In the latest Case Record of the Massachusetts General Hospital, a 77-year-old woman sought neurosurgical and neurologic consultation because of a long history of left thoracic pain, for which no cause or effective treatment had been found. Review of imaging studies revealed multiple perineurial cysts in the thoracic spine.
Tarlov or perineural cysts were first characterized in 1938 by the neurosurgeon Isadore M. Tarlov during an autopsy of the lower spine. He identified them as fluid collections in the nerve-root membranes that have restricted communication with the cerebrospinal fluid in the thecal sac.
• What is the typical location of a Tarlov cyst?
Tarlov cysts form only on the dorsal nerve roots because only the cell bodies of sensory neurons migrate out from the spinal cord during embryonic development, leaving behind a sleeve of dura and subarachnoid space. Tarlov cysts are most common at sacral levels, presumably reflecting the greater hydrostatic pressure there.
• What symptoms may be associated with Tarlov cysts?
In large studies, the prevalence of these cysts on lumbosacral MRI images ranges from 1.5 to 2.1%. In several studies, Tarlov cysts were thought to be the cause of symptoms in 20 to 30% of patients, because of the localization of the symptoms and the absence of other abnormalities on imaging. Radicular neuropathic pain caused by damage to the nerve root that bears the cyst is the most common symptom, and the most common location of the pain is in the lumbosacral region. In a study involving patients with symptomatic Tarlov cysts (84% women; mean age, 54 years), in whom other potential causes had been ruled out by neurologic examination and diagnostic testing, all patients had local or radiating pain (sciatica) or both, and 10% had bladder or bowel incontinence.
Morning Report Questions
Q: What are treatment options for symptomatic Tarlov cysts?
A: Published treatment options for apparently symptomatic cysts include perineural injection of a glucocorticoid, cyst aspiration, aspiration and injection of the cyst with blood or fibrin sealant, and surgical obliteration. There is no evidence that aspiration or perineural injection of a glucocorticoid produces anything but temporary relief, but such procedures may be used to confirm that the cysts are the cause of symptoms. Radiologically guided percutaneous aspiration of a cyst, followed by an injection of fibrin glue to seal the cyst, resulted in satisfactory pain relief in 65% of patients in one study.
Neurosurgical treatment usually involves a small sacral laminectomy, unless the cyst has already eroded through the sacrum. Large case series show complete or substantial improvement in more than 80% of patients who underwent surgery, with a less than 10% rate of mostly temporary complications.
Q: What connective tissue disorders can be associated with Tarlov cysts?
A: The Ehlers-Danlos syndrome, Marfan’s syndrome (Online Mendelian Inheritance in Man [OMIM] number, 154700), and the Loeys-Dietz syndrome have all been associated with Tarlov cysts. Sacral abnormalities are associated with Marfan’s syndrome and related disorders. The classic finding is dural ectasia (i.e., widening of the sacral canal due to pressure from a dilated or cystic lower thecal sac), often accompanied by neural foramina that have become dilated by cysts.