Condition: Arachnoiditis

Arachnoiditis is a general term for several progressive regional disorders all of which result in the inflammation of parts of the middle membrane surrounding the spinal cord and brain (arachnoid membrane) and the space defined by this membrane (subarachnoid space). Either the spinal cord or the brain may be involved; in some cases, both are affected. This disorder can also be associated with meningitis. The condition may be caused by foreign agents such as anesthesia drugs or testing dyes injected into the spine or arachnoid membrane.

Since the subarachnoid space is continuous, it would be expected that a noxious agent introduced in one place would distribute itself throughout the space. However, such is not the case. The lower spinal roots and/or the spinal cord may be affected, while regions close by remain free of inflammation; hence, the term “spinal arachnoiditis”. Similarly, the optic nerve and optic chiasm (crossing of nerve fibers) may be affected, giving rise to the term “opticochiasmatic arachnoiditis”.