Arachnoiditis (cont.)

Inflammation of the arachnoid can lead to the formation of scar tissue and can cause the spinal nerves to stick together and malfunction. The arachnoid can become inflamed because of an irritation from one of the following sources:

• Direct injury to the spine
• Chemicals: Dye used in myelograms (diagnostic tests in which a dye called radiographic contrast media is injected into the area surrounding the spinal cord and nerves) have been blamed for some cases of arachnoiditis. The radiographic contrast media responsible for this is no longer used, however. Also, there is concern that the preservatives found in epidural steroid injections may cause arachnoiditis.
• Infection from bacteria or viruses: Infections such as viral and fungal meningitis or tuberculosis can affect the spine.
• Chronic compression of spinal nerves: Causes for this compression include chronic degenerative disc disease or advanced spinal stenosis (narrowing of spinal column).
• Complications from spinal surgery or other invasive spinal procedures: Similar causes include multiple lumbar (lower back) punctures.

Diagnosing arachnoiditis can be difficult, but tests such as the CAT scan (computerized axial tomography) or MRI (magnetic resonance imaging) have helped with diagnosis. A test called an electromyogram (EMG) can assess the severity of the ongoing damage to affected nerve roots by using electrical impulses to check nerve function.

Note: Myelograms with the radiographic contrast currently in use, combined with CAT scanning, are not considered to be responsible for causing arachnoiditis or causing it to worsen.

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