Tarlov cysts are fluid-filled sacs that form on the nerve roots near the base of the spine, most commonly in the sacral region. They contain cerebrospinal fluid (the same fluid that surrounds your brain and spinal cord) and are surprisingly common, though the majority cause no symptoms at all. When they do grow large enough to compress nearby nerves, the resulting pain and neurological symptoms can be difficult to pin down, partly because many doctors aren’t familiar with the condition.
How Tarlov Cysts Form
Cerebrospinal fluid normally flows freely through the spinal canal and around the nerve roots that branch off the spinal cord. In a Tarlov cyst, that fluid gets forced into the outer covering (the sheath) of a nerve root and becomes trapped. The leading explanation is that abnormally high fluid pressure inside the spinal canal pushes cerebrospinal fluid into these nerve root sheaths, gradually stretching them into balloon-like sacs. Once the fluid enters, a one-way valve effect can develop where fluid flows in more easily than it flows out, allowing the cyst to slowly enlarge over time.
What triggers that pressure increase isn’t always clear. Trauma, heavy lifting, and childbirth have all been proposed as potential contributing factors. Some researchers believe that changes in the delicate membrane lining the spinal canal disrupt the body’s normal ability to regulate fluid pressure, making certain nerve root exits vulnerable to cyst formation.
Symptoms of Symptomatic Tarlov Cysts
Most Tarlov cysts are small and completely silent, discovered by accident on an MRI ordered for an unrelated reason. When cysts grow large enough to press on nerve tissue, though, symptoms tend to center on the lower body and can include:
- Lower back and buttock pain, often described as a burning or shocking sensation that radiates down the legs
- Numbness or weakness in the legs, along with loss of reflexes
- Bladder and bowel changes, including increased urinary frequency, incontinence, or constipation
- Sexual dysfunction
- Difficulty sitting for prolonged periods, since sitting increases pressure in the sacral area
- Headaches, particularly if the cyst affects overall cerebrospinal fluid dynamics
Larger cysts are more likely to cause symptoms than smaller ones. The symptoms often overlap with more common spinal conditions like herniated discs, sciatica, or pelvic floor disorders, which means Tarlov cysts can go undiagnosed or misdiagnosed for years. People sometimes cycle through multiple specialists before getting an accurate explanation for their pain.
How Tarlov Cysts Are Diagnosed
MRI of the lower (lumbosacral) spine is the gold standard for identifying Tarlov cysts. On imaging, they appear as thin-walled, fluid-filled structures closely associated with nerve roots. The key distinguishing feature is that the nerve root runs through the cyst wall itself rather than sitting outside it. Radiologists look for a specific signal pattern: the cyst contents match cerebrospinal fluid, appearing dark on one type of MRI sequence and bright on another.
Cyst shape can range from simple round sacs to more complex structures with internal divisions. In some cases, the bony openings in the sacrum (the sacral foramina) are visibly widened from long-term pressure. When MRI isn’t an option, a CT scan combined with a special dye injected into the spinal fluid can serve as an alternative, though it’s more invasive.
Finding a Tarlov cyst on an MRI doesn’t automatically mean it’s the source of your symptoms. Doctors need to carefully match the cyst’s location and size to the specific nerves involved in your symptoms before concluding it’s the culprit.
Nonsurgical Treatment Options
For smaller cysts, or cysts that cause pain without significant muscle weakness, conservative management is typically the first approach. This can include pain medications, physical therapy, and steroid injections. Epidural steroid injections, where anti-inflammatory medication is delivered near the cyst, have shown success in relieving symptoms for some patients. In one documented case, a single epidural steroid injection kept a patient symptom-free for at least a year. This approach tends to work best for smaller cysts that don’t involve motor nerve damage.
Physical therapy focuses on strengthening the muscles around the lower spine and pelvis to reduce the load on affected nerves. Some patients also benefit from activity modifications, like using a standing desk or a cushion designed to reduce pressure on the sacrum while sitting. Conservative treatment doesn’t shrink or eliminate the cyst, but it can make symptoms manageable enough to avoid surgery.
When Surgery Is Considered
Surgery enters the conversation when cysts are large, symptoms are severe, or conservative treatment hasn’t worked. There are several surgical approaches, and the choice depends on cyst size, location, and the surgeon’s experience.
The two most common open surgical techniques are cyst fenestration and nerve root imbrication. Fenestration involves making an opening in the cyst wall to drain the fluid, then sealing it (often with a biological glue called fibrin glue) to prevent refilling. Imbrication is more involved: the surgeon removes the cyst wall and reconstructs the nerve root sheath, essentially folding and stitching the tissue to close the space where fluid collected. A less invasive option is CT-guided aspiration, where a needle is used to drain the cyst under imaging guidance, sometimes followed by fibrin glue injection to prevent recurrence.
In a study of 97 consecutive surgical patients, 76% reported significant symptom improvement after surgery. That’s a meaningful success rate, but it also means about one in four patients didn’t see the improvement they hoped for. Cyst recurrence occurred in roughly 12% of patients overall, though the rate varied by technique. Patients who had cyst resection (removal) experienced recurrence about 29% of the time, compared to roughly 9% for other techniques.
Surgical Risks and Complications
The most significant risk of Tarlov cyst surgery is cerebrospinal fluid leak. Because the cyst is filled with spinal fluid and sits right on nerve tissue, any surgical opening creates a potential pathway for ongoing fluid drainage. A persistent leak can cause severe low-pressure headaches, and in some cases requires a second surgery to repair. Other possible complications include bacterial meningitis (infection of the spinal fluid), new or worsened nerve pain, and changes in bladder or bowel function.
Particularly large (giant) Tarlov cysts carry extra risk. Draining a large volume of cerebrospinal fluid at once can cause a sudden drop in fluid pressure around the brain, leading to intense headaches and, in rare cases, serious neurological problems. Surgeons managing giant cysts often take a more cautious approach to fluid drainage for this reason. Tarlov cysts that rupture on their own, though uncommon, are responsible for most cases of spontaneous low spinal fluid pressure and can occasionally cause significant neurological harm.
Living With a Tarlov Cyst Diagnosis
If you’ve been told you have a Tarlov cyst, the most important first question is whether it’s actually causing your symptoms. Many cysts are incidental findings that need no treatment at all. For symptomatic cysts, finding a neurosurgeon or spine specialist with specific experience treating this condition matters more than usual, since Tarlov cysts are relatively uncommon and not all spine surgeons are familiar with the specialized techniques involved.
Periodic MRI monitoring is a reasonable strategy for cysts that are currently asymptomatic or mildly symptomatic, since it can reveal whether a cyst is stable or growing. For people with significant symptoms, the path typically moves from conservative measures like physical therapy and steroid injections toward surgical consultation if those approaches fall short. The overall outlook is encouraging: most symptomatic patients find meaningful relief through one of the available treatment options, even if the process of reaching the right diagnosis and treatment plan takes longer than it should.