Arachnoiditis

Overview

Arachnoiditis is inflammation of the arachnoid, one of the three membranes (the meninges) that surround and protect the spinal cord and the nerve roots that branch from it. When this membrane becomes inflamed, it can lead to swelling, scarring, and clumping together of the nerve roots. In its more severe form, called adhesive arachnoiditis, the nerves stick together and to the surrounding tissue, which can disrupt nerve function and cause chronic pain.

Arachnoiditis most often affects the lower spine and can be a difficult condition to live with because of persistent pain and nerve symptoms. It can result from infections, injury, certain procedures or substances introduced near the spine, or chronic compression. There is no simple cure, and treatment focuses on relieving symptoms, preserving function, and improving quality of life. Understanding the condition and working closely with a medical team are important parts of managing it.

Symptoms

Symptoms vary widely depending on which nerves are affected and how severe the inflammation and scarring are. Common features include:

• Chronic pain in the lower back and legs, often described as burning, stinging, or electric
• Numbness, tingling, or a crawling sensation in the legs or feet
• Muscle cramps, spasms, or twitching
• Weakness in the legs
• Pain that worsens with activity or certain positions
• In more severe cases, problems with bladder, bowel, or sexual function
• Difficulty walking or balance problems

New or worsening loss of bladder or bowel control, or rapidly progressing leg weakness or numbness, can indicate significant nerve involvement and should be evaluated urgently.

Causes

Arachnoiditis can develop from several different triggers that irritate or damage the arachnoid membrane:

• Infections: Bacterial, viral, or fungal infections affecting the spine or meninges.
• Injury and surgery: Trauma to the spine or complications from spinal surgery.
• Substances introduced near the spine: Certain chemicals, dyes, or medications placed in the spinal area in the past have been linked to the condition.
• Chronic compression: Long-standing pressure on the spinal nerves from conditions such as severe disc disease or spinal narrowing.
• Bleeding: Blood in the spinal fluid space from injury or other causes.

In some cases, the exact trigger is not identified.

Risk Factors

• Multiple spinal surgeries or procedures
• A history of spinal infection or meningitis
• Significant spinal injury
• Chronic, severe spinal narrowing or disc disease
• Bleeding within the spinal canal
• Certain past spinal injections or procedures

Diagnosis

Diagnosis combines the clinical picture with imaging, since arachnoiditis can resemble other spinal conditions:

• History and neurological exam: Reviewing prior spinal problems, surgeries, infections, and procedures, and testing strength, sensation, and reflexes.
• MRI: The main imaging test, which can show nerve roots that are clumped together, displaced, or adherent, supporting the diagnosis.
• Other tests: Nerve studies (EMG) to assess nerve function, and additional tests to look for infection or other causes when relevant.

Because no single test is definitive, diagnosis often rests on combining characteristic symptoms with supportive imaging findings.

Treatment

There is currently no cure that reliably reverses arachnoiditis, so treatment centers on managing symptoms and maintaining function:

• Pain management: A combination of medications, which may include nerve-pain medicines, anti-inflammatory drugs, and other pain treatments, tailored to the individual.
• Physical therapy: Gentle exercise and stretching to maintain mobility, strength, and function and to reduce stiffness.
• Multidisciplinary pain programs: Combining physical, psychological, and medical approaches, which can be especially helpful for chronic pain.
• Supportive care: Counseling and support for the emotional impact of chronic pain, plus help with sleep and daily activities.
• Treating underlying causes: Addressing infection or significant compression when present.

Repeat spinal surgery is generally approached cautiously, as it does not reliably help and can sometimes worsen scarring. A coordinated plan with a pain specialist and other clinicians offers the best chance of improving quality of life.

Prevention

Not all cases can be prevented, but some steps may lower the risk:

• Treat spinal infections promptly and completely
• Discuss the risks and benefits of repeated spinal procedures with your doctor
• Seek timely care for significant spinal compression
• Follow recommended precautions around spinal injuries

When to See a Doctor

See a doctor if you have persistent back and leg pain with burning, tingling, numbness, weakness, or muscle spasms, especially after spinal surgery, injury, or infection. A neurologist, spine specialist, or pain specialist can evaluate the cause and develop a management plan.

Seek emergency care for new or worsening loss of bladder or bowel control, sudden severe weakness or numbness in the legs, or fever with severe back pain, which can indicate a serious problem such as significant nerve compression or infection that needs urgent treatment.

Related Topics

Frequently Asked Questions

References

1. National Institute of Neurological Disorders and Stroke (NINDS). Arachnoiditis Information.
2. Mayo Clinic. Back pain — Symptoms and causes.
3. American Association of Neurological Surgeons (AANS). Spinal disorders.
4. MedlinePlus, U.S. National Library of Medicine. Spinal cord diseases.