- Department of Neurosurgery, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan,
- Department of Neurosurgery, Kitakyushu Municipal Medical Center, Kitakyushu, Japan,
- Department of Neurosurgery, Fukuoka Children’s Hospital, Fukuoka, Japan,
- Department of Neurosurgery, Harasanshin Hospital, Fukuoka, Japan,
- Department of Psychiatry, Shourai Hospital, Saga, Japan.
Correspondence Address:
Takafumi Shimogawa, Department of Neurosurgery, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japa.
DOI:10.25259/SNI_517_2021
Copyright: © 2021 Surgical Neurology International This is an open-access article distributed under the terms of the Creative Commons Attribution-Non Commercial-Share Alike 4.0 License, which allows others to remix, tweak, and build upon the work non-commercially, as long as the author is credited and the new creations are licensed under the identical terms.How to cite this article: Takafumi Shimogawa1, Nobutaka Mukae1, Akiko Kanata2, Haruhisa Tsukamoto2, Nobuya Murakami3, Ai Kurogi3, Tadahisa Shono4, Satoshi O. Suzuki5, Takato Morioka4. Spinal cord deformity with aggravation of tethering in saccular limited dorsal myeloschisis during the first 2 months of life. 20-Sep-2021;12:476
How to cite this URL: Takafumi Shimogawa1, Nobutaka Mukae1, Akiko Kanata2, Haruhisa Tsukamoto2, Nobuya Murakami3, Ai Kurogi3, Tadahisa Shono4, Satoshi O. Suzuki5, Takato Morioka4. Spinal cord deformity with aggravation of tethering in saccular limited dorsal myeloschisis during the first 2 months of life. 20-Sep-2021;12:476. Available from: https://surgicalneurologyint.com/surgicalint-articles/11116/
Abstract
Background: Although the optimal timing of prophylactic untethering surgery for limited dorsal myeloschisis (LDM) with intact or subtle neurological findings diagnosed at birth remains undetermined, intentional delayed surgery is commonly used for flat and tail-like LDM. Conversely, for saccular LDM, early surgery is indicated during the postnatal period because it prevents rupture of the sac. We treated a saccular LDM patient, in whom intentional delayed surgery was selected because the sac was thickly covered with normal skin. We describe the clinical course of the case and discuss the optimal timing of the surgery.
Case Description: The patient had a dorsal midline sac in the upper lumbar region. Initial magnetic resonance imaging (MRI) after birth revealed a tethering tract that began at the dome of the sac and joined the lumbar cord. Dorsal bending of the cord at the stalk-cord union and invagination of the cord into the sac were noted. At 2 months, he was neurologically normal; however, the second MRI examination revealed that the cord tethering was aggravated. The cord was markedly displaced dorsally and to the left, with deviation of the cord to the sac out of the spinal canal. Following untethering surgery, the spinal cord deformity markedly improved.
Conclusion: Early surgery may be recommended for saccular LDM when tethering is present, including dorsal bending of the cord at the stalk-cord union and invagination of the cord into the sac observed on detailed MRI examination, even if the sac has no risk of rupture.
Keywords: Limited dorsal myeloschisis, Segmental myelocystocele, Spinal cord deformity, Tethering, Untethering
INTRODUCTION
Limited dorsal myeloschisis (LDM) is thought to originate from a small segmental failure of the dorsal closure of the neural folds during primary neurulation. At the focal limited nonclosure site, the disjunction between the cutaneous and neural ectoderm is impaired. This results in a retained fibroneural stalk linking the skin lesion and the dorsal spinal cord, which results in cord tethering.[
Although the optimal timing of prophylactic untethering surgery for LDMs with intact or subtle neurological findings diagnosed at birth remains undetermined, intentional delayed surgery is commonly selected for flat and tail-like LDM.[
CASE REPORT
The patient was a boy weighing 3055 g delivered through a scheduled repeated cesarean section at 38+2 weeks of gestation. The patient had Apgar scores of 8 and 9. Physical examination revealed a dorsal midline sac in the upper lumbar region measuring 30×30×10 mm in length × width × height that was thickly covered with normal skin [
Figure 1:
(a) A dorsal midline sac measuring 30×30×10 mm in the upper lumbar region. (b and c) Sagittal views of 3D-T1WI (b) and T2WI (c) demonstrate a tethering tract that began at the dome of the meningocele sac, ran caudally in the inner wall of the sac, and joined the lumbar cord at the L3 vertebral level. The attachment of the stalk to the dome contained a small syrinx cavity (blue arrows). The stalks comprising the anterior wall of the syrinx cavity were almost isointense on 3D-T1WI (red arrows). (d and e) Parallel coronal views of 3D-hT2WI with fat suppression (d) and parallel axial views of T2WI (e) also show that the attachment of the stalk to the dome. The spinal cord slightly deviated into the dome and was stuck at the entrance of the dome, which measured 15× 10 mm (yellow arrows in (d and e)).
At 2 months of age, he weighed 5230 g. The lumbar sac had grown to 50×40×15 mm [
Figure 2:
(a) The dome grew to 50×40×15 mm by 2 months of age. (b and c) Parallel sagittal views of T1WI (b), parallel coronal views of 3D-hT2WI with fat suppression (c), and parallel axial views of 3D-hT2WI with fat suppression (d) revealed that cord tethering was aggravated. With the deviation of the cord to the sac out of the spinal canal (yellow arrows in (c and d)), the cord was displaced dorsally and to the left. The stalk comprising the anterior wall (red arrows) of the syrinx cavity (blue arrows) became lipomatous tissue. (e-k) Schematic drawing (e) and microscopic view of the intraoperative findings (f and h-k), and intraoperative neurophysiological monitoring (g). (e and f) The cord emerged from the orifice of the spinal canal. The border between the spinal cord and stalk could be distinguished and nerve roots were found on the cord. (g) This border was neurophysiologically confirmed by tracing the evoked compound muscle action potentials (CMAPs) of the hamstring with direct stimulation with 3 mA intensity starting from the functional cord and continuing to the nonfunctional stalk. The CMAPs were evoked following stimulation at the cord (1-2); no CMAPs were evoked following stimulation at the stalk (3-8). (h) The stalk was severed just distal to the border; the syrinx cavity was opened. (i) The cord was untethered from the stalk. (j) The severed edge was approximated with a pial suture and returned to the spinal canal. (k) The orifice of the cord was tightly closed.
On the 68th day after birth, untethering and repair surgery of the sac were performed. On opening the sac, the cord emerged from the orifice of the spinal canal, which was 15 mm in diameter, with the tethering of the stalk spread widely on the inner wall of the sac [
Postoperatively, the patient did not develop neurological deficits. MRI performed on the 14th day postoperatively demonstrated that the spinal cord deformity markedly improved due to the successful untethering of the cord, although minor hemorrhage was noted at the severed edge of the stalk [
Figure 3:
(a and b) Sagittal view of T1WI (a) and coronal image of 3D-hT2WI with fat suppression (b) performed on the postoperative 14th day demonstrated that the spinal cord deformity markedly improved, although a minor hemorrhage was noted at the severed edge of the stalk. (c-f) Histopathological examination of the resected stalk stained with hematoxylin and eosin (c, d) and immunostained for glial fibrillary acidic protein (GFAP) (e and f). Higher magnification view of the area indicated by the dotted square in (c) is shown in (d and e). A central canal (CC)-like lumen lined by ependymal cells (Epen) and surrounding GFAP-immunopositive neuroglial tissues and fibrocollagenous tissue embedded with smooth muscle (SM) fibers was noted in the fibroadipose tissue (FAT). The sac was covered with finely jagged squamous epithelium (blue arrow in (c)). (f) The wall facing the syrinx cavity was composed of GFAP-immunopositive neuroglial tissue including neuronal cells and had no ependymal lining.
Histopathologically, the resected stalk included a central canal-like lumen lined by ependymal cells. Surrounding glial fibrillary acidic protein (GFAP)-immunopositive neuroglial tissues and fibrocollagenous tissues embedded with smooth muscle fibers in the fibroadipose tissue were also present [
DISCUSSION
Pang et al.[
The most characteristic morphological finding in this case was aggravation of tethering and deformity of the cord during the first 2 months of life. Kim et al.[
Another notable finding was that the LDM stalk consisting of the anterior wall of the syrinx cavity became lipomatous tissue, and histologically, most of the resected stalk consisted of fibroadipose tissue. LDMs are thought to arise from focal incomplete disjunction between the cutaneous and neuroectoderm during primary neurulation, while spinal lipomas of the dorsal type (dorsal lipomas) arise from premature disjunction. Thus, the simultaneous occurrence of an LDM and a dorsal lipoma has been well documented.[
CONCLUSION
Spinal deformities could occur due to aggravation of the tethering effect with the enlargement of the extraspinal sac. As such, early surgery may be recommended for saccular LDMs when there are any stout tethering findings, including dorsal bending of the cord at the stalk-cord union and invagination of the cord into the sac at birth, even if the surface of the sac is covered with normal skin.
Declaration of patient consent
The authors certify that they have obtained all appropriate patient consent.
Financial support and sponsorship
This work was supported by a Grant-in-Aid for Scientific Research from the Japan Society for the Promotion of Science (JSPS) (JP21K17456 to TS).
Conflicts of interest
There are no conflicts of interest.
Declaration of patient consent
The authors certify that they have obtained all appropriate patient consent.
Financial support and sponsorship
This work was supported by a Grant-in-Aid for Scientific Research from the Japan Society for the Promotion of Science (JSPS) (JP21K17456 to TS).
Conflicts of interest
There are no conflicts of interest.
Acknowledgment
We thank Drs. Yasushi Takahata and Keisuke Kokubo, Department of Neonatology, Kitakyushu Municipal Medical Center, for supporting our study. We thank Editage for editing a draft of this manuscript.
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