Spinal cord abnormalities in caudal regression syndrome

Symptomatic lower urinary tract dysfunction in sacral agenesis: Potentially high risk?

Introduction

Sacral agenesis (SA) is a caudal regression anomaly that can cause neurogenic bladder but is not generally recognized as high risk. We studied the clinical presentation, upper urinary tract, bone and spine abnormalities, and urodynamic findings in patients with SA and compared them with related high-risk conditions, anorectal malformation (ARM), and cloacal malformation.

Materials and Methods

Patient records between May 2011 and December 2015 were identified and grouped into isolated SA without an overt anomaly (Group I), SA with overt caudal regression anomalies (Group II), and ARM or cloacal malformation without the SA (Group III). Distribution of clinical and urodynamic findings and factors associated with reduced eGFR were tested with rank sum test, t-test, and unadjusted odds (P < 0.05 significant) using R statistical program (version 3.1.3).

Results

Of 605 neurogenic bladder patients treated in the study period, 39 fulfilled the inclusion criteria. 12 were Group I, 5 Group II, and 22 Group III. Long-standing lower urinary symptoms were noted in all SA patients. Group I patients were older (14.5 years vs. 6 years and 5 years for II and III). Patients with SA (Group I and II) had poor compliance (6.7 ml/cmH₂O, interquartile range [IQR] 4-13.6 ml/cmH₂O), reduced age-adjusted bladder capacity (59%, IQR 22-85%), elevated end-fill pressure (22 cmH₂O, IQR 11-28 cmH₂O), hydronephrosis (88%), and reduction in eGFR (29%), all comparable to Group III. Most had Renshaw type II SA and tethered spinal cord rather than wedge-shaped termination. Limitations include small numbers and significant selection bias.

Conclusions

Symptomatic neurogenic bladder due to SA may cause renal damage similar to ARM but often eludes diagnosis.

Sirenomelia phenotype in bmp7;shh compound mutants: a novel experimental model for studies of caudal body malformations

Sirenomelia is a severe congenital malformation of the lower body characterized by the fusion of the legs into a single lower limb. This striking external phenotype consistently associates severe visceral abnormalities, most commonly of the kidneys, intestine, and genitalia that generally make the condition lethal. Although the causes of sirenomelia remain unknown, clinical studies have yielded two major hypotheses: i) a primary defect in the generation of caudal mesoderm, ii) a primary vascular defect that leaves the caudal part of the embryo hypoperfused. Interestingly, Sirenomelia has been shown to have a genetic basis in mice, and although it has been considered a sporadic condition in humans, recently some possible familial cases have been reported. Here, we report that the removal of one or both functional alleles of Shh from the Bmp7-null background leads to a sirenomelia phenotype that faithfully replicates the constellation of external and internal malformations, typical of the human condition. These mutants represent an invaluable model in which we have analyzed the pathogenesis of sirenomelia. We show that the signaling defect predominantly impacts the morphogenesis of the hindgut and the development of the caudal end of the dorsal aortas. The deficient formation of ventral midline structures, including the interlimb mesoderm caudal to the umbilicus, leads to the approximation and merging of the hindlimb fields. Our study provides new insights for the understanding of the mechanisms resulting in caudal body malformations, including sirenomelia.

Caudal dysplasia syndrome and sirenomelia: are they part of a spectrum?

Caudal dysplasia syndrome (CDS) is associated with hypoplastic lower extremities, caudal vertebrae, sacrum, neural tube, and urogenital organs. Sirenomelia is characterized by a single lower extremity, absent sacrum, urogenital anomalies, and imperforate anus. There is controversy in the medical literature about whether sirenomelia and CDS are part of the spectrum of the same malformation. Patients with CDS and sirenomelia were identified from our pathology files from 1991 to 2006. Maternal history, pathologic examination, and radiographs were collected and tabulated. We found 9 cases with CDS and 6 with sirenomelia. Fully 7 of 9 patients with CDS (77.7%) versus none of sirenomelic babies were infants of diabetic mothers. Congenital heart disease was present in 5 patients with CDS (55.5%) and none of the infants with sirenomelia. Of 9 children with CDS 2 (22.2%) had bilateral renal agenesis versus 66% of sirenomelics. Single umbilical artery was found in 33% of cases with CDS and 100% of children with sirenomelia. External genitalia were ambiguous in 2 of 9 patients (22.2%) with CDS and in all patients with sirenomelia. Imperforate anus was found in 10 cases (66.6%) divided as 4 of 9 babies with CDS (44.4%) and all patients with sirenomelia. Three patients with CDS had concomitant maternal diabetes mellitus and chronic hypertension. These babies also had cleft lip and palate. Congenital heart disease was found in 55.5% of cases with CDS and none of the children with sirenomelia. We conclude that although CDS and sirenomelia share many similar features, they are two different entities.

Tethered cord syndrome in children: a review

✓The treatment of a patient with symptoms of a tethered spinal cord and in whom a fatty infiltrated terminal filum is found is controversial. The authors review their experience and the literature regarding this aspect of occult spinal dysraphism. From experience, transection of a fatty terminal filum in patients with symptoms related to excessive caudal cord tension is a minor procedure that generally yields good results. The most problematic issue in the literature is what patients and symptoms are best suited to surgical treatment.

Neuropathology of developmental abnormalities

Varieties of neuropathological disorders are caused by a perturbation of normal developmental processes, resulting from insults by heterogeneous etiologic factors. These factors trigger the sequence of molecular, biochemical, and morphologic alterations of the brain, resulting morphologically and/or functionally abnormal brain. The resulting brain contains basic components of the normal brain but is assembled in an abnormal way. The developmental stage when the insults occur appears to largely dictate the outcome of the pathological processes. Depending on the developmental stage involved, the morphology of the brain may be grossly abnormal or is apparently normal but functionally abnormal. The brain development progresses in an orderly fashion and can be divided into several major developmental stages; the neurulation (neural tube formation), ventral induction (formation of prosencephalon), neuroepithelial cell proliferation and migration, neuroglial differentiation and establishment of neuronal circuits. The perturbation of these developmental stages results in uniquely specific pathological outcome, regardless of the etiologic factors/agents. In this review, I will briefly discuss the normal pattern of brain development and neuropathology of the representative disorders resulting from the deviation of normal developmental processes in the individual developmental stage.

Urinary incontinence and vesicourethral dysfunction in pediatric surgical conditions

The most common cause for urinary incontinence in children with pediatric surgical conditions of the pelvic region and perineum is lower urinary tract dysfunction caused by concomitant sacral agenesis, especially in children with anorectal malformations. Another common cause is iatrogenic pelvic nerve damage secondary to reconstructive surgery. Moreover, an intrinsically altered pelvic floor anatomy as seen in some cases of complex cloacas, or disruption of pelvic floor muscles with consecutive loss of supportive structures, as in sacrococcygeal teratoma, should also be taken into consideration. It is important to understand that the causes of urinary incontinence in these children are not isolated problems concerning only the urinary tract. They may have the same negative impact on anorectal function as they have on the bladder and urethral sphincter. Therefore, children with pediatric surgical conditions of the pelvic and perineal region often will present with a combination of both fecal incontinence caused by anorectal dysfunction and urinary incontinence caused by vesicourethral dysfunction. The additional morbidity caused by urinary incontinence may have an enormous impact on the patient's life and well being, not only with regard to physical disability, but also in terms of emotional problems, social handicap, and socioeconomic burden. It is obvious that a patient's quality of life will be significantly reduced if he or she suffers from both fecal and urinary incontinence. Therefore, an integrated approach to the management of both vesicourethral and anorectal dysfunction should be developed to achieve the optimum care for these children.

Absence of connections between spinal nerves and the spinal cord in a twin fetus: a very rare malformation occasionally evidenced at autopsy

We describe a rare case of spinal cord malformation in a dichorionic diamniotic twin fetus aborted at 20 weeks' gestation due to acute chorioamnionitis with placental dysmaturity probably caused by a maternal viral infection. At autopsy, there were no connections between the spinal nerves and the spinal cord. The spinal cord lacked the posterior median fissure and gray matter; only a few neurons were present in the anterior and lateral gray columns. No chromosome anomalies were found. Although we cannot reconstruct the pathogenetic chain of events leading to this malformation, we believe that it is correlated with a maternal viral infection. We hypothesize that this viral infection altered the delicate balance between the factors inducing and those inhibiting fetal spinal neural differentiation.

Spinal lipomas

Lipomas of the spinal cord are among the most fascinating lesions encountered by the pediatric neurosurgeon. An understanding of spinal lipomas may, however, be difficult because the terminology used to describe the accumulations of spinal fat is confusing, inconsistently applied, and at times contradictory. An anatomical characterization of lipomas may assist in understanding these lesions. Lipomas of the spinal cord are very rare and cause symptoms related to mass effect and secondary compressive myelopathy. Lipomas of the conus medullaris (or lipomyelomeningocele) are the most common form of fatty masses in the spine and can be divided into dorsal, caudal, and transitional forms. These lesions are a manifestation of occult spinal dysraphism and a common cause of the tethered cord syndrome (TCS). The natural history of untreated lipomyelomeningocele, although incompletely understood, appears to be progressive neurological deterioration with loss of bladder control. Timely, careful surgical intervention may prevent significant neurological deterioration and progressive disability in the majority of children harboring these lesions. In surgical intervention the surgeon seeks to disrupt the connection between the fibrofatty mass and underlying cord as well as to reestablish normal anatomical planes. Several intraoperative video segments illustrating lipomyelomeningocele resection are included in this paper. Lipomas of the terminal filum (fatty filum) are truly occult and are also associated with TCS. Surgical treatment of filum lipomas carries significantly lower risk than that for lipomas of the conus medullaris. Again, the goal of surgery is to disrupt the connection between the abnormal fibrofatty tissue and the underlying spinal cord.

Caudal regression syndrome: MR appearance

This article reports a case of caudal regression syndrome with hypoplasia of the sacrum, accompanied by an imperforate anus with ano-vestibular fistula. Magnetic resonance images showed a characteristic wedge-shaped cord terminus and the separation of anterior and posterior spinal roots at the level of the cauda equina.

Symptomatic cystic dilatation of V ventricle: case report and review of the literature

We report a case of V ventricular cystic dilatation, presenting with specific neurological symptoms including low back pain, bilateral sciatica, weakness of dorsiflexion, and urinary retention. MRI showed a large cystic dilatation of the ventriculus terminalis. Surgical fenestration of the cyst allowed complete relief from symptoms and remission of the neurological deficit.

Glycoconjugates in normal and abnormal secondary neurulation

In chick embryos, the anterior greater portion of the neural tube develops by the folding, apposition, and fusion of the neuroectoderm. The smaller caudal portion that forms the secondary neural tube (lumbosacral and coccygeal regions) is derived from the tail bud, an aggregate of mesenchymal cells located at the caudal limit of the body. Tail bud mesenchyme, arranged in a solid cord, undergoes mesenchymal-epithelial transformation to form the secondary neural tube. Previous evidence suggests that this transformation is accompanied by modulation of cell surface glycoconjugates in the differentiating tissues. In this study, we show by lectin histochemistry and lectin blotting of proteins isolated by SDS-PAGE, that Datura stramonium agglutinin (DSA) binds preferentially to differentiating tail bud cells. This lectin is specific for beta 1-4-linked N-acetylglucosamine oligomers, such as the oligosaccharides of the poly-N-acetyllactosamine series that have been previously implicated in cell differentiation. Ultrastructural lectin cytochemistry indicates that at least some of the proteins binding DSA are localized extracellularly. The use of DSA as a teratogen resulted in embryos showing a variety of neural tube and notochord defects. We have also examined the binding of DSA to embryos that were treated with teratogenic doses of retinoic acid by sub-blastodermal injection, and find that the DSA-binding patterns are perturbed. Analysis of DSA-treated embryos using the TUNEL technique indicated that cell death was not a factor in DSA teratogenesis. This strongly suggests that the glycoconjugates of the cell surface have a role in the normal differentiation of tail bud mesenchyme into the neuroepithelium of the secondary neural tube. Perturbations of glycoconjugate activity results in defects of the secondary neural tube and associated tail bud derivatives.

Malformation of the lumbosacral spinal cord in a case of sacral agenesis

Agenesis of the sacrum is a rare anomaly that is associated with numerous visceral abnormalities, spinal cord malformation, and lower limb defects. A fatal case of sacral and lower lumbar agenesis in a 3-day-old female infant born at 38 weeks of gestation is reported. The extraneural malformations comprised an imperforate anus, a rectovaginal fistula, and musculoskeletal abnormalities, including several thoracocervical hemivertebrae and aplasia of the sacrum and the fourth and fifth lumbar vertebrae. The cervical and high thoracic spinal cord segments were normal. Disruption of secondary neurulation, possibly due to notochord dysfunction, was suggested by malformation of the ventral half of the lower thoracic spinal cord with relative preservation of the dorsal horns and, more caudally, by loss of all normal histological landmarks, including the central canal. Neither skeletal muscle nor myoblasts were found in muscle compartments that would normally have received motor innervation from the levels of the spinal cord from which anterior horn cells were absent, indicating parallel, segmental failure of myotomal differentiation in the caudal eminence.