1. Of mechanically-induced arachnoiditis (MIA)

Spinal surgery (especially multiple)

Multiple lumbar punctures

Trauma

Spinal stenosis (congenital/degenerative)

Chronic disc prolapse/ degenerative disc disease

2.Of Chemically-induced arachnoiditis (CIA)

Myelographic dyes (especially oil-based such as Myodil (Pantopaque))

Epidural steroid injections (e.g. Depo-Medrol)

Epidural anaesthesia

Other intraspinal drugs such as amphotericin B and methotrexate

Chemonucleolysis with chymopapain

3.Miscellaneous

Subarachnoid haemorrhage

Infection e.g. meningitis