what is perineural
Overview. Perineural cysts, which are also known as Tarlov cysts, are fluid-filled sacs that form on nerves at the base of the spine. A person with such cysts would likely never know it. They almost never cause symptoms. When they do cause symptoms, however, the most common is pain in the lower back, buttocks, and legs. cyst is a sac that can form anywhere in the body and is filled with air or some type of fluid. Most of these are completely benign and noncancerous. Perineural cysts are those that form in the sacrum, or the base of the spine.