Sacral Tarlov Cysts: Diagnosis and Treatment
By Wise Young, Ph.D., M.D.
W. M. Keck Center for Collaborative Neuroscience
Rutgers, State University of New Jersey, Piscataway, NJ 08854-8082
13 December 2008
Someone recently asked for an explanation of Tarlov cysts, what they are, how they are diagnosed, and the best way to treat them. I will describe below the criteria for diagnosis, the prevalence of the cysts, the symptoms, and recommended treatments.
What are Tarlov Cysts?
Tarlov cysts are fluid-filled cysts associated with sacral nerve roots, at the junction of the nerve root and root ganglion. First described by Tarlov  in 1938, when he was at the Montreal Institute of Neurology, he was careful to call these cysts perineural and to distinguish them from meningeal cysts, which would be extensions of subarachnoid space.
Computerized tomographic (CT) myelography where dye is injected into the cerebrospinal fluid (CSF) showed that Tarlov cysts are true meningeal cysts that communicate with spinal subarachnoid space [2, 3]. To demonstrate communication of Tarlov cysts with subarachnoid space, CT scans should be obtained 30-60 minutes after injection of subarachnoid dye.
In 1988, Nabors et al.  classified Tarlov cysts as a kind of extradural meningeal cyst. A Tarlov perineural cyst differs from other meningeal cysts in that there are spinal root axons within the cyst walls or the cavity of the cyst. The cysts may surround the nerve or extend into the nerve. For this reason, simple excision of the Tarlov cysts will damage the spinal root.
Prevalence and Symptoms
In his original 1938 communication, Tarlov had found these cysts in 5 of 30 cadavers (17%). In 1994, Paulsen, et al.  found 23 patients with perineural cysts out of 500 sequential lumbosacral magnetic resonance scans (4.6%). In 2005, Langdown, et al.  in Australia reported that 54 patients out of 3535 MRI scans (1.5%) obtained for lumbosacral symptoms had Tarlov cysts.
Most Tarlov cysts are asymptomatic. Tarlov initially thought that the cysts are innocuous. However, in 1948, he  reported a case of sciatica associated with a sacral perineural cyst. Paulsen, et al.  found that five of 23 patients with the cysts were symptomatic (22%) and that CT-guided cyst puncture reduced pain. In the Langdown study , 7 of 54 patients (13%) had symptoms due to the cyst.
Symptoms are variable, ranging from radicular pain  and paresthesia to urinary and bowel dysfunction [9, 10], cauda equina syndrome , and even abdominal pain , depending on the level of sacral roots involved. Pain is the most common presentation.
Most surgeons agree that asymptomatic Tarlov cysts should not be treated  and that symptomatic cysts should be treated. Several treatment options are available:
• Lumbar drainage. Bartels & Overbeeke  reported that lumbar CSF drainage relieved pain in 2 of 3 patients with symptomatic Tarlov cysts. Subsequently, they did a lumbar-peritoneal shunt in one patient to relieve the pressure. This suggests that CSF pressure contributes to the size of Tarlov cysts and that they are true meningeal cysts.
• CT-guided percutaneous decompression. Paulsen, et al.  did percutaneous CT-guided decompression of the cysts, reporting rapid reduction in symptoms and relief of pain but the symptoms returned in 3 weeks to 6 months. Patel, et al.  used CT-guidance decompression but injected fibrin glue after the decompression, finding no recurrence over 23 months.
• Decompressive laminectomy. Siqueira, et al.  did decompressive laminectomies in two patients. Sa & Sa  treated four cases with a sacral laminectomy, reporting resolution of the pain. However, the pain often recurred. Tanaka, et al.  treated 12 consecutive patients with laminectomies and imbrications of the sacral cysts.
• Laminectomy and cyst resection. Voyadzis, et al.  operated on 10 patients, carrying out sacral laminectomies and resections of the cysts. Seven of 10 patients had complete resolution of their pain but 3 (30%) showed no benefit. These three all had cysts smaller than 1.5 cm in diameter. Histology revealed nerve fibers in 75% of the cases, ganglion cells in 25%, and evidence of old hemorrhage in half.
• Laminectomy, partial cyst excision, duroplasty or plication of the cyst walls. Total cyst resection is unnecessary . Caspar, et al.  excised the cysts with duroplasty or plication of cyst wall in 15 patients with no complications and relief of pain in 13 (87%).
• Laminectomy, fenestration of cyst wall, partial resectio, and myofascial flap. Acosta, et al.  stimulated the cyst wall to find motor axons, resected parts did not have nerves, and then used a muscle flap to close the cyst. Guo, et al.  used a similar approach to resect the cyst wall, imbricated the remaining sheath, and repaired the defect with muscle and Gelfoam.
Summary and Conclusions
Tarlov cysts are fluid-filled meningeal cysts on spinal roots. Although present in 1-5% of the population, only 10% to 20% of cysts are symptomatic, manifesting as sciatica or other radicular pains, bowel and bladder problems, and other complaints. Lumbar CSF drainage and percutaneous CT-guided drainage of the cysts will relieve the symptoms temporarily. Injecting fibrin glue postpones recurrence. Resection of the cyst resolves the pain but histology revealed nerve fibers and sensory ganglion in the cyst walls. Laminectomy, fenestration and partial resection with careful neurophysiological testing to avoid motor fibers, and closure with a muscle flap is the preferred approach.
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