Exercise-induced asthma is a condition of respiratory difficulty (bronchoconstriction) that is related to histamine release,is triggered by aerobic exercise, and lasts several minutes. Causes include medical conditions, environmental factors, and medications. The image below illustrates the pathogenesis of asthma.
A myelogram is an invasive diagnostic test that uses x-rays to examine the spinal canal. A special dye is injected into the spinal canal through a hollow needle. An x-ray fluoroscope then records the images formed by the dye. Myelograms can show conditions affecting the spinal cord and nerves within the spinal canal.
This has led some doctors to suggest that thoracic disc herniations not causing symptoms are normal. Before MRI, doctors relied mainly on myelography to diagnose thoracic disc herniations. By itself, myelography only helps diagnose this condition in about half the cases. Myelography is a kind of X-ray test.