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Location of the spine, with close-up view of the spinal cord surrounded by the arachnoid membrane.

Arachnoiditis (say "uh-rak-noy-DY-tus") is inflammation of a membrane (called the arachnoid) that surrounds the spinal cord. The inflammation may be ongoing (chronic). This can cause scar tissue near the spinal cord. It can cause nerve roots to stick together and not work as they should. Symptoms may include numbness, tingling, or pain in the back and legs. The condition is rare.

It can be caused by:

  • Trauma. This includes spinal surgery and injections into the spinal cord. These may include spinal or epidural injections.
  • Chemicals. Examples are chemotherapy and contrast material.
  • Infections.

An MRI scan of the spine can help diagnose arachnoiditis.

Treatment focuses on managing symptoms.


Symptoms may include:

  • Low back numbness, tingling, burning, or pain.
  • Headaches.
  • Muscle spasms and cramps in the back and legs.
  • Constipation.
  • Problems urinating.
  • Problems with sex.
  • In severe cases, muscle weakness or paralysis.


Treatment focuses on managing symptoms and improving your function. There is no way to reverse the scarring. Symptoms may be managed with medicine, physical therapy, and counseling. Sometimes spinal cord stimulation is used for pain. Surgery is rarely part of treatment. For some people, it may be an option.


Current as of: December 20, 2023

Author: Healthwise Staff
Clinical Review Board
All Healthwise education is reviewed by a team that includes physicians, nurses, advanced practitioners, registered dieticians, and other healthcare professionals.

The Health Encyclopedia contains general health information. Not all treatments or services described are covered benefits for Kaiser Permanente members or offered as services by Kaiser Permanente. For a list of covered benefits, please refer to your Evidence of Coverage or Summary Plan Description. For recommended treatments, please consult with your health care provider.