Most Common Cause of Adhesive Arachnoiditis
The most common cause of adhesive arachnoiditis is prior spinal surgery, particularly lumbar disc surgery and its associated investigations, accounting for the majority of cases. 1, 2, 3
Primary Etiologic Factors
Surgical Causes (Most Common)
- Lumbar disc surgery and spinal procedures represent the predominant cause, with adhesive arachnoiditis occurring in 6-16% of postoperative patients 3, 4
- Revision spine surgery carries particularly high risk, with multiple surgical interventions compounding the inflammatory response that triggers adhesion formation 4
- The pathogenesis mirrors serous membrane repair (similar to peritoneal adhesions), with minimal inflammatory cellular exudate but prominent fibrinous exudate leading to scarring 3
Intrathecal Substance Administration
- Oil-based myelographic contrast agents (Pantopaque) historically caused significant arachnoiditis, especially when mixed with blood in the thecal sac 2, 3
- Water-soluble ionic contrast materials also contributed to cases, though modern non-ionic agents like Iohexol have dramatically reduced this risk 2
- Intrathecal therapeutic substances including anesthetics, chemotherapy, and steroids can trigger the inflammatory cascade 1, 3
- Recent case reports document arachnoiditis following intrathecal nusinersen therapy, highlighting ongoing risk with novel intrathecal treatments 5
Other Recognized Causes
- Spinal cord trauma and injury 1, 3
- Subarachnoid hemorrhage 3
- Infectious processes (meningitis, tuberculosis, fungal infections) 4
- Idiopathic cases occur but are rare 3
Critical Clinical Context
The combination of lumbar disc disease, its diagnostic workup (particularly with older contrast agents), and subsequent surgical treatment creates the perfect storm for arachnoiditis development 2. This explains why the lumbar region is most commonly affected and why patients with complex spinal histories face highest risk.
Important Pitfall
Do not confuse chloroprocaine (a spinal anesthetic) with chlorhexidine (a skin antiseptic) when considering iatrogenic causes—chlorhexidine neurotoxicity from incomplete drying during neuraxial procedures can cause arachnoiditis, but this is a preventable antiseptic contamination issue, not a medication effect 6, 7
Prevention Strategy
Ensure complete drying of chlorhexidine-alcohol skin antiseptic before any neuraxial procedure to prevent neurotoxic contamination that can trigger arachnoiditis 6