I would like to thank Irish Healthcare, Sharon Gillece for sharing the following research study.
General
Spine
Peter _
Yoo, MD, Non ASSR Member
Shane Lee, BA, Non ASSR
Member
Nikhil Bhagat, MD, Non ASSR Member
Huey-Jen Lee, MD, Non ASSR Member
Scientific
Paper
Purpose
(1) To
determine the incidence of extradural meningeal cysts in adult patients who
underwent routine magnetic resonance imaging (MRI) of the lumbar spine for lower
back pain. (2) To describe the current classification of sacral meningeal cysts
and its postulated pathophysiology. (3) Literature review of the clinical
significance and management of sacral extradural meningeal cysts.
Methods
& Materials
A total of
584 MRI studies of the lumber spine were retrospectively reviewed. The studies
were performed for the evaluation of lower back pain and were performed between
May 2005 and November 2005. Pediatric and trauma cases were excluded. Ages
ranged from 18 years to 80 years. Routine MRI of the lumbar spine was performed
on a 1.5 Tesla GE scanner. The study consists of sagittal T1, fast spin echo
(FSE) and short TI inversion recovery (STIR) sequences of the lumbar and sacral
spine. Axial proton and T2 weighted images of the disc spaces between L1 and S1
are also obtained. Post gadolinium axial and sagittal T1 weighted images are
only obtained in post-spinal surgery patients.
Results
A total of
7 sacral extradural meningeal cysts were identified (1.2 %). 4 of the patients
were male and 3 were female with a mean age of 49 years (range 32 years to 70
years). 5 were determined to be type I and 2 were indeterminate. All of the
cysts occurred in the sacral spine. 4 cases also demonstrated coexistent disc
disease of the lumbar spine and 1 case demonstrated a compression fracture of
L5. 2 cases demonstrated no concurrent disc disease. Of these two patients, one
patient presented with sacral and lower extremity pain with paresthesia while
the other patient complained of nonspecific lower back pain.
Conclusion
The prevalence of sacral extradural
meningeal cysts in our study is 1.2%. Sacral meningeal cysts have been
classified into three categories: extradural cysts not containing nerve root
fibers (Type I), extradural cysts containing nerve root fibers (Type II) and
intradural cysts (Type III). The exact mechanism of formation of sacral
extradural meningeal cysts is unknown. It has been postulated that the
arachnoid membrane herniates through a dural defect, which is most likely
congenital. Sacral
extradural meningeal cysts are generally considered to be incidental findings.
However, there are several published case reports that have attributed symptoms
to these lesions and these patients have undergone surgical intervention. In our
study, 2 out of the 7 cases demonstrated no coexistent disc disease. Therefore,
the clinical symptoms may be related to the sacral cysts. In light of these reports and our
findings, sacral extradural meningeal cysts should not be easily dismissed as an
incidental finding.
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