Tarlov Cysts

Tarlov cysts, are type II innervated meningeal cysts, cerebrospinal-fluid-filled (CSF) sacs most frequently located in the spinal canal of the sacral region of the spinal cord ( S1– S5) and much less often in the cervical, thoracic or lumbar spine. They can be distinguished from other meningeal cysts by their nerve-fiber-filled walls. Tarlov cysts are defined as cysts formed within the nerve-root sheath at the dorsal root ganglion. The etiology of these cysts is not well understood; some current theories explaining this phenomenon have not yet been tested or challenged but include increased pressure in CSF, filling of congenital cysts with one-way valves, inflammation in response to trauma and disease. They are named for American neurosurgeon Isadore Tarlov, who described them in 1938.

Tarlov cysts are relatively uncommon when compared to other neurological cysts. Initially, Isadore Tarlov believed them to be asymptomatic, however as his research progressed, Tarlov found them to be symptomatic in a number of patients. These cysts are often detected incidentally during MRI or CT scans for other medical conditions. They are also observed using magnetic resonance neurography with communicating subarachnoid cysts of the spinal meninges. Cysts with diameters of 1 cm or larger are more likely to be symptomatic; although cysts of any size may be symptomatic dependent on location and etiology. Some 40% of patients with symptomatic Tarlov cysts can associate a history of trauma or childbirth. Current treatment options include CSF aspiration, fibrin-glue therapy, laminectomy with wrapping of the cyst, among other surgical treatment approaches. Interventional treatment of Tarlov cysts is the only means by which symptoms might permanently be resolved due to the fact that the cysts often refill after aspiration. Tarlov cysts often enlarge over time, especially if the sac has a check valve type opening. They are differentiated from other meningeal and arachnoid cysts because they are innervated and diagnosis can in cases be demonstrated with subarachnoid communication.

Tarlov perineural cysts have occasionally been observed in patients with Marfan syndrome, Ehlers–Danlos syndrome, and Loeys–Dietz syndrome.

Signs and symptoms

Appearance

Walls of Tarlov cysts are thin and fibrous; they are prone to rupture if touched, making surgery difficult. The nerve fibers embedded in the walls of the cysts have the appearance and size of dental floss; these nerve fibers are usually not arranged in any specific alignment."Donlin Long., The Johns Hopkins Hospital Dept. of Neurosurgery, interviewed by Hsuan Chen, Oct. 6th, 2009." Histologic examination reveals the Tarlov-cyst outer wall is composed of vascular connective tissue, and the inner wall is lined with flattened arachnoid tissue. In addition, part of the lining containing nerve fibers also occasionally contains ganglion cells. The cysts can contain anywhere from a couple of milliliters of CSF to over of CSF.

Location

Tarlov cysts are most commonly located in the S1 to S4/S5 region of the spinal canal, but can be found along any region of the spine. They usually form on the extradural components of sacrococcygeal nerve roots at the junction of dorsal root ganglion and posterior nerve roots and arise between the endoneurium and perineurium. Occasionally, these cysts are observed in the lumbar and thoracic spine. However, these cysts most commonly arise at the S2 or S3 junction of the dorsal nerve root ganglion. The cysts are often multiple, extending around the circumference of the nerve, and can enlarge over time to compress neighboring nerve roots, to cause bone erosion. The cysts may be found anterior to the sacral area and have been known to extend into the abdominal cavity. These cysts, though rare, can be found to grow large - over in size, often causing severe abdominal pain from compression on the cyst itself as well as adjoining nerves.

Difference between Tarlov cysts and other spinal meningeal cysts

The following table is compilation of some key differences between Tarlov cysts, meningeal cysts, and arachnoid diverticula cysts. Although the definitions for each entity are still controversial, the following items are generally accepted.

Symptoms

Tarlov cysts are likely highly underdiagnosed as it was Isadore Tarlov's later research that led him to the understanding of their symptomology. Symptoms are based on the locations of the cysts along the spine, and follow general pathology of spinal injury:
* Pain
* Paresthesia
* Spasticity, Hypertonia
* Muscular Dysfunction or Weakness
* Radiculopathy

Although they are most frequently reported along sacral regions, they are rarely seen in other locations along the spine. Women are more likely to exhibit symptoms uri=https://rarediseases.org/rare-diseases/tarlov-cysts/ access date: September 17, 2015uri=http://www.marianjoy.org/Research/documents/PDFs/2014/Dugan_TarlovCystsFinal2.20.pdf They can also appear in clusters or bilaterally along the spine, thus symptoms can be unilateral, bilateral, or with symptoms more dominant on one side. The cases of reported symptomatic Tarlov cysts ranges from 15% to 30% of the overall reported Tarlov cyst case, depending on the source of literature. Nevertheless, these cysts are important clinical entities because of their tendency to increase in size over time, potentially causing complications and eroding the surrounding bone tissue. Patients with symptomatic Tarlov cysts near the sacrum (and not other locations of the spine) can be divided into 4 categories, according to their experienced symptoms:
* Group 1 - Pain on tailbones that radiates to the legs with potential weakness;
* Group 2 - Pain on bones, legs, groin area, sexual dysfunctions, and dysfunctional bladder;
* Group 3 - Pain that radiate from the cyst site across hips to the lower abdomen;
* Group 4 - No pain, just sexual dysfunction and dysfunctional bladder.

Common symptoms specific to sacral Tarlov cysts

Below are a list of commonly reported symptoms associated with sacral Tarlov cysts:

Back pain, perineal pain, secondary Sciatica, secondary piriformis muscle dysfunction with tertiary sciatica, Cauda equina syndrome, neurogenic claudication (pain caused by walking), neurogenic bladder, dysuria, urinary incontinence, coccygodynia, sacral radiculopathy, radicular pain, headaches, retrograde ejaculation, paresthesia, hypesthesia, secondary pelvic floor dysfunction, vaginismus, motor disorders in lower limbs and the genital, perineal, or lumbosacral areas, sacral or buttocks pain, vaginal or penile paraesthesia, Persistent Genital Aro