Blood in the subarachnoid space.

Blood is a potent irritant to nervous tissue and alone can cause arachnoiditis. In combination with chemical substances, the risk is magnified. This was first noted in relation to oil-based myelographic dyes by Howland and Curry ( [1] ) who found that in dogs, blood and dye together caused severe adverse effects. Hence dural puncture during epidural administration of drugs should be treated seriously. Common practice currently involves administration of an epidural blood patch (EBP) which aims to seal the spinal fluid leak to reduce the impact of the post-dural puncture headache (PDPH). However this practice introduces the highly irritant blood into the delicate area of the subarachnoid space. (See above). Arachnoiditis as a complication of subarachnoid haemorrhage: This has been reported by various authors. Blood in the subarachnoid space is highly irritant. Aldrete has described the acute meningeal reaction followed by a chronic reactive process involving fibrosis and adhesions. Tjandra et al. ( [2] ) gave a detailed report of two cases in which subarachnoid haemorrhage was later associated with chronic arachnoiditis, with progression to loss of spinal cord function and in one case, spinal cord cavitation causing paraplegia.