International Journal of Dermatology | 2019
Erythromelalgia: improvement in pain with transcranial magnetic stimulation
Abstract
We report a patient with severe recalcitrant erythromelalgia who had a partial and prolonged response to 3 weeks of transcranial magnetic stimulation (TMS), a novel management modality for this painful syndrome. A 24-year-old patient presented with an 8-year history of continuous severe, unrelenting, recalcitrant erythromelalgia (i.e., swelling, red, hot, and painful acral areas) affecting her feet, hands, and face. She presented with intermittent episodes that were mostly triggered by heat and exercise. Additional testing, including electromyography, thermoregulatory sweat testing, and autonomic reflex screen supported the diagnosis of primary (idiopathic) erythromelalgia with underlying small fiber neuropathy. Other differential diagnoses such as peripheral vascular disease and Raynaud’s phenomenon were ruled out because of noncorrelating clinical course. The erythromelalgia impacted greatly on her daily functioning: Every activity revolved around her attempt to cool her feet, which only provided minimal improvement, and it was painful for her to walk more than 15 yards. The patient had to miss days of school and work because of the unbearable pain, which had been recalcitrant to multiple topical and systemic treatments. She rated her average pain as 7 of 10 in severity when self-rated on a scale from 0 to 10, with 10 being the worst imaginable pain. A 3-week trial was undertaken of TMS applied to the right dorsolateral prefrontal cortex. The patient underwent 15 sessions of 1-Hz TMS—5 treatments per week over 3 weeks—using 1,600 stimulations per session at 110% of motor threshold. At the time of the treatment, she was not taking concomitant other treatments. She tolerated the TMS well and had only minor headaches during treatment. Her baseline pain rating was 7 of 10 and reduced to 6.3 at the end of week 1, to 5.2 at the end of week 2, and to 5 at the end of week 3. During follow-up, her pain ratings were 4 at months 1 and 2 and further reduced to 3 by the 3month follow-up assessment. Thus, she continued to improve in her pain ratings even 3 months after the active treatment. The area of erythema was not reduced, however. Erythromelalgia is the clinical syndrome of red, hot feet and hands, and occasionally face, that can be intensely painful. The pain can be recalcitrant to treatment. TMS is a novel noninvasive treatment that has been shown to have an antidepressant effect in randomized controlled trials for depression and is also being studied for a potential role in the treatment of chronic pain such as fibromyalgia pain. During TMS, a magnetic field is induced by the generation of an electrical current in a coil, which is placed against the scalp and applied specifically to the target area of the dorsolateral prefrontal cortex. The magnetic field promotes stimulation of the brain areas that modulate mood control and depression and suppress pain. The modality has been found to successfully decrease depression symptoms and improve mood. Our patient has been reported previously in a separate publication by Sampson et al., describing the use of TMS for refractory neuropathic pain (subject 8). We redescribe this patient to emphasize the response of her erythromelalgia to TMS treatment because it raises the possibility that this noninvasive brain