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Proposed embryogenetic mechanisms for different types of focal spinal non-disjunctional disorders. A : Congenital spinal dermal sinus tract (CSDST). B : Limited dorsal myeloschisis (LDM). C : Mixed CSDST and LDM -"orthodox" type and "conjoint" type. D : LDM with hidden dermal elements. SE : surface epithelium, NE : neuroepithelium.
Source publication
Spinal dysraphic lesions due to focal nondisjunction in primary neurulation are commonly encountered in paediatric neurosurgery, but the "fog-of-war" on these conditions was only gradually dispersed in the past 10 years by the works of the groups led by the senior author and Prof. Kyu-Chang Wang. It is now clear that limited dorsal myeloschisis and...
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... faults. For example, Rac1 and Cdc42 only involve SE fusion; thus the clinical phenotypes due to their aberrations could be different from those affecting proteins regulating NE fusion 20,28) . The embryogenetic mechanisms for the subtype FSND malformations, described in terms of morphological changes in the embryonic tissue, are as follows (Fig. 2) : 1) a CSDST develops, when fusion of the SE fails at a focal point, but the underlying NE fusion has at least been represented by some intercellular adhesions, and disjunction at this focal point does not occur. In this situation, closure of the primary neural tube immediately cranial and caudal to this focal nondisjunction spot is ...
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... features of all LDMs are 1) a cutaneous stigma and 2) an underlying fibroneural stalk anchoring the spinal cord to the skin lesion ( Fig. 9). The cutaneous marker, a pearly crater of abnormal skin, commonly known as a "ciga- rette-burn scar/mark", is due to hindrance on normal skin development by the stalk attaching to the undersurface of the SE (Fig. 2). In all instances, the fibroneural stalk, extending from the deeper side of the abnormal skin, ultimately merges with the spinal cord. Only one example of a discontinuous stalk has been documented 8) . In all LDMs, the spinal cord is tethered to the surface myofascial tissue by the fibroneural stalk 22,34,35) and by the meningeal and ...
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... the fibroneural stalk and ultimately distends the thinner, less well-supported squamous epithelial membrane on the surface into a CSF-filled, skin-based but epitheliumcapped sac. Strands of the fibroneural stalk traverse the fluid cavity of the sac to reach the part of the dome bearing the edge of the crater, where the nondisjunction occurred (Fig. ...
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... tubular structures in many cervical saccular lesions, to the translucent membrane topping a tense lumbar sac, and finally to the giant, diaphanous bubble. A transitional form between saccular and flat LDMs can be observed, due to transient increase in fluid pressure during straining, in flat LDMs with the intermittently ballooning central crater (Fig. ...
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... passes through the lamina or penetrates the dura, and where it merges with the spinal cord. In the largest LDM series published 25) , the vertebral level where the stalk merges with the spinal cord was chosen as the level of the LDM because it is usually the most unequivocal feature on MRI. The locations of the LDMs in that series are shown in Fig. 24, while the distribution of the types of LDMs is depicted in Fig. 25. Over two-thirds of LDMs in that series are located in the lower half of the spinal cord 25) ...
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... with the spinal cord. In the largest LDM series published 25) , the vertebral level where the stalk merges with the spinal cord was chosen as the level of the LDM because it is usually the most unequivocal feature on MRI. The locations of the LDMs in that series are shown in Fig. 24, while the distribution of the types of LDMs is depicted in Fig. 25. Over two-thirds of LDMs in that series are located in the lower half of the spinal cord 25) ...
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... the central feature of all LDM stalks is neuroglial tissue, a hallmark of the stalk's origin from the NE. It is either in large elongated swaths containing scattered neurons (Fig. 26A), or in nests embedded in dense fibrous tissue (Fig. 26B). Also found in every stalk is a profuse network of peripheral nerves randomly admixed with the glial nests, but in some cases, nerves are seen emanating from a central core of neuron-containing glia likened to an abortive spinal cord (Fig. 26C). Large nodules of dorsal root ...
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... the central feature of all LDM stalks is neuroglial tissue, a hallmark of the stalk's origin from the NE. It is either in large elongated swaths containing scattered neurons (Fig. 26A), or in nests embedded in dense fibrous tissue (Fig. 26B). Also found in every stalk is a profuse network of peripheral nerves randomly admixed with the glial nests, but in some cases, nerves are seen emanating from a central core of neuron-containing glia likened to an abortive spinal cord (Fig. 26C). Large nodules of dorsal root ganglion cells are seen in some cases, attesting to the ...
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... elongated swaths containing scattered neurons (Fig. 26A), or in nests embedded in dense fibrous tissue (Fig. 26B). Also found in every stalk is a profuse network of peripheral nerves randomly admixed with the glial nests, but in some cases, nerves are seen emanating from a central core of neuron-containing glia likened to an abortive spinal cord (Fig. 26C). Large nodules of dorsal root ganglion cells are seen in some cases, attesting to the occasional entrapped neural crest stem cells during formation of the neural stalk (Fig. 26D). Pacinian corpuscles (Fig. 26E) seen amongst some of these nerves suggest they are indeed sensory axons. Evidence of mesenchymal condensation around the ...
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... randomly admixed with the glial nests, but in some cases, nerves are seen emanating from a central core of neuron-containing glia likened to an abortive spinal cord (Fig. 26C). Large nodules of dorsal root ganglion cells are seen in some cases, attesting to the occasional entrapped neural crest stem cells during formation of the neural stalk (Fig. 26D). Pacinian corpuscles (Fig. 26E) seen amongst some of these nerves suggest they are indeed sensory axons. Evidence of mesenchymal condensation around the lengthening neural stalk is shown by the almost universal inclusion of numerous fibrous bands, skeletal muscle, fat (Fig. 27A), and prominent vascular channels sometimes in the form of ...
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... nests, but in some cases, nerves are seen emanating from a central core of neuron-containing glia likened to an abortive spinal cord (Fig. 26C). Large nodules of dorsal root ganglion cells are seen in some cases, attesting to the occasional entrapped neural crest stem cells during formation of the neural stalk (Fig. 26D). Pacinian corpuscles (Fig. 26E) seen amongst some of these nerves suggest they are indeed sensory axons. Evidence of mesenchymal condensation around the lengthening neural stalk is shown by the almost universal inclusion of numerous fibrous bands, skeletal muscle, fat (Fig. 27A), and prominent vascular channels sometimes in the form of a vascular glomus (Fig. 27B). ...
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... neural crest stem cells during formation of the neural stalk (Fig. 26D). Pacinian corpuscles (Fig. 26E) seen amongst some of these nerves suggest they are indeed sensory axons. Evidence of mesenchymal condensation around the lengthening neural stalk is shown by the almost universal inclusion of numerous fibrous bands, skeletal muscle, fat (Fig. 27A), and prominent vascular channels sometimes in the form of a vascular glomus (Fig. 27B). Glioependymal tissue lines the sac cavities in cases of segmental myelocystocoeles (Fig. 27C). The cutaneous "cigarette-burn mark" has the histological appearance of a dermal layer with engorged vascularity, abundant nerve fibres, and an abnormal ...
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... corpuscles (Fig. 26E) seen amongst some of these nerves suggest they are indeed sensory axons. Evidence of mesenchymal condensation around the lengthening neural stalk is shown by the almost universal inclusion of numerous fibrous bands, skeletal muscle, fat (Fig. 27A), and prominent vascular channels sometimes in the form of a vascular glomus (Fig. 27B). Glioependymal tissue lines the sac cavities in cases of segmental myelocystocoeles (Fig. 27C). The cutaneous "cigarette-burn mark" has the histological appearance of a dermal layer with engorged vascularity, abundant nerve fibres, and an abnormal collagen fiber matrix. The unevenness of its surface is due to the ruggedness of the ...
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... Evidence of mesenchymal condensation around the lengthening neural stalk is shown by the almost universal inclusion of numerous fibrous bands, skeletal muscle, fat (Fig. 27A), and prominent vascular channels sometimes in the form of a vascular glomus (Fig. 27B). Glioependymal tissue lines the sac cavities in cases of segmental myelocystocoeles (Fig. 27C). The cutaneous "cigarette-burn mark" has the histological appearance of a dermal layer with engorged vascularity, abundant nerve fibres, and an abnormal collagen fiber matrix. The unevenness of its surface is due to the ruggedness of the epidermis and dermis (Fig. 28) 16,17) ...
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... tissue lines the sac cavities in cases of segmental myelocystocoeles (Fig. 27C). The cutaneous "cigarette-burn mark" has the histological appearance of a dermal layer with engorged vascularity, abundant nerve fibres, and an abnormal collagen fiber matrix. The unevenness of its surface is due to the ruggedness of the epidermis and dermis (Fig. 28) 16,17) ...
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... question is sometimes asked what constitute the minimum criteria for a diagnosis of LDM. It has been shown that there are patients with clinical and radiological features of LDM (Figs. 29 and 30) and most of its histological features including periphery nerve fibers, but no glial tissue within the stalk (Fig. 31) 10,16,17) . In many of these patients, melanocytes are also a prominent feature. Since periphery nerves and melanocytes are neural crest derivatives, and neural crest cells are located in the primary neural tube over ...
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... The "pathognomic" cutaneous marker in both flat and saccular LDMs is a confined area of abnormal epithelium over the dorsal midline. In flat LDMs, the cutaneous lesion can be a conspicuous crater or a tiny pit. 1) Crater : the commonest skin abnormality in flat LDMs is a sunken crater on the f lat skin surface made of pinkish squamous epithelium (Fig. 32A and B), often with elevated skin margin (Fig. 32C) and sometimes surrounded by a capillary haemangioma with irregular corrugated borders (Fig. 32D) or hyperpigmented skin (Fig 32E). There are occasionally long hair emanating from the crater (Fig. 32F), and some craters are edged by hooded overhanging skin (Fig. 32G). ...
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... saccular LDMs is a confined area of abnormal epithelium over the dorsal midline. In flat LDMs, the cutaneous lesion can be a conspicuous crater or a tiny pit. 1) Crater : the commonest skin abnormality in flat LDMs is a sunken crater on the f lat skin surface made of pinkish squamous epithelium (Fig. 32A and B), often with elevated skin margin (Fig. 32C) and sometimes surrounded by a capillary haemangioma with irregular corrugated borders (Fig. 32D) or hyperpigmented skin (Fig 32E). There are occasionally long hair emanating from the crater (Fig. 32F), and some craters are edged by hooded overhanging skin (Fig. 32G). ...
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... the cutaneous lesion can be a conspicuous crater or a tiny pit. 1) Crater : the commonest skin abnormality in flat LDMs is a sunken crater on the f lat skin surface made of pinkish squamous epithelium (Fig. 32A and B), often with elevated skin margin (Fig. 32C) and sometimes surrounded by a capillary haemangioma with irregular corrugated borders (Fig. 32D) or hyperpigmented skin (Fig 32E). There are occasionally long hair emanating from the crater (Fig. 32F), and some craters are edged by hooded overhanging skin (Fig. 32G). ...
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... in flat LDMs is a sunken crater on the f lat skin surface made of pinkish squamous epithelium (Fig. 32A and B), often with elevated skin margin (Fig. 32C) and sometimes surrounded by a capillary haemangioma with irregular corrugated borders (Fig. 32D) or hyperpigmented skin (Fig 32E). There are occasionally long hair emanating from the crater (Fig. 32F), and some craters are edged by hooded overhanging skin (Fig. 32G). ...
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... of pinkish squamous epithelium (Fig. 32A and B), often with elevated skin margin (Fig. 32C) and sometimes surrounded by a capillary haemangioma with irregular corrugated borders (Fig. 32D) or hyperpigmented skin (Fig 32E). There are occasionally long hair emanating from the crater (Fig. 32F), and some craters are edged by hooded overhanging skin (Fig. 32G). ...
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... on histology. Three histological types have been documented. In the "orthodox" type, the dermal and neuroglial elements are in tandem in their respective embryologically orthodox order, i.e., an outer tract of CSDST and an inner tract of LDM elements (Fig. 39) 11) . In the "conjoint" type, the entire FSND tract is lined by both SE and NE elements (Figs. 40-42). The most treacherous Dermal sinus tract within fibro-glioneuronal stalk mixed lesions have been observed in which the dermal elements form microscopic squamous epithelial islands within the neuroglial tissue of an otherwise proper LDM tract -"LDM with hidden dermal elements" (Fig. 43) 5,38) . Rarely, parallel LDM and CSDST tracts can ...
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... LDM stalk may be exceedingly slender and attaches to the cord in a minute midline scar (Fig. 52), or the stalk flares out into a wider hold on the cord so that the cut edge on the cord resembles a gaping fish mouth (Fig. 53). The stalk may also contain a glomus of vascular channels (Fig. 54), or its deep end expands into tentacles of blood vessels that crawl on the cord (Fig. 55). Rarely, the stalk attachment is stout and ...
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Citations
... There are two opinions about the origin of FSN: a violation of primary neurulation [21,22] or secondary [20]. Our study showed that in terms of the frequency of combination with different malformations, this group of patients is closest to MMC, myeloschisis, and spinal lipoma type 1: the frequent presence of simple spina bifida was noted, while other vertebral anomalies were rare. ...
Purpose
To analyze the relationship between spinal cord and vertebral abnormalities from the point of view of embryology.
Methods
We analyzed the clinical and radiological data of 260 children with different types of spinal cord malformations in combination with vertebral abnormalities.
Results
Among 260 individuals, approximately 109 presented with open neural tube defects (ONTDs), 83 with split cord malformations (SCMs), and 83 with different types of spinal lipomas. Pathological spina bifida emerged as the most frequent vertebral anomaly, affecting 232 patients, with a higher prevalence in ONTD. Vertebral segmentation disorders, including unsegmented bars, butterfly vertebrae, and hemivertebrae, were present in 124 cases, with a higher prevalence in SCM. The third most common spinal anomaly group consisted of various forms of sacral agenesis (58 cases), notably associated with blunt conus medullaris, spinal lipomas, and sacral myelomeningocele. Segmental aplasia of the spinal cord had a typical association with segmental spinal absence (N = 17).
Conclusion
The association between SCM and neuroenteric cyst/canal and vertebral segmentation disorders is strong. High ONTDs often coincide with pathological spina bifida posterior. Type 1 spinal lipomas and focal spinal nondisjunction also correlate with pathologic spina bifida. Segmental spinal absence or dysgenesis involves localized spinal and spinal cord aplasia, sometimes with secondary filar lipoma.
... Limited dorsal myeloschisis (LDM) is a form of spinal dysraphism characterized by "a focal 'closed' midline skin defect and a fibroneural stalk that links the skin lesion to the underlying spinal cord" [1,2]. The embryological origin of the lesion has been hypothesized to be an incomplete disjunction between the cutaneous and neural ectoderms during primary neurulation, thereby preventing complete midline skin closure and allowing persistence of a connection (i.e., a fibroneural stalk) between the disjunction site and the dorsal surface of the primary neural tube [3]. The fibroneural stalk has variable thickness, complexity, and length. ...
... This leads some surgeons to reason that the stalk can be cut where it is anchored to the cord to achieve untethering but leave most of the length of a long LDM stalk in situ in order to avoid multi-level laminectomy and the risk of future kyphotic deformity. However, it has recently been found that a significant percentage of "innocent" looking LDM stalks contains embedded squamous epithelial cell nests which have been known to grow into large dermoid cysts within the spinal canal in later life if part of the stalk was left behind [3]. A modification of surgical technique is suggested that avoids long segment laminectomies but still enables complete excision of long LDM stalks after identification of its dural entry and its merge point with the cord. ...
... The rationale for the untethering-only group is to minimize the number of levels of laminectomy in cases of long LDM stalks, in order to diminish the possibility of late spinal deformity. However, most follow-op series are not long enough to observe the development of inclusion cysts observed in Pang et al.'s cohort of LDM [3]. ...
Objective
The fibroneural stalk of an LDM has variable thickness, complexity, and length, which can span 5 to 6 vertebral segments from its skin attachment to its “merge point” with the dorsal spinal cord. Therefore, complete resection may require extensive multi-level laminotomies. In this technical note, a modification of the procedure is presented that avoids long segment laminectomies while ensuring complete excision of long LDM stalks.
Results
An illustrative case of resection of LDM is presented using skip laminectomies. The technique ensures complete removal of the stalk, thus reducing the risk of future intradural dermoid development, while at the same time minimizes the risk for delayed kyphotic deformity.
Conclusions
A technique of “skip-hop” proximal and distal short segment laminectomies in cases of LDM optimizes the objectives of complete stalk resection with preservation of spinal integrity.
... It encompasses a wide spectrum of developmental errors that manifest as conditions associated with herniation of meninges and, or neural elements via a defective neural arch. 1 One such example involves focal nondisjunction of the primary neural tube in its spinal cord region, resulting in a normal or near-normal spinal cord, except for a physical tract anchoring the dorsal surface of the spinal cord to the base of a characteristic skin lesion. 2 At this point in time, this rare subgroup (henceforth, referred to as 'FNPN') is hypothesized to originate from a common embryonic mechanism; and includes congenital dermal sinus (CDS), limited dorsal myeloschisis (LDM), and their mixed lesions. [3][4][5][6] These unique cases support the hypothesis that CDS and LDM are within a spectrum of an anomaly that is caused by failure of complete dysjunction between cutaneous and neural ectoderms during primary neuralation. ...
... [3][4][5][6] These unique cases support the hypothesis that CDS and LDM are within a spectrum of an anomaly that is caused by failure of complete dysjunction between cutaneous and neural ectoderms during primary neuralation. 2,7 In addition, each of these conditions are differentiated histologically: LDM is characterised by a fibroneural stalk containing neuroglial tissue, while CDS has a tract lined by keratinising stratified squamous epithelium. 2,6,8 Tracts that consist of varied components of LDM and CDS are categorized as 'mixed' types. ...
... 2,7 In addition, each of these conditions are differentiated histologically: LDM is characterised by a fibroneural stalk containing neuroglial tissue, while CDS has a tract lined by keratinising stratified squamous epithelium. 2,6,8 Tracts that consist of varied components of LDM and CDS are categorized as 'mixed' types. 2,4 At the time of this writing, treatment recommendations for FNPN are not fully established. ...
Purpose
Tethered cord due to focal nondisjunction of primary neuralisation (FNPN) is a rare form of spinal dysraphism. We present our institutional experience in managing children diagnosed with FNPN.
Materials and methods
This is a single institution, retrospective study approved by the hospital ethics board. Patients below 18 years of age diagnosed with CDS, LDM or their mixed lesions, and subsequently underwent intervention by the Neurosurgical Service, KK Women’s and Children’s Hospital, are included.
Results
From 2001 to 2021, 16 FNPN patients (50% males) were recruited. Eight of them had CDS (50.0%), seven had LDM (43.8%), and one patient had a mixed CDS and LDM lesion (6.2%). The average duration of follow up was 5.7 years and the mean age of surgery was 6 months old. Thirteen patients underwent prophylactic intent surgery (81.2%) and three had therapeutic intent surgery (18.8%). All patients did not have new neurological deficit or required repeat surgery for cord retethering. We observed that detethering surgery performed at or less than three months old was associated with having a wound infection (p = .022).
Conclusions
Our study reports that early recognition and timely intervention are mainstays of management for FNPN. We advocate a multi-disciplinary approach for good outcomes.
... Limited dorsal myeloschisis is thought to be a defect in the next consecutive stage after gastrulation, that of primary neurulation, when the neural plate folds up dorsally with the surface ectoderm still attached to its two "shoulders" (the neural folds), which ultimately undergo dorsal fusion in the midline to complete the shape of the primary neural tube. LDM probably results from a focal non-fusion of the conjoint surface and neural ectoderms, and consequent nondisjunction of the one ectoderm from the other so that a physical link, or stalk, often containing neural or meningothelial tissue, remains, connecting the base of the future skin to the dorsal midline of the otherwise completely formed spinal cord [4][5][6][7]. ...
... In the extreme case, the affected hemi-neural plate completely fails to elevate, resulting in an open hemi-myelomeningocoele [3]. If somehow the affected hemi-neural plate elevates and the two edges oppose each other but fail to undergo proper midline fusion, disjunction between the surface and neural ectoderms on each side may be halted, perhaps due to malfunction of the Rho GTPases system, including Rac 1 and Cdc42, at the surface-neuroectoderm border that normally enables the disjunction process [6,7]. A hemi-LDM will result (Fig. 12). ...
This is a case report of an exceedingly rare case of a limited dorsal myeloschisis (LDM) with its stalk inserted on the midline dorsal surface of one of a pair of hemicords in a type II split cord malformation. This entity, literally a “hemi-LDM,” has been seen only once by the senior author in his catalogue of over 200 cases of LDM (Pang et al., 2020), nor has it been reported elsewhere before. We postulate that here the mechanism of focal nondisjunction of the hemi-neural plate during primary neurulation, which produces LDMs, occurs at the cusp of the consecutive developmental stages of gastrulation and primary neurulation, right after the appearance of the hemi-neural plates and hemi-notochords caused by the endomesenchymal tract. This child also had a terminal lipoma attached to the end of the conus, indicating that disruption of all three tandem stages of neural tube formation, namely, gastrulation, primary neurulation, and secondary neurulation, can occur in the same individual.
... Limited dorsal myeloschisis (LDM) was firstly described as a distinctive form of spinal dysraphism, characterized by a fibroneural stalk linking the skin lesion to the underlying 3 spinal cord [1,2]. The embryogenesis of LDM is hypothesized to be incomplete disjunction between the cutaneous and neural ectoderms during primary neurulation, which prevents complete midline skin closure and allows a persistent fibroneural stalk including glial fibrillary acidic protein (GFAP)-immunopositive neuroglial tissues between the disjunction site and the dorsal neural tube [1][2][3] (Fig. 1a, b). ...
... Limited dorsal myeloschisis (LDM) was firstly described as a distinctive form of spinal dysraphism, characterized by a fibroneural stalk linking the skin lesion to the underlying 3 spinal cord [1,2]. The embryogenesis of LDM is hypothesized to be incomplete disjunction between the cutaneous and neural ectoderms during primary neurulation, which prevents complete midline skin closure and allows a persistent fibroneural stalk including glial fibrillary acidic protein (GFAP)-immunopositive neuroglial tissues between the disjunction site and the dorsal neural tube [1][2][3] (Fig. 1a, b). Based on its external skin manifestations, LDM is originally classified as saccular or nonsaccular (flat) [1,2]. ...
... In the original description by Pang et al. [1,2], 3 dysraphic malformations (spinal lipoma of dorsa-type [dorsal lipoma], congenital dermal sinus [CDS], and split cord malformation) were associated with LDMs in frequencies not accountable by mere coincidence, and which have important implications in their genesis. While the detailed clinicopathological findings of CDS and split cord malformation have been fully described [3][4][5][7][8][9][10], there is no detailed report of dorsal lipoma. ...
Purpose
Limited dorsal myeloschisis (LDM) is thought to arise from focal incomplete disjunction between the cutaneous and neural ectoderm during primary neurulation, while spinal lipoma of dorsal-type (dorsal lipoma) arises from premature disjunction. Thus, simultaneous occurrence of an LDM and dorsal lipoma are not surprising, and may represent slightly different perturbations of disjunction caused by the same insult in neighboring loci. However, the clinicopathological findings of the LDM with dorsal lipoma have not been fully determined.
Methods
Of 21 patients with LDM, 3 (14.3%) had dorsal lipoma. We retrospectively analyzed the clinicopathological findings of these 3 patients, especially the histopathological distribution of the fibrocollagenous LDM tract and fibroadipose tissue of the lipoma.
Results
Patients 1 and 2 had flat skin lesions, while patient 3 had a human tail-like cutaneous appendage. In the tethering stalks linking the skin lesion at the lumbosacral lesion to the low-lying conus medullaris of the three patients, fibrocollagenous tissues embedding adipose tissues at the subcutaneous site, and with abundant adipose tissues at the extradural site, were changed to fibroadipose tissue at the intradural site. While glial fibrillary acidic protein-immunopositive neuroglial tissues were observed in 2 (patients 1 and 2), peripheral nerve fibers were observed in every stalk. Smooth muscle fibers were noted in patient 1, while a large amount of striated muscle fibers were seen in patients 2 and 3.
Conclusion
These cases showed various tissues with different origins in the stalk. There may also be a seamless continuation between fibrocollagenous LDM tissue at the distal site and lipomatous tissue at the proximal site. Peripheral nerve fibers and smooth muscle fibers of neural crest origin may be dragged into the stalk during incomplete disjunction, while the striated muscle fibers of mesodermal origin may enter the stalk along with the lipomatous tissues during premature disjunction.
Introduction:
Congenital dermal sinus (CDS) is an open neural tube defect (NTD) that occurs in 1 in 2500 births a year and often goes undetected until patients present with complications like infection and neurological deficits. Early diagnosis and repair of CDS may prevent formation of these complications. In utero diagnosis of these lesions may improve long-term outcomes by enabling referral to specialty services and planned postnatal repair, however only two such cases have been reported in the literature. We present a third case of in utero diagnosis of CDS with a description and discussion of findings from surgical exploration and pathology.
Case presentation:
Routine prenatal ultrasound scan detected a tethered cystic structure arising from the back of the fetus at 20 weeks gestation. Dedicated fetal ultrasound confirmed the presence of a cystic lesion protruding through a lamina defect while fetal magnetic resonance imaging (MRI) showed an intact spinal cord and meninges, suggesting a diagnosis of CDS. Neurosurgery followed along closely and took the child for surgical exploration on day 2 of life. A fibrous stalk with an intradural component and associated cord tethering was excised. Histology showed fibrous tissue without an epithelial-lined lumen.
Conclusion:
CDS is a form of NTD that occurs from nondisjunction of the cutaneous ectoderm and neuroectoderm during formation of the neural tube. Slight differences in how this error occurs can explain variations seen in this spectrum of disease, including CDS without an epithelial-lined lumen as seen in this case. Newborns with CDS can go undiagnosed for years and present with long-term complications. Fetal imaging can assist in early recognition and surgical excision of CDS in newborns.
Objective
To evaluate the prenatal diagnosis of closed dysraphism (CD) and its correlation with postnatal findings and neonatal adverse outcomes.
Methods
A retrospective cohort study including pregnancies diagsnosed with fetal CD by prenatal ultrasound (US) and magnetic resonance imaging (MRI) at a single tertiary center between September 2011 and July 2021.
Results
CD was diagnosed prenatally and confirmed postnatally in 12 fetuses. The mean gestational age of prenatal imaging was 24.2 weeks, in 17% the head circumference was ≤fifth percentile and in 25% the cerebellar diameter was ≤fifth percentile. US findings included banana sign in 17%, and lemon sign in 33%. On MRI, posterior fossa anomalies were seen in 33% of cases, with hindbrain herniation below the foramen magnum in two cases. Mean clivus‐supraocciput angle (CSA) was 74°. Additional anomalies outside the CNS were observed in 50%. Abnormal foot position was demonstrated prenatally in 17%. Neurogenic bladder was present in 90% of patients after birth.
Conclusion
Arnold Chiari II malformation and impaired motor function can be present on prenatal imaging of fetuses with CD and may be associated with a specific type of CD. Prenatal distinction of CD can be challenging. Associated extra CNS anomalies are frequent and the rate of neurogenic urinary tract dysfunction is high.
The publication of a comprehensive report on limited dorsal myeloschisis by the senior author (DP) in 2010 has brought full attention to the concept of limited myeloschisis that he first formulated in 1992 and ignited interests in the whole spectrum of focal spinal nondisjunctional disorders. Now that focal nondisjunctional disorders have become well known, new clinical reports on these conditions or relevant subjects are frequently seen. Here we present an updated review on the full spectrum of focal spinal nondisjunctional disorders and extend the scope to include a discussion on the embryogenesis of cranial focal nondisjunctional malformations.KeywordsLimited dorsal myeloschisisDermal sinus tractDermoidNondisjunctionDysraphismFocal spinal nondisjunctional disordersFocal cranial nondisjunctional disordersEncephalocele
Introduction
Limited dorsal myeloschisis (LDM) with nonsaccular (flat) skin lesions has features similar to those of congenital dermal sinus (CDS); both show a tethering tract extending from the skin lesion to the intraspinal space. CDS may be found within the fibroneural LDM stalk because of the shared origin of the LDM and CDS. Thus, it can be difficult to distinguish between LDM and CDS. We surgically treated a boy in whom CDS and filar lipoma were located in close proximity to each other at the dural cul-de-sac, mimicking flat LDM. Herein, we describe the comprehensive clinicopathological findings of this patient.
Case presentation
The patient was noted at birth to have a small dimple in the lumbosacral region. Magnetic resonance images showed a slender tethering tract that started from the skin lesion, entered the dural sac through the dural cul-de-sac, and joined the low-lying conus at L2-3, which is characteristic of LDM. However, the operative and histopathological findings revealed that the epidural stalk was pure CDS, terminating at the dura, and that the intradural stalk was a filar lipoma. Both were present in close proximity at the dural cul-de-sac and were approximately 1 mm in diameter.
Conclusion
The diagnosis of LDM and CDS should be established on the basis of a comprehensive analysis of clinical, neuroradiological, operative, and histopathological findings.
