Occult intrasacral meningocele
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An occult intrasacral meningocele is a rare congenital lesion characterised by the presence of a cyst within the sacral thecal sac. It is an extradural sacral arachnoid cyst, not a true meningocele, since meninges are not involved.
It is associated with spinal dysraphism, tethered cord syndrome and Tarlov cysts. Most of the time, it is a fortuitous finding on MRI in teenagers or elderly, but very large cysts can be symptomatic. It is rarely diagnosed in children.
Radiographic features
CT-scan
Typically seen as a hypo-attenuating lesion (isodense to CSF) enlarging the sacral thecal sac which may displace the nerve roots.
MRI
MRI is the best modality to evaluate an occult intrasacral meningocele. It consists of an extradural sacral arachnoid cyst, where signal characteristics are typically :
-
T1:
: hypointensehypointense (follows CSF signal) -
T2:
: hyperintensehyperintense (follows CSF signal) -
T1C+ (Gd):
:no enhancement -
DWI:
: hypohypo-intense- no-no restricted diffusion
Differential diagnosis
General imaging differential considerations include:
- Tarlov cyst
- dorsal meningocele
- dural dysplasia
-
caudal regression syndrome: only when the cyst is very large, but easily distinguishable on MRI
.
See also
-<p>An<strong> occult intrasacral meningocele</strong> is a rare congenital lesion characterised by the presence of a cyst within the sacral thecal sac. It is an extradural sacral <a href="/articles/arachnoid-cyst" title="arachnoid cyst">arachnoid cyst</a>, not a true meningocele, since meninges are not involved.</p><p>It is associated with <a href="/articles/spinal-dysraphism" title="spinal dysraphism">spinal dysraphism</a>, <a href="/articles/tethered-cord" title="tethered cord syndrome">tethered cord syndrome</a> and <a href="/articles/tarlov-cyst" title="Tarlov cysts">Tarlov cysts</a>. Most of the time, it is a fortuitous finding on MRI in teenagers or elderly, but very large cysts can be symptomatic. It is rarely diagnosed in children.</p><h4>Radiographic features</h4><h5>CT-scan</h5><p>Typically seen as a hypo-attenuating lesion (isodense to CSF) enlarging the sacral thecal sac which may displace the nerve roots. </p><h5>MRI</h5><p>MRI is the best modality to evaluate an occult intrasacral meningocele. It consists of an extradural sacral arachnoid cyst, where signal characteristics are typically :</p><ul>-<li>-<strong>T1</strong> : hypointense (follows CSF signal)</li>-<li>-<strong>T2</strong> : hyperintense (follows CSF signal)</li>-<li>-<strong>T1C+ (Gd) </strong>: no enhancement</li>-<li>-<strong>DWI</strong> : hypo-intense - no restricted diffusion</li>-</ul><h4>Differential diagnosis</h4><p>General imaging differential considerations include</p><ul>-<li><a href="/articles/tarlov-cyst" title="Tarlov cyst">Tarlov cyst</a></li>-<li><a href="/articles/dorsal-meningocele" title="Dorsal meningocele">dorsal meningocele</a></li>-<li><a href="/articles/dural-dysplasia" title="Dural dysplasia">dural dysplasia</a></li>-<li>-<a href="/articles/caudal-regression-syndrome" title="Caudal regression syndrome">caudal regression syndrome</a> : only when the cyst is very large, but easily distinguishable on MRI.</li>-</ul><h4>See also</h4><ul><li><a href="/articles/meningocoele" title="Meningocele">meningocele</a></li></ul>- +<p>An<strong> occult intrasacral meningocele</strong> is a rare congenital lesion characterised by the presence of a cyst within the sacral thecal sac. It is an extradural sacral <a href="/articles/arachnoid-cyst">arachnoid cyst</a>, not a true meningocele, since meninges are not involved.</p><p>It is associated with <a href="/articles/spinal-dysraphism">spinal dysraphism</a>, <a href="/articles/tethered-cord">tethered cord syndrome</a> and <a href="/articles/tarlov-cyst">Tarlov cysts</a>. Most of the time, it is a fortuitous finding on MRI in teenagers or elderly, but very large cysts can be symptomatic. It is rarely diagnosed in children.</p><h4>Radiographic features</h4><h5>CT-scan</h5><p>Typically seen as a hypo-attenuating lesion (isodense to CSF) enlarging the sacral thecal sac which may displace the nerve roots. </p><h5>MRI</h5><p>MRI is the best modality to evaluate an occult intrasacral meningocele. It consists of an extradural sacral arachnoid cyst, where signal characteristics are typically :</p><ul>
- +<li>
- +<strong>T1: </strong> hypointense (follows CSF signal)</li>
- +<li>
- +<strong>T2: </strong> hyperintense (follows CSF signal)</li>
- +<li>
- +<strong>T1C+ (Gd): </strong>no enhancement</li>
- +<li>
- +<strong>DWI:</strong> hypo-intense-no restricted diffusion</li>
- +</ul><h4>Differential diagnosis</h4><p>General imaging differential considerations include:</p><ul>
- +<li><a href="/articles/tarlov-cyst">Tarlov cyst</a></li>
- +<li><a href="/articles/dorsal-meningocele">dorsal meningocele</a></li>
- +<li><a href="/articles/dural-dysplasia">dural dysplasia</a></li>
- +<li>
- +<a href="/articles/caudal-regression-syndrome">caudal regression syndrome</a>: only when the cyst is very large, but easily distinguishable on MRI</li>
- +</ul><h4>See also</h4><ul><li><a href="/articles/meningocoele">meningocele</a></li></ul>
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