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Tarlov cyst

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Tarlov cysts, also known as perineural cysts[1], are cerebrospinal fluid (CSF) filled sacs located in spinal canal of S1 to S4 region of vertebrae and can be distinguished from other meningeal cysts by nerve-fiber filled walls. Tarlov cysts are defined as cysts formed within the nerve root sheath at dorsal root ganglion.[2] The cause of formation for these cysts are not clear, and the current theories explaining this phenomenon have not been tested or challenged.

Tarlov cysts are relatively common when compared to other neurological cysts, but they are usually asymptomatic. These cysts are often incidentally detected via MRI or CT scans when patients are under examination for other medical reasons. Cysts with diameter of over 1.5 cm are more likely to be symptomatic, and surgical treatment should be considered if all symptom relieving options have been exhausted. No current treatment had promised to be effective due to the unclear pathogenesis and pathophysiology of Tarlov cysts. Current treatment options includes extraction of CSF, complete/partial removal of cysts, fibrin glue therapy, as well as others surgical methodologies.

Classification

Tarlov cysts are considered Type II leisons and are defined as extradural meningeal cysts with nerve fibers.[3] Nabors and al classified Arachnoïd cysts according to three types:

- Type I : extra-dural, no nerve roots or rootlets such as intra-sacral méningocèles, probably from congenital origin, that develop from the dural bag to which they are connected by a little collar. They are found at the very place where a dorsal nerve root comes out the dural bag. They are sometimes difficult to be precisely identified and can be “seen” as a type II cyst on pictures. These ones are often associated with some foramina hole enlargement, and with a scalloping of the vertebrae. It is very important to distinguish them from the sacral meningocelaes going to the pelvis area et very often associated with other congenital abnormalities ( teratomes, dermoïdes, lipomes, and other abnormalities( uro-genital and ano-rectal) - Type II: Extra-dural with a nerve root inside (such as Tarlov or perineural cysts). There are very often not only one but multiple and mostly found in the sacrum area. There are of two kinds: Tarlov (perineural) cysts are after the posterior root ganglion, with nerve fibres inside or nerve tissue in the walls, they are not communicating with the perineural arachnoïdian space. They normally are very small in the upper rachidian part, but can be bigger (to 3cm) when located in the lower part of the sacrum. The second kind in this type is meningeal diverticulaes. They are located before the nerve root ganglion, with nerves fibres inside and are largely communicating with the subarachnoïdian space. 75% of all extra dural cysts (except for Tarlov cysts) are located in the thoracic area, 20% in the lumbar and sacral area, and 5% in the cervical area. Most of them are located behind or on the side of the dural bag. 50% can spread towards the foramina hole. They are large, communicating with subarachnoïdian spaces, and can be large enough to extend to 6 vertebrae levels. There is bone erosion in the foramina hole, or rachidian canal with enlargement for most of extra dural cysts. - Type III: intra-dural, congenital or made because of traumas…and are rarely associated with other abnormalities. They are very rare. 75% are found in the dorsal area. Most of the congenital ones are located behind the spinal cord on the contrary of those happening because of a trauma…that mostly are located anterior to the spinal cord.


T [3][4]

Characteristics and Symptoms

Physical Characteristics

Appearance

The walls of Tarlov cysts are thin and fibrous; they are prone to rupture if touched, making surgery difficult. The nerve fibers that are embedded in the walls of the cysts has the appearance and size of dental floss, and these nerve fibers are usually not arranged in any specific alignment.[5] Histologic examination reveals the Tarlov cyst outer wall is composed of vascular connective tissue, and the inner wall is lined with flattened arachnoid. In addition, part of the lining containing nerve fibers also occasionally contains ganglion cells.[6] The cysts can contain anywhere from a couple milliliter of CSF to over 2.5 liters liters of CSF.[5][7][8].

Location

Tarlov cysts are located in the S1 and S4 region of the spinal cord. 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 [9]. Occasionally, these cysts are observed in the thoracic spine.[6] However, these cysts most commonly arise at the S2 or S3 junction of the dorsal nerve root ganglion.[4][10] 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.[11]. 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 3 - 4 cm. 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.[3] Although the definitions for each entity are still controversial, the following items are generally accepted.

Tarlov Cyst Meningeal Diverticula & Arachnoid Diverticula
Only potential communication with spinal subarachnoid space Communicates freely with spinal subarachnoid space
Delayed filling in myelograms Rapid filling of myelograms
Found distal to the junction of posterior nerve root and dorsal root ganglian in sacral region Found proximal to dorsal root ganglion throughout vertebral column
Walls contain nerve fibers Walls lined by arachnoid mater with no signs of neural element
Often form in pleural, extending around the circumference of nerve root No pattern of formation in regards to numbers

Symptoms

Tarlov cysts are often asymptomatic; the cases of reported symptomatic Tarlov cysts ranges from 15% to 30% of the overall reported Tarlov Cyst Cases depending on the source of literature. Nevertheless these cysts are important clinical entities because of its tendency to increase in size over time, potentially causing complications and eroding the surrounding bone tissue[4][11][12]. Patients with symptomatic Tarlov cysts can be divided into 4 categories according to their experienced symptoms[5]:

  • 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

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

Backpain, perineal pain, Sciatica, Cauda Equina syndrome, dysuria, urinary incontinence, coccygodynia, sacral radiculopathy, radicular pain, headaches, retrograde ejaculation, paresthesia, hypesthesia, motor disorders in lower limbs and the genital, perineal, or lumbossacral areas, sacral or buttocks pain, vaginal or penile paraesthesia, sensory changes over buttocks, perineal area, and lower extremity [4][6][11][13] Difficulty walking, Severe lower abdominal pain

Etiology/Causes

Theory of Cystic Formation

There are several hypotheses proposed regarding the formation of Tarlov cysts, including: inflammation within the nerve root cysts followed by inoculation of fluids, developmental or congenital origin, arachnoidal proliferation along and around the exiting sacral nerve root, and breakage of venous drainage in the perineuria and epineurium secondary to hemosiderin deposition after trauma.[9] Tarlov himself theorized that the perineurial cysts form as a result of blockage of venous drainage in the perineurium and epineuriium secondary to hemosiderin deposition after local trauma.[11][14] Another theory gaining increasing popularity over the past decade is one postulated by Fortuna et al.; it described perineurial cysts to be the results of congenital arachnoidal proliferation along the exiting sacral nerve roots.[7] The cause of these cysts are still unknown and the proposed theories have not been tested or challenged.[5]

Theory of Cystic Enlargement

Tarlov cysts are known to have the tendency to enlarge over time. The prominent theory that explains this phenomenon reasons the enlargement of the cysts is due to the cerebrospinal fluid being pushed into the cyst during systole pulsation but unable to get out during diastole, resulting in enlargement over time. However, this theory has yet to be tested. Although growth in the cysts occur, it is still unknown to how often, or at what condition these cyst form, or if any underlining condition is essential for the formation and enlargement of these cysts. Many patients have been diagnosed for 20 years, showing a very thin sacrum bone "protecting" a large meningeal cyst. MRIs regularly made do not show any enlargement or any change.The "erosion" theory might be a "simplification" in regard of the life of a bony structure. Another view is that the shape of the bone, according to the fact that between the bone and the cyst strong and solid ligaments are existing,that the walls of the cysts are very fragile compared to ligaments and bones, when looking "eroded" means a congenital cyst or that was formed before the person to be about 25 years old. There are many people having cysts and no remodelling of the bone: neuroradiologist tell that those are due to a cause that took place when older than 25 years old (see behind)

Bone Development and Structure

Because bone is made up of minerals and is hard, many people think that it is not living material. But a bone in a living animal consists of both living tissue and non-living substances. Within the "alive bone" are blood vessels, nerves, collagen, and living cells including: • osteoblasts (cells that help form bone), and • osteoclasts (cells that help eat away old bone). In addition, bone contains cells called osteocytes, which are mature osteoblasts that have ended their bone-forming careers. These cells engage in metabolic exchange with the blood that flows through the bones. The nonliving, but very important, substances in bone are the minerals and salts. Besides the metabolically active cellular portion of bone tissue, bone is also made up of a matrix (a bonding of multiple fibers and chemicals) of different materials, including primarily collagen fibers and crystalline salts In particular, it is the collagen fibers and the calcium salts that help to strengthen bone. In fact, the collagen fibers of bone have great tensile strength (the strength to endure stretching forces), while the calcium salts, which are similar in physical properties to marble, have great compressional strength (the strength to endure squeezing forces). These combined properties, plus the degree of bondage between the collagen fibers and the crystals, provide a bony structure that has both extreme tensile and compressional strength . Thus, bones are constructed in exactly the same way that reinforced concrete is constructed. The steel of reinforced concrete provides the tensile strength, while the cement, sand, and rock provide the compressional strength. However, the compressional strength of bone is greater than that of even the best reinforced concrete, and the tensile strength approaches that of reinforced concrete. But, even with their great compressional and tensile strengths, neither bone nor concrete has a very high level of torsional strength (the strength to endure twisting). In fact, bone fractures often occur as a result of torsional forces that are exerted on an arm or a leg.


.[5] The Blood Theory


Many authors state that The blood, and breakdown products, acting as a foreign body substance in the subarachnoid space produce local adhesive arachnoiditis with no symptoms but can also create cystic degeneration. . The subarachnoid space abhors all foreign body substances. Even the presence of injected air is considered to be a "foreign body." Blood is definitely considered a foreign body (particularly the breakdown products of blood). Repeat exposure to foreign body substances in the subarachnoid space can initiate auto-immune amnestic reactions which may potentiate and magnify the ongoing inflammatory process.



Few clinicians appreciate that significant pathologic change can occur unaccompanied by clinical symptoms because of the body's remarkable ability to adjust to, and compensate for, slowly occurring insult. This is particularly true of nervous system which does not respond well to acute change or acute insult (i.e. sudden trauma, acute intracranial haemorrhage or acute rupture of an aneurysm). The ability of the body to compensate is an important reason why most individual afflicted with adhesive arachnoiditis have few in the way of clinical symptoms. This state is, however, a tenuous one, which can change dramatically with only minimal additional insult, mostly when the individual is also afflicted of meningeal (arachnoïd or Tarlov cysts).



We also live in a medical era where frequent (inadvertent) lumbar punctures are performed by ill-advised blind-technique in cases of attempted epidural steroid administration or epidural anaesthesia..

It is not unusual for patients to experience, as a complication of spinal tap, continued leakage of cerebro-spinal fluid producing postural headache, light-headedness and inability to function due to these complaints. The commonly employed treatment for this is a "blood patch." Blood drawn from a vein is purposely injected into the supposed epidural space as a means of "patching" the leaking fluid.

Appropriate blood patches routinely introduce some blood into the subarachnoid space and inappropriate ones may introduce as much as 10-12cc of blood directly into the subarachnoid space. How much blood, introduced how often, is necessary to create adhesive arachnoiditis? This question has not yet been answered. We only know at this point in time, that blood, and its breakdown products, can serve to create adhesive arachnoiditis and the introduction of any foreign body substance (for any purpose) into the subarachnoid space is not a wonderful idea.


Not to forget to mention that arachnoïd cysts, meningeal cysts are very frequently induced by a dormant Arachnoïditis and that only that area of the spine, where the “cysts” are can be the cause for neuropathic pain and a limitation of functions syndrome.( Charles Burton-The Burton report http://www.burtonreport.com/ , Dr Sarah Fox http://www.theaword.org/,Dr Aldrete - Arachnoïditis: The evidence revealed jan.2010, editorial Allil ISBN 978-607-7504-25-2)

Detection

Two most commonly used and effective examination method for Tarlov Cysts are MRI and CT. Both CT and MRI are good imaging procedures that allow the detection of extradural spinal masses such as Tarlov cysts. In fact, most of the cysts are asymptomatic and are found incidentally during CT or MRI examinations for other reasons.[13]

MRI

MRI, or Magnetic Resonance Imaging, is considered the imaging study of choice in identifying Tarlov cysts. MRI provides better resolution of tissue density, absence of bone interference, multiplanar capabilities, and is noninvasive. Plain films may show bony erosion of the spinal canal or of the sacral foramina On MRI pictures, the signal is the same as the CSF one.

If MRI made with a contrast medium:

- The signal in the cyst is the same as in the dural bag. - The signal for cysts due to traumas…is a little stronger at the periphery or nerve root location - The signal is more important for other causes: synovial cysts, dermoïdes or épidermoïdes cysts, teratomes…

From : “Imagerie par Résonnance Magnétique de la Tête et du rachis »

Case 87,93 : kystes méningés rachidiens, pages 684 et 685

Par Jean Claude Tamraz, C. Outin, M. Forjaz Secca - 2004 - Medical - 717 pages

Editeur : Springer Verlag

Principes d'imagerie par résonance magnétique de la tête, de la base du crâne et du rachis Approche anatomo-clinique et guide d'interprétation Tamraz, J., Outin, C., Forjaz Secca, M., Soussi, B. 2ieme ed. revue et augmentée, 2004, XII, 717 p., Broché ISBN: 978-2-287-59742-8 .[6]

CT

CT, or computed tomography scan is another examination method often used for the diagnosis of Tarlov cyst. Unenhanced CT scans may show sacral erosion, asymmetric epidural fat distribution, and cystic masses that are have the same density with CSF [6]. CT Myelogram is minimally invasive [15], and could be employed when MRI cannot be performed on patient.

Misdiagnosis

The term Tarlov cysts, or 'sacral perineurial cyst', has often been misused for referring to other cystic lesions in the sacral region. Tarlov cysts are often detected through MRI or CT Myelography; these tools are very useful in spotting cysts at the region, but they cannot distinguish one major difference between Tarlov cysts and other cysts - the fact the walls contains nerve fibers. Therefore, the final diagnosis of a Tarlov cyst is not a radiological but rather a histopathological diagnosis [9] These cysts are sometimes also misdiagnosed as lumbar disc herniation or lumbar spinal stenosis, especially when they are pressing on the S-1 nerve root [14].

Treatment

Because of the unclear pathogenesis and pathophysiology of Tarlov cysts, there is no consensus on the optimal treatment of symptomatic sacral perineurial cysts. There are a few treatments available for alleviating the symptoms caused by these cysts, but their effectiveness are debatable. Therefore, operative criteria for regarding Tarlov cysts includes: 1) MRI results indicating the existence of sacral perineural cyst; 2) the diameter of cyst is more than 1.5 cm; 3) neurological symptoms and signs attributed to sacral perineural cysts that are serious enough to warrant treatment; 4)no or little response to medical and physical therapy and 5) no contraindications for the surgery.[9] The two major treatment types are the extraction of cerebrospinal fluids from the cyst, and the complete/partial removal of cyst from infected area. But because the cyst walls are lined with nerves, this may not be an option. The morbidity has been seen to be higher on patients that have bilateral cysts on the same spinal level. It had been reported that a positive filling defect and larger cyst size (>1.5 cm) is a good indicator for successful treatment outcome.[5][7][9] Although fibrin glue therapy had been proved to be a promising therapy in the treatment of these cysts, there have been cases of the fibrin seeping back up into the spine affecting other nerves. It is not recommended for use at present in by the Health Department in some countries. Nevertheless, all types of surgical treatment poses common risks, including neurological deficits, infection and inflammation, spinal headache, urinary disturbances, and leakage of cerebrospinal fluids.

References

  1. ^ Ju CI, Shin H, Kim SW, Kim HS (2009). "Sacral perineural cyst accompanying disc herniation". J Korean Neurosurg Soc. 45 (3): 185–7. doi:10.3340/jkns.2009.45.3.185. PMC 2666123. PMID 19352483. Retrieved 2010-04-09. {{cite journal}}: Unknown parameter |month= ignored (help)CS1 maint: multiple names: authors list (link)
  2. ^ Goyal RN, Russell NA, Benoit BG, Belanger JM. Intraspinal cysts: a classification and literature review. Spine 1987;12:209-213
  3. ^ a b c Nabors MW, Pait TG, Byrd EB, et al. Updtated Assessment and Current Classification of Spinal Meningeal cysts. J Neurosurg. 1988;68:366-377
  4. ^ a b c d Singh, P. K., Singh, V. K., Azam, A., & Gupta, S. (2009). Tarlov Cyst and Infertility. Journal of Spinal Cord Medicine, 32(2), 191-197.
  5. ^ a b c d e f “Donlin Long., The Johns Hopkins Hospital Dept. of Neurosurgery, interviewed by Hsuan Chen, Oct. 6th, 2009.”
  6. ^ a b c d e Nadler, S. F., Bartoli, L. M., Stitik, T. P., & Chen, B. Q. (2001). Tarlov cyst as a rare cause of S1 radiculopathy: A case report. Archives of Physical Medicine and Rehabilitation, 82(5), 689-690.
  7. ^ a b c Tanaka, M., Nakahara, S., Ito, Y., Nakinishi, K., Sugimoto, Y., Ikuma, H., et al. (2006). Surgical results of sacral perineural (Tarlov) cysts. Acta Medica Okayama, 60(1), 65-70.
  8. ^ Ishii, K., Yuzurihara, M., Asamoto, S., Doi, H., & Kubota, M. (2007). A huge presacral Tarlov cyst - Case report. Journal of Neurosurgery-Spine, 7(2), 259-263.
  9. ^ a b c d e Guo, D. S., Shu, K., Chen, R. D., Ke, C. S., Zhu, Y. C., & Lei, T. (2007). Microsurgical treatment of symptomatic sacral perineurial cysts. Neurosurgery, 60(6), 1059-1065.
  10. ^ Hefti, M., & Landolt, H. (2006). Presacral mass consisting of a meningocele and a Tarlov cyst: successful surgical treatment based on pathogenic hypothesis. Acta Neurochirurgica, 148(4), 479-483.
  11. ^ a b c d Tarlov, I. M. (1970). Spinal Perineurial and Meningeal Cysts. [Journal]. J. Neurol. Neurosurg. Psychiat., 33, 10.
  12. ^ Tarlov, I. M. (1953). Sacral Nerve-Root Cysts- Pathogenesis and Clinical Significance. Journal of Nervous and Mental Disease, 117(2), 3.
  13. ^ a b Moldes, M. R., Rodriguez-Losada, J. S., Garcia, D. L., Agudo, V. C., Pais, J. M. J., & Martin, M. G. (2008). Tarlov Cyst and Symptomatic Bladder Disfuction. Actas Urologicas Espanolas, 32(10), 1035-1036.
  14. ^ a b Tao Zhang, Zhenhua Li, Weiming Gong, Bingwei Sun, Shuheng Liu, Kai Zhang, Dezhen Yin, Peng Xu, Tanghong Jia (2007) Percutaneous Fibrin Glue Therapy for Meningeal Cysts of the Sacral Spine with or without Aspiration of the Cerebrospinal Fluid. J Neurosur Spine 7: 145-150
  15. ^ Lee, J. Y., Impekoven, P., Stenzel, W., Lohr, M., Ernestus, R. I., & Klug, N. (2004). CT-guided percutaneous aspiration of Tarlov cyst as a useful diagnostic procedure prior to operative intervention. Acta Neurochirurgica, 146(7), 667-670.
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