Tarlov cyst

Tarlov cysts, also called perineural cysts, are CSF filled dilatations of the nerve root sheath at the dorsal root ganglion (posterior nerve root sheath). These are type II spinal meningeal cysts that are, by definition, extradural but contain neural tissue.

Epidemiology

They occur in ~5% of the population, more commonly in women.

Associations

They have been occasionally associated in patients with connective tissue disorders:

• Marfan syndrome ⁵
• Ehlers-Danlos syndrome
• Sjögren syndrome
• Loeys-Dietz syndrome

Clinical presentation

The prevalence and severity of symptoms in patients with Tarlov cysts is controversial. Traditionally, and still largely the dominant view, it has been believed that like other spinal meningeal cysts, most Tarlov cysts are incidentally found and are asymptomatic. In some patients it appears that Tarlov cysts are the cause of symptoms, such as perineal pain/discomfort or lower back pain or sphincter/sexual dysfunction ³. Large cysts may cause local pressure effect and remodel bones. However, symptoms don't appear to correlate well with size ². 

Radiographic features

While they are most common in the lower lumbar spine and in the sacrum, they can occur anywhere in the spine. 

Most Tarlov cysts appear as CSF intensity simple cystic structures closely related to sacral and lower lumbar nerves.The sacral foramina may be widened. Morphology can vary from a simple rounded cyst to a complex loculated cystic mass.

History and etymology

It was initially described by I M Tarlov in 1938 ¹.

Differential diagnosis

Usually, the diagnosis is self-evident and no alternatives should be entertained. Occasionally appearances are atypical and possible differential considerations include:

• dural ectasia
• spinal synovial cyst
• meningocele
• nerve sheath tumour
• spinal metastases

See also

• spinal meningeal cyst
• spinal meningeal cyst classification