Arachnoiditis describes a pain disorder caused by the inflammation of the arachnoid, one of the membranes that surround and protect the nerves of the spinal cord.

The arachnoid can become inflamed because of:

• An irritation from chemicals
• Infection from bacteria or viruses
• A direct injury to the spine
• Chronic compression of spinal nerves
• Complications from spinal surgery or other invasive spinal procedures

Inflammation can sometimes lead to the formation of scar tissue and adhesions, which cause the spinal nerves to “stick” together. If arachnoiditis begins to interfere with the function of one or more of these nerves, it can cause a number of symptoms, including:

• Numbness
• Tingling
• Characteristic stinging and burning pain in the lower back or legs
• Debilitating muscle cramps, twitches, or spasms
• Bladder, bowel, and sexual function problems
• Paralysis of the lower limbs (in severe cases)

Arachnoiditis causes chronic pain and neurological deficits and does not improve significantly with treatment. Aging and pre-existing spinal disorders can make an accurate prognosis problematic. The outlook for someone with arachnoiditis is complicated by the fact that the disorder has no predictable pattern or severity of symptoms.

Arachnoiditis remains a difficult condition to treat, and long-term outcomes are unpredictable. Most treatments for arachnoiditis are focused on pain relief and the improvement of symptoms that impair daily function. A regimen of pain management, physiotheraphy, exercise, and psychotheraphy is often recommended. Surgical intervention is controversial since the outcomes are generally poor and provide only short-term relief.