Overview

Tarlov Cysts (TC), or perineural cysts, are sacs filled with Cerebrospinal Fluid (CSF) that form in your spine. Tarlov cysts are non-cancerous and most often asymptomatic. However, when they are compressing or distorting nerve fibres, they can cause debilitating symptoms. TCs are reported more often in people assigned female at birth (AFAB) than in people assigned male at birth (AMAB). The probability of experiencing this condition also increases with age, with the average age of patients being 40 to 50 years. TCs are more likely to form in the sacral region of your spine, where they may damage the nerves responsible for leg, pelvis and buttock sensations.¹ Tarlov Cysts are a rare condition and may be overlooked as a potential cause of chronic pain.² In cases of symptomatic TCs, treatments range from anti-inflammatory medications to open surgery. 

What Is a Tarlov Cyst?

A Tarlov Cyst is a pocket of tissue filled with CSF that forms on the nerve root sleeves of the spine. TCs usually appear in the sacral region of the spine (the tail end of your spinal cord). Still, they can also manifest in the lumbar³ and cervical^4,5 spine. A TC always has a spinal nerve root within its cavity or walls.⁶ The nerve root that is more likely to be affected is the dorsal nerve root, which is responsible for sensory signals.²

TCs often come in multiples and vary in size. The average diameter ranges from 5 to 30 mm, and the size and number increase with age.

Causes 

The causes behind TC formation remain largely unclear. It also remains unclear why only a small number of people with TCs become symptomatic. However, the medical community generally agrees that TCs originate from an increased CSF pressure in the spine, which encourages the nerve root sleeve to distort and dilate. The distortion may create areas for CSF to pool in specific areas, leading to cyst formation.¹

Valved versus non-valved 

Depending on concurrent factors and events, a cyst might develop to be either valved or non-valved. This characteristic will determine treatment options and might also impact the symptoms' severity, timing, and progression.² A non-valved cyst has a wide neck, allowing the flow of CSF in and out of the cyst. Valved cysts, on the other hand, have a narrow neck, and the CSF flow is unidirectional–the fluid can enter the cavity but can’t leave it.¹

Contributing factors

Some conditions may predispose a patient to develop TCs. Specifically, conditions that weaken connective tissue can facilitate their appearance. With weaker connective tissues, the dural sac, which envelops the spine and holds CSF, can expand more easily in response to increased CSF pressure. 

Studies associate TC with the following connective tissue disorders:

• Loeys-Dietz Syndrome 
• Marfan Syndrome 
• Ehler-Danlos syndromes¹ 

The presence of other spinal conditions, such as bulging or herniated discs, can also exacerbate the symptoms of TC.⁷ 

Symptomatic Tarlov Cysts

Tarlov Cysts are a rare condition. They are found accidentally in 2-6% of all spinal Magnetic Resonance Imaging (MRI) studies. Within that small percentage, only 13-22% of TC patients are symptomatic. However, when symptoms do arise, they can severely impact a patient's quality of life. 

As different dorsal nerve roots along the spine carry sensory information for different portions of the body, symptoms will vary depending on the position of the TC along the spine.

TCs in the sacral spine are the most common and often produce the following symptoms: 

• Pelvic pain or numbness
• Chronic lower back pain
• Radicular pain in the buttock and leg
• Worsening of pain while sitting or standing: these positions may increase local CSF pressure near the sacrum, further activating the ball-valve mechanism⁸
• Bladder dysfunction leading to increased urinary urgency and incontinence
• Bowel dysfunction leading to faecal incontinence 
• Sexual dysfunction¹

The sensory symptoms mentioned above are likely caused by TCs’ characteristic positioning at the dorsal nerve root. In your body, the dorsal nerve roots carry sensation signals. In contrast, the ventral roots control your motor (movement) abilities. Since TCs usually protrude near the dorsal roots, the most common symptoms of TCs tend to be pain, numbness, and “pins and needles” (paresthesia).²

Symptoms of TC usually begin in the 4th and 5th decades of a patient’s life and can persist for years or even decades. This degree of chronic pain and constant discomfort can lead TC patients to develop secondary symptoms of mood disorders, such as depression.⁹

Diagnosis

Identifying a TC is very straightforward and can be done through an MRI. However, diagnosing TC as a cause for neurological symptoms can be tricky. The challenge comes from a combination of reasons:

• Symptomatic TC is often present with other spinal conditions, such as disc herniation⁹
• Symptomatic TCs share features with many other conditions, such as cauda equina syndrome and spinal malignancies⁶
• Most TCs are asymptomatic, leading healthcare providers to believe that other comorbid conditions are the actual cause² 

Your healthcare provider usually does an initial assessment by discussing your medical history and symptoms. 

MRI scans of both the lumbar and sacral areas are used to assess the health of the lower spine. MR images help to find any potential cysts, along with any other spinal conditions that might be causing your symptoms. 

If TCs in your spine are identified as a potential cause of nerve damage, your doctor might also request a Computed Tomography (CT) Myelogram. CT Myelograms can track the flow of CSF in the cyst and determine whether your TCs are valved. This detail helps in the design of targeted treatment plans and in lowering the risks of post-treatment complications.¹ 

Both imaging techniques can also reveal any potential structural damage done by the cyst, such as bone erosion.¹⁰

Ruling out other conditions 

The symptomatic presentation of TC is very similar to other neuropathies, some of which do not originate in the spine. For this reason, medical specialists suggest combining diagnostic methods to identify any symptomatic correlations with TCs. Healthcare professionals may perform electrophysiological exams to check for the location and extent of the nerve injuries.² They might also inject your TCs with anesthetics or aspirate the cyst fluid to see if the symptoms alleviate.¹

Treatment options

Due to the rarity of the condition, there is no existing standard on the appropriate treatment for TC. Reported treatments vary depending on the severity of the symptoms, cyst characteristics (valved or non-valved), and any coexisting health conditions. 

Non-surgical treatments

Conservative options tend to be the first line of treatment for most TC patients.¹¹ These treatments are also preferred for mild symptoms or when patients refuse surgical interventions.¹ Previously employed treatments include: 

• Pain relief medication: non-steroidal anti-inflammatory and neurotrophic drugs may help reduce irritation or inflammation of the affected nerves, potentially alleviating symptoms⁶
• Physical Therapy: exercises that improve range of motion and mobility have been proven effective to help with some instances of symptomatic TC⁴ 
• Lifestyle Adjustments: in specific cases, weight has been identified as a symptom aggravator for TC. A combination of Keto Diet and physical activity was proven helpful in improving a TC patient’s quality of life, by enhancing their mobility, sleep, and mood, which in turn contributed positively to their pain management¹²

It must be noted that, while the least invasive, these treatment options are also the least effective, with some patients reporting higher pain levels following these therapies.¹¹

Minimally invasive procedures

Minimally invasive procedures involve microsurgeries done through the skin using needles (percutaneous). These treatments have the benefit of a lower risk of post-surgical complications than open surgeries.

Cyst aspiration, followed by injecting an adhesive, is the most common minimally invasive treatment. In this procedure, the CSF is aspirated from the cyst through a needle. The cyst is then closed with a sealant to prevent CSF from re-entering. 

The common risks of this treatment include CSF leakage from the cyst area, temporary sciatica and allergic responses to the sealant. There is also a risk of cyst recurrence due to the breakdown of the sealant over time.¹

Surgical options

Surgeons tend to perform a combination of open surgeries on a single TC to produce the optimal outcome. Some of the methods attempted include:

• Cyst resection: the cyst is removed completely
• Cyst fenestration: communication between the cyst’s cavity and the subarachnoid space is opened, rendering it a non-valved cyst
• Cyst imbrication: the cyst is “flattened” by folding it internally (towards the neck) and sutured it into place

Most of these surgical options begin with a sacral laminectomy, where a portion of the vertebra is removed to provide space to operate on the cyst. 

Open surgical treatment is reported to have the same success rate as minimally invasive percutaneous treatments (70-80%), but the risks tend to be greater. Patients have reported post-op symptoms such as bladder dysfunction or incontinence.⁸

Summary 

Tarlov cysts are rare, fluid-filled sacs that form along the spine's nerve roots, commonly in the sacral region. They are usually asymptomatic, but they can cause significant pain and neurological symptoms when they compress surrounding nerves. If you are dealing with symptomatic TCs you might be experiencing pain in the lower back, genital area, legs and potential bladder dysfunction. Because of their overlap with other spinal conditions, the diagnosis of symptomatic TCs can be challenging. Still, the development of targeted testing is facilitating this condition’s recognition. Treatments vary from conservative pain management to surgical intervention, depending on the cyst's characteristics and the severity of symptoms. As awareness and understanding of TC grow, timely diagnosis and targeted care can significantly improve outcomes for those affected.