====== Pseudomeningocele ======

Abnormal collection of [[cerebrospinal fluid]] (CSF) that communicates with the CSF space around the brain or spinal cord. 

Pseudomeningocele is the term used to describe fluid accumulation due to the leakage of cerebrospinal fluid into the surrounding soft tissue. 

===== Etiology =====

[[Iatrogenic pseudomeningocele]] 

[[Traumatic Cervical Pseudomeningocele]]

===== Diagnosis =====

Pseudomeningocele on myelography or MRI: suggests [[nerve root avulsion]] (very proximal); however, 15% of pseudomeningoceles are not associated with [[avulsion]]s, and 20% of avulsions do not have pseudomeningoceles
((Carvalho GA, Nikkhah G, Matthies C, et al. Diagnosis of root avulsions in traumatic brachial plexus inju- ries: value of computerized tomography myelogra- phy and magnetic resonance imaging. J Neurosurg. 1997; 86:69–76))
((Hashimoto T, Mitomo M, Hirabuki N, et al. Nerve root avulsion of birth palsy: comparison of myelog- raphy with CT myelography and somatosensory evoked potential. Radiology. 1991; 178:841–845)).

Determining the exact location of dural violation after traumatic pre-ganglionic ([[avulsion]]) injury of the [[brachial plexus]] with associated progressively enlarging [[pseudomeningocele]] is critical for treatment, but current imaging by MR and [[CT myelogram]] remains inadequate as there are often only indirect imaging features. 
Lee et al. published the first case of using dynamic CT myelography to visualize "CSF flow jet," revealing the exact location of dural violation resulting in the expanding pseudomeningocele, providing crucial information for perioperative planning
((Lee MJ, Lobo RR, Smith BW, Yang LJ, Srinivasan A. CSF flow jet: novel CT
myelogram finding of CSF leak through dural tear in traumatic pseudomeningocele. 
Clin Imaging. 2019 Nov 20;61:33-35. doi: 10.1016/j.clinimag.2019.09.010. [Epub
ahead of print] PubMed PMID: 31954349.
)).
===== Differential diagnosis =====

post-op [[Spinal epidural abscess]] may appear similar to pseudomeningocele
((Spiegelmann R, Findler G, Faibel M, et al. Postoperative Spinal Epidural Empyema: Clinical and Computed Tomography Features. Spine. 1991; 16:1146–1149)).

In contrast to a [[meningocele]], in which the fluid is surrounded and confined by dura mater, in a pseudomeningocele, the fluid has no surrounding membrane but is contained in a cavity within the soft tissues.

===== Complications =====
It may cause complications such as cosmetic deformities, chronic meningitis, and/or impingement on vital structures resulting in neurological deficits; nevertheless, life-threatening posterior fossa cyst formation is a rare event.

===== Treatment =====

Treatment for pseudomeningocele is conservative or may involve neurosurgical repair.

=====Postoperative pseudomeningocele=====
Pseudomeningocele is a known operative complication of Chiari decompression with significant morbidity.

===== Case series =====

===2015===
A retrospective analysis of 150 consecutive patients from November 1991 to June 2011 was conducted. Symptomatic pseudomeningocele was defined clinically; to meet definition it must have required operative intervention. Variables evaluated included sex, age, use of graft, and use of operative sealant. The Chi-square, Fisher test, and the two-sample t-test were used as appropriate to determine significance. Multiple logistic regression was used to determine independent risk factors for complication.

A total of 67.3% of patients were female, with average age being 39.7 years. A total of 67.3% of patients had a graft placed with the most common being fascia lata. Only nine patients (6%) presented with pseudomeningocele. Factors observed to be significantly associated with pseudomeningocele development were age and use of sealant. Age and sealant use were also independent risk factors for complication. Adjusted for the significant effect of age, odds for complication among patients with sealant usage were 6.67 times those for patients without sealant. Adjusted for the significance of sealant usage, there is a 6% increase in odds for complication for every year increase in patient's age.

A statistically significant relationship exists between age and sealant use and the risk of developing a postoperative pseudomeningocele. Emphasis and attention must be placed on meticulous closure technique. This information can aide in preoperative planning and patient selection
((Menger R, Connor DE Jr, Hefner M, Caldito G, Nanda A. Pseudomeningocele
formation following chiari decompression: 19-year retrospective review of
predisposing and prognostic factors. Surg Neurol Int. 2015 May 7;6:70. doi:
10.4103/2152-7806.156632. eCollection 2015. PubMed PMID: 25984384; PubMed Central
PMCID: PMC4427815.
)).
===== Case reports =====

===2014===
A postoperative [[pseudomeningocele]] was treated with [[lumbar drain]] and [[fibrin glue]]. Performed for persistent right [[pleural effusion]], [[CT myelogram]] failed to show communication between the [[cerebrospinal fluid]] (CSF) and pleural space-even on 2-hour delayed images. Subsequent [[In DTPA cisternogram]] clearly demonstrated [[CSF leakage]] into the right pleural space at 2 hours, and surgical repair yielded good results. [[radionuclide cisternography]] is a highly useful method to detect CSF leak, especially when it is occult on [[CT]] yet suspected clinically
((Howard BA, Gray L, Isaacs RE, Borges-Neto S. Definitive Diagnosis of Cerebrospinal Fluid Leak Into the Pleural Space Using 111In-DTPA Cisternography. Clin Nucl Med. 2014 Sep 18. [Epub ahead of print] PubMed PMID: 25243944.)).

===== References =====