This last study has an estimation that is at least ten times higher than the prevalence previously reported. This study recruited individuals based on self-identification of symptoms (after self-identification, patients were invited for an assessment of an EM diagnosis), instead of participants that are identified through secondary and tertiary referrals as in the other studies. Prevalence in China
Epidemic EM appears quite common in female middle school students of southern China, most likely due to a sharp decline in temperature following by a rapid increase of temperature. It has been postulated that epidemic erythromelalgia might be related to a poxvirus (ERPV) infection. 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. For temperature-related theory, the acral (foot and hand) small superficial arteries intensely constrict and dilate during the sharp decline of temperature, whereas a sharp increase of temperature, the intense expansion of capillaries irritate the nerve endings around, and thus lead to syndromes including (first and second degree) burning pain, increased temperature, erythema and swelling. History
The first reported case was in 1878 by Silas Weir Mitchell who suggested the term erythromelalgia to describe a syndrome of red congestion and burning pain in the hands and feet. He distinguished it from the painful red limbs seen in some patients with gout or rheumatoid arthritis.
Thoracic spinal stenosis, at the level of the mid-back, is much less common.In lumbar stenosis, the spinal nerve roots in the lower back are compressed which can lead to symptoms of sciatica (tingling, weakness, or numbness that radiates from the low back and into the buttocks and legs).Cervical spinal stenosis can be far more dangerous by compressing the spinal cord. Cervical canal stenosis may lead to myelopathy, a serious condition causing symptoms including major body weakness and paralysis. Such severe spinal stenosis symptoms are virtually absent in  lumbar stenosis, however, as the spinal cord terminates at the top end of the adult lumbar spine, with only nerve roots (cauda equina) continuing further down. Cervical spinal stenosis is a condition involving narrowing of the spinal canal at the level of the neck. It is frequently due to chronic degeneration, but may also be congenital or traumatic. Treatment frequently is surgical. Signs and symptoms
Common
Standing discomfort (94%)
Discomfort/pain, in shoulder, arm, hand (78%)
Bilateral symptoms (68%)
Numbness at or below the level of involvement  (63%)
Weakness at or below the level of involvement  (43%)
Pain or weakness in buttock / thigh only (8%)
Pain or weakness below the knee (3%)

Neurological disorders
Cervical (spondylotic) myelopathy, a syndrome caused by compression of the cervical spinal cord which is associated with "numb and clumsy hands", imbalance,   loss of bladder and bowel control, and weakness that can progress to paralysis. Pinched nerve, causing numbness.