What Is a Tarlov Cyst: Causes, Symptoms & Treatment

A Tarlov cyst is a fluid-filled sac that forms on the nerve roots in the spine, most often in the sacral region near the base of the spine. These cysts sit within the nerve root sheath itself, which is why they are also called perineural cysts. They were first described by the neurosurgeon Isadore Max Tarlov in the mid-twentieth century and bear his name.¹ Most Tarlov cysts never cause any trouble and are discovered by accident on imaging done for unrelated back complaints, but a meaningful minority grow large enough to press on nerves and produce pain, bladder problems, or other symptoms that can be genuinely disabling.

How Tarlov Cysts Form

Tarlov cysts contain cerebrospinal fluid (CSF), the clear liquid that normally surrounds the brain and spinal cord. The leading explanation for how they develop centers on what researchers call a “ball-valve mechanism.” In short, CSF flows into a small pocket along a nerve root, but something about the anatomy prevents that fluid from flowing back out freely. Over time, the one-way accumulation of fluid stretches the pocket into a cyst.² The pressure inside these cysts is real and measurable; one surgical series found that pressure within the cyst ranged from about 3 to 12 mmHg depending on the patient’s position.³

Activities that raise spinal fluid pressure, such as coughing, straining, or prolonged sitting, can push more fluid into the cyst and worsen symptoms. This helps explain why people with symptomatic Tarlov cysts often notice that their pain fluctuates with posture and physical activity rather than staying constant.

How Common Are They

Tarlov cysts show up more often than most people realize, but the vast majority remain silent. When researchers looked at spinal MRI scans performed on patients with back pain, roughly 4.5 to 8.5 percent had at least one Tarlov cyst. One study of over 380 patients undergoing MRI for back pain found cysts in about 6.5 percent of them.⁴ A separate review of more than 1,200 MRI scans done for suspected disk herniations put the figure at about 2 percent.⁵ The difference depends on how hard you look and which population you study, but prevalence somewhere in the low single digits is a reasonable ballpark.

Of the people who have a Tarlov cyst on imaging, only a fraction develop symptoms. One case-based review estimated that about 15 to 16 percent of people with Tarlov cysts become symptomatic.⁶ That means the overwhelming majority of Tarlov cysts are incidental findings that need no treatment. This distinction between “present on a scan” and “actually causing problems” is one of the most important things to understand about the condition, and it is a source of confusion for patients and sometimes for their doctors.

What Symptoms Look Like When Cysts Become Problematic

When a Tarlov cyst does grow large enough to compress a nerve, the symptoms depend on which nerve root is affected. Because most of these cysts sit in the sacral region, the most common complaints involve the lower back, buttocks, and legs.

Pain: Low back pain that radiates into one or both legs is the hallmark. Some patients experience classic sciatica, with shooting pain running from the buttock down the back of the thigh.⁷ The pain often worsens with sitting, standing for long periods, or any activity that increases spinal fluid pressure.⁸
Bladder and bowel issues: Because the sacral nerves control pelvic organ function, larger cysts can cause urinary urgency, difficulty emptying the bladder, constipation, or a feeling of incomplete emptying.
Urogenital symptoms: Women with cysts larger than about one centimeter are more likely to report urogenital problems, including sexual dysfunction and pelvic pain.⁹
Radiculopathy: Numbness, tingling, or weakness in the legs may develop when the cyst presses on the nerve root hard enough to interfere with nerve signaling.¹⁰

In rare cases, a large cyst can cause cauda equina syndrome, a serious condition where the bundle of nerves at the base of the spinal cord is compressed enough to cause sudden weakness in the legs or loss of bladder and bowel control.⁸ This is a medical emergency and is very uncommon, but it is worth knowing about.

Who Is More Likely to Get Symptomatic Cysts

Women are affected far more often than men, though researchers do not fully understand why. In surgical case series and referral populations, women outnumber men by wide margins. One review noted that among patients with symptomatic spinal cysts, women were overwhelmingly represented, with a disproportionate number having heritable disorders of connective tissue.¹¹

The link to connective tissue disorders is one of the more interesting threads in the research. Ehlers-Danlos syndrome (EDS), a group of genetic conditions that weaken connective tissue throughout the body, has been associated with Tarlov cyst formation. The logic makes intuitive sense: if the tissue surrounding your nerve roots is weaker or stretchier than normal, it is more vulnerable to the hydraulic forces that push CSF into those pockets.¹² Other connective tissue conditions like Marfan syndrome may share a similar relationship, though the evidence is thinner.

Trauma to the sacral area, including falls or difficult childbirth, has also been proposed as a trigger. The idea is that an injury could damage the nerve sheath just enough to create the initial pocket that later fills with fluid. Pregnancy itself can be relevant: large presacral Tarlov cysts discovered during pregnancy have prompted doctors to choose cesarean delivery to avoid the increased pressure on the cyst that vaginal delivery would cause.¹³

Getting Diagnosed

MRI is the first-line imaging tool for identifying Tarlov cysts. On an MRI scan, the cysts appear as well-defined, fluid-filled pouches along the nerve roots, and they are easy to spot once someone is looking for them.¹⁴ The trouble is that many radiologists note them as incidental findings and move on without further comment, leaving the patient and their referring doctor to puzzle over whether the cyst could be responsible for their symptoms.

When there is uncertainty about whether a cyst is actually causing the patient’s problems, CT myelography can help. In this procedure, contrast dye is injected into the spinal fluid space and then a CT scan is performed. A characteristic feature of Tarlov cysts is that they fill with contrast on a delayed basis, hours after injection, because the one-way valve lets fluid in slowly.¹⁵ This delayed filling helps distinguish them from other spinal cysts that communicate freely with the surrounding fluid.

The classification system most commonly referenced groups spinal meningeal cysts into three types. Tarlov cysts fall into the Type II category: extradural cysts that contain nerve root fibers within their walls.¹⁴ This detail matters for treatment planning because it means the nerve tissue is embedded in the cyst wall, and any surgical approach has to account for that to avoid neurological damage.

Why Misdiagnosis Is Common

One of the most frustrating aspects of symptomatic Tarlov cysts is how frequently they are overlooked or misattributed. Because the symptoms overlap heavily with common conditions like lumbar disk disease, piriformis syndrome, and pelvic floor dysfunction, patients can spend years being treated for the wrong problem. In one documented case, a man with a symptomatic cyst experienced spermatorrhea for over a decade before the true cause was identified; both he and his doctors had assumed it was a genitourinary condition.¹⁶

There is also a reverse problem: other conditions can mimic Tarlov cysts on imaging. A sacral schwannoma, a type of nerve sheath tumor, can look strikingly similar to a Tarlov cyst on MRI, but it requires a fundamentally different treatment approach.¹⁷ One important clue is that schwannomas tend to show a visible enhancing capsule on contrast-enhanced MRI, while a simple Tarlov cyst does not enhance.¹⁸ If your imaging report casually mentions a “perineural cyst” and your symptoms are worsening, it is reasonable to ask whether contrast-enhanced imaging has been done to rule out other possibilities.

Conservative and Interventional Treatment

Because most Tarlov cysts are asymptomatic, the majority require no treatment at all. For cysts that do cause mild or intermittent symptoms, the initial approach is typically conservative: pain management with medication, physical therapy to strengthen the surrounding musculature, and avoidance of activities that aggravate symptoms. Some patients find relief from targeted epidural steroid injections. In a small case series, patients with pelvic pain from sacral Tarlov cysts experienced close to complete pain relief for periods ranging from six months to two years after caudal epidural steroid injections.¹⁹

When conservative measures fail, the most widely studied minimally invasive option is CT-guided aspiration of the cyst combined with injection of a fibrin sealant. In this procedure, performed under local and intravenous sedation, a needle is placed into the cyst under CT guidance, the CSF inside is drained, and a biological glue (fibrin sealant) is injected to seal the cavity and prevent refilling. The largest published series treated 213 consecutive patients this way. At one year, about 82 percent were satisfied with their results, with over half reporting excellent outcomes. At three to six years of follow-up, about 74 percent remained satisfied, and there were no serious complications.²⁰

A 15-year review from a single institution that managed 95 patients with various interventional approaches found that about two-thirds of treated patients saw improvement in at least one symptom. Aspiration with fibrin glue injection was the most commonly used technique and trended toward better outcomes than aspiration alone, though the difference did not reach statistical significance.²¹

When Surgery Becomes Necessary

For patients whose symptoms are severe, who have failed less invasive treatments, or whose cysts keep refilling after aspiration, open surgery is the next step. Surgical approaches include cyst fenestration (opening the cyst and draining it) and nerve root imbrication (plicating or folding the redundant nerve sheath to reduce the space the cyst can occupy). Both techniques aim to decompress the affected nerves while preserving their function.²²

Outcomes after surgery are generally favorable. In a series of 97 consecutive surgical patients, about 76 percent reported excellent or good outcomes. However, surgery carries real risks. The complication rate in that series was about 17.5 percent. CSF leaks were the most frequent complication, occurring in about 10 percent of surgical patients, and some required reoperation. Two patients developed postoperative cauda equina syndrome, and wound infections occurred in a small number.²³

Cyst recurrence is a legitimate concern with any treatment approach. A systematic review comparing surgical and percutaneous (needle-based) techniques found that while both achieved similar rates of symptom improvement at around 89 percent, cyst recurrence was significantly lower after surgery (about 8 percent) than after percutaneous approaches (about 20 percent).²⁴ The tradeoff is that surgery also carries higher complication rates, roughly 21 percent compared to about 12 percent for percutaneous procedures.²⁴ Interestingly, symptom recurrence rates were essentially the same between the two approaches, sitting around 20 to 21 percent during the follow-up periods studied. So even when the cyst stays deflated after surgery, the symptoms do not always stay away, which suggests that nerve damage from long-standing compression may not always reverse.

The Impact on Daily Life

For people who fall into the symptomatic minority, the effect on quality of life can be substantial and underrecognized. A study comparing women with symptomatic Tarlov cysts (many of whom had been symptomatic for over nine years) to a matched group of patients with chronic back pain from degenerative or inflammatory conditions found that the Tarlov cyst group reported significantly more symptoms involving the lower limbs, pelvis, tailbone, bowel, and bladder. They were also significantly more likely to have reduced their social activities, stopped working, and experienced social decline compared to the control group with other causes of chronic back pain.²⁵

Part of the burden is medical. But part is psychosocial. Because the condition is not well known even among physicians, patients frequently report feeling dismissed or told that their cyst is “just incidental” even when their symptoms align perfectly with its location and size. The years of misdiagnosis described earlier are not unusual. Finding a specialist who takes these cysts seriously when they are causing problems, and who has experience treating them, can itself be a long and discouraging process.

Pregnancy and Other Situational Triggers

Certain life circumstances can aggravate Tarlov cysts or bring previously silent ones to clinical attention. Pregnancy is one. The increased abdominal pressure, weight gain, and hormonal changes that loosen connective tissue during pregnancy can all contribute to cyst enlargement. In at least one documented case, large presacral Tarlov cysts discovered during pregnancy were considered risky enough that cesarean delivery was chosen to avoid the mechanical forces of vaginal birth pushing on the cysts.¹³

Heavy lifting, chronic constipation, prolonged sitting (a concern for desk workers and long-distance drivers), and any repeated Valsalva-type maneuver can theoretically worsen symptoms by raising spinal fluid pressure. None of these factors cause a cyst to form out of nothing, but in someone who already has one, they can tip a quiet cyst into a symptomatic one. This also means that ergonomic adjustments, activity modification, and managing constipation are all reasonable parts of a conservative management plan.

Finding a Specialist

Because Tarlov cysts sit in a gray zone between neurosurgery, radiology, and pain medicine, there is no single specialty that “owns” the condition. Many general neurologists and orthopedic surgeons see them infrequently and may default to reassurance without further workup. If you have a cyst that you and your doctor suspect is symptomatic, a neurosurgeon or interventional neuroradiologist with specific experience managing these cysts is your best starting point. The interventional radiologists who perform CT-guided fibrin glue procedures, and the spine surgeons who do cyst fenestration or imbrication, are a relatively small group. Patient advocacy organizations maintain referral lists that can help narrow the search, and asking a prospective surgeon how many Tarlov cyst procedures they have performed is a perfectly reasonable first question. A center that has published on their outcomes is a strong signal of relevant experience.²⁵

1
PubMed. Isadore Max Tarlov (1905-1977) and the controversial Tarlov cyst: historical perspective
2
Neurocirugía (English Edition). Clinical Research Hydrostatic pressure mechanism and surgical efficacy of Tarlov cysts
3
Neurocirugía (English Edition). Clinical Research Hydrostatic pressure mechanism and surgical efficacy of Tarlov cysts – Section: Introduction / Discussion
4
PubMed Central. Tarlov cysts in back pain patients: prevalence, measurement method and reporting points
5
PubMed. Incidental findings of the lumbar spine at MRI during herniated intervertebral disk disease evaluation
6
American Journal of Case Reports. A Hidden Condition: Multiple Tarlov Cysts Unveiled in a Young Woman Seeking Primary Care for Debilitating Low Back Pain
7
PubMed Central. Sciatic neuralgia associated with a perineural (Tarlov) cyst
8
Annals of Physical and Rehabilitation Medicine. PO071 The Tarlov cyst: A cause of sciatica
9
PubMed Central. Urogenital symptoms in women with Tarlov cysts
10
PubMed Central. Tarlov cyst: A rare cause of radiculopathy
11
Journal of Neurosurgery: Spine. Spinal manifestations of Ehlers-Danlos syndrome: a scoping review – Section: Tarlov Cysts
12
PubMed Central. A Case of a Tarlov Cyst in A Pediatric Patient With Ehlers-Danlos Syndrome
13
PubMed Central. Large presacral Tarlov cysts in pregnancy
14
PubMed. Updated assessment and current classification of spinal meningeal cysts
15
Journal of Neurosurgery: Spine. Tarlov cysts: a study of 10 cases with review of the literature
16
PubMed Central. Neglected Tarlov cysts: a case of a Tarlov cyst with spermatorrhea
17
PubMed. Giant cystic sacral schwannoma mimicking tarlov cyst: a case report
18
ResearchGate. Delayed Diagnosis of Thoracic Schwannoma Misinterpreted as Perineural Cyst: A Case Report of Chronic Neuropathic Pain with Favorable Surgical Outcome
19
PubMed. Minimally invasive interventional therapy for Tarlov cysts causing symptoms of interstitial cystitis
20
PubMed Central. Treatment of 213 Patients with Symptomatic Tarlov Cysts by CT-Guided Percutaneous Injection of Fibrin Sealant
21
Journal of neurointerventional surgery. Interventional approaches to symptomatic Tarlov cysts: A 15-year institutional experience
22
PubMed Central. Surgical management of symptomatic Tarlov cysts: cyst fenestration and nerve root imbrication-a single institutional experience
23
PubMed Central. Operative Treatment of Tarlov Cysts – Outcomes and Predictors of Improvement after Surgery: A Series of 97 Consecutive Patients and a Systematic Review of Literature
24
Journal of Neurosurgery: Spine. Sacral Tarlov perineurial cysts: a systematic review of treatment options
25
PubMed Central. Management of Tarlov cysts: an uncommon but potentially serious spinal column disease—review of the literature and experience with over 1000 referrals