The Sporting Nerve Part 1 | The Sporting Nerve Part 2 | Piriformis | Contralateral Tests
Sciatica: Is Extension the Right Choice? | Trouble Shooting with Scapular Stabilisation
Wrist Technique during Median Neurodynamic Testing | Tarlov's Cysts
Asymmetry and Diagnosis: Are We Neurodynamic Mirror Images?
Feature Article - Tarlov's Cysts
Tarlov's cysts are relatively rare but, when present, they typically occur in the lumbosacral region. They are cystic extensions of malformed dura which can contain cerebrospinal fluid. They are therefore frequently under a certain fluid pressure created by cerebrospinal fluid production in the cerebral ventricles. It is this constant pressure that may produce reabsorption of the neighbouring bone and the bone adopting the shape of the cyst.
Cystic erosion of bone can occur in large structures such as the sacrum and can also include the bony parts of the intervertebral foramen. Some cysts extend through the foramen and along the spinal nerve. In the case of the nerve roots that pass deep into the sacrum (eg. S1, 2, 3) prior to entering the pelvis, the cyst can follow the path of the nerve root into the radicular canal, sometimes producing significant disappearance of bone deep in the sacrum.
In performing some cadaver dissections in preparation for analysis of biomechanical function of the lumbar dura and nerve roots, we encountered a case of Tarlov's cysts in which a bubble-shaped erosion approximately 1 cm in diameter was evident in the upper sacrum. I have also encountered patients with Tarlov's cysts and other therapists have shown an interest in learning more about this condition.
Figure 1 - Bubble-shaped erosionFigure 1. Bubble-shaped erosion of the sacrum by a Tarlov's cyst. Cephalad to right of picture, caudad to left.
The dura has been opened and the cauda equina exposed.
Notice the apparent hole where the superior surface of the sacrum would normally be (white asterisk).
Figure 2 - Tarlov's cyst removedFigure 2. Tarlov's cyst removed from the upper surface of sacrum.
Size - 1 cm in diameter, approximately.
Figure 3 - Radiological IllustrationFigure 3. Radiological illustration in a patient with Tarlov's cysts.
Note that a cyst forms an extension of dura and, in this case, probably contains cerebrospinal fluid
Potential Effects Tarlov's Cysts
Whilst no measurements of neural tissue movement in the presence of Tarlov's cysts compared with normal have been performed, it seems that altered mechanical function of the nerve roots and dura are plausible outcomes for some patients.
However, care must be taken because of the nature of the pathology. Severity and stability of symptomatology, presence of neurological signs and sensitivity to movement are important aspects of selection of physical techniques for these patients.
Clinical Presentation in Cases of Tarlov's Cysts
The presentation of patients with Tarlov's cysts is variable. It is likely that, in some patients, the cysts develop and persist for significant periods of time before being noticed, and some might remain asymptomatic until some form of insult or incident occurs.
However, in patients with Tarlov's cysts who I have treated for back pain and limb symptoms, pain and neurological symptoms are common. Neurodynamic tests and neurological testing can also be abnormal, along with spinal movements.
Whilst detailed subjective and physical examination (including neurological testing) may give an impression of the status of the patient, definitive diagnosis relies on radiological investigation using CT or MRI.