What it means
Nerve roots leave the spinal canal wrapped in a thin sleeve that holds spinal fluid. A Tarlov cyst, also called a perineural cyst, forms when part of that sleeve balloons into a pocket of fluid. They are most often found at the sacral nerve roots, can be single or several, and look bright on T2 MRI images like other fluid. Most people never know they have one.
When it matters
Most Tarlov cysts are found by chance, cause no symptoms and usually need no follow-up. Rarely, a large cyst presses on nearby nerves or thins the surrounding bone. It may then be linked to pain in the low back, buttock or legs, or to bladder changes. When symptoms seem to fit, doctors may review the cyst on more detailed images or involve a spine specialist.
Questions to ask your doctor
- How large is the cyst, and which nerve root is it on?
- Could the cyst be related to any of my symptoms?
- Does it need any follow-up imaging?
