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 erythromelalgia in southern China remains unknown although several erythromelalgia-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 erythromelalgia. 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 erythromelalgia 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 erythromelalgia 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 erythromelalgia and 91.2% had pharyngitis. Subsequently, a virus - erythromelalgia-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.
The initial procedures of choice are goniotomy or trabeculotomy if the cornea is clear, and trabeculectomy ab externo if the cornea is hazy. The success rates are similar for both procedures in patients with clear corneas. Trabeculectomy and shunt procedures should be reserved for those cases in which goniotomy or trabeculotomy has failed. Cyclophotocoagulation is necessary in some intractable cases but should be avoided whenever possible because of its potential adverse
effects on the lens and the retina. Epidemiology
In the United States, the incidence of primary congenital glaucoma is about one in 10,000 live births. Worldwide, the incidence ranges from a low of 1:22,000 in Northern Ireland to a high of 1:2,500 in Saudi Arabia and 1:1,250 in Romania. In about two-thirds of cases, it is bilateral. The distribution between males and females varies with geography. In North America and Europe, it is more common in boys, whereas in Japan it is more common in girls. Congenital glaucomaIncidence: one in every 10000-15000 live births. Bilateral in up to 80% of cases. Most cases are sporadic (90%). However, in the remaining 10% there appears to be a strong familial component. See also
Axenfeld syndrome
Peters-plus syndrome
Weill–Marchesani syndrome

References
Further reading
Lively GD, Alward, WL, Fingert JH. Juvenile open-angle glaucoma: 22-year-old Caucasian female referred in 1990 for evaluation of elevated intraocular pressure (IOP). EyeRounds.org. September 17, 2008. External links
231300
137750; MYOC
137750; CYP1B1
Juvenile Glaucoma at eMedicine on eMedicine
Glaucoma for Children on AAPOS. Congenital Primary Glaucoma on patient.info
GeneReview/NCBI/NIH/UW entry on Primary Congenital Glaucoma
Glaucoma entry on PGCFA