Tarlov Cyst

Tarlov cysts are fluid-filled sacs that form on nerve roots, most often in the lower part of the spine (sacrum). Also known as perineural cysts, they are usually benign (non-cancerous) and often do not cause any symptoms. When symptoms do occur, they are typically due to the cyst pressing on nearby nerves.

What is Tarlov Cyst?

A Tarlov cyst is a type of fluid-filled sac that develops on the nerve roots, most commonly found in the lower spine (sacrum). These cysts are also called perineural cysts. While many people have Tarlov cysts, most do not experience any symptoms, and the cysts are often discovered by chance during imaging tests for other conditions.

Tarlov cysts are essentially small pouches filled with cerebrospinal fluid (CSF), which is the fluid that surrounds and protects the brain and spinal cord. They typically form along the nerve roots of the sacral spine, specifically between the S1 and S4 segments. These cysts are considered benign, meaning they are not cancerous. Studies suggest that Tarlov cysts are relatively common, affecting about 5% to 9% of the general population. However, only a small percentage of these individuals, estimated to be less than 1%, ever develop symptoms. For those who do, symptoms usually arise when the cyst grows large enough to press on the surrounding nerves. The exact reason why Tarlov cysts form is not fully understood. They are distinct from other types of spinal cysts because they involve the nerve root itself. Understanding their nature is key to managing any potential symptoms they might cause.

Symptoms

Most Tarlov cysts do not cause any symptoms. However, if a cyst grows large enough to press on a nerve, it can lead to pain, numbness, or weakness in the lower back, buttocks, or legs. Symptoms can vary widely among individuals and often worsen with certain activities or positions.

When Tarlov cysts do cause symptoms, the most common complaint is pain. This pain can occur in the lower back, buttocks, or the back of the legs. Some people describe it as a dull ache, while others experience sharp, shooting pain. The pain may also radiate down the leg, similar to sciatica. Beyond pain, other symptoms can include numbness, tingling, or a pins-and-needles sensation in the legs, feet, or perineum (the area between the genitals and anus). Muscle weakness in the legs or feet may also occur. In some cases, large cysts can press on nerves that control bladder and bowel function, leading to difficulties with urination, frequent urges, or constipation. Sexual dysfunction is also possible. Symptoms often get worse with activities like standing, walking, coughing, or sneezing. Sitting for long periods can also aggravate the pain. Many people find some relief when lying down. The severity of symptoms can fluctuate, with periods of worsening and improvement.

Causes & risk factors

The exact cause of Tarlov cysts is not fully known, but they are thought to be present from birth (congenital) in many cases. While not a direct cause, some theories suggest that trauma, injury, inflammation, or bleeding in the spine might trigger symptoms or cyst enlargement in individuals who already have these cysts.

Tarlov cysts are often considered congenital, meaning they are present at birth. However, they may not cause symptoms until later in life, if at all. The reason why some people develop symptoms while others do not remains unclear. While the cysts themselves may be congenital, certain events are believed to potentially contribute to their enlargement or the onset of symptoms. These include physical trauma or injury to the spine, inflammation in the spinal area, or bleeding (hemorrhage) within the cyst or surrounding tissues. However, these are considered potential triggers rather than direct causes of the cysts forming. Currently, there are no specific risk factors, such as age, gender, or lifestyle choices, that are definitively linked to developing symptomatic Tarlov cysts. Research continues to explore the underlying mechanisms and potential triggers for these cysts.

How it's diagnosed

Tarlov cysts are often discovered by chance during imaging tests, such as an MRI, performed for other reasons. If symptoms suggest a cyst, a doctor will conduct a physical exam and neurological assessment. Magnetic resonance imaging (MRI) is the preferred method to confirm the diagnosis and evaluate the cyst's size and location.

When a person experiences symptoms that could be related to a Tarlov cyst, a doctor will typically start with a thorough physical examination. This includes a neurological assessment to check reflexes, sensation, and muscle strength in the legs and feet. The doctor will also ask about your medical history and the nature of your symptoms. The most effective way to diagnose Tarlov cysts is through imaging studies. Magnetic resonance imaging (MRI) of the spine is the gold standard. An MRI can clearly show the fluid-filled cysts and their relationship to the nerve roots and surrounding spinal structures. It helps differentiate Tarlov cysts from other spinal conditions that might cause similar symptoms, such as herniated discs or spinal stenosis. Sometimes, a computed tomography (CT) myelogram may be used. This involves injecting a contrast dye into the spinal canal before a CT scan, which can help visualize the cysts and any leakage of cerebrospinal fluid. Electromyography (EMG) and nerve conduction studies (NCS) might also be performed to assess nerve function and identify which nerves are affected.

Treatment options

Treatment for Tarlov cysts depends on whether they are causing symptoms. Asymptomatic cysts usually do not require treatment. For symptomatic cysts, initial approaches focus on managing pain. More invasive options, such as draining the cyst or surgery, are considered for severe, persistent symptoms that do not respond to conservative care.

For individuals with Tarlov cysts who do not experience any symptoms, treatment is generally not necessary. The focus is on monitoring the cyst over time if it was found incidentally. When symptoms are present, conservative treatments are usually tried first. These may include over-the-counter pain relievers, prescription pain medications, or medications specifically for nerve pain, such as gabapentin or pregabalin. Physical therapy can also help manage pain and improve mobility. Some people find relief from alternative therapies like acupuncture, though scientific evidence for these is limited. If conservative treatments are not effective, more invasive options may be considered. One approach is cyst aspiration, where a doctor uses a needle to drain the fluid from the cyst. This can provide temporary relief, but cysts often refill. To prevent refilling, fibrin glue may be injected into the cyst after aspiration. Surgery is typically reserved for severe, debilitating symptoms that have not responded to other treatments. Surgical goals include decompressing the affected nerve root by opening the cyst (fenestration) or removing it. However, surgical outcomes can vary, and there are risks involved, such as cerebrospinal fluid leaks, infection, or nerve damage. A Cochrane review noted that evidence for surgical effectiveness is limited and studies often have a high risk of bias, highlighting the complexity and uncertainty surrounding surgical interventions.

Recovery & outlook

The recovery and outlook for individuals with Tarlov cysts vary greatly depending on whether symptoms are present and how they respond to treatment. Many people with these cysts never develop symptoms and live normal lives. For those with symptoms, treatment aims to manage pain and improve quality of life, but symptoms can sometimes recur.

For the majority of people with Tarlov cysts, the outlook is excellent because they remain asymptomatic throughout their lives. These cysts are often discovered by chance and do not require any intervention. For individuals who experience symptoms, the path to recovery can be more challenging. Conservative treatments, such as pain management and physical therapy, can help many people find relief and improve their daily functioning. However, these treatments often manage symptoms rather than curing the underlying issue. If more invasive treatments like aspiration or surgery are pursued, recovery involves managing post-procedure pain and adhering to rehabilitation protocols. While some individuals experience significant relief, symptoms can sometimes recur even after successful treatment. The long-term outlook for symptomatic Tarlov cysts is highly individual. It's often considered a chronic condition that may require ongoing management to maintain comfort and function. Open communication with your healthcare provider is essential to develop a personalized management plan.

When to see a doctor

You should see a doctor if you experience new or worsening symptoms that might be related to a Tarlov cyst. These include persistent pain in your lower back, buttocks, or legs, along with numbness, tingling, or weakness. It is especially important to seek medical attention if you develop new problems with bladder or bowel control.

While many Tarlov cysts are harmless, certain symptoms warrant a medical evaluation. You should contact your doctor if you notice any of the following: * **Persistent or worsening pain:** If you have ongoing pain in your lower back, buttocks, or legs that does not improve with rest or over-the-counter pain relievers. * **Neurological changes:** New or increasing numbness, tingling, or weakness in your legs, feet, or around your perineum. * **Bladder or bowel dysfunction:** Any new difficulty controlling your bladder or bowels, such as increased urgency, incontinence, or severe constipation. These symptoms can indicate significant nerve compression and require prompt attention. These signs could suggest that a Tarlov cyst is pressing on nerves, or they might indicate another spinal condition. A healthcare professional can accurately diagnose the cause of your symptoms and recommend the most appropriate course of action.

Frequently asked questions

Are Tarlov cysts dangerous?

Tarlov cysts are generally not considered dangerous because they are benign (non-cancerous) and most do not cause any symptoms. However, if a cyst grows large enough to press on nerves, it can cause significant pain, neurological problems, and affect bladder or bowel function, which can severely impact quality of life. In these symptomatic cases, medical evaluation and treatment may be necessary.

Can Tarlov cysts go away on their own?

Tarlov cysts typically do not go away on their own. They are fluid-filled sacs that remain present on the nerve roots. While symptoms may fluctuate or even resolve temporarily, the cysts themselves usually persist. Treatment focuses on managing symptoms rather than making the cyst disappear, though some procedures aim to reduce its size or decompress the nerve.

What makes Tarlov cysts painful?

Tarlov cysts become painful when they enlarge and press on the surrounding nerve roots in the spine. This compression can irritate or damage the nerves, leading to pain, numbness, tingling, or weakness in the areas supplied by those nerves, such as the lower back, buttocks, and legs. The fluid pressure within the cyst can also contribute to discomfort.

Is surgery always needed for Tarlov cysts?

No, surgery is not always needed for Tarlov cysts. Most cysts do not cause symptoms and therefore do not require any treatment. For symptomatic cysts, conservative treatments like pain medication and physical therapy are usually tried first. Surgery is typically considered only for severe, persistent symptoms that have not responded to other treatments, due to the potential risks involved.

Can Tarlov cysts cause headaches?

While not a common symptom, Tarlov cysts can sometimes be associated with headaches, particularly if there is a leak of cerebrospinal fluid (CSF) from the cyst. A CSF leak can lead to a decrease in spinal fluid pressure, which may cause headaches that worsen when sitting or standing and improve when lying down. This is a less frequent presentation but can occur.

How common are Tarlov cysts?

Tarlov cysts are relatively common. Studies suggest that they may be present in about 5% to 9% of the general population. However, it's important to note that the vast majority of these cysts are asymptomatic, meaning they do not cause any problems or symptoms. Only a small fraction, estimated to be less than 1% of those with cysts, ever develop symptoms requiring medical attention.

Sources

• MedlinePlus — Tarlov Cyst
• Mayo Clinic — Tarlov Cyst
• Cochrane Library — Tarlov Cyst