vibratory urticaria
This very rare form of angioedema develops in reply to contact with vibration. In vibratory angioedema, symptoms develop within two to five minutes after contact with vibration and dissolve after about an hour. Patients with this disorder do not suffer from dermographism or pressure urticaria. Vibratory angioedema is diagnosed by holding a vibrating device such as a laboratory vortex machine against the forearm for four minutes. Speedy swelling of the whole forearm extending into the upper arm is also noted later. The principal treatment is avoidance of vibratory stimulants. Antihistamines have also been proven helpful.