. In the column titled "Comments on specific drug," the entry "Increases concentration of digoxin" pertains to telmisartan (Micardis) rather than to candesartan (Atacand). The corrected version of the table is available on the AFP Web site at www.aafp.org/afp/20011015/1393.html.

Send letters to Jay Siwek, M.D., Editor, American Family Physician, 11400 Tomahawk Creek Pkwy., Leawood, KS 66211-2672; fax: 913-906-6080; e-mail: afplet@ aafp.org. Please include your complete address, telephone number, and fax number. Letters should be submitted on disk, double-spaced, fewer than 500 words, and limited to one table or figure and six references. Please submit a word count. Letters submitted for publication in AFP must not be submitted to any other publication. Possible conflicts of interest must be disclosed at time of submission. Submission of a letter will be construed as granting the AAFP permission to publish the letter in any of its publications in any form. The editors may edit letters to meet style and space requirements.