Toes during an EM flareup In general,<unk>  seems to consist of neuropathological and microvascular alterations. How this occurs in secondary<unk>  is poorly understood and may be specific to the underlying primary condition. Primary conditions that have been shown to elicit<unk>  are listed in diagnosis, below. Primary<unk>  is a better understood autosomal dominant disorder. The neuropathological symptoms of primary<unk>  arise from hyperexcitability of C-fibers in the dorsal root ganglion. Specifically, nociceptors (neurons responsible for the sensation and conduction of painful stimuli) appear to be the primarily affected neurons in these fibers. This hyperexcitability results in the severe burning pain experienced by patients. While the neuropathological symptoms are a result of hyperexcitability, microvascular alterations in<unk>  are due to hypoexcitability. The sympathetic nervous system controls cutaneous vascular tone and altered response of this system to stimuli such as heat likely results in the observed microvascular symptoms. In both cases, these changes in excitability are typically due to mutation of the sodium channel NaV1.7. These differences in excitability alterations between the sympathetic nervous system and nociceptors is due to different expression of sodium channels other than NaV1.7 in them. What causes epidemic<unk>  in southern China remains unknown although several<unk> -associated poxviruses were isolated from throat swabs of several patients at different counties and from two different seasons. Side effect of medication Several medications, including verapamil and nifedipine, as well as ergot derivatives such as bromocriptine and pergolide, have been associated with medication-induced<unk> . Mushroom poisoning The consumption of two species of related fungi, Clitocybe acromelalga from Japan, and Clitocybe amoenolens from France, has led to several cases of mushroom-induced<unk>  which lasted from 8 days to 5 months. Possible infectious cause An epidemic form of this syndrome occurs in secondary school students in rural areas of China. A large epidemic<unk>  was occurred in Hubei province of China in 1987 and the disease was characterized by burning pain in the toes and soles of the feet, accompanied by foot redness, congestion, and edema; a few patients had fever, palpitations, headache, and joint pain. 60.6% of patients had a common cold before the onset of<unk>  and 91.2% had pharyngitis. Subsequently, a virus -<unk> -related poxvirus (ERPV) - was repeatedly isolated from throat swabs of six separate patients from two different counties and Wuhan city in Hubei province. The genome of this virus has been sequenced and it appears that this virus is related to a strain of mousepox. Serological characterization can easily distinguish human ERPV from ectromelia virus and vaccinia virus by cross-neutralization and plaque reduction assays Since this virus has not yet been isolated from other outbreaks in other parts of southern China to date this putative association needs to be further investigated. The finding of the specific antibody conversion to ATIs of ERPV in patients' paired sera strengthens the evidence for a possible aetiological role of human ERPV in epidemic<unk> .
Erythromelalgia
Coxalgia
Pathergy
Chromesthesia
Pressure urticaria
Heat urticaria
Onycholysis
Allodynia