Electro-Diagnostic Tests


A magnetic resonance imaging scan, or MRI, is used to see small changes in the body that cannot be seen with a normal x-ray. Magnets and radio waves are used to make a computer picture of the parts of the body the doctor wants to study.

MRI scans of muscles may be helpful in selection of a site for muscle biopsy in patients with suspected inflammatory myopathy when a first muscle biopsy turns out to be negative.

If you have myositis, the doctor may study the affected muscles using an MRI to get a better picture of any muscle damage. Read more...


An electromyogram, or EMG, is a test that measures the activity of the muscles. The test gathers information about the muscular and nervous systems.

An EMG is a way of finding causes of muscle weakness or paralysis; muscle problems such as muscle twitching; numbness, tingling or pain; and nerve damage or injury. Read more...

Orbital Myositis

In orbital myositis, diagnosis rules out thyroid eye disease which usually is characterized by a more acute onset, more severe pain, and a rapid response to systemic corticosteroid therapy. Diagnosis is done by A- and B-mode ultrasound. The B-scan commonly demonstrates masses or swelling in the posterior portion of Tenon's space. If fluid also surrounds the optic nerve sheath, there is a rather characteristic "T sign."

An A-scan provides more or less accurate determinations of muscle diameters but probably cannot aid in a definitive diagnosis. In modern medicine, the preference is upfront CT scan and MRI orbit13. Histopathological examination usually shows inflammation. In the absence another disease, these atypical presentations are considered to be idiopathic orbital inflammation.




Updated February 2014




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