Arachnoiditis

What is arachnoiditis?

Arachnoiditis is a rare condition that happens when there’s inflammation of the arachnoid. The arachnoid is one of the membranes that surround and protect the spinal cord and its nerves. 

Inflammation is a normal response of the body’s immune system and can include swelling, redness, or pain in a part of the body as a response to injury or infection. Inflammation of the arachnoid may be the immune system’s response to: 

• Infection from bacteria or viruses
• Direct injury to the spine
• Complications from spinal surgery or other invasive spinal procedures (procedures that involve breaking the skin)

Inflammation can sometimes lead to scar tissue or adhesions (bands of scar tissue that form on surfaces inside the body), which cause the spinal nerves to “stick” together.

When arachnoiditis affects a person’s lower back, it can cause the following in the lower back or legs: 

• Chronic and persistent pain
• Numbness
• Tingling
• A characteristic stinging and burning pain

These symptoms happen when the inflammation interferes with how the person’s spinal nerves work. Some people with arachnoiditis of the lower back have muscle cramps, twitches, or spasms that affect their daily lives and ability to function. It may also affect bladder, bowel, and sexual function. In serious cases, arachnoiditis can cause paralysis in the legs.

While arachnoiditis of the lower back is the most common, the condition can also affect the cervical (neck) and thoracic (chest) regions of the spine. Arachnoiditis in the cervical or thoracic spine causes a condition known as myelopathy, which may be associated with cysts forming in the spinal cord (syringomyelia). Cervical arachnoiditis may cause weakness, loss of sensation, and pain in the arms and legs. Thoracic arachnoiditis may cause weakness, loss of sensation, and pain in the chest, abdomen, pelvis, and legs.

How is arachnoiditis diagnosed and treated?

Diagnosing arachnoiditis

Arachnoiditis is rare and can be challenging to diagnose. A doctor will diagnose the condition after performing a physical exam and reviewing the person’s medical history and symptoms. The doctor may also order imaging tests—such as MRI (magnetic resonance imaging) or CT (computed tomography). 

Sometimes, more tests—such as lumbar puncture to collect and test cerebrospinal fluid (CSF)—can help doctors identify an infection. In some cases, doctors may use myelography, which involves the injection of a contrast dye into the spinal canal to enhance imaging of the spine by CT or X-ray. Myelography can help detect arachnoiditis and its scarring effects. And an electromyogram (EMG) can help determine the severity of the nerve damage.

Find out more about neurological diagnostic tests and procedures.

Treating arachnoiditis

Arachnoiditis is a complex condition to treat. Treatment focuses on relieving chronic pain and improving symptoms that affect the person's daily functioning. Learn more about pain and pain research. 

Doctors often recommend a combination of pain management, physical therapy, exercise, and counseling (talk therapy). Surgery is not typically recommended or effective for arachnoiditis in the lower back—or when the person’s arachnoiditis extends over three spinal segments into other spinal regions. But in cases of focal arachnoiditis, where the condition is found in only one particular area of the spine, surgery to remove scar tissue may help.

What are the latest updates on arachnoiditis?

NINDS, a part of the National Institutes of Health (NIH), is the leading federal funder of research on the brain and nervous system. NINDS conducts and supports studies to better understand conditions such as arachnoiditis primarily through research on pain. NINDS is vigorously seeking new treatments for pain and nerve damage with the end goal of treating and even reversing conditions like arachnoiditis.

Information about NIH-supported research on pain and related conditions like arachnoiditis is available through the NIH RePORTER, a searchable database of current and previously funded studies. RePORTER also includes links to publications and resources from these projects.

For research articles and summaries on pain and arachnoiditis, search PubMed, which contains citations from medical journals and other sites.

How can I or my loved one improve care for people with arachnoiditis?

Clinical trials increase our understanding of arachnoiditis and related disorders with the goal of improving how doctors treat them. Consider participating in a clinical trial so clinicians and scientists can learn more about arachnoiditis. Clinical research with human participants helps researchers learn more about a disorder and perhaps find better and safer ways to detect, treat, or prevent disease.

All types of participants are needed—those who are healthy or may have an illness or disease—of all different ages, sexes, races, and ethnicities. This helps make sure that study results apply to as many people as possible, and that treatments will be safe and effective for everyone who will use them.

For information about participating in clinical research, visit NIH Clinical Research Trials and You. Learn about clinical trials currently looking for people with arachnoiditis at Clinicaltrials.gov, a searchable database of current and past clinical studies and research results.

Learn about related topics

• Meningitis
• Encephalitis
• Pain