Occult intrasacral meningocoele

Occult intrasacral meningocoele 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 meningocoele, 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 the elderly, but very large cysts can be symptomatic. It is rarely diagnosed in children.

Typically seen as a hypoattenuating lesion (isodense to CSF) enlarging the sacral thecal sac, which may displace the nerve roots.

MRI is the best modality to evaluate an occult intrasacral meningocoele. 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

General imaging differential considerations include

Share article

Article information

rID: 19861
Tags: cases, spine
Synonyms or Alternate Spellings:
  • Sacral extradural arachnoid cyst
  • Occult intrasacral meningoceles
  • Occult intrasacral meningocele
  • Occult intrasacral meningocoeles
  • Sacral extradural arachnoid cysts

Support Radiopaedia and see fewer ads

Cases and figures

  • Drag
    Sacral meningeal cyst
    Drag here to reorder.
  • Updating… Please wait.
    Loadinganimation

    Alert accept

    Error Unable to process the form. Check for errors and try again.

    Alert accept Thank you for updating your details.