Kieran Murphy

I began treating patients with symptomatic Tarlov cysts 12 years ago at the Johns Hopkins Hospital. At Toronto Western Hospital (University of Toronto), I see 4–7 women a week with Tarlov cysts. Many cannot sit and stand through the patient encounter. I was reluctant initially, but these patients were suffering and some were suicidal. These patients suffer from sacral and radicular back pain, with some also having pelvic and perineal pain. Sadly, they are often written off as having psychiatric issues by many orthopedic surgeons and neurosurgeons. I have now evaluated over 400 patients and treated over 300, giving us long-term 5- and 10-year follow-up data. Through a process of exclusion, I select patients for whom the  Tarlov cysts are the cause of their sacral, pelvic, or sciatic pain.

After the first few patients, I developed the 2-needle technique as a way of making the treatment procedure less painful. Two 18G spinal needles are introduced into the cyst through the thinned overlying lamina or through a defect that the cyst has eroded in the bone. I always use CT fluoroscopic guidance. One needle is placed superficially and the other is placed deep in the cyst. I remove both stylets. The superficial venting needle equalizes pressure in the cysts as I aspirate CSF through the deeper needle. An air-fluid level is created and, if it is sustained over a few minutes, I inject Tisseel fibrin. The volume of fibrin is about 80% of the fluid volume I aspirated.

For some unknown reason, there is a practice of saying in diagnostic spine reports that these cysts are asymptomatic; however, there is no basis for this claim, as the literature reporting on these patients actually says the opposite.

The key strategy for predicting painful Tarlov cysts includes a thorough clinical history and physical examination. I only treat cysts with narrow necks on MRI. The cyst must correlate with the dermatomal distribution of the patient’s pain. Larger cysts tend to be more symptomatic due to the erosion or remodeling of the adjacent lamina and vertebral body by the cyst.

Physicians may note certain features on MRI to confirm that a patient has a treatable Tarlov cyst as opposed to another type of cystic lesion. Cysts with T2 signal greater than the CSF signal in the thecal sac tend to be narrow-necked. If the signal intensity of the cyst is equal to that of CSF, the neck is usually wide and I do not treat them.

On rare occasions, I will inject a small amount of bupivacaine into a cyst as a test to confirm the source of pain. This procedure is always preceded by 2-needle aspiration. This has given sustained relief in some patients.

It is important to understand that women may experience back pain for different reasons than men; for example, women may have extraspinal sciatica from mass effect of adnexal masses and endometriosis on the lumbar sacral plexus. In addition, piriformis syndrome is more common in women than men, and endometriosis causes cyclical sciatica. These are new thoughts for neuroradiologists and are the topics of an upcoming paper. I am a coinvestigator on a $2.5 million grant at Johns Hopkins to study these patients genetically. Some have connective tissue disorders and have multiple Tarlov and perineural cysts. Some seem to have an acquired disease. This work with the Hopkins Genetics Institute is ongoing.

This is another example of the fact that innovation and discovery come from doing difficult things.

Please visit my ResearchGate page for more information: https://www.researchgate.net/profile/Kieran_Murphy3

Read this article at AJNR.org …