Tarlov Cyst (Sacral Perineural Cyst)

Tarlov cysts sit in the sleeve of a sacral nerve root and fill with cerebrospinal fluid, sometimes through a valve-like connection with the fluid space around the spinal cord, which allows them slowly to enlarge. They are found in a meaningful proportion of adults who have MRI scans of the pelvis or lower spine, and the overwhelming majority are entirely symptomless. Because they are so often incidental, they are also frequently misinterpreted — sometimes even mistaken on pelvic scans for other structures — so an important part of my role is simply to recognise the cyst for what it is and to reassure.

When a Tarlov cyst does cause symptoms, it is usually a larger cyst pressing on the sacral nerve roots. Symptoms can include pain in the lower back, buttock, tailbone or the back of the leg, altered sensation, and — because the sacral nerves supply the pelvic organs — sometimes bladder, bowel or sexual symptoms. Some people describe pain that is worse when sitting or standing and eases on lying down. The difficulty is that these symptoms are common and often have other causes, so careful assessment with a detailed history, examination and MRI is needed to judge whether the cyst is genuinely responsible before any treatment is considered.

For the great majority of people, no treatment is needed beyond reassurance and simple management of symptoms. Where a cyst is confidently shown to be the cause of significant, persistent symptoms, several treatment options exist and are weighed carefully and individually. These include image-guided percutaneous procedures, such as draining the cyst and injecting fibrin sealant to seal it, and open surgery to decompress and repair the cyst and its connection with the fluid space. The evidence, including systematic reviews and sizeable series, shows that well-selected treatment can relieve symptoms, while also being honest that cysts can recur and that patient selection is everything. This is a niche area, and treatment is reserved for those in whom the cyst is clearly the culprit.

For nearly everyone with a Tarlov cyst, the outlook is excellent because the cyst is a harmless, incidental finding requiring nothing more than reassurance. For the small number with genuinely symptomatic cysts, carefully chosen treatment can improve symptoms and quality of life, though as with any procedure there are risks and the possibility of recurrence. My priority is always to separate the cyst that truly matters from the far more common one that does not, and to avoid unnecessary intervention.

• —Paredes Mogica JA, et al. Sacral Tarlov perineurial cysts: a systematic review of treatment options. J Neurosurg Spine 2024. (PMID 38100766)
• —Murphy K, et al. Treatment of 213 patients with symptomatic Tarlov cysts by CT-guided percutaneous fibrin sealant. AJNR Am J Neuroradiol 2016. (PMID 26405086)
• —Burke JF, et al. Microsurgical treatment of sacral perineural (Tarlov) cysts: case series and review. J Neurosurg Spine 2016. (PMID 26745352)
• —Elsawaf A, et al. Surgical excision of symptomatic sacral perineural Tarlov cyst: case series and review. Eur Spine J 2016. (PMID 27154168)
• —Tanaka M, et al. Surgical results of sacral perineural (Tarlov) cysts. Acta Med Okayama 2006. (PMID 16508691)
• —Tracz J, et al. Interventional approaches to symptomatic Tarlov cysts: a 15-year institutional experience. J Neurointerv Surg 2024. (PMID 37402574)
• —Feigenbaum F, et al. Prospective validation of the Tarlov Cyst Quality of Life Scale. World Neurosurg 2022. (PMID 35700862)
• —Tani S, et al. Prevalence of spinal meningeal cyst in the sacrum. Neurol Med Chir (Tokyo) 2013. (PMID 23438659)
• —Kim S, et al. Tarlov cysts misdiagnosed as adnexal masses in pelvic sonography: a literature review. Front Med (Lausanne) 2020. (PMID 33425933)
• —Konar SK, et al. Isadore Max Tarlov and the controversial Tarlov cyst: historical perspective. J Neurosurg Spine 2016. (PMID 26516664)
• —Kaptanoğlu E, et al. Growth of a giant Tarlov (perineural) cyst with intrapelvic extension. Eur Spine J 2024. (PMID 39042321)
• —Mastantuoni C, et al. Symptomatic Tarlov cyst resolution after CT-guided percutaneous trans-sacral fibrin glue injection. Surg Neurol Int 2024. (PMID 38741984)