To the Editor:
In previous publications (1-3), we described the use of the clonidine patch in the diagnosis and treatment of reflex sympathetic dystrophy (RSD) and other syndromes involving sympathetically maintained pain. Since those publications, we have had numerous inquiries regarding the technique to use in treating patients with RSD.
Accordingly, we are providing the following information:
1. The choice for application site should be a region of allodynia (hypersensitive skin). Application near a stiff joint is also desirable.
2. When the patch is changed every 3 days, the patient should stroke the skin to determine if desensitization of the skin has taken place. If desensitization does not take place at the lowest dose (0.1 mg) after four patches (12 days), increase the dose to 0.2 mg. If desensitization does not occur after four more patches, increase the dose to 0.3 mg. If desensitization does not occur after four patches on 0.3 mg, we consider clonidine a failure and conclude that the patient probably has sympathetically independent pain. The dose should not be increased to the next higher level if the patient experiences serious side effects (see below).
3. For 2 years, we have been treating patients with the clonidine patch and have noted few side effects. However, patients should be cautioned that clonidine may cause:
-Dry mouth, which is usually managed by drinking water or chewing gum.
-Daytime drowsiness, which usually goes away after 3 days. However, the patient should be cautioned against driving and working around dangerous machinery during that time.
-A decrease in blood pressure caused by orthostatic hypotension (dizziness caused by standing). It is helpful to monitor blood pressure at home once a day or when symptoms are suspected.
-Skin irritation. If this occurs, we recommend moving the patch slightly from that site or taking a drug “holiday” for 2 – 3 days before reapplying the patch. Rarely have we had to discontinue the patch altogether because of an allergy to clonidine.
4. Our clinical observation and one shared by others (4) is that when RSD symptoms spread, the new site may experience sympathetically maintained pain even though the primary site may experience sympathetically independent pain. Therefore, the new RSD site tends to be responsive to the beneficial effects of exercise as well as sympathetic block (i.e., the clonidine patch or sympathetic nerve blocks).
5. To be most effective, the treatment of RSD usually requires the application of multiple modalities. Therefore, some patients receive antidepressants, sympathetic blocks, and other modalities as their medical conditions dictate. More than one patch, as tolerated by the patient, may be applied to cover a greater region of the body. However, as noted in previous publications, the beneficial effects of clonidine may be expected to spread beyond the borders of each patch. Some of our patients have been managing their RSD symptoms for more than a year with the clonidine patch and without the need for further nerve blocks. Some patients have undergone partial remission while on the clonidine patch. Therefore, it may be helpful to discontinue the patch every 6 months on a trial basis to determine if remission has occurred.
References
1. Kirkpatrick AF, Derasari M.Glodek JA. Piazza PA Postherpetic neuralgia: A possible application for topical clonidine. (Letter) Anesthesiology 1992: 76: 1065-1066.
2. Kirkpatick AF. Treatment of reflex sympathetic dystrophy by local application of the clonidine patch. (Abstract) Reg Anesth 1992: 17: 64.
3. Draseri M. Kirkpatrick AF, Glodek JA, Piazza PA. Treatment of myfacial trigger points, postherpetic neuralgia and reflex sympathetic dystrophy with topical clonidine. (Abstract) Reg Anesth 1992 17: 144.
4. Robert Schwartzman, M.D. Personal communication.
ANTHONY F. KIRKPATRICK, M.D., Ph.D.
MANJUL DERASARI, M.D.
Department of Anesthesiology
Pain Consult Center
University of South Florida College of Medicine
