Significance of Pseudomeningocele After Decompressive Surgery for Chiari I Malformation
Artur Balasa1, Przemysław Kunert1, Mateusz Bielecki1
1Department of Neurosurgery, Medical University of Warsaw, Warsaw, Poland.
Background:
Pseudomeningoceles (PMCs) as abnormal collections of cerebrospinal fluid are quite common findings on follow-up MRI after Chiari decompression surgery (CDS). However, the importance of their identification has not been truly determined, especially when PMCs are described occasionally in the process of radiological follow-up. We retrospectively analyzed surgical outcomes and imaging findings after CDS depending upon the occurrence and thickness of PMCs.
Methods:
A total of 76 adult patients who underwent CDS were analyzed. The clinical and radiological outcomes of patients with a pseudomeningocele (wPMC) were evaluated and compared to those of patients without a pseudomeningocele (w/oPMC). Radiological morphometric measurements were performed and compared between groups. Comparisons of the maximal PMC thickness were made within the wPMC group.
Results:
PMCs were recognized in 27 (35.5%) patients, of whom 3 (11.1%) required reoperation. Differences in satisfactory result rates regarding gestalt assessment and Chicago Chiari Outcome Scale were statistically insignificant between the w/oPMC and wPMC groups (p = 1 and p = 0.56, respectively). The postoperative syringomyelia decrease and cerebellar tonsil elevation were similar between the groups (p = 1 and p = 0.74, respectively) in the long-term follow-up. Additionally, the clinical or radiological outcomes with radiological details were not related to PMC thickness in the long-term follow-up. However, radiological details showed the cooccurrence of PMCs with a postsurgical of cerebello-tentorial distance increase (p < 0.05), basion-pontomedullary sulcus distance decrease (p < 0.05) and tonsillo-graft distance decrease (p < 0.05).
Conclusions:
We found no significant relationships between PMC presence or thickness and clinical or radiological outcomes. However, postoperative changes within the posterior fossa associated with PMCs resemble brain sagging, which occurs in intracranial hypotension. Therefore, extradural cerebrospinal fluid escape may also be responsible for symptoms in some patients with PMCs after CDS.
Insights
Pseudomeningoceles (PMCs) after Chiari decompression surgery (CDS) are common but do not impact clinical outcomes. Postoperative posterior fossa changes associated with PMCs may indicate cerebrospinal fluid escape, potentially causing symptoms.
Area of Science:
- Neurosurgery
- Radiology
- Cerebrospinal Fluid Dynamics
Background:
- Pseudomeningoceles (PMCs), collections of cerebrospinal fluid, are frequent findings post-Chiari decompression surgery (CDS).
- The clinical significance of PMCs identified during radiological follow-up remains unclear.
Purpose of the Study:
- To evaluate the impact of pseudomeningocele occurrence and thickness on surgical and radiological outcomes after Chiari decompression surgery.
- To investigate the relationship between PMCs and postoperative changes in the posterior fossa.
Main Methods:
- Retrospective analysis of 76 adult patients who underwent CDS.
- Comparison of clinical and radiological outcomes between patients with (wPMC) and without (w/oPMC) pseudomeningoceles.
- Morphometric measurements of the posterior fossa and PMC thickness were performed.
Main Results:
- Pseudomeningoceles were present in 35.5% of patients; 11.1% required reoperation.
- No statistically significant differences in satisfactory outcomes, syringomyelia decrease, or cerebellar tonsil elevation were observed between wPMC and w/oPMC groups.
- PMC presence or thickness did not correlate with long-term clinical or radiological outcomes.
- PMCs were associated with increased cerebello-tentorial distance, decreased basion-pontomedullary sulcus distance, and decreased tonsillo-graft distance.
Conclusions:
- The presence or thickness of pseudomeningoceles after CDS is not significantly related to clinical or radiological outcomes.
- Postoperative posterior fossa changes associated with PMCs resemble brain sagging seen in intracranial hypotension.
- Extradural cerebrospinal fluid escape may contribute to symptoms in some patients with PMCs following CDS.
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