of prophylactic antibiotic was proven to be efficacious for the prevention of infection in lumbar spine surgeries. Epidural post-operative fibrosis Epidural scarring following a laminectomy for disc excision is a common feature when re-operating for recurrent sciatica or radiculopathy. When the scarring is associated with a disc herniation and/or recurrent spinal stenosis, it is relatively common, occurring in more than 60% of cases. For a time, it was theorized that placing a fat graft over the dural could prevent post operative scarring. However, initial enthusiasm has waned in recent years. In an extensive laminectomy involving 2 or more vertebra, post operative scarring is the norm. It is most often seen around the L5 and S1 nerve roots. Adhesive arachnoiditis Fibrous scarring can also be a complication within the subarachnoid space. It is notoriously difficult to detect and evaluate. Prior to the development of magnetic resonance imaging, the only way to ascertain the presence of arachnoiditis was by opening the dura. In the days of CT scanning and Pantopaque and later, Metrizamide myelography, the presence of arachnoiditis could be speculated based on radiographic findings. Often, myelography prior to the introduction of Metrizamide was the cause of arachnoiditis. It can also be caused by the long term pressure brought about with either a severe disc herniation or spinal stenosis. The presence of both epidural scarring and arachnoiditis in the same patient are probably quite common. Arachnoiditis is a broad term denoting inflammation of the meninges and subarachnoid space. A variety of causes exist, including infectious, inflammatory, and neoplastic processes. Infectious causes include bacterial, viral, fungal, and parasitic agents. Noninfectious inflammatory processes include surgery, intrathecal hemorrhage, and the administration of intrathecal (inside the dural canal) agents such as myelographic contrast media, anesthetics (e.g. chloroprocaine), and steroids (e.g. Depo-Medrol, Kenalog). Lately iatrogenic arachnoiditis has been attributed to misplaced Epidural Steroid Injection therapy when accidentally administered intrathecally. The preservatives and suspension agents found in all steroid injectates, which aren't indicated for epidural administration by the U.S. Food & Drug Administration due to reports of severe adverse events including arachnoiditis, paralysis and death, have now been directly linked to the onset of the disease following the initial stage of chemical meningitis. Neoplasia includes the hematogenous spread of systemic tumors, such as breast and lung carcinoma, melanoma, and non-Hodgkin lymphoma. Neoplasia also includes direct seeding of the cerebrospinal fluid (CSF) from primary central nervous system (CNS) tumors