Pseudomeningoceles are abnormal collections of cerebrospinal fluid (CSF) that occur due to leakage from the CSF-filled spaces surrounding the brain and/or spinal cord as a result of trauma or surgery.
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Epidemiology
Spinal pseudomeningoceles can occur in <2% of patients following laminectomy or discectomy 4.
Pathology
The salient feature of a pseudomeningocele is that it contains CSF that communicates with the CSF surrounding the brain or spinal cord and it is not lined by dura.
In brachial plexus injury, the key feature is that the nerve root avulsion pseudomeningocele does not contain any neural elements.
Specific types
Radiographic features
CT
Typically appears as a hypoattenuating collection that extends to the dura with minimal peripheral enhancement and with similar attenuation to CSF elsewhere.
MRI
The pseudomeningocele follows CSF signal on all sequences.