The authors of this study set out to assess the frequency and type of vascular changes and neurologic abnormalities in patients with erythromelalgia. Erythromelalgia is a syndrome characteristic for heat, tingling, burning, erythema and pain of the affected limb.
This is a prospective study of patients with no spontaneous symptoms at the time of their visit and with provoked symptoms. There were sixty-seven patients presenting with erythromelalgia at Mayo Clinic, Rochester, Minn, from 1999 through 2001. Vascular studies were perfomed on the test patients; vascular function with and without symptoms was assessed by measurement of local skin temperature, laser Doppler flow, and transcutaneous oximetry. Neurologic assessment included electromyography, nerve conduction studies, and autonomic reflex screening. The authors used the quantitative sudomotor axon reflex test (QSART), adrenergic function testing, heart rate response to deep breathing, and the Valsalva ratio. QSART involved the application of acetylcholine to the suspect area and measuring the response after application.
The authors' results are as follows: autonomic reflex screening was performed on 57 (85%) of the 67 patients. 46 (81%) had abnormal quantitative sudomotor axon reflex test results, which was interpreted as a decrease or no sweat response; 14 (25%) had abnormal adrenergic function; and 15 (26%) had abnormal cardiovagal function. Electromyography and nerve conduction studies were performed in 24 (36%) of the 67 patients, 14 (58%) had abnormal electromyographic results and 10 (42%) had abnormal nerve conduction study results. Vascular function studies, with and without symptoms present, were performed in 13 of the 67 patients. During symptoms, the mean temperature of the toe skin increased by 7.8 degrees C, and blood flow increased 10.2-fold with a decrease in oxygen saturation.
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A study that answers the questions that were sought to be answered; is erythromelalgia: vasculopathy, neuropathy, or both? As per the analysis by the authors, it is both a neuropathy and a vasculopathy. Why? Both QSART and O2 saturation were changed by the onset of erythomelalgia. A detractor to the study is the fact that only 13 patients could be stimulated for erythromelalgia, and no standardized activity stimulation could be reproduced in all patients. Hence, each patient had his/her own activity to evoke erythromelalgia. Perhaps as we better understand this disorder we will be able to understand how to evoke it uniformly across all test subjects. This study is a step in that direction, but the authors failed to offer suggestions for further studies.
Arch Dermatol 2003 Oct; 139(10):1337-43.
COPYRIGHT 2004 Journal of Drugs in Dermatology
COPYRIGHT 2004 Gale Group
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