Tarlov cysts, also known as perineural cysts or sacral nerve root cysts, are sacs filled with cerebrospinal fluid (CSF) that form on the roots of nerves as they exit the spinal cord. They are most commonly found in the sacral region of the spine, the area at the very base of your back that connects to the pelvis (the tailbone area).

To understand how these cysts form, it is helpful to use an analogy.

• Think of your spinal cord as a main water line, and the nerve roots that exit from it as smaller, delicate hoses. The entire system is bathed in a gently flowing, pressurized fluid called cerebrospinal fluid (CSF).
• A Tarlov cyst is like a tiny, weak spot on the wall of one of these nerve root “hoses” that begins to balloon outward.
• Crucially, many of these cysts are believed to have a one-way valve-like mechanism. This means that with each pulse of CSF pressure (which changes with coughing, sneezing, or straining), a tiny amount of fluid can be forced into the ballooning cyst, but it cannot easily get out.
• Over many years, this one-way valve effect causes the cyst to slowly inflate, like a balloon being gradually filled with water. As the cyst expands, it can put significant pressure on the nerve it grew from, on adjacent nerve roots, and it can even erode the surrounding sacral bone. It is this compression and bone erosion that can cause severe, chronic pain and neurological symptoms.

In my experience, patients are often surprised to learn they have Tarlov cysts after an MRI done for back pain or sciatica, they’re usually unaware such cysts even exist.

The exact underlying cause of why the nerve root sheath is weak and prone to forming a cyst in some people is unknown. It is believed that the predisposition to form these cysts is congenital, meaning a person is born with the potential for them to develop. The cysts themselves then often develop or enlarge slowly over a person’s lifetime. While they contain nerve fibers in their walls, they are considered benign and are not cancerous or pre-cancerous.

Patients sometimes ask if lifestyle caused them. I clarify that these cysts aren’t linked to posture or fitness, and are often congenital or slowly acquired over time.

A person is born with the underlying anatomical predisposition to form Tarlov cysts. They are not contagious and are not caused by a specific lifestyle factor. However, a pre-existing, asymptomatic cyst can sometimes become enlarged and symptomatic after a specific event that increases cerebrospinal fluid pressure.

Potential triggers that may cause a previously silent cyst to become problematic include:

• Direct Trauma: A significant fall onto the tailbone or lower back.
• Motor Vehicle Accidents.
• The Strain of Childbirth.
• Heavy Lifting or straining.

In many cases, however, individuals with symptomatic Tarlov cysts have no history of a specific traumatic event. The cysts simply enlarge gradually over time until they reach a critical size where they begin to cause symptoms. The condition is diagnosed more frequently in women than men.

Clinically, the exact cause is unclear, but I often explain that they may develop from nerve root sheath dilation, possibly triggered by trauma, inflammation, or cerebrospinal fluid pressure changes.

The most important thing to understand is that the vast majority of Tarlov cysts are small, do not grow, and are completely asymptomatic. They are extremely common incidental findings on MRI scans performed for other reasons, like lower back pain from a herniated disc.

When Tarlov cysts do become large enough to cause symptoms, the symptoms are a direct result of the pressure they exert on the sacral nerve roots and surrounding bone. The symptoms are often chronic, progressive, and can be quite debilitating.

Pain: The Hallmark Symptom

The most common symptom is chronic pain.

• The pain is typically centered in the sacrum (tailbone), lower back, and buttocks.
• It can radiate down the back of the legs in a pattern similar to sciatica.
• The pain is often described as aching, burning, or a deep, gnawing pressure.
• A key feature is that the pain is often positional. It is typically made worse by sitting or standing for long periods and may be relieved by lying down on one’s side.

Neurological Symptoms

As the cysts compress the nerve roots, they can cause a range of neurological symptoms in the legs, feet, and pelvic area.

• Numbness, tingling, or “pins-and-needles” sensations.
• A feeling of burning pain in the soles of the feet.
• Weakness in the legs or feet.
• Loss of reflexes.

Bladder, Bowel, and Sexual Dysfunction

The sacral nerves are crucial for controlling the function of the pelvic organs. Therefore, large symptomatic Tarlov cysts can cause:

• Bladder Dysfunction: Urinary urgency, frequency, hesitancy, or incontinence.
• Bowel Dysfunction: Chronic constipation due to impaired nerve function to the bowel.
• Sexual Dysfunction: Painful intercourse (dyspareunia) in women or erectile dysfunction in men.

Clinically, I look for a correlation between MRI findings and the patient’s symptoms, as not all cysts seen on scans are the source of pain.

The diagnostic journey for symptomatic Tarlov cysts can be long and frustrating. The primary challenge is not in identifying the cyst itself, but in definitively correlating the cyst with the patient’s specific symptoms. Because back pain and sciatica are so common, and incidental Tarlov cysts are also common, many doctors are reluctant to attribute a patient’s pain to a cyst unless it is very large and there is clear evidence of nerve compression or bone erosion.

The diagnostic process requires a specialist, usually a neurologist or a neurosurgeon.

1. Magnetic Resonance Imaging (MRI): This is the gold standard for identifying Tarlov cysts. A high-resolution MRI of the lumbar and sacral spine will clearly show the fluid-filled sacs emerging from the nerve roots. The MRI can show the size of the cysts and whether they are causing significant compression of the nerve roots or erosion of the surrounding sacral bone.
2. CT Myelogram: This is a more specialized and invasive test that can sometimes provide additional information. It involves injecting contrast dye into the spinal canal and then performing a CT scan. This test can show whether CSF is actively flowing into and getting trapped within the cysts, which can support the idea that they are under pressure and causing symptoms.
3. Exclusion of Other Causes: A crucial part of the process is a thorough evaluation to rule out more common causes of the patient’s symptoms, such as a herniated disc, spinal stenosis, or gynecological issues.

In my experience, a careful neurological exam paired with imaging helps determine if the cyst is likely causing the patient’s symptoms or if another condition is responsible.

Managing Tarlov cysts is a complex and often controversial topic. The most important principle is that asymptomatic, incidentally discovered Tarlov cysts require absolutely no treatment or monitoring.

Treatment is reserved only for those individuals in whom there is a very strong correlation between large, erosive cysts and their specific, debilitating neurological symptoms, and after other causes have been ruled out.

1. Conservative and Pain Management (First-Line Approach)

This is the starting point for all symptomatic patients. The goal is to manage the pain and improve function without invasive procedures.

• Medications for Neuropathic Pain: The pain from Tarlov cysts is nerve pain. Therefore, standard painkillers are often ineffective. The mainstay of medical treatment includes drugs that are used to treat nerve pain, such as:
  • Anti-seizure medications like gabapentin or pregabalin.
  • Low-dose tricyclic antidepressants like amitriptyline.
• Physical Therapy: A specialized physical therapist can provide gentle manual therapy, nerve gliding exercises, and core strengthening exercises to help manage pain and improve function. Aggressive stretching or high-impact therapy can sometimes worsen symptoms.
• Pain Management Procedures: A pain management specialist may attempt procedures like trans-sacral nerve blocks. Injecting an anesthetic and steroid around the affected nerve root can provide temporary pain relief and can also serve as a diagnostic tool. If the pain goes away after the block, it provides stronger evidence that the cyst and its associated nerve are the source of the pain.

2. Procedural and Surgical Treatment

These options are reserved for patients with severe, debilitating symptoms that have not responded to conservative management. These are highly specialized procedures with significant risks and should only be performed by a neurosurgeon with extensive experience in treating Tarlov cysts.

• Fibrin Glue Injection: This is a minimally invasive procedure. A doctor uses imaging guidance to insert two needles into the cyst. One needle is used to drain all the CSF fluid out of the cyst, and the second needle is used to inject a biological “fibrin glue.” The goal is to seal the one-way valve at the neck of the cyst to prevent it from refilling.
• Neurosurgery: This is the most invasive option. The surgeon performs a laminectomy to access the sacrum, opens the cyst, drains the fluid, and then attempts to repair or obliterate the cyst wall, often by packing it with fat or muscle tissue to prevent recurrence. This surgery carries significant risks, including the potential for nerve damage or a persistent CSF leak.

I’ve seen conservative approaches like pain management, physical therapy, and activity modification work for many, though a few require neurosurgical evaluation when symptoms are severe.

Tarlov cysts are a common, and usually completely harmless, anatomical finding on spinal MRIs. For the vast majority of people, they are an incidental curiosity that will never cause a problem. However, for a small subset of individuals, these cysts can enlarge and become a source of a real and debilitating chronic pain syndrome that is often misunderstood and misdiagnosed. The journey for these patients is often challenging to seek validation of their symptoms. While there is no simple cure, a comprehensive management plan, starting with conservative pain management and physical therapy, and progressing to specialized procedures only in select cases can offer a path toward reducing pain. In my experience, patients often feel relieved just to have an explanation for their chronic pain but understanding when a Tarlov cyst is actually the cause is key to choosing the right management.

American Association of Neurological Surgeons (AANS). (n.d.). Tarlov Cysts. Retrieved from https://www.aans.org/Patients/Neurosurgical-Conditions-and-Treatments/Tarlov-Cysts

National Organization for Rare Disorders (NORD). (2023). Tarlov Cysts. Retrieved from https://rarediseases.org/rare-diseases/tarlov-cysts/

Tarlov Cyst Disease Foundation. (n.d.). What is a Tarlov Cyst? Retrieved from https://www.tarlovcystfoundation.org/