PMC5431438_01
MRI, CT and intraoperative findings in case 1. (a) T2-weighted sagittal image of the lumbosacral region and (b) transverse image at the level of S3 on MRI. (a) The fistula was revealed to be hyperintense (arrowhead) and tethered the conus medullaris up to the caudal aspect of S3 (arrow). Rectal narrowing was secondary to ventral displacement of the caudal vertebra (asterisk). (b) The conus medullaris presented possible caudal displacement (arrow). (c) T2-weighted sagittal image of the lumbosacral region and (d) transverse image at the level of S1 in a 1.5-year-old male domestic shorthair cat without spinal issues. (c) The conus medullaris is the terminus of the caudal aspect of L7-S1 (arrow). (d) The dural sac does not contain the conus medullaris at the cranial aspect of S1. (e) A three-dimensional reconstruction dorsal image of the lumbosacral region on CT revealed the lack of the dorsal arches of S3, Cd1 and Cd2 vertebrae. (f) The fistula was connected to the dural sac and caused caudal traction of the conus medullaris after incision of the meninges
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CT (Aquilion 64-slice scanner; Toshiba) were performed. The palpable dermoid fistula was hyperintense on T2-weighted images (T2WI) and hypointense on T1-weighted images (T1WI), and was connected to the dural sac on the conus medullaris. This fistula appeared to have retracted the spinal cord caudally (Figure 1a-d). CT images revealed the lack of the dorsal arches of S3, Cd1 and Cd2 vertebrae and ventral displacement of the caudal vertebra (Figure 1e). Severe fecal impaction was also present. After the incision of the meninges, the fistula caused caudodorsal displacement and traction of the conus medullaris (Figure 1f).
(a) Follow-up MRI 1 month after surgery in case 1. The conus medullaris is observed to release the tethering and terminates at the caudal aspect of L7 (arrow). Rectal narrowing is also improved (asterisk). (b) Histopathology; excised tissues showed a segment of a neuropil in the dermis. The space within the spinal cord parenchyma (asterisk), including multiple small capillaries, glial cells and occasional neurons, is the central canal lined by ependymal cells. Haematoxylin and eosin staining
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A follow-up MRI revealed the release of the conus medullaris tethering and an improvement in rectal narrowing (Figure 2a). Based on these findings, the lesion was diagnosed as a meningomyelocele (Figure 2b).
PMC5431438_02
MRI, CT and intraoperative findings in case 2. (a) T2-weighted sagittal image on MRI. The dermoid fistula was hypointense and detected as a tubular structure (arrowheads), which was connected to the dural sac, and the tethered spinal cord was retracted dorsally (arrow). (b) A three-dimensional reconstruction dorsal image on CT revealed a dorsal laminar defect between the spinous processes of T5 and T6. (c) The tubular structure was connected to the dural sac (arrow)
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CT revealed a dorsal lamina defect between the spinous processes of T5 and T6 (Figure 3a,b). T5 and T6 were performed. The tubular structure connected to the dural sac was observed (Figure 3c).
Case 2. (a) A postoperative MRI examination revealed the removal of the tubular structure and release from tethering of the spinal cord. (b) Gross and (c,d) histopathological findings. A histopathological evaluation showed meningeal-like cells surrounded by well-differentiated collagen fibres. (c) Haematoxylin and eosin staining. (d) Immunohistochemically, these meningeal-like cells were positive for anti-E-cadherin
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A postoperative MRI examination confirmed the removal of the tubular structure and untethering of the spinal cord (Figure 4a). This confirmed the diagnosis of a meningocele (Figure 4b-d).