PMC7328493_01
MRI sequences of all three cases. All lesions were predominantly
hyperintense on T2-weighted (T2W) images and isointense on T1-weighted
(T1W) images, with no clear contrast enhancement following gadolinium
administration. Spinal cord dorsal tenting and atrophy was a common
feature. (a) T2W midsagittal sequence of the spinal column from T11 to
S3 in case 1 showed incomplete closure of the dorsal vertebral column.
Tissue extending from the dura is seen attaching to the overlying dermis
(arrow), with spinal cord tenting, atrophy and syringomyelia. (b) T2W
transverse sequence at the level of L2-L3 in case 1 demonstrating the
stalk attaching to the dermis. (c) T1W midsagittal sequence of the
spinal column from C2 to L2 in case 2 showed tissue extending from the
dura to the dermis at the level of T8-T9 (arrow). (d) T2W transverse
sequence at the level of T8 in case 2. (e) T2W midsagittal sequence of
the T5-S1 spinal column in case 3 displaying the midline defect at the
level of L4 (arrow). (f) T2W transverse sequence at the level of L4 in
case 3
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MRI of the thoracolumbar vertebral column (Figure 1c,d) confirmed the presence of a defect in the dorsal lamina at T8-T9, with dorsal elevation of the spinal cord and dorsolateral cord compression. CT (Figure 7) and MRI (Figure 1e,f) of the thoracolumbar spine were performed, revealing a bifid abnormality of the L4 vertebra.
T2-weighted midsagittal MRI from T11 to S3 in case 1 showed adhesion of
the dura to the previous dorsal laminectomy site with persistent
dilation of the subarachnoid space with cerebrospinal fluid and
associated cord compression (arrow)
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Repeat MRI revealed suspected adhesion of the dura to the overlying laminal defect with persistent subarachnoid dilation (Figure 2).
Histopathology with haemotoxylin and eosin stain from case 1 were
consistent with a diagnosis of limited dorsal myeloschisis (LDM).
Additional immunohistochemistry confirmed cells were of neural origin.
(a) A cavitated space within the centre of the fibroneural stalk is seen
lined by an epithelium, consistent with glioependymal tissue from case 1
(x 20). (b) Neuronal bodies (arrows) shown from case 1 are
characteristic of LDM (x 10). (c) Immunohistochemistry. Positive
staining with S100 confirms that these cells are of neural origin (x
2.5). (d) Immunohistochemistry. Clusters of glial fibrillary acidic
protein (GFAP)-positive glial cells are seen within the fibroneural
stalk. The glioependymal lining also stains positively with GFAP (x
2.5)
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Histology of the resected tissue was consistent with a diagnosis of LDM (changes seen similar to that in Figure 3).
PMC7328493_02
MRI sequences of all three cases. All lesions were predominantly
hyperintense on T2-weighted (T2W) images and isointense on T1-weighted
(T1W) images, with no clear contrast enhancement following gadolinium
administration. Spinal cord dorsal tenting and atrophy was a common
feature. (a) T2W midsagittal sequence of the spinal column from T11 to
S3 in case 1 showed incomplete closure of the dorsal vertebral column.
Tissue extending from the dura is seen attaching to the overlying dermis
(arrow), with spinal cord tenting, atrophy and syringomyelia. (b) T2W
transverse sequence at the level of L2-L3 in case 1 demonstrating the
stalk attaching to the dermis. (c) T1W midsagittal sequence of the
spinal column from C2 to L2 in case 2 showed tissue extending from the
dura to the dermis at the level of T8-T9 (arrow). (d) T2W transverse
sequence at the level of T8 in case 2. (e) T2W midsagittal sequence of
the T5-S1 spinal column in case 3 displaying the midline defect at the
level of L4 (arrow). (f) T2W transverse sequence at the level of L4 in
case 3
10.1177_2055116920924307-fig1.jpg
PMC7328493_02_10.1177_2055116920924307-fig1.jpg
fig1-2055116920924307
MRI of the thoracolumbar vertebral column (Figure 1c,d) confirmed the presence of a defect in the dorsal lamina at T8-T9, with dorsal elevation of the spinal cord and dorsolateral cord compression. CT (Figure 7) and MRI (Figure 1e,f) of the thoracolumbar spine were performed, revealing a bifid abnormality of the L4 vertebra.
Histopathology with haemotoxylin and eosin stain from case 1 were
consistent with a diagnosis of limited dorsal myeloschisis (LDM).
Additional immunohistochemistry confirmed cells were of neural origin.
(a) A cavitated space within the centre of the fibroneural stalk is seen
lined by an epithelium, consistent with glioependymal tissue from case 1
(x 20). (b) Neuronal bodies (arrows) shown from case 1 are
characteristic of LDM (x 10). (c) Immunohistochemistry. Positive
staining with S100 confirms that these cells are of neural origin (x
2.5). (d) Immunohistochemistry. Clusters of glial fibrillary acidic
protein (GFAP)-positive glial cells are seen within the fibroneural
stalk. The glioependymal lining also stains positively with GFAP (x
2.5)
10.1177_2055116920924307-fig3.jpg
PMC7328493_02_10.1177_2055116920924307-fig3.jpg
fig3-2055116920924307
Histology of the resected tissue was consistent with a diagnosis of LDM (changes seen similar to that in Figure 3).
The cutaneous defects varied in appearance. (a) An area of whorled hair
with no palpable skin depression was seen at the level of T8-T9
vertebrae in case 2. (b) A saccular cutaneous lesion was evident
overlying the mid-lumbar region with fluid discharge, likely
cerebrospinal fluid in origin, as a result of rupture of the membranous
sac in case 3. (c) A suspected limited dorsal myeloschisis cutaneous
saccular lesion was seen in a juvenile pug not included in this study,
but included here to show the characteristic appearance
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It had a distinct area of whorled hair overlying the T8 vertebra dorsally (Figure 4a). The cat was also noted to have a subcutaneous mass lesion overlying the mid lumbar vertebral column, which had previously shown discharge of a clear fluid suspected to be CSF (Figure 4b).
Intraoperative image of case 2 showing the fibroneural stalk extending to
attach to the overlying dermis
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A dorsal surgical approach to the defect was made (Figure 5).
The fibroneural stalk can be seen in its entirety attaching to the
overlying dermis after complete surgical excision (case 2)
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The fibroneural stalk was dissected from surrounding tissues (Figure 6) and a dorsal laminectomy performed.
CT images showing the defect in case 3. (a) Midsagittal CT sequence from
T1 to S3 showing the defect in the L4 vertebra (arrow). (b) Transverse
CT sequence at the level of L4 vertebra
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CT (Figure 7) and MRI (Figure 1e,f) of the thoracolumbar spine were performed, revealing a bifid abnormality of the L4 vertebra.