Arachnoiditis: An Overview

Inside the symptoms, diagnosis, and treatment of this rare spinal disorder that often presents with chronic back pain and leg pain.

Some spinal and lumbar pain can be caused by an often difficult to diagnose condition known as arachnoiditis, clinically known as adhesive arachnoiditis (AA). The condition is an inflammation of one of three membranes that surround the brain and spinal cord. That inflammation can eventually generate scar tissue, which may cause those nerves to stick together and cause irritations and further inflammation that translates into pain.2

Due to its low prevalence rate – an estimated 11,000 new cases of arachnoiditis are diagnosed each year in the United States, according to the National Organization for Rare Disorders,  this disorder isn’t always recognized and can be misdiagnosed as other forms of chronic pain, such as Ehlers-Danlos Syndrome (EDS).

Arachnoiditis affects more women than men as one of the primary causes has been linked to complications from obstetric epidurals given during child labor. Specifically, if an epidural needle accidentally punctures the spinal membrane, it can trigger inflammation and scar tissue development around the spinal cord nerves, but these cases are extremely rare (less than 1 in 3,000, according to data published in the journal of the American Society of Anesthesiologists). In fact, anyone who undergoes spinal surgery or spinal procedures, including epidural steroid injections, can be at risk. It’s believed that an increase in surgeries and the use of spinal anesthesia has caused more instances of the condition.

Source: 123RF

Primary Symptoms

The most common symptom of arachnoiditis is continual pain in the lower back or legs, but in some cases, pain can be felt in other parts of the body. Pain can be accompanied by numbness, tingling (including a sensation of bugs crawling on the skin) or sharp pain in the legs. In some cases, patients report muscle cramps or spasms. The condition may also cause bladder or bowel problems and sexual dysfunction.

As arachnoiditis progresses, symptoms may worsen or become permanent. In few cases, this has led to paralysis of the lower limbs. A minor trip or fall can trigger a delayed onset of symptoms, sometimes as many as 15 to 20 years after exposure to the true cause, and factors such as aging, other chronic spinal conditions, obesity, lack of exercise, and genetics can make the disorder more prominent.


There are several ways that the arachnoid—that is, the middle layer of the spinal canal covering, can become inflamed:

  • Direct injury to the spine or spinal canal covering, whether from fall or other major trauma, or a complication from a spinal surgery or procedure
  • Toxic chemicals, such as radiographic dye used in a diagnostic test or steroid injection
  • Viral or bacterial infection, such as meningitis, syphilis, or tuberculosis
  • Chronic spinal compression conditions caused by degenerative disc disease or spinal stenosis, as well as osteoporosis, kyphoscoliosis (the abnormal curvature of the vertebrae), and arthritis.

Occasionally, more than one factor can contribute to the condition. Generally, arachnoiditis caused by injury or surgery is more localized to a particular part of the body, while inflammation due to the introduction of chemicals may cause more widespread complications.


A diagnosis of arachnoiditis is often made after other conditions have been ruled out, known as a “diagnosis of exclusion,” according to Neel Mehta, MD, medical director of pain medicine at the Weill Cornell Pain Medicine Center-New York Presbyterian Hospital, in New York.         

Patients whose symptoms may indicate arachnoiditis will need to undergo a complete medical history and a physical evaluation. In addition, a doctor will likely refer the patient for an MRI with intravenous contrast to confirm a diagnosis.


Arachnoiditis is not curable so treatment generally revolves around managing the disorders’ associated pain and symptoms to improve daily function and quality of life. Care is often multi-disciplinary in nature, involving a combination of medication, physical therapy to preserve function and range of motion, integrative medicine, and interventional procedures, such as spinal cord stimulation (SCS) or intrathecal drug delivery.SCS involves transmitting an electrical signal directly into the spinal cord. Intrathecal drug delivery involves the delivery of medication directly into the spinal fluid via an injection or implanted pump.

With regard to medications, opioids are often avoided in patients with this disorder due to their side effects and potential long-term effects. Instead, patients may be prescribed common nerve pain medications such as gabapentin and pregabalin, but they should be aware of the risk of side effects and dependence. Ketamine and lidocaine infusions may be helpful in reducing inflammation.

Some patients have found the use of cannabis to be helpful in relieving symptoms, according to Dr. Mehta. Psychotherapy may be helpful as well if the patient is experiencing emotional effects of the condition, such as anxiety or depression, which can be progressive and debilitating.

In some cases, surgery may be used to temporarily relieve symptoms but is not recommended as it generates more scar tissue.

New Research

Dr. Mehta pointed out that there is hope for patients suffering from the long-term effects of arachnoiditis. “Recent research has shown that low-dose naltrexone derived as an antidote for opioid overdose has been seen to trigger the body to release endorphins and a reduction in inflammatory pathways in the body,” he says. It’s also important to note that the radiographic chemicals believed to be responsible for past cases of arachnoiditis are not currently used in diagnostic testing.

For more information, view the Arachnoiditis pages of the:


This article was also reviewed by PPM Editor Emeritus Forest Tennant, MD, who heads the Arachnoiditis Research and Education Project in West Covina, CA

Updated on: 12/21/20
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