arachnoiditis

Arachnoiditis is an inflammatory condition of the arachnoid mater or 'arachnoid', one of the membranes known as meninges that surround and protect the central nervous system. The outermost layer of the meninges is the dura mater (Latin for hard) and adheres to inner surface of the skull and vertebrae. The arachnoid is under or "deep" to the dura and is a thin membrane that adheres directly to the surface of the brain and spinal cord.

== Signs and symptoms == Arachnoid inflammation can lead to many painful and debilitating symptoms which can vary greatly in each case, and not all people experience all symptoms. Chronic pain is common, including neuralgia, while numbness and tingling of the extremities can occur with spinal cord involvement, and bowel, bladder, and sexual functioning can be affected if the lower part of the spinal cord is involved. While arachnoiditis has no consistent pattern of symptoms, it frequently affects the nerves that supply the legs and lower back. Many patients experience difficulty sitting for long (or even short) periods of time due to discomfort or pain. == Etiology == Arachnoiditis has been described as having many different etiologies. As an infectious source, tuberculosis, syphilis, candida, mycosis, and HIV. As a mechanical source, spinal and cranial surgery, trauma, and disc herniation. Prior disease including ankylosing spondylitis, autoimmune vasculitis, and Guillain–Barré syndrome have been known to cause arachnoiditis. Chemical causes include morphine, myelograms with oil-based radiographic contrast agents, phenolic solutions, chlorhexidine, epidural injection of steroids and antibiotics, blood in subarachnoid hemorrhage, epidural blood patches and anesthetics.