Tarlov cysts, also referred to as perineurial cysts or meningeal cysts, are fluid-filled sacs that usually appear in the sacral region of the spinal cord. The cysts are named after Dr. Isadore Tarlov who first discovered them in 1938. While Tarlov cysts are rare, their symptoms can be debilitating, and people who suffer from this condition usually experience pain in the lower back, legs, and buttocks, as well as bowel and bladder dysfunctions. Some synonyms that describe the same type of cysts include, but are not limited to, sacral nerve root cysts, extradural cysts, and arachnoid diverticula. These terms are used interchangeably depending on the medical context and severity of the condition.