Tarlov cysts
Overview
Perineurial (Tarlov) cysts are meningeal dilations of the posterior spinal nerve root sheath that most often affect sacral roots and can cause a progressive painful radiculopathy. Tarlov cysts are most commonly diagnosed by lumbosacral magnetic resonance imaging and can often be demonstrated by computerized tomography myelography to communicate with the spinal subarachnoid space. The cyst can enlarge via a net inflow of cerebrospinal fluid, eventually causing symptoms by distorting, compressing, or stretching adjacent nerve roots. It is generally agreed that asymptomatic Tarlov cysts do not require treatment. When symptomatic, the potential surgery-related benefit and the specific surgical intervention remain controversial. The authors describe the clinical presentation, treatment, and results of surgical cyst fenestration, partial cyst wall resection, and myofascial flap repair and closure in a case of a symptomatic sacral Tarlov cyst. They review the medical literature, describe various theories on the origin and pathogenesis of Tarlov cysts, and assess alternative treatment strategies
Symptoms
Symptoms may be initiated by trauma incurred in an event such as a fall, auto accident or heavy lifting. The onset may be gradual or sudden, mild or severe, and the progression and ultimate severity of symptoms differ widely. Tarlov cysts in the disease stage usually cause pain neurological dysfunction in the path of the affected nerve root. Tarlov cysts differ in structure. A cyst might incorporate nerve elements or be free of them. A cyst can be valved or non-valved. A valved cyst has a structure in its neck that makes it easier for spinal fluid to enter the cyst than to leave. In a non-valved cyst, spinal fluid flows freely between the cyst and the dural tube. Tarlov cysts are typically on posterior roots; anterior cysts are rare. Multiple Tarlov cysts are not uncommon. Although a large cyst can cause symptoms by pressing on an adjacent structure, symptoms may also be caused by hydrostatic forces of the spinal fluid inside the cyst exerting pressure on nerves in the cyst or cyst wall.1 The pulsations of spinal fluid causes the cyst to expand, potentially stretching nerve elements and causing or increasing symptoms.2 Therefore, cysts even smaller than one centimeter can be highly symptomatic. The most common symptoms are pain in the low back, buttocks and legs, but the thighs, legs and feet may or may not be involved.3 Symptoms can be opposite-sided. Tarlov cysts can also cause pain and disorders in the organs of elimination and reproduction, hypoesthesia, paresthesias, and neurogenic claudication (pain in the thigh from lack of blood supply).4 The postures of sitting, standing, walking, and bending are typically painful, and reclining flat on the side is usually the only posture that offers relief.
Diagnosis
Despite advancements in diagnosis, there remains a great deal of controversy regarding the optimal treatment of symptomatic Tarlov cysts. Nonsurgical therapies include lumbar CSF drainage[2,4] and CT scanning guided cyst aspiration,[23,24] neither of which prevents symptomatic cyst recurrence. Neurosurgical techniques for symptomatic perineurial cysts include simple decompressive laminectomy,[33] cyst and/or nerve root excision,[20,37,38,41,42] and microsurgical cyst fenestration and imbrication.[16] Although no consensus exists on the definitive treatment of symptomatic Tarlov cysts, we believe surgical methods have yielded the best long-term results to date. We describe the case of one patient with a symptomatic Tarlov cyst to illustrate the surgical treatment involving cyst fenestration, partial resection of the cyst wall, and myofascial cutaneous flap closure reinforcement. We also review the literature, summarizing various theories on the origin and pathogenesis of Tarlov cysts, and assess current treatment options