Adhesive arachnoiditis is a chronic inflammation of the arachnoid mater — the middle of the three membranes surrounding the spinal cord and nerve roots — followed by progressive scarring and fibrosis. As scar tissue accumulates, nerve roots clump together, adhere to the arachnoid membrane, and lose their normal mobility, leading to persistent and often severe neurological dysfunction.

How Does It Develop?

The process begins with an inflammatory insult that triggers fibrous scar tissue deposition. Over time, nerve roots either cluster into a central mass or adhere to the walls of the thecal sac. Three classical MRI patterns have been described: Type 1, in which nerve roots aggregate centrally (“empty sac” appearance); Type 2, in which roots are adherent to the periphery of the sac; and Type 3, representing a solid fibrotic mass obliterating the subarachnoid space entirely.

Causes

The main causes include:

• Iatrogenic: Intrathecal contrast agents (myelography), epidural or intrathecal injections, spinal surgery
• Infection: Tuberculous meningitis, bacterial or viral meningitis
• Trauma: Spinal cord injury, lumbar puncture complications
• Chemical: Intrathecal corticosteroid crystals, certain anesthetic agents
• Idiopathic: No identifiable cause is found in a significant proportion of cases

Symptoms

The condition most commonly manifests in the lower back and legs, though thoracic or cervical involvement can affect the upper extremities as well. The most frequently reported complaints are:

• Chronic burning or electric shock-like pain
• Numbness, tingling, and weakness in the limbs
• Bladder and bowel dysfunction
• Sexual dysfunction
• Significant difficulty sitting and walking
• Headache when CSF circulation is impaired

Symptoms typically follow an asymmetric and fluctuating course, with periods of exacerbation alternating with relative stability.

Diagnosis

T2-weighted MRI is the gold standard. The normal fan-like distribution of nerve roots is replaced by clumping or peripheral adherence. Phase-contrast MRI or myelography may be added to assess CSF flow dynamics. Electrophysiological studies (EMG/NCS) can provide supporting evidence of functional nerve impairment.

Treatment

No curative treatment currently exists; all available approaches target symptom management.

• Pain management: Neuropathic agents (gabapentin, pregabalin), opioids, TENS
• Interventional: Spinal cord stimulation, intrathecal drug delivery systems
• Rehabilitation: Physical therapy, aquatic exercise programs
• Experimental: Anti-inflammatory protocols, hyaluronidase injections (limited evidence)

Prognosis

Adhesive arachnoiditis generally follows a progressive course, though the rate of progression varies considerably between individuals. Early diagnosis and appropriate symptom management can meaningfully improve quality of life. Given the chronic pain and functional limitations involved, the condition carries a substantial psychosocial burden, making a multidisciplinary care approach essential.