Chronic extradural compression of spinal cord leads to syringomyelia in rat model

Abstract

Background: Syringomyelia is a common spinal cord lesion. However, whether CSF blockage is linked to the formation and enlargement of syringomyelia is still controversial. The current model of syringomyelia needs modification to more closely mimic the clinical situation. Methods: We placed cotton strips under the T13 lamina of 40 8-week-old rats and blocked CSF flow by extradural compression. After 4 and 8 weeks, MRI was performed to evaluate the morphology of syringomyelia and the ratio of spinal cord diameter to syrinx diameter calculated. Locomotor function was evaluated weekly. Spinal cord sections, staining and immunohistochemistry were performed 8 weeks after surgery, the ratio of the central canal to the spinal cord area was calculated, and ependymal cells were counted. In another experiment, we performed decompression surgery for 8 rats with induced syringomyelia at the 8th week after surgery. During the surgery, the cotton strip was completely removed without damaging the dura mater. Then, the rats received MRI imaging during the following weeks and were sacrificed for pathological examination at the end of the experiment. Results: Syringomyelia formed in 82.5% (33/40) of rats at the 8-week follow-up. The Basso, Beattie and Bresnahan (BBB) scores of rats in the experimental group decreased from 21.0±0.0 to 18.0 ±3.9 in the first week after operation but returned to normal in later weeks. The BBB score indicated that the locomotor deficit caused by compression is temporary and can spontaneously recover. MRI showed that the syrinx is located in the center of the spinal cord, which is very similar to the most common syringomyelia in humans. The ratio of the central canal to the spinal cord area reached (2.9 ± 2.0) × 10 −2 , while that of the sham group was (5.4 ± 1.5) × 10 −4. The number of ependymal cells lining the central canal was significantly increased (101.9 ± 39.6 vs 54.5 ± 3.4). There was no syrinx or proliferative inflammatory cells in the spinal cord parenchyma. After decompression, the syringomyelia size decreased in 50% (4/8) of the rats and increased in another 50% (4/8). Conclusion: Extradural blockade of CSF flow can induce syringomyelia in rats. Temporary locomotor deficit occurred in some rats. This reproducible rat model of syringomyelia, which mimics syringomyelia in humans, can provide a good model for the study of disease mechanisms and therapies.

Relationship Between Syrinx Resolution and Cervical Sagittal Realignment Following Decompression Surgery for Chiari I Malformation Related Syringomyelia Based on Configuration Phenotypes

“…It is characterized by typical syrinx separation on imaging morphology, which we have initially confirmed in rat models of syringomyelia. 30 However, that still needs to be better understood whether it belongs to a transitional state of syringomyelia or a special configuration, which will certainly lead us to potential implications for the exploration of the hydrodynamics and biological mechanisms during syringomyelia formation and resolution.…”

“…Its particularity lies in that the reactivity following the change of CSF circulation seems to be more sensitive, and it shows stronger adaptability and reducibility than other types of syringomyelia, which not only reflects in the greater changes in the cervical lordosis during the syrinx formation with a shorter natural history but also in the more obvious syrinx resolution and a relatively better prognosis after removing the intradural obstruction and dredging the circulation of CSF. In terms of syrinx width, both moniliform type and distended type belong to the category with a larger S/C ratio; from the perspective of syrinx morphology, syrinx separation is the typical imaging manifestation for moniliform type, and some studies have preliminarily confirmed syrinx separation might be related with the ependymal cells surrounding the central canal of the spinal cord [ 29 , 30 ], which would be a source of endogenous stem cells, heralding a potential endogenous approach to SCI repair. While it is still unknown the specific pathophysiological mechanism of syrinx separation in chronic SCI.…”

Wireless Epidural Electrical Stimulation in Combination With Serotonin Agonists Improves Intraspinal Metabolism in Spinal Cord Injury Rats

“…S3), compromising the normal function of the corresponding spinal cord segments. Hence, to avoid potential bias arising from post-traumatic syringomyelia, data on metabolism at the T7-T8 vertebral level were discarded (36,37). Furthermore, data on metabolism at the T9-T11 level were not included in the statistical analysis because thoracic spinal cord segments mainly innervate the intercostal muscles for respiration, not locomotion (38).…”

Phenotypes and Prognostic Factors of Syringomyelia in Single-Center Patients With Chiari I Malformation: Moniliform Type as a Special Configuration

“…Surgical management initially focused on treating the etiology of the syringomyelia, 9 primarily by re-establishing the physiologic pathways of cerebrospinal fluid (CSF) in the SAS. 10 Mostly, the surgical goal is to reconstruct the craniovertebral junction (CVJ) with duraplasty. 11 Previous studies have suggested that early diagnosis and surgical intervention such as posterior fossa decompression (PFD) have made it possible to reduce the size of the syrinx.…”

“…In recent years, with the widespread use of magnetic resonance imaging (MRI), there was an increasing number of patients screened with syringomyelia. Surgical management initially focused on treating the etiology of the syringomyelia [ 9 ], primarily by re-establishing the physiologic pathways of cerebrospinal fluid (CSF) in the SAS [ 10 ]. Mostly, the surgical goal is to reconstruct the craniovertebral junction (CVJ) with duraplasty [ 11 ].…”