1 IntroductionrnTarlov cysts,which develop between the endoneurium and perineurium,are perineurai cysts that are defined as cerebrospinal fluid (CSF)-filled saccular lesions commonly located in the extradural space of the sacral spinal canal[1].They are rare,showing up in 1.5％ to 4.6％ of patients receiving magnetic resonance imaging (MRI) for their lumbosacral symptoms,and only 1％ or less of Tarlov cysts are considered to be symptomatic[2,3].