Spinal arachnoiditis is an insidious disease caused by an inflammatory process of the arachnoid membrane resulting from many possible causes, such as myelograms with oil-based radiographic contract agents and multiple back surgeries. Diagnosis is based on symptoms and magnetic resonance imaging. Arachnoiditis can also mimic the symptoms of other diseases, such as spinal cord tumors, cauda equina syndrome, arachnoiditis ossificans, and syringomyelia. Unfortunately, there is no cure, only treatment of the chronic symptoms. It is an incurable disease that can cause minor to severe symptoms from unexplained rashes to neurologic defects.