Neurosurgical management and pathology of lumbosacral lipomas with tethered cord

Current Global Research Trends of Tethered Cord Syndrome Surgery: A Scientometric and Visual Analysis

BACKGROUND

Since tethered cord syndrome (TCS) may lead to neurologic and motor dysfunction, surgeries often are applied to relieve the symptoms. The aim of the research was to explore the current global research trends of TCS surgery.

METHODS

In this article, articles on TCS surgery in the Web of Science Core Collection from 1980 to 2023 were searched. Research trends, countries, institutions, journals, authors, highly cited articles, and key words were analyzed using bibliometric methods. The literature co-citation network was mapped using VOSviewer, and research hotspots and trends were analyzed using CiteSpace.

RESULTS

A total of 432 publications were included. The number of publications and related research interest in the field of TCS surgery has increased globally year by year. The United States is the largest contributor (154 publications). The journal Childs Nervous System has the greatest number of publications (48 publications) and the most frequently cited journal is Neurosurgery (973 citations). In network visualization, the institution with the greatest contribution is University of California System (16 publications). Lee JY and Wang KC are the authors with the greatest number of publications (8 publications), and the most frequently cited author is Klekamp J (268 citations). Neurogenic bladder and spina bifida may be the next hot spot in this field.

CONCLUSIONS

This study will help researchers to identify the mainstream research directions and the latest hotspots in the field of TCS surgery and provide a reference for further research.

Dekyphosis operation combined with limited osteotomy to treat the symptomatic adult tethered cord syndrome with complicated malformations: A case report

RATIONALE

Tethered cord syndrome (TCS) represents a spectrum of neurological symptoms that are caused by constant or intermittent axial traction of the terminal cone of the spinal cord due to abnormal positioning. It is uncommon for abnormal structures of TCS to be accompanied by split cord malformation, thoracic spinal stenosis, and other spinal cord diseases.

PATIENT CONCERNS

A 45-year-old male patient visited our hospital due to severe lower back pain, extensive left lower limb muscle weakness, and intermittent claudication.

DIAGNOSES

TCS combined with stenosis of the thoracic canal, split cord malformation, and kyphosis deformity.

INTERVENTIONS

The patient underwent Dekyphosis operation combined with limited osteotomy symptoms.

OUTCOMES

The patient felt the right lower limb improved after surgery. At 4-month follow-up, a radiological examination showed adequate decompression of the spinal cord and a good internal fixation position. Overall, the patient's clinical symptoms significantly improved.

CONCLUSION

This is a rare case of TCS combined with thoracic disc herniation and bony mediastinum. A more conservative invasive surgical approach was elected and markedly improved the patient's symptoms. Additional clinical cases are needed to confirm the stability and feasibility of this surgical approach.

Pediatric Nondysraphic Intramedullary Lipoma : Report of Two Cases and Review of the Literature

Pediatric nondysraphic intramedullary lipoma is very rare, and only limited cases have been reported. In the present case, we present two infant patients with these pathologies who were surgically treated. Previous literature on 20 patients with these diseases who had undergone surgical treatments was analyzed. Surgical treatment should be considered in most symptomatic patients, and laminoplastic laminotomy and internal debulking of the lipoma under intraoperative neurophysiological monitoring are mostly recommended.

Limited dorsal myeloschisis without extradural stalk continuity to coexisting congenital dermal sinus

Limited dorsal myeloschisis (LDM) is characterized by a fibroneural tethering stalk linking the skin lesion to the underlying spinal cord. LDM without an extradural stalk is rare. A full-term boy was noted at birth to have a dimple in the upper back (dorsal skin of the lower thoracic region). Computed tomographic scan showed spina bifida at the T9-12 vertebral level and osteochondral tissue at the T10 level. Magnetic resonance imaging (MRI) demonstrated a tiny dorsal lipoma at the T8 vertebral level, but the intradural tethering tract was not apparent. At 18 days of age, the congenital dermal sinus (CDS) tract started from the dimple and terminated at the osteochondral tissue, without continuity of the dura mater, and the osteochondral tissues were resected. At age 2 years 8 months, he developed spastic paresis of the right foot. On MRI, the tethering tract from the dorsal lipoma became apparent. During the second surgery at age 2 years 11 months, the intradural stalk started from the dorsal lipoma and joined the inner surface of the dura mater was untethering from the cord. Postoperatively, right spastic paresis was improved. Histological examination of the intradural stalk revealed the distribution of S100-immunopositive peripheral nerve fibers, which is one of the histopathological hallmarks of LDM. We speculated that the extradural stalk with coexisting CDS originally linked from the skin lesion subsequently regressed and was replaced by fibroadipose tissue with osteochondral tissue migration. Intradural exploration should always be seriously considered in these disorders of persisting neurocutaneous connection.

Wound closure with a mesh and liquid tissue adhesive (Dermabond Prineo) system in pediatric spine surgery: a prospective single-center cohort study incorporating parent-reported outcome measures

OBJECTIVE

Wound healing can be challenging in children undergoing spine surgery for neurological conditions due to a high risk of cerebrospinal fluid (CSF) leakage and wound infection. In adults, use of the Dermabond Prineo (DP) skin closure system, which consists of both tissue adhesive glue and a self-adhesive mesh, for wound closure of medium-length surgical incisions has been reported. The aim of this study was to investigate the efficiency and cosmetic outcome of DP for wound closure in extra- and intradural pediatric neurological spine surgery.

METHODS

In this prospective cohort study, 47 children underwent 50 spine procedures using DP for wound closure between 2018 and 2022 at a single institution. Patient demographic and surgical data were collected. The primary outcome was revision surgery for wound healing disorders, while secondary outcomes were infections, minor wound healing disorders, and both physician and parental satisfaction (parent-reported outcome measures [PROMs]) at last follow-up.

RESULTS

Among 50 spinal (45 intra- and 5 extradural) interventions, 1 patient (2%) underwent revision surgery for a cutaneous CSF fistula and pseudomeningocele. Minor wound healing disorders occurred after 16 surgeries, which did not require surgical wound revision and resolved completely. No allergic reactions to DP or surgical site infections within 30 days were observed. The parents and the medical team described wound care as significantly facilitated since wound dressing changes were not needed. Three families (6.4%) encountered difficulties in wound care, and 46 (97.9%) were satisfied with DP. The cosmetic outcome based on PROMs was excellent, with a mean score of 8 (IQR 2) on a scale from 1 to 10. At long-term follow-up, a mean of 11.3 ± 10.7 months after surgery, physicians rated the cosmetic outcome on the visual analog scale (median score 9, IQR 1) and Hollander scale (median score 6, IQR 1). The outcomes were similar among the different pathologies and age groups and did not differ in patients with and without syndromic malformations.

CONCLUSIONS

The application of DP is simple, enables good patient comfort, facilitates both professional and parental wound care, and leads to excellent cosmetic results. DP possibly aids in the reduction of postoperative CSF leakage and infections after pediatric neurological spine surgery.

Sacral Spina Bifida Occulta: A Frequency Analysis of Secular Change

Substantial relaxation of natural selection beginning around 1900 changed the mutation/selec­tion balance of modern genetic material, producing an increase in variable anatomical structures. While multiple structures have been affected, the temporal increase in variations of the sacrum, specifically, ‘Sa­cral Spina Bifida Occulta,’ have been reliably demonstrated on a localised scale. Calculation of largescale frequency has been hindered by the localised nature of these publications, the morphological variability of this variation, and potential pathological associations, which have produced divergent classifications, and conflicting reported rates of occurrence. A systematic review of the reported literature was conducted to provide an objective analysis of Sacral Spina Bifida Occulta frequency from 2500 BCE to the present. This review was designed to compensate for observed inconsistencies in reporting and to ascertain, for the first time, the temporal trajectory of this secular trend. A systematic review of Sacral Spina Bifida Occulta lit­erature was conducted through the strict use of clinical meta-analysis criteria. Publications were retrieved from four databases: PubMed, Embase, the Adelaide University Library database, and Google Scholar. Data were separated into three historical groups, (1 = <1900, 2 = 1900 to 1980 and 3 = >1980), and frequency outcomes compared, to determine temporal rates of occurrence. A total of 39/409 publications were included in the final analysis, representing data for 16,167 sacra, spanning a period of 4,500 years. Statistically significant results were obtained, with total open S1 frequen­cy increasing from 2.34%, (79 to 1900CE), to 4.80%, (1900 to 1980CE) and to 5.43% (>1980CE). These increases were significant at p<0.0001, with Chi-squared analysis. A clear secular increase in the global frequency of Sacral Spina Bifida Occulta has been demonstrated from 1900 to the present. This research provides a novel and adaptable framework for the future assessment of variation distribution, with impor­tant implications for the fields of biological anthropology and bioarchaeology.

Intramedullary abscess at thoracolumbar region transmitted from infected dermal sinus and dermoid through retained medullary cord

Background:

A retained medullary cord (RMC) is a relatively newly defined entity of closed spinal dysraphism that is thought to originate from regression failure of the medullary cord during secondary neurulation. A congenital dermal sinus (CDS) may provide a pathway for intraspinal infections such as repeated meningitis. Intramedullary abscesses are the rarest but most serious complication of a CDS.

Case Description:

We treated a female infant with an intramedullary abscess in the thoracolumbar region, which was caused by infection of the CDS. Surgery revealed that the cord-like structure (C-LS) started from the cord with the intramedullary abscess, extended to the dural cul-de-sac, and further continued to the CDS tract and skin dimple. The boundary between the functional cord and the non-functional CL-S was electrophysiologically identified, and the entire length of the C-LS (the RMC) with an infected dermoid cyst was resected. As a result, the abscess cavity was opened and thorough irrigation and drainage of the pus could be performed. Histopathological examination of the C-LS revealed an infected dermoid cyst and abscess cavity with keratin debris in the fibrocollagenous tissue. The abscess cavity had a central canal-like ependymal lined lumen (CCLELL), with surrounding glial fibrillary acidic protein (GFAP)-immunopositive neuroglial tissues.

Conclusion:

We demonstrated that the transmission of an infection through the RMC was involved in the development of the intramedullary abscess. A good postoperative outcome was obtained because a terminal ventriculostomy for pus drainage could be achieved by excising the nonfunctional RMC.

[Expert consensus on diagnosis and treatment of spina bifida]

Spina bifida and tethered spinal cord are congenital diseases that can lead to severe disability. At present, most doctors in relevant specialties in China still have insufficient understanding of spina bifida, resulting in high incidence and aggravation of its complications. To provide guidance for the diagnosis and treatment of spina bifida and tethered spinal cord in China, experts from neurosurgery, urology, orthopedics, spine surgery, and rehabilitation departments who have experiences in the diagnosis and treatment of spina bifida discussed and summarized their experiences, and referred to the relevant literature on the diagnosis and treatment of spina bifida at home and abroad. Expert consensus was formed in the following aspects: concept, classification, and pathological changes of spina bifida; diagnosis; treatment process and operation timing; principles and methods of treatment; rehabilitation; and follow up. This expert consensus can provide reference for relevant care providers of spina bifida in China.

Spinal cord deformity with aggravation of tethering in saccular limited dorsal myeloschisis during the first 2 months of life

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.

Surgical histopathology of a filar anomaly as an additional tethering element associated with closed spinal dysraphism of primary neurulation failure

Background:

Closed spinal dysraphism of primary neurulation failure could be associated with filar anomalies, such as filar lipoma or thickened and tight filum terminale (TFT), resulting from impaired secondary neurulation. Retained medullary cord (RMC) is a remnant of the cavitary medullary cord originating from the secondary neurulation failure. Some filar lipomas are known to contain a central canal-like ependyma-lined lumen with surrounding neuroglial tissues (E-LC w/NGT), that is, a characteristic histopathology of RMC. To clarify the embryological background of these filar anomalies, we evaluated the histopathological findings.

Methods:

Among 41 patients with lesions of primary neurulation failure who underwent initial untethering surgery, the filum including cord-like structure (C-LS) was additionally resected in 10 patients (five dorsal and transitional lipomas; five limited dorsal myeloschisis). We retrospectively analyzed the clinical, neuroradiological, intraoperative, and histopathological findings.

Results:

Among 10 patients, two patients were diagnosed with RMC based on morphological features and intraoperative neurophysiological monitoring. The diagnosis of filar lipoma was made in six patients, since various amounts of fibroadipose tissue were histopathologically noted in the filum. Two patients were diagnosed with TFT, since the filum was composed solely of fibrocollagenous tissue. E-LC w/NGT was noted not only in both C-LSs of RMCs but also in two out of six fila both with filar lipomas and fila with TFTs.

Conclusion:

These findings provide further evidence for the idea that entities, such as filar lipoma, TFT, and RMC, can be considered consequences of a continuum of regression failure occurring during late secondary neurulation.

Subpial Lumbar Lipoma Associated with Retained Medullary Cord

Subpial lipomas, which are also known as nondysraphic intramedullary spinal cord lipomas, are not associated with spinal dysraphism resulting from the failed primary neurulation. Retained medullary cord (RMC) is a newly defined entity of closed spinal dysraphism that originates from the late arrest of secondary neurulation. We treated a 6-year-old boy presented with myoclonus of the lower limbs, who had subpial lipoma at the lumbar cord, just rostral to the low-lying conus, which was tethered by a cord-like structure (C-LS) continuous from the conus and extending to the dural cul-de-sac. Following cord untethering from C-LS and minimal debulking of the lipoma, the myoclonus was improved. Histological examination of C-LS revealed a large central canal-like structure in the neuroglial core and the diagnosis of RMC was made. Subpial lipomas can be incidentally coexistent with spinal dysraphism resulting from the failed secondary neurulation, such as RMC.

Two Cases of Large Filar Cyst Associated with Terminal Lipoma: Relationship with Retained Medullary Cord

BACKGROUND

A small, incidental filar cyst associated with terminal lipoma is thought to be caused by failure of secondary neurulation; however, the precise embryologic background is not fully understood. Retained medullary cord (RMC) also originates from late arrest of secondary neurulation. The central feature of RMC histopathology is a central canal-like ependyma-lined lumen with surrounding neuroglial core.

CASE DESCRIPTION

We surgically treated 2 patients with a large cyst in the rostral part of the filum and lipoma in the caudal filum. At cord untethering surgery, the filum was severed at the caudal part of the cyst. Histopathologically, the filar cyst was the cystic dilatation of the central canal-like structure at the marginal part of the lipoma. The central canal-like structure was continuous caudally in the lipoma, and its size decreased toward the caudal side.

CONCLUSIONS

The present findings support the idea raised by Pang et al that entities such as filar cyst, terminal lipomas, and RMC can all be considered consequences of a continuum of regression failure occurring during late secondary neurulation.

Embryology of Spinal Dysraphism and its Relationship to Surgical Treatment

Spinal dysraphism is an umbrella term that encompasses a number of congenital malformations that affect the central nervous system. The etiology of these conditions can be traced back to a specific defect in embryological development, with the more disabling malformations occurring at an earlier gestational age. A thorough understanding of the relevant neuroembryology is imperative for clinicians to select the correct treatment and prevent complications associated with spinal dysraphism. This paper will review the neuroembryology associated with the various forms of spinal dysraphism and provide a clinical-pathological correlation for these congenital malformations.

Congenital Dermal Sinus Elements in Each Tethering Stalk of Coexisting Thoracic Limited Dorsal Myeloschisis and Retained Medullary Cord

INTRODUCTION

The embryogenesis of limited dorsal myeloschisis (LDM) likely involves impaired disjunction between the cutaneous and neural ectoderms during primary neurulation. Because LDM and congenital dermal sinus (CDS) have a shared origin in this regard, CDS elements can be found in the LDM stalk. Retained medullary cord (RMC) is a closed spinal dysraphism involving a robust, elongated, cord-like structure extending from the conus medullaris to the dural cul-de-sac. Because the RMC is assumed to be caused by impaired secondary neurulation, concurrent RMC and CDS cannot be explained embryologically. In the present article, we report a case in which CDS elements were noted in each tethering stalk of a coexisting LDM and RMC.

CASE PRESENTATION

A 2.5-month-old boy with left clubfoot and frequent urinary and fecal leakage had 2 tethering tracts. The upper tract, which ran from the thoracic tail-like cutaneous appendage, had CDS elements in the extradural stalk and a tiny dermoid cyst in the intradural stalk immediately after the dural entry. In the lower tract, which ran from the lumbosacral dimple, the CDS as an extradural stalk continued to the RMC at the dural cul-de-sac. Both stalks were entirely resected through skip laminotomy/laminectomy at 1 stage to untether the cord and resect the CDS elements.

CONCLUSION

Surgeons should be aware that CDS elements, in addition to LDM, may coexist with RMC that extends out to the extradural space.

Whole spine MRI is not required in investigating uncomplicated paediatric lumbosacral lipoma. A retrospective single-institution review

PURPOSE

Lumbosacral lipoma (LSL) is a severe occult spinal dysraphism, frequently associated with neurological, urological and orthopaedic complications. Whole spine imaging is typically performed to identify concomitant, but spatially separate, congenital anomalies. Our hypothesis: the incidence of additional, clinically significant abnormalities of the neuraxis is low; thus, imaging should be optimised at the lumbosacral region. We aim to assess the prevalence and relevance of LSL-associated lesions.

METHOD

A single-centre, retrospective, radiological review using a prospectively maintained operative database.

INCLUSION CRITERIA

children (< 16 years) with confirmed diagnosis of LSL and received whole spine MRI. Fatty filum, syndromic cases and cutaneous stigmata above lesion level were excluded. Data was extracted from radiological imaging, reports and clinical correspondence.

RESULTS

One hundred twelve patients (40:72, M:F) aged 0.5 years (0.2-2.7) (median ± IQR) with LSL had whole spine MRI between 2001 and 2017. Classification of LSL: transitional 48 (43%); dorsal 30 (27%); caudal 28 (25%) and chaotic 6 (5%). Additional anomalies included syringohydromyelia 44 (39%), subcutaneous tract 19 (17%), abnormal vertebral segmentation 18 (16%), dermoid cyst 1 and 1 Chiari I deformity. There were no Chiari II malformations. No child required surgery for an associated lesion. Binary logistic regression revealed no factors associated with predicting secondary lesions.

CONCLUSIONS

In congenital LSL, additional anomalies of the neuraxis are typically loco-regional rather than pan-CNS and additional lesions are rarely clinically significant. The loco-regional distribution of anomalies suggests that only lumbosacral spinal imaging is required in the initial evaluation of LSL. Such a policy would lessen the anaesthetic/sedation time for children and reduce imaging cost per patient. MRI protocols could be refined to optimise imaging quality at the region of interest.

Human tail-like cutaneous appendage with a contiguous stalk of limited dorsal myeloschisis

PURPOSE

Limited dorsal myeloschisis (LDM) is characterized by a fibroneural stalk linking the skin lesion to the underlying spinal cord. On account of the external skin lesion, all LDMs are either flat (nonsaccular) or saccular, and a human tail-like cutaneous appendage has not been reported.

METHODS

In our 14 LDM patients, 2 had tail-like appendages. We retrospectively analyzed the relationship between the appendage and the LDM tract from the clinicopathological findings of these 2 patients.

RESULTS

Preoperative magnetic resonance imaging including three-dimensional heavily T2-weighted images demonstrated an intradural tethering tract, but failed to reveal the precise communication with the appendage. However, surgery revealed the extradural and intradural slender stalk, starting at the base of appendage and running through the myofascial defect. Histological examination demonstrated that there was a tight anatomical relationship between the fibroadipose tissue of the appendage and the fibrocollagenous LDM stalk.

CONCLUSION

When there is potential for an LDM stalk in patients with an appendage, a meticulous exploration of the stalk leading from an appendage is required. Clinicians should be aware of possible morphological variations of skin lesions associated with LDM.

Surgical histopathology of limited dorsal myeloschisis with flat skin lesion

PURPOSE

Limited dorsal myeloschisis (LDM) is characterized by two invariable features: a focal closed neural tube defect and a fibroneural stalk linking the skin lesion to the underlying spinal cord. Although detailed histopathological findings of the LDM stalk were originally described by Pang et al., the precise relationship between the histopathological findings and clinical manifestations including intraoperative findings has not been fully determined.

METHODS

We retrospectively analyzed the histopathological findings of the almost entire stalk and their relevance to the clinical manifestations in six Japanese LDM patients with flat skin lesions.

RESULTS

Glial fibrillary acidic protein (GFAP)-immunopositive neuroglial tissues were observed in three of the six patients. Unlike neuroglial tissues, peripheral nerve fibers were observed in every stalk. In four patients, dermal melanocytosis, "Mongolian spot," was seen surrounding the cigarette-burn lesion. In three of these four patients, numerous melanocytes were distributed linearly along the long axis of the LDM stalk, which might represent migration of melanocytes from trunk neural crest cells during formation of the LDM stalk.

CONCLUSION

Immunopositivity for GFAP in the LDM stalk was observed in as few as 50% of our patients, despite the relatively extensive histopathological examination. We confirm that the clinical diagnosis of LDM should be made based on comprehensive histopathological examination as well as clinical manifestations. The profuse network of peripheral nerve fibers in every stalk and the high incidence of melanocyte accumulation associated with dermal melanocytosis might assist the histopathological diagnosis of LDM.

Enlargement of sacral subcutaneous meningocele associated with retained medullary cord

BACKGROUND

A retained medullary cord (RMC) is a rare closed spinal dysraphism with a robust elongated neural structure continuous from the conus and extending to the dural cul-de-sac. Four cases of RMC extending down to the base of an associated subcutaneous meningocele at the sacral level have been reported.

CLINICAL PRESENTATION

We report an additional case of RMC, in whom serial MRI examination revealed an enlargement of the meningocele associated with RMC over a 3-month period between 8 and 11 months of age, when he began to stand. At the age of 12 months, untethering of the cord was performed. Histologically, the presence of ependyma-lined central canals in the dense neuroglial cores was noted in all cord-like structures in the intradural and intrameningocele sacs and at the attachment to the meningocele.

CONCLUSION

It is conceivable that the hydrodynamic pressure with standing position and the check valve phenomenon were involved in meningocele enlargement. We should be mindful of these potential morphological changes.

Retained medullary cord extending to a sacral subcutaneous meningocele

BACKGROUND

A retained medullary cord (RMC) is a rare closed spinal dysraphism with a robust elongated neural structure continuous from the conus and extending to the dural cul-de-sac. One case extending down to the base of a subcutaneous meningocele at the sacral level has been reported.

CLINICAL PRESENTATION

We report on three cases of closed spinal dysraphism, in which a spinal cord-like tethering structure extended out from the dural cul-de-sac and terminated at a skin-covered meningocele sac in the sacrococcygeal region, which was well delineated in curvilinear coronal reconstructed images of 3D-heavily T2-weighted images (3D-hT2WI). Intraoperative neurophysiology revealed the spinal cord-like tethering structure was nonfunctional, and histopathology showed that it consisted of central nervous system tissue, consistent with RMC. The tethering structure histologically contained a glioneuronal core with an ependymal-like lumen and smooth muscle, which may indicate developmental failure during secondary neurulation.

CONCLUSIONS

When the RMC extending to a meningocele is demonstrated with the detailed magnet resonance imaging including 3D-hT2WI, decision to cut the cord-like structure for untethering of the nervous tissue should be made under careful intraoperative neurophysiological monitoring.

Neurosurgical pathology of limited dorsal myeloschisis

PURPOSE

The term limited dorsal myeloschisis (LDM) was used by Pang et al. (2010) to describe a distinct clinicopathological entity. LDMs are characterized by two invariable features: a focal-closed neural tube defect and a fibroneural stalk that links the skin lesion to the underlying spinal cord.

METHODS

We retrospectively analyzed the neurosurgical pathologic findings of four LDM patients.

RESULTS

Case 1 had a saccular skin lesion with nonterminal abortive myelocystocele at T11-12. Cases 2, 3, and 4 had a non-saccular (flat) skin lesion in the lumbosacral region. The morphologic features of the lesion in case 2 were those of meningocele manque. Cases 3 and 4 had accompanying non-LDM anomalies, caudal-type lipoma and type II split-cord malformation with neurenteric cyst, respectively. At preoperative diagnosis of the LDM stalk, magnetic resonance imaging, including 3D heavily T2-weighted image was useful; however, minute findings were often missed in the complicated cases 3 and 4. All patients had a favorable outcome following untethering of the stalk from the cord. The central histopathological feature of the LDM stalk is neuroglial tissue in the fibrocollagenous band; however, the stalk in cases 2 and 4 did not have glial fibrillary acidic protein-immunopositive neuroglial tissues.

CONCLUSIONS

Therefore, the diagnosis of LDM should be made based on comprehensive evaluation of histologic and clinical findings.

Ependyma-Lined Canal with Surrounding Neuroglial Tissues in Lumbosacral Lipomatous Malformations: Relationship with Retained Medullary Cord

BACKGROUND

An ependyma-lined canal with surrounding neuroglial tissues can be present in lumbosacral lipomatous malformations; however, the precise embryological significance is still unclear.

METHOD

Six out of 50 patients with lipomatous malformations had ependymal structures. We retrospectively analyzed the clinical, neuroradiological, and histological findings of these patients to demonstrate the relationship with the embryological background of the retained medullary cord (RMC), which normally regresses, but was retained here because of late arrest of secondary neurulation.

RESULTS

Five (13.9%) of 36 patients with filar and caudal types and 1 of 3 lipomyelomeningoceles had ependymal structures, while none with dorsal and transitional types had these tissues. Histologically, the ependymal structures surrounded by neuroglial tissue and containing various amounts of adipose tissue bear a striking resemblance to the ependymal structures in RMC.

CONCLUSION

The 13.9% incidence of association between the ependymal structures and filar and caudal types is thought to be because of second ary neurulation failure with the same embryological background as that of RMC. Dorsal and transitional types, resulting from primary neurulation failure, therefore, did not have ependymal structures.