Histological structure of filum terminale in human fetuses

The Surgical Histopathology of the Filum Terminale: Findings from a Large Series of Patients with Tethered Cord Syndrome

This study investigated the prevalence of embryonic and connective tissue elements in the filum terminale (FT) of patients with tethered cord syndrome (TCS), examining both typical and pathological histology. The FT specimens from 288 patients who underwent spinal cord detethering from 2013 to 2021 were analyzed. The histopathological examination involved routine hematoxylin and eosin staining and specific immunohistochemistry when needed. The patient details were extracted from electronic medical records. The study found that 97.6% of the FT specimens had peripheral nerves, and 70.8% had regular ependymal cell linings. Other findings included ependymal cysts and canals, ganglion cells, neuropil, and prominent vascular features. Notably, 41% showed fatty infiltration, and 7.6% had dystrophic calcification. Inflammatory infiltrates, an underreported finding, were observed in 3.8% of the specimens. The research highlights peripheral nerves and ganglion cells as natural components of the FT, with ependymal cell overgrowth and other tissues potentially linked to TCS. Enlarged vessels may suggest venous congestion due to altered FT mechanics. The presence of lymphocytic infiltrations and calcifications provides new insights into structural changes and mechanical stress in the FT, contributing to our understanding of TCS pathology.

Ectopic dorsal root ganglion in cauda equina mimicking schwannoma in a child

Background

A heterotopic dorsal root ganglion (DRG) is sometimes observed in the vicinity of dysplastic neural structures during surgery for open spinal dysraphism; however, it is rarely associated with closed spinal dysraphism. Distinguish from neoplasms by preoperative imaging study is difficult. Although the embryopathogenesis of a heterotopic DRG has been speculated to be migration disorder of neural crest cells from primary neural tube, its details remain unelucidated.

Case Description

We report a pediatric case with an ectopic DRG in cauda equina associated with a fatty terminal filum and bifid sacrum. The DRG mimicked a schwannoma in the cauda equina on preoperative magnetic resonance imaging. Laminotomy at L3 revealed that the tumor was entangled in the nerve roots, and small parts of the tumor were resected for biopsy. Histopathologically, the tumor consisted of ganglion cells and peripheral nerve fibers. Ki-67 immunopositive cells were observed at the periphery of the ganglion cells. These findings indicate the tumor comprised DRG tissue.

Conclusion

We report detailed neuroradiological, intraoperative and histological findings and discuss the embryopathogenesis of the ectopic DRG. One should be aware of the possibility of ectopic or heterotopic DRGs when cauda equina tumors are observed in pediatric patients with neurulation disorders.

Variability in the distance from the end of the gray matter to the end of the conus medullaris: a case-triggered histological investigation

OBJECTIVE

The background for this investigation was the dramatic course of a 14-year-old girl with a spontaneous hemorrhage in the area of the conus medullaris resulting in a complete cross-sectional syndrome with bladder and bowel dysfunction. Despite immediate surgical treatment, the patient showed close to no postoperative improvement. Subsequent histopathological examination of the removed masses revealed a cavernoma. To better understand the link between the site and symptoms of conus medullaris lesions, the authors performed a literature search and then histological examination of the conus medullaris of 18 cadaveric specimens from body donors.

METHODS

After a literature search regarding the histological features of the structure of the conus medullaris did not lead to satisfying results, the authors performed histological examination of the conus medullaris in 18 cadaveric specimens from body donors. The largest (a) and smallest (b) diameters of the conus medullaris were measured, noting individual variations in the distance from the caudal ending of the gray matter to the macroscopically visible end of the conus medullaris. Correlations of these differences with sex, body height, gray matter transverse diameter, and cross-sectional area at the end of the gray matter were analyzed.

RESULTS

Gray matter displayed in the form of a butterfly figure was found along almost the entire length of the conus medullaris. The specific slide containing the end of the gray matter was noted. The distance between the caudal ending of the gray matter in the conus and the macroscopical end of the conus medullaris was defined as the gray matter to cone termination (GMCT) distance. There were great individual variations in the distance from the caudal ending of the gray matter to the macroscopically visible end of the conus medullaris. Analysis of the correlations of these differences with sex, body height, gray matter transverse diameter, and cross-sectional area at the end of the gray matter showed no significant sex-specific differences in the GMCT distance. Patient body height and transverse diameter at the end of the gray matter were found to be correlated positively with the GMCT distance. Moreover, greater height also correlated positively with the cross-sectional area at the end of the gray matter.

CONCLUSIONS

This report is, to the authors' knowledge, the first published description of the histological structure of the conus medullaris and can serve as the basis for a better understanding of neurological deficits in patients with a conus medullaris syndrome. Findings that gray matter can be detected far into the conus medullaris, with large individual differences in the endpoint of the gray matter, are important for operative care of intramedullary masses and vascular malformations in this area. It is therefore important to use electrophysiological monitoring during these operations.

Expression of Sigma-Class Glutathione-S-Transferase in Fetal and Pediatric Filum Terminale Samples: A Comparative Study

Background and objectives: The pathophysiology of tethered cord syndrome (TCS) in children is not well elucidated. An inelastic filum terminale (FT) is the main factor underlying the stretching of the spinal cord in TCS. Our study aimed to investigate the expression of glutathione-S-transferase (GST) in children and fetal FT samples in order to understand the relationship between this enzyme expression and the development of TCS. Materials and Methods: FT samples were obtained from ten children with TCS (Group 1) and histological and immunohistochemical examinations were performed. For comparison, FT samples from fifteen normal human fetuses (Group 2) were also analyzed using the same techniques. Statistical comparison was made using a Chi-square test. Results: Positive GST-sigma expression was detected in eight (80%) of 10 samples in Group 1. The positive GST-sigma expression was less frequent in nine (60%) of 15 samples from Group 2. No statistically significant difference was detected between the two groups (p = 0.197). Conclusions: Decreased FT elasticity in TCS may be associated with increased GST expression in FT. More prospective studies are needed to clarify the mechanism of the GST-TCS relationship in children.

The pathology of lumbosacral lipomas: macroscopic and microscopic disparity have implications for embryogenesis and mode of clinical deterioration

AIMS

Lumbosacral lipomas (LSL) are congenital disorders of the terminal spinal cord region that have the potential to cause significant spinal cord dysfunction in children. They are of unknown embryogenesis with variable clinical presentation and natural history. It is unclear whether the spinal cord dysfunction reflects a primary developmental dysplasia or whether it occurs secondarily to mechanical traction (spinal cord tethering) with growth. While different anatomical subtypes are recognised and classified according to radiological criteria, these subtypes correlate poorly with clinical prognosis. We have undertaken an analysis of surgical specimens in order to describe the spectrum of histological changes that occur and have correlated the histology with the anatomical type of LSL to determine if there are distinct histological subtypes.

METHODS AND RESULTS

The histopathology was reviewed of 64 patients who had undergone surgical resection of LSL. The presence of additional tissues and cell types were recorded. LSLs were classified from pre-operative magnetic resonance imaging (MRI) scans according to Chapman classification. Ninety-five per cent of the specimens consisted predominantly of mature adipocytes with all containing thickened bands of connective tissue and peripheral nerve fibres, 91% of samples contained ectatic blood vessels with thickened walls, while 22% contained central nervous system (CNS) glial tissue. Additional tissue was identified of both mesodermal and neuroectodermal origin.

CONCLUSIONS

Our analysis highlights the heterogeneity of tissue types within all samples, not reflected in the nomenclature. The diversity of tissue types, consistent across all subtypes, challenges currently held notions regarding the embryogenesis of LSLs and the assumption that clinical deterioration is due simply to tethering.

Histopathology of the filum terminale in children with and without tethered cord syndrome with attention to the elastic tissue within the filum

PURPOSE

To compare histologically transected fila from pediatric patients with tethered cord syndrome (TCS), with and without a low conus, with controls, focusing on collagenous and elastic tissue.

METHODS

Thirty fila from patients with TCS, including 5 where minimal cautery was used prior to filum section, were compared with fila from 27 pediatric cadavers without TCS (controls). Sections of fila were stained with H&E, Masson trichrome and Verhoeff von Gieson elastic stains, and 7 with Gordon and Sweet's reticulin stain.

RESULTS

Fila from controls showed loose fibrous connective tissue (FCT) with thin and evenly dispersed elastic fibers (EFs). Reticulin fibers (RFs) were seen in blood vessel walls and nerve twigs. Fat was identified microscopically in 2 fila. All fila from patients with TCS had dense FCT. The EFs were in normal numbers in 17, and focally or diffusely decreased in 13. All 25 patients where the fila were cauterized during resection had thick and coiled EFs. Coiling was not seen when minimal cautery was applied. RFs were seen in blood vessel walls and nerve twigs. Fat was identified in 19 patients. Findings were similar, whether the conus termination was normal or low.

CONCLUSION

The fila of all patients with TCS, whether or not the conus was low, showed abnormal FCT. EFs were decreased in 48 % of patients; however, there were thick and coiled EFs in all patients. Coiling of EFs, initially thought to be an abnormality in patients, is considered most likely to be a result of cautery (i.e., artifactual/iatrogenic coiling).

Urodynamic outcomes of detethering in children: experience with 46 pediatric patients

AIM

Tethered cord syndrome (TCS) manifests with neurological and urological complaints. Surgical detethering is the main treatment for TCS. Children with urological symptoms are required objective pre- and postoperative evaluations in order to predict urological outcome. The aims of this study are to investigate the effects of detethering procedure on the urodynamic tests and to determine the relationship between the changes of urodynamic tests and the patients' age and gender.

MATERIAL AND METHODS

The data of urodynamic tests in 46 pediatric patients, who underwent surgery for TCS, were retrospectively evaluated. Bladder capacity, post-voiding residual urine volume, maximum intravesical pressure, and bladder compliance of each patient were measured in preoperative period and at the third month after surgery. These parameters were statistically compared, and the correlations of these parameters with age, gender, and etiology of the TCS were also investigated.

RESULTS

Bladder capacity and post-voiding residual urine volume were decreased and maximum intravesical pressure and bladder compliance were increased after surgery for TCS. The decrease in bladder capacity was significant in patients older than 10 years (p < 0.05). The increase in maximum intravesical pressure was also positively correlated with age (p < 0.05). But the increase in bladder compliance was negatively correlated with age (p < 0.05).

CONCLUSION

Bladder capacity, post-voiding residual urine volume, and bladder compliance are mainly affected by surgery in patients with TCS. From the urological viewpoint, children older than 10 years are most likely to benefit from surgery for TCS.

Ectopic ganglion in cauda equina: case report

Macroscopic ectopic or heterotopic ganglionic tissue within the cauda equina is a very rare pathological finding and is usually associated with spinal dysraphism. However, it may mimic genuine neoplasms of the cauda equina. The authors describe a 29-year-old woman with a history of back pain, right leg pain, and urinary incontinence in whom imaging demonstrated an enhancing mass located in the cauda equina at the L1-2 interspace. The patient subsequently underwent biopsy and was found to have a focus of ectopic ganglionic tissue that was 1.3 cm in greatest dimension. To the authors' knowledge, ectopic or heterotopic ganglionic tissue within the cauda equina in a patient without evidence of spinal dysraphism has never been reported. This patient presented with imaging and clinical findings suggestive of a neoplasm, and an open biopsy proved the lesion to be ectopic ganglionic tissue. The authors suggest that ectopic ganglionic tissue be added to the list of differential diagnoses of a space-occupying lesion arising from the cauda equina.

The Filum Terminale Revisited: A Histological Study in Human Fetuses

Previous studies have suggested that secondary neurulation provides no functional neurons but only the filum terminale. However, no studies have confirmed that the coccygeal and lower sacral nerves do not originate from the secondary neural tube but only from the primary tube. To obtain a better understanding of these relationships, we examined sagittal or frontal sections from 20 embryonic and fetal specimens ranging from 6 to 14 weeks of gestation. During the growth of the vertebral column as well as the subsequent upward migration of the caudal end of the dural sac, the secondary neural tube was stretched to maintain the original attachment to the coccyx or the lower sacral vertebra. The filum-like structure showed much individual variability but in all cases appeared to be derived from the stretched neural tube. Intermediate age morphology revealed that the secondary neural tube itself provided an initial filum terminale before the ascent of the dural sac. Given that the coccygeal and lower sacral nerves are likely to originate from the secondary neural tube, these parts of the tube persisted and differentiated into spinal neurons to form the anococcygeal nerves. Likewise, the filum terminale was also most likely to contain some neurons that persisted postnatally. Depending on the timing and site of degeneration of the secondary neural tube, individual variations could occur in proportion to the amount of sensory and motor elements in the anococcygeal nerve supply.

Tethered cord syndrome in children: a single-center experience with 162 patients

PURPOSE

Tethered cord syndrome (TCS) is not an uncommon clinical problem in children. The aim of this retrospective study is to document our experience on the surgical treatment of TCS in childhood.

METHODS

The data of 162 children who underwent surgical treatment for TCS in a 15-year period were reviewed retrospectively. Their demographic, clinical, radiological, and surgical features were documented. They were divided into two groups as primary and secondary TCS, and the surgical technique for each group was demonstrated. Untethering the spinal cord and correction of the associated malformation were the standard surgical technique for each patient. The results of the treatment were summarized.

RESULTS

Among the 162 children, 101 (62.3%) of them were female and 61 were male with a mean age of 62 months. Primary TCS was detected in 43 patients while secondary TCS was found in 119 (73.4%) patients. Hypertrichosis was the most common physical finding while back pain was the common complaint. Lipoma, split cord malformation, dermal sinus tract, and myelomeningocele were the associated malformations for secondary TCS.

CONCLUSIONS

Children should be individualized for the treatment of TCS. Each patient must be evaluated neurologically and radiologically for the accurate diagnosis. Surgical untethering is the safe and effective method of treatment for children with TCS.