What is Tarlov cyst?

Tarlov cysts, also known as perineurial cysts, are type II innervated meningeal cysts, cerebrospinal-fluid-filled (CSF) sacs most frequently located in the spinal canal of the S1-to-S4 region of the spinal cord (much less often in the cervical, thoracic or lumbar spine), and can be distinguished from other meningeal cysts by their nerve-fiber-filled walls. Tarlov cysts are defined as cysts formed within the nerve-root sheath at the dorsal root ganglion. The etiology of these cysts is not well understood; some current theories explaining this phenomenon have not yet been tested or challenged but include increased pressure in CSF, filling of congenital cysts withone way valves, inflammation in response to trauma and disease. They are named for neurologist Isadore Tarlov, who described them in 1938.

Tarlov cysts are relatively common when compared to other neurological cysts. Initially, Isadore Tarlov believed them to be asypmptomatic, however as his research progressed, Tarlov found them to be symptomatic in a number of patients. These cysts are often detected incidentally during MRI or CT scans for other medical conditions. Cysts with diameters of 1cm are larger are more likely to be symptomatic, although cysts of any size may be symptomatic dependent on location and etiology. Some 40% of patients with symptomatic Tarlov cysts can associate a history of trauma or childbirth. Current treatment options include CSF aspiration, complete or partial removal, fibrin-glue therapy, laminectomy with wrapping of the cyst, amongst other surgical treatment approaches. Interventional treatment of Tarlov cysts is the only means by which symptoms might permanently be resolved due to the fact that the cysts often refill after aspiration. Tarlov cysts often enlarge over time, especially if the sac has a check valve type opening. They are differentiated from other meningeal and arachnoid cysts because they are innervated and diagnosis can in cases be demonstrated with subarachnoid communication.

Tarlov perineurial cysts have occasionally been observed in patients with Marfan syndrome, Ehlers-Danlos syndrome, and Loeys-Dietz syndrome.