Arachnoiditis is a medical condition defined as inflammation or swelling of the arachnoid membrane, which protects and surrounds the spinal cord and the nerves. Synonyms for arachnoiditis include spinal adhesive arachnoiditis, arachnoiditis fibrosis, arachnitis, and arachnoid fibrosis. These terms are often used interchangeably in medical literature to describe the same condition. Arachnoiditis can be caused by infections, surgery, spinal cord injury, or degenerative diseases. The symptoms can range from mild to severe and may include chronic pain, numbness, tingling, muscle weakness, and bladder problems. Treatments include pain medication, physical therapy, and surgery in severe cases.