Causes of Arachnoiditis and How It Is Treated

Arachnoiditis is a rare, painful condition characterized by inflammation of the arachnoid mater, one of the membranes covering the central nervous system (comprised of the brain and spinal cord). This can lead to symptoms ranging from chronic nerve pain and erectile dysfunction to the loss of bladder or bowel control.

Arachnoiditis is often the unintended consequence of a medical procedure involving the spine but can also result from infections and other conditions. Arachnoiditis symptoms can be managed with different types of medication and physical therapy.

This article explains the causes and symptoms of arachnoiditis, including how this uncommon neurological disorder is diagnosed and treated.

What Causes Arachnoiditis?

The arachnoid is the middle layer of the meninges, the three membranes that encase the brain, spinal cord, and spinal nerve roots. (The other two are the outer dura mater and inner pia mater.) The swelling of the arachnoid places direct pressure on spinal nerves, causing symptoms that vary based on the location and severity of the inflammation.

Arachnoiditis is usually due to direct or indirect injury to the spine arising from conditions like:

• Complications of spinal surgery: Including injuries to the cervical spine that can cause chronic nerve pain or injuries to the lumbar spine that can cause paralysis or the loss of bowel control
• Misplaced epidural injections: In which a steroid, anesthetic, or other injected drugs are accidentally trapped in the dura mater
• Multiple lumbar punctures ("spinal taps"): Which can cause bleeding, spinal hematoma (bruising), or arachnoidal fibrosis (scarring)
• Spinal cord infections: Such as viral meningitis or bacterial tuberculosis
• Spinal compression: Caused by advanced spinal stenosis or degenerative disc disease
• Spinal trauma: Resulting in intrathecal hemorrhage (bleeding within the meninges)
• Spinal tumors: Including benign or malignant tumors that compromise arachnoidal membranes

What Are the Symptoms of Arachnoiditis?

Symptoms of arachnoiditis can vary. In some cases, the condition may be mild and barely noticeable, while other cases cause severe disability. Symptoms may only appear months or years after an injury or infection.

Symptoms of arachnoiditis include:

• Numbness or tingling in the legs
• Severe shooting pains in the back and legs
• Leg weakness
• Burning or pins-and-needles sensation of the feet
• Headaches
• Crawling or "dripping" sensations on the skin
• Muscle spasms, cramps, and twitching
• Episodes of blurred vision
• Episodes of overheating or sweating
• Erectile dysfunction

The condition can become chronic due to the formation of scar tissue that causes spinal nerves to stick together and permanently fuse.

Even so, arachnoiditis is rarely life-threatening.

Complications

Symptoms of arachnoiditis can become severe and even permanent if the scar tissues begin to calcify (harden like bone). This can lead to a rare complication known as arachnoiditis ossificans.

With arachnoiditis ossificans, chronic nerve pain may be accompanied by:

• Loss of bladder or bowel control
• Impairment of fine motor skills, such as writing
• Difficulty walking
• Inability to sit or stand for long periods
• Paralysis of the lower extremities

Symptoms of arachnoiditis ossificans are often irreversible and can even progress, causing significant disability and a reduction in your quality of life.

How Arachnoiditis Is Diagnosed

Arachnoiditis can be difficult to diagnose, in part because its symptoms are similar to those of many other diseases.

Arachnoiditis is generally suspected when multiple symptoms are present, such as when chronic nerve pain (neuralgia) is accompanied by transient vision changes and bladder dysfunction.

Physical Exam

The diagnosis of arachnoiditis will typically begin with a review of your symptoms and medical history. A physical exam will include an evaluation of your reflexes as well as the range of motion of your legs.

People with arachnoiditis will often lack the ability to extend their legs fully (a key diagnostic clue) and will take short, guarded steps when walking.

Lab Tests

Arachnoiditis is characterized by chronic inflammation of the central nervous system. This can be detected with blood tests that detect generalized inflammation, such as.

• Erythrocyte sedimentation rate (ESR): Which measures inflammation based on how fast red blood cells settle to the bottom of a test tube
• C-reactive protein (CRP): Which measures the level of a protein produced by the liver in response to inflammation

Together, these tests cannot diagnose arachnoiditis but may help support a diagnosis.

Imaging Studies

Imaging studies are generally the most effective way to diagnose arachnoiditis as they can help pinpoint the underlying cause, such as degenerative disc disease or a spinal cord tumor.

Options include:

• Computed tomography (CT): Which composites multiple X-ray images to create three-dimensional "slices" of the body, including the spinal column
• Magnetic resonance imaging (MRI): Which uses magnetic and radio waves to create highly detailed images of soft tissues⁠, such as the meninges and spinal nerve roots
  

Procedures

If an infection is suspected, a lumbar puncture (spinal tap) may be ordered to extract a sample of cerebrospinal fluid for evaluation in the lab.

An electromyogram (EMG) is another valuable tool that can assess the severity of nerve damage by measuring electrical activity.

How Is Arachnoiditis Treated?

There is no cure for arachnoiditis. Treatment is focused on the control and alleviation of chronic nerve pain. The approach is not unlike those used to treat other chronic pain disorders, such as fibromyalgia, although a single approach has yet to prove consistently effective in all cases.

Medications

Depending on the severity and location of the symptoms, certain drugs may be prescribed to help control chronic nerve pain and other symptoms of arachnoiditis.

These include:

• Anti-inflammatory drugs: Such as the steroid drug prednisone, the injected nonsteroidal anti-inflammatory drug (NSAID) ketorolac, and the oral NSAID Tivorbec (indomethacin)
• Analgesic painkillers: Such as the opioid drug fentanyl, low-dose anesthetics like ketamine, or topical analgesics like lidocaine
• Neuropathy medications: Such as Lyrica (pregabalin) and Neurontin (gabapentin) commonly used to treat post-shingles neuralgia and diabetic neuropathy
• Minocin (minocycline): A tetracycline antibiotic that can suppress inflammatory chemicals called cytokines
• Diuretics ("water pills"): Lke Diamox (acetazolamide) which helps reduce cerebrospinal fluid pressure

Pain Management

As a chronic and sometimes permanent condition, arachnoiditis is rarely treated with medications alone. Instead, healthcare providers will typically recommend a combination of medications, physical therapy, and routine exercise to help minimize pain while preserving the range of motion of your lower extremities.

Psychotherapy may also be recommended to teach you how to cope with chronic pain. This may involve mindfulness-based stress reduction and medications that help treat acute anxiety or depression.

Mobility devices may also be considered. Standing wheelchairs and Segways are especially useful as they help you remain upright. However, both are costly and rarely covered by health insurance.

Developing Strategies

Surgery, including a surgical nerve block, is rarely used to treat arachnoiditis due to high failure rates. However, newer techniques like spinal cord stimulation (SCS) are demonstrating positive results in some.

A spinal cord stimulator is an implanted device that sends electrical impulses to the spinal cord. Also known as a dorsal column stimulator, the device reduces the excitability of nerve cells and, with it, the transmission of pain signals to the brain.

A 2015 study in the Journal of Pain reported that SCS delivered complete pain relief in a single patient with arachnoiditis who did not respond to other therapies. Within a month, no other treatments were needed. Further research is needed.

Summary

Arachnoiditis is inflammation of a membrane surrounding the brain and spinal cord, called the arachnoid. Symptoms include chronic nerve pain, headaches, pins-and-needles sensations, and vision problems. Severe cases can cause a loss of bladder or bowel control and even paralysis of the lower extremities.

Arachnoiditis can be caused by injuries, infections, or diseases of the arachnoid or other parts of the central nervous system. The diagnosis involves a physical exam, blood tests, and imaging studies. Treatment is typically treated with medications and other forms of chronic pain management.