Tarlov cysts are formed within the nerve root sheath at the posterior root of a spinal nerve. This disease is more common in women than in men. These perineural/perineurial cysts appear as ballooned areas of the outer covering of the nerve root.
The fluid-filled abnormal sacs affect the sacral region of the spine, in particular, and are also known as sacral nerve root cysts. The cysts can form anywhere along the spine, although the base of the spine is the most common area. Some patients have cysts at many or even at all sections of the spine.
Although the root cause of Tarlov cyst disease is yet to be elucidated, there are a number of studies which suggest that the Tarlov cyst is owing to the dilation of the nerve root covering. This leads to the cerebrospinal fluid that fills the subarachnoid space (the space between the arachnoid layer and the innermost pia mater coverings of the brain and the spinal cord) becoming locked inside the perineurium to form a cyst.
Significant clinical evidence shows that patients with connective tissue disorders, for example, those with Marfan, Ehlers–Danlos, Sjogren's, and Loeys–Deitz syndromes, are at a greater risk for developing Tarlov cysts. Some other conditions such as traumatic injuries and pain in the spinal cord may also result in cyst formation.
Tarlov cyst disease is often asymptomatic. However, when the fluid in the cyst puts pressure on the nerve and the nearby nerve roots, the cyst grows in size and becomes symptomatic.
Depending on the section of the spinal column, the location, and the size of the cyst, the symptoms and severity of the condition vary across patients as follows:
- Pain in the lower back, buttocks, back of thighs, abdomen, legs, and feet
- Pain in the upper back, hands, arms, and chest
- Paresthesia/dysesthesia in the legs/feet
- Pain when sitting or standing, and sneezing or coughing
- Difficulty in emptying the bladder and sexual dysfunction
- Diminished reflexes, loss of sensation on the skin
- Chronic headaches, blurred vision, double vision, dizziness
The most commonly used methods for the diagnosis of Tarlov cysts are:
- Magnetic resonance imaging (MRI) and
- Computed tomography (CT) scan
An MRI gives a clearer picture of the cyst and surrounding nerve tissue as well as its coats, and is widely preferred. If the symptoms are related to the lower sections of the spine (as is common in most patients), then a full sacral spine MRI covering the S1–S5 vertebra up to the coccyx/tailbone is recommended. For symptoms in the upper spine (which is seen less frequently), appropriate cervical (C1–C7), thoracic (T1–T12), or lumbar (L1–L5) MRI is carried out.
CT scan employs multiple X-rays to disclose the typical bone erosion of the spine, while the cross-sectional image of the organ’s tissue structure is also visualized.
Another useful diagnostic imaging procedure is the myelogram test. The examination involves the introduction of a spinal needle into the spinal canal. The contrast fluid is injected into the subarachnoid space using real-time X-ray. It outlines the spinal cord, nerve roots, and other tissues
Asymptomatic Tarlov cyst disease should be closely monitored at frequent intervals to see if there is an increase in cyst size or if any other symptoms develop. There is no specific proven treatment for patients with symptomatic Tarlov cysts.
Treatment is patient-specific, ranging from simple drugs to complex surgery and other procedures. In general, treatments are classified as 1) nonsurgical and 2) surgical procedures.
Pain may be temporarily controlled using nonsteroidal anti-inflammatory drugs (NSAIDs), which treat nerve irritation and inflammation. Some patients may find relief immediately, whereas for others it may take some time to reap the benefits. Another proven technique in pain management is the transcutaneous electrical nerve stimulation (TENS). Electrical impulses are sent through the skin to the cutaneous and deep nerves that help control pain.
Physical therapy (PT) such as heat, ultrasound, and transcutaneous electronic stimulation are found to be very effective. However, these treatments may, like the above, work for some patients but not for others.
A minimally invasive technique, such as fibrin glue injection under C-arm fluoroscopy guidance, can be an effective procedure.
If the above forms of therapy do not yield results, surgical removal of cysts may be suggested. However, in medical literature, there are ongoing discussions about this procedure, as the cyst is a part of the nerve and therefore cannot be excised. Therefore, to treat large Tarlov cysts, they are sliced with one or more cuts and the cerebrospinal fluid is drained out.
The pooling of knowledge derived from the research and treatment of this disease by various investigators, sharing of information from procedures that are performed, studying and sharing the known side effects, and quantifying the improvement in each patient’s health will help in building effective treatment procedures. These data will provide a wealth of insights to the medical community to promote research toward determining the cause and cure of this rare disease.