Our goal is to study through this observation and review of the literature the role of Tarlov cyst in the occurrence of lombosciatalgias and therapeutic possibilities.

Mrs. H.M 48 years old, with no notable medical history, is hospitalized in Physical Medicine and Functional Rehabilitation department CHU Sahloul for a right S1 radiculopathy associated with a subjective feeling of lower extremity weakness evolving for one year. Clinical examination found a spinal syndrome, absence of discoradicular conflict signs and a plantar flexion deficit of the right ankle. A lumbar MRI reported a cystic lesion in right neural foramen of S2 of 15mm size. The patient received two epidural by the sacro coccygeal hiatus separated by an interval of 6 days. The evolution was characterized by improved lombo-radicular pain.

Perineural (Tarlov) cysts are meningeal dilatations of the posterior spinal nerve root sheath that found most commonly in the sacral roots, but can see much more rarely, lumbar, dorsal and cervical roots. These cysts are relatively rare and most of them are asymptomatic. Some cysts can have nerve compression, causing sacral or lumbar pain syndromes, sciatica or rarely as cauda equina syndrome. The Tarlov cysts are typically benign lesion. These cysts are rarely sources of complications due to distorting, compressing, or stretching of adjacent sacral nerve roots. These are symptomatic in 12% of cases and responsible of 0.2% of the lumbosacral radicular pain. An MRI gives a much better soft tissue contrast and is currently the gold-standard investigation in identifying perineural cysts and to study their relationship with surrounding structures. Treatment may be medical or surgical that is aimed at symptomatic Tarlov cysts.