Occult intrasacral meningocele
Updates to Article Attributes
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 - Nabor type Ib meningeal cyst. It is not a true meningocele, since meninges are not involved.
It is associated with spinal dysraphism, tethered cord syndrome and Tarlov cysts. It is usually a fortuitous finding on MRI in teenagers or the elderly, but very large cysts can be symptomatic. It is rarely diagnosed in children.
Radiographic features
CT
Typically seen as a hypoattenuating 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: hypointense (follows CSF signal)
- T2: hyperintense (follows CSF signal)
- T1C+ (Gd): no enhancement
- DWI: hypointense, 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><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> - Nabor <a href="/articles/classification-of-spinal-meningeal-cysts-1">type Ib meningeal cyst</a>. It is 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>. It is usually a fortuitous finding on MRI in teenagers or the elderly, but very large cysts can be symptomatic. It is rarely diagnosed in children.</p><h4>Radiographic features</h4><h5>CT</h5><p>Typically seen as a hypoattenuating lesion (isodense to <a href="/articles/cerebrospinal-fluid-1">CSF</a>) 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>- +<p><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> - Nabor <a href="/articles/classification-of-spinal-meningeal-cysts-1">type Ib meningeal cyst</a>. It is not a true <a title="Meningocele" href="/articles/meningocele-3">meningocele</a>.</p><p>It is associated with <a href="/articles/spinal-dysraphism-2">spinal dysraphism</a>, <a href="/articles/tethered-cord">tethered cord syndrome</a> and <a href="/articles/tarlov-cyst">Tarlov cysts</a>. It is usually a fortuitous finding on MRI in teenagers or the elderly, but very large cysts can be symptomatic. It is rarely diagnosed in children.</p><h4>Radiographic features</h4><h5>CT</h5><p>Typically seen as a hypoattenuating lesion (isodense to <a href="/articles/cerebrospinal-fluid-1">CSF</a>) 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>
-</ul><h4>See also</h4><ul><li><a href="/articles/congenital-spinal-meningocele">meningocele</a></li></ul>- +</ul>
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