What Is Arachnoiditis

Arachnoiditis is a rare, chronic neurological condition involving inflammation of the arachnoid mater — one of the three protective membranes (meninges) that surround and protect the spinal cord and its nerve roots.

Key Features

• Inflammation leads to scarring, fibrosis, and adhesions (scar tissue that causes nerve roots to clump together or stick to the spinal cord).
• This disrupts normal cerebrospinal fluid (CSF) flow and nerve function, resulting in severe, often debilitating pain and neurological problems.
• It most commonly affects the lower spine (lumbar region, involving the cauda equina), but can occur anywhere along the spinal cord.

Common Causes

Arachnoiditis is usually triggered by an insult to the arachnoid membrane:

• Spinal procedures (most common): Surgery, repeated epidural steroid injections, spinal anesthesia, or myelograms (especially older oil-based contrast agents).
• Infections: Bacterial/viral meningitis, tuberculosis, or other spinal infections.
• Trauma or bleeding: Spinal injury, hemorrhage (subarachnoid hemorrhage).
• Chemical irritation: From injected substances, chemotherapy, or other irritants.
• Other: Chronic compression (e.g., from disc disease or stenosis), autoimmune conditions, or rarely idiopathic (unknown cause).

Symptoms

Symptoms vary widely but often include:

• Chronic pain — Severe, burning, stinging, or electric-shock-like pain in the lower back, legs, buttocks, or perineum (between genitals and rectum). Often described as “the worst pain imaginable.”
• Numbness, tingling, or “pins and needles” (paresthesia) in the legs or feet.
• Muscle weakness, spasms, or cramps.
• Bladder, bowel, or sexual dysfunction (e.g., incontinence, retention, or impotence).
• Fatigue, joint pain, or difficulty walking.
• In severe cases: Paralysis or mobility loss.

Symptoms can appear weeks to years after the triggering event and tend to be progressive without management.

Diagnosis

• Clinical history of symptoms + possible inciting event (e.g., prior surgery or injection).
• Imaging: MRI is the preferred test (shows nerve root clumping, adhesions, empty sac sign, or CSF flow issues). CT myelography may be used in some cases.
• No single definitive lab test; diagnosis is often one of exclusion after ruling out other causes.

Treatment and Management

There is no cure, and treatment focuses on symptom relief and preventing worsening:

• Pain management: Medications (e.g., NSAIDs, opioids in some cases, gabapentinoids, antidepressants), spinal cord stimulation, or pain pumps.
• Physical therapy and rehabilitation to maintain mobility.
• Anti-inflammatory or other therapies: Corticosteroids (sometimes), though long-term use is limited.
• Surgery: Rarely helpful and can worsen scarring; used only for specific complications like syringomyelia.
• Lifestyle support: Assistive devices, psychological support for chronic pain.

Prognosis varies — it is not usually fatal but can significantly reduce quality of life. Early recognition and multidisciplinary care help many people manage symptoms.

If you suspect arachnoiditis (especially with a history of spinal interventions and unexplained burning pain), consult a neurologist, pain specialist, or spine expert promptly. Resources like the National Institute of Neurological Disorders and Stroke (NINDS), Cleveland Clinic, or patient advocacy groups can provide further support. Research into better treatments continues.