What Happens In Human Spinal Cord Injuries?

NOTE: 
Below is an article I was sent that explicitly defines how Tarlov, Perineural and Menigeal Cysts form following trauma.

I am thrilled to have finally found an understandable explination as to why I have Tarlov Cysts, and how I got them from an MVA. That portion of the article is underlined for ease of use for those like me, who are, and have been searching for answers to this question.


ARTICLE:
 
Although the spinal cord is protected by the bony vertebrae of the spinal column, it can still be injured ...with disastrous consequences. According to statistics gathered in 1996 by the National Institutes of Health, more than 10,000 Americans experience spinal cord injuries each year and more than 200,000 are living with permanent paralysis in their arms or legs.

People with spinal cord injuries can also lose sensation and -- depending where along the spinal cord the injury occurs -- control over critical body functions, including the ability to breathe. And because two-thirds of spinal cord injuries occur in people who are 30 years old or younger, the resulting disabilities can affect their entire adult lives.
 
Usually, injuries to the spinal cord injuries do not result in a cut through the cord; instead, they crush the thin, fibrous extensions of nerve cells that are surrounded by the vertebrae. These extensions are called axons, the long, thin strings of nerve cell cytoplasm that carry electrical signals up and down the spinal cord. The axons of nerve cells with similar functions run in groups or pathways. Some carry sensory information upward to the brain; others run downward from the brain to control the body's movements. An injury to the spinal cord can damage a few or many of these pathways. Nevertheless, a person can often recover some functions that were lost because of the initial injury.

The damage that occurs to spinal cord axons within the first few hours after injury is complex and it occurs in stages. The normal blood flow is disrupted, which causes oxygen deprivation to some of the tissues of the spinal cord. Bleeding into the injured area leads to swelling, which can further compress and damage spinal cord axons. The chemical environment becomes destructive, due primarily to the release of highly reactive molecules known as free radicals. These negatively charged ions can break up cell membranes, thus killing cells that were not injured initially. Blood cells called macrophages that invade the site of injury to clean up debris may also damage uninjured tissue. Non-neuronal cells including astrocytes may divide too often, forming a scar that impedes the regrowth of injured nerve cell axons.

The early events that follow a spinal cord injury can lead to other kinds of damage later on. Within weeks or months, cysts often form at the site of injury and fill with cerebrospinal fluid, the clear, watery fluid that surrounds the brain and spinal cord. Typically, scar tissue develops around the cysts, creating permanent cavities that can
elongate and further damage nerve cells. Also, nerve cell axons that were not damaged initially often lose their myelin, a white, fatty sheath that normally surrounds groups of axons and enhances the speed of nerve impulses.

Over time, these and other events can contribute to more tissue degeneration and a greater loss of function. Scientists are trying to understand how this complex series of disruptive events occurs so they can find ways to prevent and treat it. They are also trying to identify treatments that will enhance some of the normal -- but often limited -- kinds of recovery that can occur after a spinal cord injury.

Another complication in spinal cord injury stems from the variety of nerve fibers and cell types that make up the tissue. In the spinal cord, axons run in bundles or pathways up and down the cord. The downward or descending pathways from the brain to the spinal cord carry nerve signals that control voluntary movements. The upward or ascending pathways carry sensory information -- about touch, temperature, pain, and body position -- from the entire body to the brain. Researchers believe that the ascending and descending pathways, as well as different groups of nerve cells (also called neurons) that lie entirely within the spinal cord, may require individualized treatments to regenerate and regain their functions.

"Do the descending motor pathways from the brain into the spinal cord need the same things [for recovery] as sensory fibers that go from the spinal cord to the brain?" asks Barbara Bregman, a neuroscientist in the department of anatomy and cell biology at Georgetown University in Washington, D.C. "It is important to know what the cells need and when they need it."

For example, if scientists are going to be able to devise ways to repair damaged spinal cord tissue, they may need to use special combinations of nourishing proteins -- called neurotrophic factors -- to help damaged axons to regrow and regain some function. The damaged cells may also require a specific environment in which to recover. So researchers study the chemical composition of the non-cellular material -- the extracellular matrix -- that surrounds healthy neurons in the spinal cord and in the peripheral nervous system that serves the rest of the body. Additionally, damaged spinal
cord neurons may require the presence -- or even the absence -- of different kinds of nonneuronal cells for regrowth and functional recovery.

Although scientists are beginning to understand the cellular and molecular events that occur after spinal cord injury, one question continues to dominate the research: Why don't the brain and spinal cord repair themselves?

Additional reading:
1. M. E. Schwab and D. Bartholdi. "Degeneration and regeneration of axons in the lesioned spinal cord." Physiol. Rev. 76 (2): 319-370 (1996).

2. M.E. Schwab. "Bridging the gap in spinal cord regeneration." Nature Med. 2 (9): 976-977. 1996.

IJO India Journal Of Orthopeadics (click here for link to site)

Excellent information about treatment of symptomatic Tarlov Cysts.

I love it whenever I see countries taking a true, determined interst in their residents health care. This is a perfect example of India taking a lead on rare diagnosis treatment and care.


CASE REPORT Table of Contents
Year : 2007 | Volume : 41 | Issue : 4 | Page : 401-403
Tarlov cyst: Case report and review of literature


Bhagwat Prashad, Anil K Jain, Ish K Dhammi
University College of Medical Sciences and Guru Teg Bahadur Hospital, Shahadara, Delhi, India


Click here for correspondence address and email
Abstract


We describe a case of sacral perineural cyst presenting with complaints of low back pain with neurological claudication. The patient was treated by laminectomy and excision of the cyst. Tarlov cysts (sacral perineural cysts) are nerve root cysts found most commonly in the sacral roots, arising between the covering layer of the perineurium and the endoneurium near the dorsal root ganglion. The incidence of Tarlov cysts is 5% and most of them are asymptomatic, usually detected as incidental findings on MRI. Symptomatic Tarlov cysts are extremely rare, commonly presenting as sacral or lumbar pain syndromes, sciatica or rarely as cauda equina syndrome. Tarlov cysts should be considered in the differential diagnosis of patients presenting with these complaints.


Keywords: Low back pain, sacral perineural cyst, sciatica, tarlov cyst
How to cite this article:
Prashad B, Jain AK, Dhammi IK. Tarlov cyst: Case report and review of literature. Indian J Orthop 2007;41:401-3


How to cite this URL:
Prashad B, Jain AK, Dhammi IK. Tarlov cyst: Case report and review of literature. Indian J Orthop [serial online] 2007 [cited 2011 Apr 12];41:401-3. Available from: http://www.ijoonline.com/text.asp?2007/41/4/401/37007
Tarlov cysts were first described in 1938 as an incidental finding at autopsy. [1] Tarlov described a case of symptomatic perineural cyst and recommended its removal. Since then a few cases have been reported in the literature. [2],[3],[4]


Paulsen reported the incidence of Tarlov cysts as 4.6% in back pain patients (n=500). Only 1% of back pain patients (n=500) were symptomatic. [4] The patient may present as low back pain, sciatica, coccydynia or cauda equina syndrome. The cysts are usually diagnosed on MRI, which reveals the lesion arising from the sacral nerve root near the dorsal root ganglion. [5]


Tarlov advised extensive surgery with sacral laminectomy and excision of the cyst along with the nerve root. [6] Paulsen reported CT-guided percutaneous aspiration of these perineural cysts for relief of sciatica. [4] Recently, microsurgical excision of the cyst has been advocated, combined with duraplasty or plication of the cyst wall. [7]


We report a case of symptomatic Tarlov cyst presenting as back pain, to increase the awareness of this rare entity in the orthopedic community.




Case Report Top




A 29-year-old female presented with right thigh pain off and on for nine months. The pain was not associated with specific time, posture or activity and it used to get relieved by non steroidal antiinflammatory drugs (NSAID). Clinical examination at this stage did not reveal any findings at spine, bilateral hips and left thigh.


For last three months, the intensity and duration of pain had increased, which was now unrelieved by taking NSAID. The pain had progressed to the lower back and bilateral upper thigh up to the ankle. The pain was aggravated by activity and prolonged standing and was more bothersome in the evening. She used to get up in the middle of the night with pain. Later the patient started having rest pain as well. Examination showed no spinal tenderness. Straight leg raising was 50° on the right side and normal on the left side. There was mild blunting of sensations along the S1 and S2 dermatome on the right side, no motor deficit in both lower limbs.


X-ray of the lumbosacral spine did not reveal any abnormality [Figure - 1]. The MRI of the spine revealed fluid-filled cystic lesion, arising from the second sacral nerve root on the right side and measuring 2cm in diameter [Figure - 2].


The patient was taken for sacral laminectomy, excision of the cyst and plication of the cyst wall, while retaining the nerve root [Figure - 3]. Histopathological examination of the cyst wall showed nerve cells, which confirmed the diagnosis of Tarlov cyst.


Patient appreciated relief of pain immediately after the surgery. Postoperative period was uneventful and the patient made prompt recovery. On nine months followup, the patient had no pain in lower limbs and back. The patient is back at her job and is asymptomatic. Postoperative MRI taken at nine months [Figure - 4] did not show any evidence of recurrence of the cyst.




Discussion Top




Tarlov cysts are rare causes of low back pain. They are more common in females. [4],[7] Clinical presentation of Tarlov cysts is variable. The cysts may cause local and/or radicular pain. The dominant syndrome is referable to the caudal nerve roots, either sciatica, sacral or buttocks pain, vaginal or penile paraesthesia or sensory changes over the buttocks, perineal area and lower extremity. Depending on their location, size and relationship to the nerve roots, they may cause sensory disturbances or motor deficits to the point of bladder dysfunction. Tenderness on firm pressure over the sacrum may be present. Commonly, the symptomatology is intermittent at its onset and is most frequently exacerbated by standing, walking and coughing. Bed rest alleviates the discomfort. [8]


Plain X-rays are usually normal. However, they may reveal characteristic bone erosion of the spinal canal or anterior or posterior neural foramina. [9] A CT scan can demonstrate cystic masses isodense with CSF located at the foramina. Bony changes may also be present. [10] An MRI gives a much better soft tissue contrast and is currently the investigation of choice for perineural cysts. The cysts demonstrate low signal on T-1 weighted images and high signal on T-2 weighted images, similar to CSF. [5] Myelography showing the filling of the meningocele sac 1h after injection of contrast medium is highly suggestive of a perineural cyst. [11]


Microscopic features of the cyst were described by Tarlov. The early stage in cyst formation is that of a space between the arachnoid which covers the root or the perineurium and the outer layer of the pial cover of the root or the endoneurium. It usually begins in one portion of the circumference of the perineural space, the larger cysts compressing the nerve root to one side. The cyst occupies the posterior root abutting the proximal portion of the dorsal ganglion. Its main part is bordered by reticulum or by nerve fibers. [1]


The pathogenesis of perineural cysts is uncertain. Tarlov felt that hemorrhage into the subarachnoid space caused accumulations of red cells which impeded the drainage of the veins in the perineurium and epineurium, leading to rupture with subsequent cyst formation. Four out of the seven patients in Tarlov's 1970 article had a history of trauma. [8] Schreiber and Haddad also supported this posttraumatic cause of cyst formation. [12] Because many of the patients with perineural cyst in their series did not have histories of trauma, Fortuna et al . believed that the perineural cysts were congenital, caused by arachnoidal proliferations within the root sleeve. [13]


There is no consensus on a single method of treatment. Various methods have been advocated. Tarlov advised that symptomatic, single perineural cysts should be completely excised together with the posterior root and ganglion from which they arise. [8] Paulsen reported CT-guided percutaneous aspiration of these perineural cysts in two patients for the relief of sciatica caused by compression. [4] According to Caspar microsurgical excision of the cyst combined with duraplasty or plication of the cyst wall is an effective and safe treatment of symptomatic sacral cysts. The parent nerve root is always left intact. [7]


Tarlov cysts are a documented cause of sacral radiculopathy and other radicular pain syndromes. They must be considered in the differential diagnosis of patients presenting with these clinical presentations and appropriately treated by cyst excision.




References Top


1. Tarlov IM. Perineural cysts of the spinal nerve roots. Arch Neural Psychiatry 1938;40:1067-74. Back to cited text no. 1
2. Chaiyabud P, Suwanpratheep K. Symptomatic Tarlov cyst: Report and review. J Med Assoc Thai 2006;89:1047-50. Back to cited text no. 2 [PUBMED]
3. Acosta FL Jr, Quinones-Hinojosa A, Schmidt MH, Weinstein PR. Diagnosis and management of sacral Tarlov cysts. Case report and review of the literature. Neurosurg Focus 2003;15:E15. Back to cited text no. 3
4. Paulsen RD, Call GA, Murtagh FR. Prevalence and percutaneous drainage of cysts of the sacral nerve root sheath (Tarlov cysts). AJNR Am J Neuroradiol 1994;15:293-9. Back to cited text no. 4 [PUBMED]
5. Rodziewicz GS, Kaufman B, Spetzler RF. Diagnosis of sacral perineural cysts by nuclear magnetic resonance. Surg Neurol 1984;22:50-2. Back to cited text no. 5 [PUBMED]
6. Tarlov IM. Cysts (perineurial) of the sacral roots. J Am Med Assoc 1948;138:740-4. Back to cited text no. 6
7. Caspar W, Papavero L, Nabhan A, Loew C, Ahlhelm F. Microsurgical excision of symptomatic sacral perineurial cysts: A study of 15 cases. Surg Neurol 2003;59:101-6. Back to cited text no. 7 [PUBMED] [FULLTEXT]
8. Tarlov IM. Spinal perineurial and meningeal cysts. J Neural Neurosurg Psychiatry 1970;33:833-43. Back to cited text no. 8
9. Taveras JM, Wood EH. Diagnostic neuroradiology. 2 nd ed. Vol 2. Williams and Wilkins: Baltimore; 1976. p.1139-45. Back to cited text no. 9
10. Tabas JH, Deeb ZL. Diagnosis of sacral perineural cysts by computed tomography. J Comput Tomogr 1986;10:255-9. Back to cited text no. 10
11. Nishiura I, Koyama T, Handa J. Intrasacral perineurial cyst. Surg Neurol 1985;23:265-9. Back to cited text no. 11
12. Schreiber F, Haddad B. Lumbar and sacral cysts causing pain. J Neurosurg 1951;8:504-9. Back to cited text no. 12
13. Fortuna A, La Torre E, Ciappetta P. Arachnoid diverticula: A unitary approach to spinal cysts communicating with the subarachnoid space. Acta Neurochir (Wien) 1977;39:259-68. Back to cited text no. 13


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